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RestorationofPerformanceandRecoveryinEliteLevelRugbyUnionAdamGrainger-UniversityofSalford,Salford,UK(00371562)

A THESIS SUBMITTED TO THE SCHOOL OF HEALTH SCIENCES AT SALFORD UNIVERISTY IN PARTIAL FULFILLMENT OF THE DEGREE OF DOCTOR OF PHILOSOPHY, FEBRUARY 2017.

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Contents

Listoftables………………………………………………………………………………………………………......vii

Listoffigures…………………………………………………………………………………………………….......viii

Acknowledgements………………………………………………………………………………………………….x

Declaration…………………………………………………………………………………………………………......xi

Abbreviations…………………………………………………………………………………………………….......xii

Abstract………………………………………………………………………………………………………………….xv

1 Introduction..............................................................................................................................11.1 Matchdemandsinrugbyunion................................................................................................11.2 Restorationofperformancepostrugbymatchplay..........................................................11.3 Theeffectofrugbymatchplayuponrecovery....................................................................2

2 LiteratureReview...................................................................................................................42.1 Demandsofrugbyunion.............................................................................................................52.1.1 Physicalcharacteristicsandperformancecapabilitiesofarugbyunionplayer...........92.1.1.1 Playinglevelsandphysicalcharacteristics.............................................................................................92.1.1.2 Positionalphysicalcharacteristicsofanelitelevelrugbyunionplayer.................................102.1.1.2.1 Strengthandpowerofeliterugbyunionplayers....................................................................112.1.1.2.2 Speedcapabilitiesofeliterugbyunionplayers........................................................................112.1.1.2.3 Aerobicandanaerobicabilityofeliterugbyunionplayers.................................................122.1.1.2.4 Bodymassandcompositionofeliterugbyunionplayers....................................................20

2.1.1.3 Whichphysicalelementsenhancethelikelihoodofsuccessofanelitelevelrugbyunionplayer?.....................................................................................................................................................................................20

2.1.2 TheuseofGPSdataforoptimalperformance...........................................................................212.1.3 TrainingweekstructureandRPE...................................................................................................222.1.4 Summary....................................................................................................................................................23

2.2 Methodsofstrengthandpowertrainingandassessmentinrugby...........................242.2.1 Resistancetrainingmethods.............................................................................................................242.2.2 Strengthandpowertrainingspecifically.....................................................................................242.2.2.1 Effectofstrengthandpowertrainingonsubsequentperformance.........................................25

2.2.3 Implicationsforpractitioners...........................................................................................................262.2.4 Summary....................................................................................................................................................27

2.3 PerformanceTests,FatigueandAssociatedRecovery....................................................282.3.1 TestsofPerformance............................................................................................................................282.3.2 Fatiguescience.........................................................................................................................................282.3.2.1 Centralfatigue..................................................................................................................................................332.3.2.2 Peripheralfatigue............................................................................................................................................332.3.2.3 Biochemistryoffatigue.................................................................................................................................342.3.2.3.1 Depletionandfatigue...........................................................................................................................342.3.2.3.2 Metabolicby-productsandfatigue.................................................................................................352.3.2.3.3 Neuralfatigueandtheexcitation-contraction-relaxationprocesses..............................36

2.3.3 Neuromuscularfatigue.........................................................................................................................362.3.3.1 Mechanismsofneuromuscularfatigue..................................................................................................36

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2.3.3.2 Modelsoffatigue.............................................................................................................................................372.3.4 Factorsaffectedbyfatiguewhichareimportantforperformance...................................402.3.5 Assessingfatigue.....................................................................................................................................402.3.6 Fatigueandrugby...................................................................................................................................422.3.7 RestorationofPerformance...............................................................................................................462.3.8 Recoveringfromteamsportactivities..........................................................................................472.3.9 Whatisreadiness?.................................................................................................................................512.3.10 Summary..................................................................................................................................................52

2.4 MethodsofAssessingFatigue,RecoveryandReadiness................................................532.4.1 Maximalandsub-maximalperformancetests...........................................................................542.4.1.1 Maximalstrengthtesting.............................................................................................................................562.4.1.2 MaximalJumptesting....................................................................................................................................582.4.1.2.1 Commonusesofjumptesting...........................................................................................................582.4.1.2.2 Jumptestingtools..................................................................................................................................582.4.1.2.3 Jumptesting–kineticandoutcomebasedmeasures............................................................612.4.1.2.4 Jumpperformancetoassessfatigue..............................................................................................622.4.1.2.5 Therelevanceofjumptestingineliteperformancesettings..............................................63

2.4.1.3 Maximalergometertesting.........................................................................................................................652.4.2 Runningspecificperformancetestsforfootballcodes..........................................................652.4.3 Perceptualfeelingsofwell-being.....................................................................................................672.4.4 Biochemicalmarkers............................................................................................................................692.4.4.1 Muscledamageandbiochemicalresponse..........................................................................................702.4.4.2 Hormonalresponse........................................................................................................................................712.4.4.3 Metabolicresponsetorugbygameplay................................................................................................722.4.4.4 Considerationsforbiochemicaltesting.................................................................................................73

2.4.5 Heartratederivedmeasures.............................................................................................................742.4.5.1 Restingheartrate............................................................................................................................................742.4.5.2 Heartratevariability.....................................................................................................................................742.4.5.3 Heartraterecovery........................................................................................................................................772.4.5.4 Considerationsforheartratederiveddataandresponsestoexercise...................................79

2.4.6 Summary....................................................................................................................................................792.5 StrategiesusedtoEnhanceRestorationofPerformanceandRecovery...................802.5.1 Commonlyusedrecoverymodalities............................................................................................802.5.1.1 Icebathsandcontrastwatertherapy.....................................................................................................812.5.1.2 WholeBodyCryotherapy(WBC)..............................................................................................................822.5.1.3 Compressiongarments.................................................................................................................................832.5.1.4 Activerecovery.................................................................................................................................................842.5.1.5 Sportsmassage.................................................................................................................................................852.5.1.6 Sleeptoaidrecovery......................................................................................................................................862.5.1.7 Nutritionalinterventionstoaidrecovery.............................................................................................872.5.1.8 Restanddayswithouttraining.................................................................................................................892.5.1.9 Selectingtheappropriaterecoverymodality.....................................................................................91

2.5.2 Summary....................................................................................................................................................922.6 Relevanceofreadinessandrestorationresearch............................................................932.6.1 Theimportanceofreadiness.............................................................................................................932.6.2 Meaningfulchange.................................................................................................................................942.6.3 Improvingreadiness.............................................................................................................................962.6.4 Limitationsoftheresearchtodate.................................................................................................97

2.7 Summaryofresearchproposed..............................................................................................98

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2.7.1 Researchquestionsproposed...........................................................................................................99

3 MatchCharacteristicsinanEliteRugbyUnionPlayingSeason..........................1003.1 Abstract........................................................................................................................................1003.2 Introduction...............................................................................................................................1003.3 Method..........................................................................................................................................1043.3.1 ExperimentalApproach....................................................................................................................1043.3.2 Matchanalysis.......................................................................................................................................1053.3.3 StatisticalAnalyses.............................................................................................................................106

3.4 Results..........................................................................................................................................1063.4.1 Matchcharacteristicsbetweenforwardsandbacks............................................................1063.4.2 Matchcharacteristicsbetweentheninepositionalgroups...............................................108

3.5 Discussion...................................................................................................................................1173.5.1 Limitationsofthisstudy...................................................................................................................122

3.6 PracticalApplications.............................................................................................................1243.7 Implicationsofexperimentalchapter3forsubsequentstudies..............................125

4 WithinandBetween-SessionReliabilityofJumpPerformanceinEliteRugbyUnionPlayers.............................................................................................................................1264.1 Abstract........................................................................................................................................1264.2 Introduction...............................................................................................................................1264.3 Materialsandmethods...........................................................................................................1294.3.1 Participants............................................................................................................................................1294.3.2 Jumps........................................................................................................................................................1294.3.2.1 CountermovementJump(CMJ)technique.........................................................................................1294.3.2.2 SquatJump(SJ)technique.........................................................................................................................1294.3.2.3 SingleLegDropJumps(SLDJ)technique............................................................................................130

4.3.3 Procedure................................................................................................................................................1304.3.3.1 Instrument........................................................................................................................................................1304.3.3.2 JumpHeightandFlighttime.....................................................................................................................131

4.3.4 StatisticalAnalyses.............................................................................................................................1314.4 Results..........................................................................................................................................1314.4.1 Within-sessionvariabilityandreliability..................................................................................1314.4.2 Between-session..................................................................................................................................134

4.5 Discussion...................................................................................................................................1344.5.1 Within-session......................................................................................................................................1344.5.2 Between-session..................................................................................................................................1344.5.3 Limitationsofthisstudy...................................................................................................................135


5 CountermovementJumpinEliteRugbyPlayers–Acomparisonbetweendevices..........................................................................................................................................1375.1 Abstract........................................................................................................................................1375.2 Introduction...............................................................................................................................1375.3 Method..........................................................................................................................................1395.3.1 Participants............................................................................................................................................1395.3.2 Procedure................................................................................................................................................1405.3.2.1 CountermovementJump(CMJ)technique.........................................................................................140

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5.3.2.2 Instruments.....................................................................................................................................................1405.3.2.2.1 Forceplate...............................................................................................................................................1405.3.2.2.2 OptoJump.................................................................................................................................................141

5.3.2.3 Dataanalysis....................................................................................................................................................1415.3.2.3.1 JumpHeightandFlightTime..........................................................................................................1415.3.2.3.2 Force-timeanalysis.............................................................................................................................142

5.3.3 StatisticalAnalyses.............................................................................................................................1425.4 Results..........................................................................................................................................1435.4.1 JumpheightmeasuresfromOptoJumpandforceplate......................................................143

5.5 Discussion...................................................................................................................................1455.5.1 JumpheightmeasuresfromOptoJumpincomparisontoforceplate...........................1455.5.2 ReliabilityofOptoJumpandforceplate......................................................................................1475.5.3 JumpheightincomparisontoRFD..............................................................................................1495.5.4 Limitationsofthisstudy...................................................................................................................150


6 Between-SessionReliabilityofaCountermovementJumpinEliteRugbyPlayersPreGame......................................................................................................................1536.1 Abstract........................................................................................................................................1536.2 Introduction...............................................................................................................................1536.3 Method..........................................................................................................................................1546.3.1 Participants............................................................................................................................................1546.3.2 Procedure................................................................................................................................................1556.3.2.1 Instrument........................................................................................................................................................1556.3.2.2 CountermovementJump(CMJ)technique.........................................................................................1556.3.2.3 JumpHeightandFlightTime...................................................................................................................155

6.3.3 StatisticalAnalyses.............................................................................................................................1556.4 Results..........................................................................................................................................1566.4.1 Between-sessionreliabilityofasingleCMJpertestingday..............................................156

6.5 Discussion...................................................................................................................................1566.5.1 Limitationsofthisstudy...................................................................................................................157


7 ChangeinCountermovementJumpPerformanceandWell-beingScoresofProfessionalRugbyUnionPlayersPost-match...............................................................1607.1 Abstract........................................................................................................................................1607.2 Introduction...............................................................................................................................1607.3 Method..........................................................................................................................................1637.3.1 Participants............................................................................................................................................1637.3.2 ExperimentalApproach....................................................................................................................1637.3.3 Jumptesting...........................................................................................................................................1647.3.4 Self-reportwell-beingquestionnaires........................................................................................1647.3.5 MatchanalysisandGPSdata..........................................................................................................1657.3.6 StatisticalAnalyses.............................................................................................................................165

7.4 Results..........................................................................................................................................1667.4.1 ChangesinCMJperformancepretopost-match...................................................................166

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7.4.2 ChangesinWBperformancepost-match..................................................................................1677.4.3 AcomparisonofchangesinCMJperformancepreandpost-matchbetweenforwardsandbacks............................................................................................................................................1687.4.4 AcomparisonofchangesinWBperformancepreandpost-matchbetweenforwardsandbacks................................................................................................................................................................1697.4.5 RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscores…....................................................................................................................................................................1707.4.6 RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscoresacrosspositionalgroups..................................................................................................................................171

7.5 Discussion...................................................................................................................................1717.5.1 NormalCMJchange.............................................................................................................................1727.5.1.1 CMJperformancebetweenpositionalgroups..................................................................................173

7.5.2 NormalWBchange.............................................................................................................................1747.5.2.1 WBscoresbetweenpositionalgroups.................................................................................................175

7.5.3 Performancereductionacross170hoursassessingbothCMJandWB......................1767.5.4 RelevanceofGPSparametersuponCMJperformanceandWBscores........................1767.5.4.1 RelevanceofGPSparametersuponCMJperformanceandWBscoresbetweenpositionalgroups 177

7.5.5 Limitationsoftheresearch..............................................................................................................1787.6 Practicalimplications.............................................................................................................1797.7 Implicationsofexperimentalchapter7forsubsequentstudies..............................180

8 QuantificationofGPSimpactsusingvideoanalysisinEliteLevelRugbyUnion…..........................................................................................................................................1818.1 Abstract........................................................................................................................................1818.2 Introduction...............................................................................................................................1818.3 Method..........................................................................................................................................1848.3.1 Participants............................................................................................................................................1848.3.2 Experimentalapproach.....................................................................................................................1858.3.3 Matchanalysis.......................................................................................................................................1858.3.3.1 GPSanalysis.....................................................................................................................................................1858.3.3.2 Videoanalysis.................................................................................................................................................186

8.3.4 Statisticalanalyses..............................................................................................................................1868.4 Results..........................................................................................................................................1878.5 Discussion...................................................................................................................................1908.5.1 Impactsresultingfromcollisions.................................................................................................1918.5.2 Impactsresultingfromchangesofdirection,accelerationsanddecelerations.......1918.5.3 Impactcategorisation........................................................................................................................1938.5.4 Limitationsoftheresearch..............................................................................................................1938.5.5 Futureresearchdirections..............................................................................................................194

8.6 Practicalapplications..............................................................................................................195

9 Thesisdiscussion...............................................................................................................1979.1 Introductionandrecapofexistingresearch...................................................................1979.2 Majorfindingsoftheresearch.............................................................................................1979.3 Limitationsoftheresearchconducted..............................................................................2009.3.1 “Realworld”limitations....................................................................................................................2009.3.2 LimitationsofCMJprotocolimplemented................................................................................201

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9.3.3 GPSlimitations......................................................................................................................................2039.4 Practicalapplicationsandfutureresearchdirectionsasaresultoftheresearchconducted...............................................................................................................................................2059.4.1 Futurejumptestingprotocoltoassessrestorationofperformance............................2059.4.2 Applicationofsubjectiveandobjectivemeasuresofrestoration..................................2079.4.3 Position-specifictestsofperformancerestoration..............................................................2079.4.4 FutureGPSintegrationforrecoveryintervention................................................................2099.4.5 Athleticresilience,trainingloadsandhastenedrestorationofperformance...........2119.4.6 Physiologicalandpsychologicalrestorationpostrugbyunionmathplay.................213

9.5 Finalconclusion........................................................................................................................214

10 References.........................................................................................................................215

11 Appendix............................................................................................................................24511.1 AppendixA...............................................................................................................................24511.2 AppendixB...............................................................................................................................24611.3 AppendixC................................................................................................................................247

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Listoftables

Table2.1:PlayerpositionsandroleswithinthegameadaptedfromDuthieetal.(2003).……….p5

Table2.2:Researchshowinglimitationsofmatchdistancedatainrugbyunion.…………………….p6

Table2.3:Researchshowinglimitationsofmatchintensitydatainrugbyunion.…………………....p7

Table2.4:Researchshowingmatchsprintingdatainrugbyunion………………………………………...p7

Table2.5:Researchshowinglimitationsofmatchheartratedatainrugbyunion.…………………..p8

Table2.6:Researchshowingassessmentofupperbodyandlowerbodystrengthcharacteristicsofdifferentrugbyunionplayinglevels.…………………………………………………………………………...…..p14

Table2.7:Researchshowingassessmentofupperbodyandlowerbodypowermeasurementcharacteristicsofdifferentrugbyunionplayinglevels.………………………………………………………..p15

Table2.8:Researchshowingassessmentofshortsprintcharacteristicsofdifferentrugbyunionplayinglevels…………………………………………………………………………………………………………………….p16

Table2.9:Researchshowingassessmentofagilitycharacteristicsofdifferentrugbyunionplayinglevels.…………..………………………………………………………………………………………………………..p17

Table2.10:Researchshowingassessmentofaerobicandanaerobiccharacteristicsofdifferentrugbyunionplayinglevels………………………………………………………………………………………………...p18

Table2.11:Researchshowingphysicalcharacteristicsofrugbyunionplayers…………………….p19

Table2.12:Exercisefatiguemodelsandthetheoriesassociatedwiththem…………………………p39

Table2.13:Anoverviewofperformancemeasuresutilisedinrugby…………………………………...p54

Table3.1:Physicalcharacteristicsofplayersassessed……………………………………………………...p104

Table3.2:Exampletrainingweek.…………………………………………………………………………………….p105

Table3.3:Categorisationofdistancescoveredandimpacts….……………………………………………p106

Table3.4:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals),effectssizesandstatisticalpower,acrossdistancedataforforwardsandbacks…………………p107

Table3.5:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals),effectsizesandstatisticalpower,acrossimpactzonesforforwardsandbacks…………………...p107

Table3.6:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossselectedmatchdemandsdataforallpositions………………………………………………………..p109

Table3.7:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossdistancedataforallpositions(symbolspresentedontable20)……………………………...p112

Table3.8:Keyfordescriptivedistancedataintable3.7………………………………………………….....p113

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Table3.9:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossimpactsdataforallpositions…………………………………………………………………………………p116

Table4.1:Descriptive(mean±standarddeviations)andreliabilitystatistics,withintestingdaysforjumpheightforCMJ,SJandSLDJ………………………………………………………………………………….p131

Table4.2:Descriptive(mean±standarddeviations)andreliabilitystatistics,betweentestingdaysforCMJ,SJandSLDJ………………………………………………………………………………………………….p134

Table5.1:Descriptive(mean±standarddeviations)andreliabilitystatistics,withintestingdaysforCMJheightandRFD(N.s-1)…………………………………………………………………………………………..p143

Table5.2:Descriptive(mean±standarddeviations)andreliabilitystatistics,betweentestingdaysforCMJheight(cm)andRFD(N.s-1)…………………………………………………………………………..p145

Table7.1:Categorisationofdistancescoveredandimpacts……………………………………………….p165

Table7.2:RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscores……………………………………………………………………………………………………………………………...p170

Table7.3:RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscoresacrosspositionalgroups…………………………………………………………………………………………………..p171

Table8.1:Categorisationofimpactzones………………………………………………………………………….p186

Table8.2:KeyofsignificantdifferencesinpercentagedistributionofimpactsacrossZones4,5and6foreachactivityrelatingtoFigure8.3…………….…………………………………………………….....p190

Listoffigures

Figure2.1:Schematicoffatiguemodels………………………………………………………………………...........p31

Figure2.2:SchematicofmusclefatiguemechanismsadaptedfromAbbissandLaursen(2005)……………………………………………………………………………………………………………………………….p32

Figure2.3:TrainingadaptationtheoryadaptedfromBompaandHaff(2009)……………………...p49

Figure4.1:Bland-AltmanplotforCMJwithinsessionone………………………………………………….p132

Figure4.2:Bland-AltmanplotforSJwithinsessionone………………………………………………...…..p132

Figure4.3:Bland-AltmanplotforSLDJLwithinsessionone………………………………………………p133

Figure4.4:Bland-AltmanplotforSLDJRwithinsessionone……………………………………………...p133

Figure5.1:Anillustrationofthetestsetup,showingtheOptoJumpsittingalongsidetheforceplate………………………………………………………………………………………………………………………………..p141

Figure5.2:RelationshipbetweenOptoJumpjumpheight(fromflighttime)andforceplateflighttimeduringthesamejump,usingpooleddata…………………………………………………………………..p144

Figure5.3:Relationshipbetweenjumpheightfromflighttimeonaforceplateandjumpheightderivedfromvelocityattake-offonaforceplate,usingpooleddata…………………………………..p144

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Figure5.4:Relationshipbetweenjumpheightfromvelocityattake-offonaforceplateandjumpheightderivedfromflighttimeonanOptoJump,usingpooleddata……………………………............p145

Figure6.1:CMJheightfortestingdaysoneandtwo…………………………………………………………..p156

Figure7.1:ComparisonofCMJperformancespreandpost-match(n=59).………………………….p168

Figure7.2:Changesinwellbeingscorespretopost-match(n=59)……………………………………..p169

Figure7.3:ChangesinCMJperformancepretopost-match(Forwardsn=31;Backsn=28)...p170

Figure7.4:ChangesinWBscorepretopost-match(Forwardsn=31;Backsn=28)…………......p170

Figure8.1:FrequencyofimpactsinZones4,5and6foreachactivity……………..…………………p188

Figure8.2:PercentageofimpactsinZones4,5and6foreachactivity……………………………….p189

Figure8.3:PercentagedistributionofimpactsacrossZones4,5and6foreachactivity………………………………………………………………………………………………………………….…………p190

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AcknowledgementsIamdelightedtoacknowledgecolleagues,friendsandfamilyforthesupportandinspirationIhavereceivedovertheperiodofmycandidature.

Firstandforemost,Iwouldliketothankmyprincipalsupervisor,DrPaulComfort,whosepatienceanddiligence,aswellashispracticalandacademicexperience,hasbeeninvaluabletome.IalsooffermysincereappreciationtomyassociatesupervisorDrJohnMcMahon,whomIamespeciallygratefulforyourassistanceduringthekineticcomparisonsectionsofthiswork.BothPaulandJohn’spracticalknowledgeandloveforsportsscienceinspiredmethroughoutthiscandidacyandpushedmetoworkoutsidemycomfortzoneinthelaboratory.TheircapacitytoreplytoemailsandprovidevaluablefeedbackonmanydraftversionswasinvaluableandIsincerelythankyou.Additionally,IamextremelygratefulfortheopportunitytocompletemyPhDatSalfordUniversity,andIwouldliketoacknowledgethesupportthatSaleSharksRugbyClubplayedinthisprocess.

Ifinishbythankingthoseclosesttome.Iamforevergratefultomywifeforherabsoluteconfidenceinme.Thankyouforthenever-endingsupportyoushowedmethroughoutthislongprocessandforyourunderstandingofthetimethistookawayfromthefamily.Fromamanwhohasworkedinteamsportsallhislife,IcanfirmlysayyouarethebestteammateIhaveeverseen.Additionally,IwouldliketothankmytwochildrenforbeingsounderstandingwhenDaddywasignoringtheirrequestsashehadhisheadinhiswork!Itisnowtimeformetogiveattentionbacktoyou!Amentionalsoformymotherinlawwhohassupportedmethroughoutthisjourneyandunderstoodmydesiretocompletethisbodyofwork.Lastly,thankyoutomyparentswhostartedmeonthepathtoeducationmanyyearsagoandIhopeIhavemadeyouprouddespitetheupsanddownsalongtheway.

Thisresearchwasnotsupportedbyanyexternalfinancialsupportandtheauthorhasnoconflictofinterestwiththeproductsexamined.

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Declaration

IcertifythatthethesisIhavepresentedforexaminationforthePhDdegreeofSalfordUniversityissolelymyownwork.Thecopyrightofthisthesisrestswiththeauthor.Quotationfromitispermitted,providedthatfullacknowledgementismade.Thisthesismaynotbereproducedwithoutmypriorwrittenconsent.Iwarrantthatthisauthorisationdoesnot,tothebestofmybelief,infringetherightsofanythirdparty.

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Abbreviations

(%1RM)–PercentageOneRepetitionMaximum(1RM)-OneRepetitionMaximum(acute:chronic)–Acutetochronictrainingloadratio(ANS)-AutonomicNervousSystem(ASSQ)-AthleteSleepScreeningQuestionnaire(ATP)-AdenosineTriphosphate(AU)-ArbitraryUnits(BAM)-TheBriefAssessmentofMoodquestionnaire(bpm)-Beatsperminute(C)-Cortisol(CA++)-CalciumCalcification(CHO)-Carbohydrate(CI)-ConfidenceInterval(CK)-CreatineKinase(cm)-centimetres(CMJ)-CountermovementJump(CNS)-CentralNervousSystem(CP)-CreatinePhosphate(CT)-ComputerisedTomography(CV)-CoefficientofVariance(CWI)-ColdWaterImmersion(CWT)-ContrastWaterTreatment(DJ)-DropJump(DJ-RSI)-DropJumpReactiveStrengthIndex(DOMS)-DelayedOnsetofMuscleSoreness(DSL)-DynamicStressLoad(ECC)-Excitation-ContractionCoupling(ECR)-TheExcitation–Contraction–RelaxationCycle(EIMD)-ExerciseInducedMuscleDamage(EMG)-Electromyography(F)-Force(FOR)-FunctionalOverreaching(FT:CT)-FlighttimetoContractionTime(g)-grams(G)-GravitationForce(GAS)-TheGeneralAdaptationTheory(GI)-GlycaemicIndex(GPS)-GlobalPositioningSystem(H+)-HydrogenIon(HF)-HighFrequency(HFF)-HighFrequencyFatigue(HIMS)-HeartRateIntervalMonitoringSystem(HR)-HeartRate(hr:min)-hoursandminutes(HRex)-HeartRateExertion(HRR)-HeartRateRecovery(HRR%)-HeartRateRecoverypercentage(HRR60s)-HeartRateRecoverywithin60seconds(HRV)-HeartRateVariability(HSR)–HighSpeedRunning(Hz)-Hertz(ICC)-InterclassCorrelationCoefficients

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(IMTCP)-IsometricMidThighPull(JH)-JumpHeight(kg/s)-Kilogramspersecond(km)-Kilometres(km/h)-Kilometresperhour(LFF)-LowFrequencyFatigue(L/min)–Litresperminute(rMSSD)–Rootmeansquareofsuccessivedifferencesusedtoassessheartratevariability(LNSD1)–Vagal-relatedheartratevariabilityindex(LPM)-Loadperminute(MAS)-MaximalAerobicSpeed(m)–Metres(min)-Minute(ms)-Milliseconds(m.s-1)–Metrespersecond(ml.kg.min-1)-Unitsofmilimiletresofoxygenperkilogramofbodyweightperminute(mmol.l)-Millimolesperlitre(mmol.l-1)-Millimolesperlitreperkilogram(mmolglucosyl.kg.DM-1)–Muscleglycogenlevelsperkilogram(MP)MetabolicPower(mRFD)–Meanrateofforcedevelopment(MRI)-MetabolicReactionIndex(MRIS)-MagneticResonanceImagingScan(MRS)-MagneticResonanceSpectroscopy(MSFT)-MultiStageFatigueTest(MVIC)-MaximalVoluntaryContraction(N)–Newtons(N.s-1)–Newtonspersecond(NFL)-NationalFootballLeague(NFOR)-NonFunctionalOverreaching(NMF)-NeuromuscularFatigue(NREM)-NonRapidEyeMovement(OR)-Overreaching(OTS)-OvertrainingSystem(PAP)–PostActivationPotentiation(PFK)-Phosphofructokinase(Pi)–Phosphates(pgml-1)-Picogrampermillilitre(Pmax)-Maximalpower(PNN50)-ProportionofnumberofpairsofsuccessiveNNintervalsdividedbythetotal(POMS)-ProfileofMoodStatesquestionnaire(PP)-PeakPower(PRFD)-PeakRateofForceDevelopment(R-RInterval)–ThecalculationusedtoassessthetimebetweenanytwoQRScomplexes(REM)-RapidEyeMovement(Rest-Q-76Sport)-TheRecoverySportQuestionnaireforAthletesconsistingof76statements(Rest-Q-Sport)-TheRecoverySportQuestionnaireforAthletes(RFD)-RateofForceDevelopment(RHIE)-RepeatedHighIntensityEfforts(RHR)-RestingHeartRate(RLMSP)-RugbyLeagueMatchSimulationProtocol(RMSSD)-RootMeanSquareoftheSuccessiveDifferences(RPE)-RateofPerceivedExertion(RTP)–Returntoplay

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(s)-Seconds(SD1)-ShortTermHeartRateVariability(SDD)-SmallestDetectableDifference(SEM)-SmallestErrorofMeasurement(SFRA)-Stimulus-Fatigue-Recovery-AdaptationTheory(SJ)-SquatJump(SLDJ)-SingleLegDropJump(SM)-SystemMass(SNDN)–ThestandarddeviationofnormalR-Rintervals(SSC)-StretchShorteningCycle(SWC)-SmallestWorthwhileChange(T)-Testosterone(T:C)-TestosteronetoCortisolratio(TL)-TrainingLoad(TRIMP)-TrainingImpulsetomonitorTrainingLoad(U/L)-UnitsperLitre(v)–Velocity(VJD)-Verticaljumpdisplacement(VGRF)–Verticalgroundreactionforce(V02max)-Themaximalrateofoxygenconsumptionasmeasuredduringincrementalexercise(W)–Watts(WADA)-WorldAnti-DopingAgency(WB)-Well-beingquestionnaire(WBC)-WholeBodyCryotherapy(w/kg)Wattsperkilogram(YoYoIE2)-Yo-YoIntermittentEnduranceTestStage2(YoYoIR1)-Yo-YoIntermittentRecoveryTestStage1(YoYoIR2)-Yo-YoIntermittentRecoveryTestStage2

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Abstract

Fatigueinthedayspostrugbyunionmatchplayisexpected,yetaccurateassessmentoffatigueneedstobequantifiedviaspecificperformancetesting,tobetteradvisepractitionersregardinglikelyposition-specifictime-courseofrecovery.Resultsfromthisthesissupportthenotionthatcountermovementjump(CMJ)providessensitiveandreliabledataforjumpperformancemonitoringineliterugbyunionsettings,withachangeinjumpheightof≥1.7%notedasmeaningful.AdditionalfindingsfromthisthesissupporttheuseofasingleCMJ(measuringjumpheight)usinganOptoJump,asareliablemeasure(CV<10%)forassessingpost-matchlevelsofjumpperformancewhenaforceplateisnotreadilyavailable.Theanalysisofninepositionalgroupswithinthisthesisaddedtothecurrentknowledgebaseofmatchdemandsresearch,withdifferencesidentifiedbothbetweenbacksandforwardsandalsowithinthesetwopositionalgroups.Whenassessingtime-courseofrecoverypost-matchplay,CMJperformancewasreducedat60hourspost-match,90hourspost-matchand170hours(sevendays),yetwell-beingscorewasreducedtoagreaterextent(-9%)andforalongertime-coursethanCMJ(-6%).Unlikehypothesised,itisrecommendthatpractitionersbeadvisedtoconsiderbacksashavingalongertime-courseofrecovery,comparedtoforwards,withthedecrementinperformanceforupto7dayspost-matchwithinbothpositionalgroupshavingimplicationsfortrainingprescriptionbetweenmatches.Lastly,ashypothesised,collisionsaccountedforahigherpercentageofthehighermagnitudeimpactsthanothermatchdemandssuchasaccelerations,decelerationsandchangesofdirection.Thedifferencesinactivitieswhichaccountfortheimpactclassificationisanimportantconsiderationforfutureglobalpositioningsystems(GPS)applicationineliterugbyunionsettingswhenassessinglikelyfatiguecreatedbymatchplay,withtheuseofbothvideoanalysisalongsideGPSdatarecommended.

1 Introduction

1.1 Matchdemandsinrugbyunion

Rugbyunionlikewithmanyotherteamsportsisasportofintermittentactivitiesofbothhighintensityandlowintensityperiods,withmanygaitchangesperformedduringgamephases(Austin,Gabbett,&Jenkins,2011a;Quarrie,Hopkins,Anthony,&Gill,2013).Theabilitytoidentifyandunderstandthespecificdemandsplaceduponsportsperformersduringmatch-playandtrainingsituationshaslongsincebeenrecognisedasacrucialfactorindevelopingappropriatetrainingandrecoveryprogrammeswhichmayelicitimprovedperformance(Coughlan,Green,Pook,Toolan,&O'Connor,2011;Quarrieetal.,2013;Roberts,Trewartha,Higgitt,El-Abd,&Stokes,2008).Importantaspectsforsuccessfulperformancewithinrugbyunionmatchplayincludestrength,power,speedandbothaerobicandanaerobiccapacity(Argus,Gill,Keogh,Hopkins,&Beaven,2010;Cunniffe,Proctor,Baker,&Davies,2009),withincreasesinsizeandstrengthamongstplayersnotedtocorrelatewithonfieldperformance(Argusetal.,2010).

Increasedcommercialinterestinrugbyunionsinceitbecameprofessionalin1995hasledtoplayersreceivingbetteranalysisandmanagementoftrainingtooptimiseperformanceinmatches,resultinginthegamereportedtobecomingfaster,containingmorephasesandinvolvingbigger,fasterandmorephysicalplayers(Lombard,Durandt,Masimla,Green,&Lambert,2015;Quarrieetal.,2013).Atypicalprofessionalrugbyseasoninthenorthernhemispherecontainsover30games(Quarrieetal.,2016),andinvolvesbluntforcetraumaandhighrunningvolumesintrainingandmatches.Recentinvestigationsintothetrainingandmatchloadthatplayersencounterwasnotedasaconcern(Quarrieetal.,2016),withthemanagementofloadrecognisedasanimportantelementinenablingprofessionalplayerstoperformregularlyinanoptimalstate.Distancescoveredingameshavebeenreportedtovaryfrom5000-7000macrosspositionalgroups(Cahill,Lamb,Worsfold,Headey,&Murray,2013;Robertsetal.,2008),withbacksgenerallycompletingmoredistancethanforwardsandinternationalplayerscoveringagreaterdistancethanclubprofessionalsoverthesamegameduration.Thedistancecoveredwithinmatchsituationsconsistofarangeofsprints,changesofdirection,jumpsandcontacts(withbothoppositionplayersandtheplayingsurface),thereforecreatingfatigueandmuscledamage.

1.2 Restorationofperformancepostrugbymatchplay

Theintenseexerciseassociatedwithrugbyunionmatchplayhasbeenshowntocausetemporalimpairmentsinimmunefunctionwithdisturbancesinimmunitylastingupto38hourspost-recovery(Cunniffeetal.,2010).Timeperiodsforareductioninperformancepost-rugbymatchhavealsobeenreportedbyWestetal.(2014)whonotedCMJ[peakpoweroutput(PPO)]decreasedbelowbaselineat12hours(baseline6100±565Wvs.12h5680±589W;p=0.004)and36hours(5761±639W;p<0.001),buthadrecoveredat60hours(5950±505W;p=0.151).Thevolumeandintensityofwork,includingassociatedtraumafromcontactsituationscompletedinarugbyunionmatchplaycanresultinillnessandinjurypotentialandincreasedexerciserecoverytime,meaningpost-competitionrecoveryperiodsareanintegralcomponentinthemanagementoftheplayers(Cunniffeetal.,2010).Theneedtorestoreperformanceassoonaspossibleisofimportancewithineliterugbyunionwhere

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gamesareweeklyandoftenthenumberofdaysbetweengamesisaslowasfivewithinmanyprofessionalrugbycompetitions.Playersthereforeneedtorestoreperformancetoenablecompletionofmeaningfultrainingbetweengames,whichwillincreasethechanceofoptimalperformance,andsuccessinsubsequentgamesdespitetheassociatedfatigueandtraumacreatedbypriormatchdemands.

1.3 Theeffectofrugbymatchplayuponrecovery

Acompetitivegameofrugbyunionlastsforapproximately90minutesandinvolveshighintensityactivitiesincludingmomentsofbluntforceimpactandsprinting(Austinetal.,2011a).DatafromarecentstudyintheEnglishPremiershiprugbyunionleague,reportedmatchdistancesaveragedacrossaseasonasbeing5850±1101mforforwardsand6545±1055mforbackspergame(Cahilletal.,2013),withhighintensityboutsandhighimpactforcesbeingamajorsourceofcumulativefatiguethroughoutagame.Cunniffeetal.(2009)revealedthattheaveragenumberofimpactswasover1000pergame.Correlationsbetweenthetotalnumberofimpactsexperiencedwithineliterugbyleaguematchplayandcompromisedneuromuscularfunctionassessedviajumpperformanceinthe48hourspost-matchhavebeenreported(McLellan&Lovell,2012).Takarada(2003)concludedthatdirectimpactsoftacklesonthebodywerethemajorcauseofmuscledamage,butthatrepeatedintermittentsprintingwasalsoamajorcontributor.Boththetraumacausedfromcontactandeccentricactions(oftenexperiencedduringdecelerationphasesofachangeofdirectionmovement)reducesthecapacityofthedamagedmuscletogenerateforce.McLellanandLovell(2012)researchedfatigueinrugbyleagueandreportedthathomeostasisonlyreturned48hourspost-matchandthatbluntforcetraumaandenergysystemdepletionshouldbefurtherinvestigatedtooptimisesubsequentperformance.WithintheresearchbyMcLellanandLovell(2012)itisimportanttonotethattheassessmentofhomeostasisconcernedrateofforcedevelopment(RFD)duringjumpingtasksandthatbiochemicalmarkersofhomeostasistooklongertorecover(120hours).Inanotherrugbyleaguestudyexaminingchangesinneuromuscularfatigue,perceptualandhormonalmeasurespost-matchplay(McLean,Coutts,Kelly,McGuigan,&Cormack,2010)CMJ(flighttimeandrelativepower),perceptionoffatigueandoverallwell-beingwerealsosignificantlyreducedforupto48hourspost-match.

Neuromuscularfatigue(NMF)isarecentlyexaminedareaofrecoveryandfatigueassessmentinrugbyunionresearch(Marrieretal.,2016;Westetal.,2014).NMFisconsideredacomplexareaofperformance,involvingbothacuteandchronicaspects,someofwhichrelatetoaspectsofmuscledamageandsomewhichrelatetoenergysystems.DespiteNMFbeingmultifacetedandcomplexinnature,thisresearchwillfocusuponchronicfatiguethatisexperiencedpost-matchandnotacutefatiguethatismorecommonlyexperiencedduringrugbyuniongames,butdissipateswithaperiodofrestinbetweenmatchinvolvements.ManyoftheotherfactorsinvolvedwithinfatigueresearchareexaminedinmoredetailwithinChapter2.Itisimportantforpractitionerstoacknowledgethateachfatiguefactordetailedbelowmayrequireadifferentapproachtooptimiserecovery.Agreaterunderstandingofplayerglobalfatigue,playerwell-beingandtherelationshipwithreadinesstotrainaftermatchplayiskeyforimprovedrecoveryandeffectivemanagementofsubsequenttrainingweeks.Theimportanceofsuchresearchisfurtheremphasisedwhenconsideringthatalinkexistsbetweensubsequentperformanceandinjuryriskasaresultofsub-optimalrecoverypost-matchinrugbyleague(Murray,Gabbett,&Chamari,2014).Theassessmentofrecoveryandrestorationofperformanceinthedayspost-

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matchviamonitoringtoolsoutlinedbelowshouldenablecoachesineliterugbytomakeinformeddecisionsupontiming,frequencyandintensityoftraininginthedayspost-matchandislikelytoresultinoptimalrecovery,reducedinjuryriskandimprovedchanceofsuccessfulsubsequentmatchperformances.

Theaimofthisthesiswastobetterunderstandtime-courseofrecoverypostrugbyunionmatchplay,whilealsoidentifyingmonitoringtoolsthatcanenablepractitionerstomakeinformeddecisionsuponfuturetrainingprescriptioninthedayspost-match.Anothermajorobjectiveofthisresearchwastodetermineifthistime-coursediffersacrosspositionalgroups.ThisthesiswilladdtotheknowledgeofperformancemeasuresthatcandetectmeaningfulchangeinNMFasaresultofspecificmatchcharacteristicsinrugbyunion.Eliterugbyunionplayerswereassessedviaexaminationofbothgamedatatakenfromglobalpositioningsystems(GPS)andvideofootageassessingmovementrequirementsandthematchloadinvolvementforninepositionalgroups.Thisinnovativemethodologyprovidesthesequencesofindividualposition-specificmovementpatternsandtheresultantaffectthismayhaveuponfatiguelevels,thereforefurtherenablingmoreinformeddecisionstobemadeinthedayspost-matchplayacrossmultiplepositionalgroups.

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2 LiteratureReview

Thesubsequentliteraturereviewcoversabroadoverviewofmatchdemandsinrugbyunionandassessesthephysiologicalattributeseliteplayersrequireforoptimalperformance,whileconsideringthespecifictrainingmethodscommonlyutilisedforpreparingrugbyplayersformatchplay.Researchrevieweduponmatchdemandsandphysiologicalcostofgameplaywillprovideabackgroundagainstwhichtocomparesubsequenttime-courseofrecoveryinvestigations,withspecifictrainingmethodsexaminedduetotheirlikelyinfluenceupontime-courseofrecovery.Performancetests,fatiguesciencespecificallyandmethodsofassessingfatiguewerereviewedtodevelopanunderstandingofmeasuringrestorationofperformancepostrugbyunionmatchplay,andbetterguidefutureinvestigationsassessingtime-courseofrecovery.Lastly,commonlyusedstrategiesforenhancingrestorationofperformancepost-exercisearereviewedtoprovideclarityupontheinfluenceofmodernsportssciencepracticesupontime-courseofrecoveryandtheimportanceofthesemethodswithineliterugbysettings.

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2.1 Demandsofrugbyunion

Professionalrugbyunionplayersrequirewell-developedaerobicandanaerobicfitnessforcompetition(Cunniffeetal.,2009).Rugbyunionisplayedintwo40minutehalves(Green,Blake,&Caulfield,2011)withtheballonaverageinplayfor30minutes;injurytime,conversions,penaltyshotsortheballbeingoutofplaymakesuptheremainderofthematchtime(Greenetal.,2011).Eachteamconsistsofeightforwardsandsevenbacks(Duthie,Pyne,Marsh,&Hooper,2006),eachhavingadesignatedpositionandrole,requiringdifferentforce-generatingandneuromuscularabilities(Table2.1).Allplayerstoadegreeareinvolvedinballcarrying,whilstalsocompetingandmaintainingpossessionoftheballrequiringphysicalattributessuchasspeed,agility,powerandstrength(Crewther,Lowe,Weatherby,Gill,&Keogh,2009;Greenetal.,2011).

Table2.1:PlayerpositionsandroleswithinthegameadaptedfromDuthieetal.(2003)

PositionalGroup

Playerposition Physicalattributes Reasoning

Forwards(1-8)

Frontrow(1-3) Strengthandpower. Gainballpossession,closeoppositioncontact,limitedballrunning.

Secondrow(4-5) Tall,largebodymassandpower. Jumpheightduringlineouts,closeoppositioncontact.

Looseforwards(6-8) Strengthpower,speedandendurance.

Gainandretainpossession.

Backs(9-15)

Halfbacks(9-10) Speed,endurance. Controlballpossessionandevadeopposition.

Midfieldbacks(12-13) Strengthspeedandpower. Highcontactincidencewithopposition.

Outsidebacks(11,14-15) Speed Evadeopposition,largeamountsofchasing,defensiveandsupportwork.

Robertsetal.(2008)foundplayerstocoverdistancesof5408-6190monaveragedependingupontheirpositionalrole,withbacksgenerallycoveringthegreaterdistances(consistingofmultiplehighintensityactivitiesincludingsprinting,jumpingandchangeofdirectionatvariousvelocities).Thesedemands(distance,accelerationsandchangeofdirection)meanthatplayersneedtoexhibitgoodlowerlimbcontrolduringhighvelocitymovementsinordertoperformeffectivelyandminimisetheriskofinjury.Forwardsperformhigh-intensitystaticexertionforlongerperiodsthanbacks,spendingeightminutesinintensescrummaging(eachlasting5-20s)andfiveminutesinrucksandmauls;contributingto15%oftotalgametime;comparedtofourminutesofhigh-intensitystaticexertionbythebacks(Docherty,Wenger,&Neary,1988;Duthie,Pyne,&Hooper,2003a;Robertsetal.,2008).RecentresearchbySchoeman,Coetzee,andSchall(2015)assessingdifferencesbetweenplayingpositionandcollisionrateswithinprofessionalrugbyunion,notedsignificantdifferencesbetweenforwardsandbacksregardingcollisionrates(p≤0.05)thereforeemphasisingthevaryingdemandsofrugbyunionmatchplay.Similarly,usingarollingaverageapproachDelaneyetal.(2016)notedsmalltomoderateincreasesinrelativedistanceandaverageaccelerationsbetweenhalfbacksandlooseforwardscomparedtotightfiveforwardsininternationalrugbyunionmatchplay(ES=0.27-1.00).

Duringthecourseofagame,playersarerequiredtousearangeofenergysystems,combininglow-intensityactivitywithboutsofvariousanaerobichigh-intensitymovementsandpower-

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basedtasksinoffensiveanddefensivephasesofplay.Rugbyunionisintermittentinnaturecontaininghighlyexplosivesprintsandhighintensityrunningwithperiodsofinactivity,thusrecognisingtheimportanceforallplayerstoobtaingoodaccelerationandlower-limbexplosivepower.MeansprintdistancesduringgameswerereportedbyDuthieetal.(2006)torangebetween11-20m.Studiesusingtime-motionanalysisfoundsprinting(>6.7m.s-1)occurredonaverage16±15and23±19timesforforwardsandbacksrespectively,lastingonaverage1.2±0.2s(Robertsetal.,2008),withsprintingbeingfoundtocontribute10-15%oftotal“ballinplay”gametime(Austinetal.,2011a).Highintensityrunsareperformed41±16and59±28timesforforwardsandbacksrespectivelylastingonaverage1.3-1.5s(Robertsetal.,2008).Coughlanetal.(2011)reportedthatplayerscompleted75%oftheirmatchactivitiesatlowintensity,withbacksenteringhighintensityzonesmorefrequently,whiletheforwardwasexposedtoahighernumberofimpactsandtotalbodyloadmeasuredviaanaccelerometer.Tables2.2,2.3and2.4summariseresearchthatillustratethematchdemandsofdistance,intensityandsprintingvariablesinrugbyunion,withthelimitationsofeachstudyrecognised.

Table2.2:Researchshowinglimitationsofmatchdistancedatainrugbyunion

Metric Reporteddata Limitationsofresearchandadditionalinformation

Distances • (Robertsetal.,2008)5408-6190monaverage• (Cahilletal.,2013)5850±1101mforforwardsand6545±1055mforbackspergame

• (Coughlanetal.,2011)averagedistanceof6715m• (Quarrieetal.,2013)meandistancecoveredpermatchrangedfrom5400to6300m

• (Cunniffeetal.,2009)6953mduringplay• (Jones,West,Crewther,Cook,&Kilduff,2015)significantdifferencesbetweenpositionalgroupsfortotalabsolutedifferencecovered(p<0.05)(Tightforwards4757±885m;Looseforwards5244±866m;Halfbacks5693±823m;Insidebacks5907±709m;Outsidebacks6272m±1065)

• (Reid,Cowman,Green,&Coughlan,2013)6369mforforwardsand6842mforbackspergame

• Datatakenfromplayersplaying80minutesonly

• Distancescovereddependentuponpositionalrole

• Robertsetal.(2008)datacapturedbyfivedistributedvideocameras

• Cahilletal.(2013)datatakenacrossaseasonwithbackstravellinggreater(p<0.05)absoluteandrelativedistancesthantheforwards

• Coughlanetal.(2011)GPSsamplingfrequencyof5Hz

• Cahilletal.(2013)GPSsamplingfrequencyof5Hz

• Cunniffeetal.(2009)GPSsamplingfrequencyof1Hz

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Table2.3:Researchshowinglimitationsofmatchintensitydatainrugbyunion


Intensity • (Coughlanetal.,2011)playerscompleted75%oftheirmatchactivitiesatlowintensity,withbacksenteringhighintensityzonesmorefrequently,whiletheforwardwasexposedtohighernumberofimpactandtotalbodyload

• (Quarrieetal.,2013)distanceatspeeds>6m.s-1(252mforforwardsand450mforbacks)

• (Robertsetal.,2008)highintensityrunsareperformed41±16and59±28timesforforwardsandbacksrespectivelylastingonaverage1.3-1.5s

• (Cunniffeetal.,2009)forwardenteredthelowerspeedzone(6-12km/honagreaternumberofoccasionsthantheback(315vs.229)butspentlesstimestandingandwalking(66.5vs.77.8%)

• (Jonesetal.,2015)significantdifferencesbetweenabsolutedistancescoveredwalking,striding,high-intensityrunning,low-speedrunningandhigh-speedrunning(p<0.05)(Tightforwards0.8±0.6;Looseforwards1.9±1.2;Halfbacks2.7±1.3;Insidebacks4.2±1.7;Outsidebacks4.3±1.6)

• (Reidetal.,2013)thatthelooseheadproprecordedthehighestnumberofentriesinbothstandingandnon-purposefulmovement(1040m)andwalkingzones(1737m),withthecentre(732m)andfullback(1230m)thelowestvaluesinthisrange(0-1.7m.s)


• Coughlanetal.(2011)datacollectedduringaninternationalRugbyUniongame,yetinvolvedonlytwoplayers(onebackandoneforward)

• Coughlanetal.(2011)noteddifferencesintotalimpacts(838forwards;backs573)

• Quarrieetal.(2013)Datataken763playersfromvideorecordingsof90internationalmatches,withdistancecoveredbyplayersatspeeds(inexcessof>5m.s)reportedtobehigherduringinternationalmatchesthanwhencompetingatlowerlevelsoftheprofessionalgame

Table2.4:Researchshowingmatchsprintingdatainrugbyunion


Sprinting • (Duthieetal.,2006)meansprintdistancesrangingbetween11-20mduringgames

• (Robertsetal.,2008)sprintingoccurredonaverage16±15and23±19timesforforwardsandbacksrespectively,lastingonaverage1.2±0.2s

• (Austinetal.,2011a)sprintingbeingfoundtocontribute10-15%oftotal“ballinplay”gametime

• (Cahilletal.,2013)sprinting(Backs50±76m)(Forwards37±64m)• (Cunniffeetal.,2009)backsperformedagreaternumberofsprints(>20km/h)thantheforwards(34vs.19)

• (Jonesetal.,2015)insideandoutsidebacksperformedasignificantlygreaternumberofsprints(20,SD=7and20,SD=6)comparedtolooseforwards(10,SD=6)andhalfbacks(12,SD=5;p<0.05),whiletightforwardscompletedtheleastnumberofsprintscomparedtoallotherpositionalgroups(4,SD=3;p<0.05)


• Backrowforwardscoveredthegreatestdistancesatsprinting(95%Vmax)speeds,particularlythenumber8position(77m)

Despiteforwardscompletingthemajorityoftheiractivitiesatalowspeedintensity,heartrateisstillwithinhighintensityranges,asduringperiodsoflowspeedintensityforwardscouldberecoveringfromhighintensityboutsofactivity,orinvolvedinstaticmovementssuchasrucksandmauls,thatdespitebeingconductedatlowspeedsareknowntoinvolvehighexertion(Duthieetal.,2003a;Robertsetal.,2008).Backs,incontrast,werereportedbyQuarrieetal.(2013)tomovegreaterdistancesatspeeds>6m.s-1comparedtoforwards.Thisgreater

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distanceatspeeds>6m.s-1(252mforforwardsand450mforbacks)wasduetobackscoveringagreateraveragesprintdistancethanforwardswhenconductingtheirmovementdemandsduringgames.RecentdevelopmentinGPStechnologyhasattemptedtoaccountforthesestaticexertions,withdynamicstressload(DSL)beingonesuchmetricthathasbeenutilisedrecently(StatSports,NorthernIreland),withclaimsthatDSLcanaccountfortheaspectsoffatiguethatarenotmeasuredviatheaccelerometer.DSLis,however,unproveninitsreliabilityandapplicabilitytorugbyunionsettings.Inaddition,recentresearchassessingmetabolicpowerasameasureofexternalload(Highton,Mullen,Norris,Oxendale,&Twist,2016)hasillustratedthatthismetricunderestimatestheenergyexpenditureduringintermittentcollisionbasedsportsandthereforeshouldbeusedwithcaution.Duetothecomplexityofassessingstaticexertionsandtheresultanteffecttheyhaveuponfatigue,thisresearchwillonlyassessthedynamicinvolvementsofmatchplayandimpactsclassifiedfromGPS.Incorporationofindicesdevelopedbysoftwarecompanies,suchastheDSLassociatedwithStatSports,hasnotbeenincludedwithinpastresearch.Insteadtherelationshipbetweendynamicmovementsandrestorationandrecoveryratespost-matchplaywereassessed.

Duetothedifferenceinmovementpatternsandactivitiesundertakenbypositionalgroups,theexertionandeffectuponheartratesduringrugbyunionmatchplayisexpectedtodiffer,yetfewstudieshavebeenpublishedinthisarea(asisnotedwithinTable2.5).Thisdifferenceincardiovascularresponsetomatchplaybetweenpositionalgroupsneedsfurtherinvestigation.However,ithasbeenreportedthathighdemandsareplacedonaplayer’scardiovascularcapacityandisreflectedinheartratesaveraging172beatsperminute(bpm)whichequatesto80to85%VO2maxduringthecourseofamatch(Cunniffeetal.,2009).Deutsch,Maw,Jenkins,andReaburn(1998)collectedheartratesduringcompetitionandconcludedthatforwardsexperiencedahighermeanlevelofexertionthanbacks,withforwardsspending72%withinhighexertionHRzone.Backsincontrastwerereportedtospendthemajority(37%)oftheirmatchexertioninamoderateHRzone.

Table2.5:Researchshowinglimitationsofmatchheartratedatainrugbyunion


Heartrateexertion • Cunniffeetal.(2009)reportedthatheartratesaveraging172beatsperminute(bpm)andplayersexerting80to85%VO2maxduringthecourseofagame

• Cunniffeetal.(2009)onlyinvolvedtwoplayers(oneforwardandoneback)usinga1HzGPSunit

• Deutschetal.(1998)reportedthatforwardsspending72%withinhighexertionHRzone,withbacksincontrastreportedtospendthemajority(37%)oftheirmatchexertioninamoderateHRzone

• Deutschetal.(1998)datatakenfromeliteunder19playersupontwentyfourplayersacrosssixgames

Thedifferenceinmatchdemandswithinpositionalgroupsappearstobevast,withthenatureofrepeatedhighintensityeffort(RHIE)effortsbeingspecifictopositionandtheresultanteffectthishasupontime-courseofrecoverypost-matchalsodiffering(Cahilletal.,2013;Quarrieetal.,2013;Smart,Hopkins,Quarrie,&Gill,2014).Whenconsideringthedifferingmovement

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patternsandloadexperiencedbyeliterugbyunionplayers,itisinterestingtonotethatQuarrieetal.(2013)recommendthatpractitionersprovideforwardswithmoretimetorecoverpost-matchthanbacks,giventhegreatercontactloadstheysustainandsubsequentlongerrestorationofperformancetimeperiods.InrecentresearchbyMurrayetal.(2014)investigatingtheeffectofdifferentbetween-matchrecoverytimesontheactivityprofilesandinjuryratesofnationalrugbyleagueplayers,position-specificrecoverystrategieswererecommended.However,inconsiderationthattheresearchbyMurrayetal.(2014)isbasedonrugbyleagueandmuchoftheRHIEresearchalsobeingfromrugbyleague(Austin,Gabbett,&Jenkins,2011b;Johnston&Gabbett,2011),rugbyunionspecificdataneedsexamined.

Despitepreviousresearchineliterugbyunion,presentingdatauponplayermatchdemands,priorresearchhasnotincludedmatchcharacteristicsforplayersthathaveplayedlessthantheentiregame(<80minutes).Futuredatacollectionassessingmatchdemandsneedstofocusuponallparticipantswithinthematchtoascertainagreaterunderstandingoftherequireddemands,regardlessofwhethertheyplayedtheentiregameornot.Itisunrealistictoviewaplayerthathasplayedfor40minutesaslikelytocompletehalfthematchdemandsofaplayerthathasplayedfor80minutes.Instead,asiscommonlyacceptedwithinmodernrubyunion,playersareaskedtoplayforlessthan80minutesandaresubstitutedwithaplayerofthesameposition,whichincreasesthematchdemandsexpectedasplayersknowtheyarenotbeingaskedtoperformforthedurationofthematch(Quarrie&Hopkins,2007).Thissuggeststhatmatchdemandassessmentshouldfollowthisformat.Anotherareaoffocusforthisresearchistheuseof10HzGPSunitswithinmatchcharacteristicsdata,aspreviousresearchhascollecteddataatdifferentsamplingfrequencies(Cahilletal.,2013;Coughlanetal.,2011;Cunniffeetal.,2009).WhenconsideringthatrecentresearchbyRampininietal.(2015)showstheimprovedaccuracyof10HzGPSinassessingdistancecoveredandhighspeedrunningmetrics,itisfurtheremphasisedthattheuseofenhancedsamplingfrequenciesisafutureareaoffocuswithinmatchcharacteristicsknowledge.Matchcharacteristicsdatathatencompasses10HzGPSanalysisisneededacrossavarietyofplayingtimedurationsinnorthernhemisphererugbyunion.ThisuseofahighersamplingfrequencyalongwithananalyticalapproachthataimstodevelopagreaterunderstandingofpositionalmatchdemandswithineliterugbyunionwilllikelyidentifydifferencesbetweenbothforwardsandbacksandthesmallerpositionalgroupsoutlinedinTable2.1.

2.1.1 PhysicalcharacteristicsandperformancecapabilitiesofarugbyunionplayerPhysicalcharacteristicsandperformancevaluesforprofessionalrugbyplayersarenotwelldocumented,perhapsduetothesensitivenatureofthedataandthecompetitionformarginalgainsthatexistbetweenprofessionalteams.Thefollowingsectionsdetailthedifferenceinphysicalcharacteristicsandperformancecapabilitiesbetweenplayinglevels,whilealsoprovidingdatauponwhichelementsdistinguishanelitelevelrugbyunionplayerfromanon-elitelevelplayer.

2.1.1.1 PlayinglevelsandphysicalcharacteristicsPhysicalcapabilitiesofeliterugbyplayersdifferfromamateurplayerswiththedifferencesinstrengthandpowerbetweenplayinglevelsbeinglikelyduetomaturation,trainingageandbodymass(Argus,Gill,&Keogh,2012).Bothlowerbody(5-15%)andupperbody(3-5%)maximalstrengthincreaseswerereportedbetween2004and2007ineliterugbyplayers,withtheseincreasesinsizeandstrengthnotedtocorrelatewithon-fieldperformance(Argusetal.,

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2010).Significantdifferenceswerealsonotedbetweenanthropometricandphysicalperformanceacrossplayinglevels,withplayersathigherlevelsgenerallybeingtallerandheavierandcapableofimprovedperformancebasedonphysicalperformancetests(Argus,Gill,&Keogh,2012).ResearchbyLombardetal.(2015)supportstheviewthatunder20playersaresmallerthanseniorplayersandthatagegradeplayerspresentlowerstrengthandsprintvalues,despitehavingdevelopedphysicallyovertimeasrepresentedinTables2.6and2.8.PhysicalperformancetestscommonlyutilisedinrugbyunionareexaminedinmoredetailinChapter2.3,withtheeffectoffatigueonperformancemeasuresalsocritiquedinChapter2.3.

2.1.1.2 PositionalphysicalcharacteristicsofanelitelevelrugbyunionplayerSomeofthefirstdatapublisheduponphysicalcharacteristicsofrugbyunionplayersintheprofessionalerawerepresentedbyQuarrieetal.(1995)whonotedsignificantdifferencesbetweenforwardsandbacksonanthropometricandphysicalperformancevariables.FurtherresearchbyQuarrie,Handcock,Toomey,andWaller(1996)showedsignificantpositionaldifferencesbetweenpositionalgroups,withfrontrowforwardstypicallybeingendo-mesomorphicsomatotypes,whilelocksandlooseforwardsweretallerthanthefrontrowforwards.Itisthereforeevidentthatthephysicalcharacteristicsofelitelevelrugbyunionplayersareposition-specificandeverevolvingasthegamebecomesmoreprofessional.Morerecently,Wood,Coughlan,andDelahunt(2016)presenteddatafromIrishprofessionalrugbyunionplayers,showingthatforwards(1.85±0.06mand96.88±9.00kg)weresignificantly(p<0.05)tallerandheavierthanbacks(1.79±0.05mand81.97±7.09kg).TheresearchbyWoodetal.(2016)did,however,showthatforwardsdisplayedsignificantlylower(p<0.05)physicalperformanceforanumberoftestsincomparisontobacks(CMJ,Forwards38.37±4.00cm,Backs41.31±4.44cm;10msprinttimeForwards1.85±0.07s,Backs1.77±0.06s;150mshuttletest,Forwards675.90±82.46m,Backs711.71±27.46m)(Tables2.6–2.11).

Physicalperformance(speed,powerandaerobicability)differsbetweenforwardsandbacks,yetfewerpositionaldifferenceswerenotedbetweenthesmallerpositionalgroupssuchaspropsandlooseforwardsamongsttheforwardsandhalfbacksandoutsidebacksamongstthebacks.MuchofthephysicalperformancedatanotedbyQuarrie,Handcock,etal.(1996)isdetailedinChapter2.1.1,yetthesub-eliteleveloftheplayerswithinthisresearchmakesitsworthlimited.Duthieetal.(2003a)reportedforwardstohavesuperiorabsoluteaerobicandanaerobicpowerandmuscularstrength,however,whenconsideringbodymass,resultsfavourbacks.MorerecentresearchbyBell,Evans,Cobner,andEston(2005)notedthatrugbyunionbacks(84.5%)hadasignificantlylowerleantissuemassthanforwards(75.8%),andthatforwards(20.6%)hadagreaterfatmassthanbacks(11.1%).Gamerelatedfatiguehasalsobeennotedtodifferbetweenforwardsandbacksinprofessionalrugby,withTee,Lambert,andCoopoo(2016)notingthatforwardsexperiencedprogressivelygreaterperformancedecrementsduringmatchplaythanbacks,whowerefoundtomaintainperformanceintensity,despitethematchdemandsencountered.

Positionaltrendswerenotedwithinaballisticbenchthrowinsemi-professionalrugbyunionplayers(McMaster,2015),withforwardsproducingagreatermaximalpeakpower(PP)duringacountermovementbenchthrow(785±129W)aswellasconcentriconlybenchthrow(736±194W),comparedtobacks(718±105W;683±92W)respectively.AdditionalsupportfordifferencesinmaximalstrengthhasbeennotedbyMcMaster(2015),withforwardsgenerallydemonstratinggreaterstrengthlevelthanbacks(Table2.6).Backsaresignificantlylighterthan

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forwards(Duthieetal.,2003a)duetotheirrequirementforincreasedmobilityaroundthefieldandreducedinvolvementinscrumsandrucks.Thisreductioninthenumberofcontactsituationshasledtobacksrequiringlowermaximalstrengthlevels.ThisisillustratedinTable2.6,showingreducedonerepetitionmaximum(1RM)performancesinalltestedmeasures(Smart,Hopkins,&Gill,2013)comparedtoforwards.Smartetal.(2013)notedthatlooseforwardsarethelightestoftheforwardgroupwithameanbodymassof101.6±7.9kg.Thisreductioninbodymasscouldbethereasonbehindreducedmaximalupperbodystrengthinbothbenchpressandchinupscomparedtoallotherforwardpositions.Aslooseforwardshaveasmallerinvolvementinscrums,rucksandmauls(Lindsay,Draper,Lewis,Gieseg,&Gill,2015),theneedforthispositionalbodyweightisthereforeemphasised.

Findingsinmaximumspeedresearcharedifferentfromthepositionaltrendsinmaximalstrength,asbacksarefasterthanforwards(Smartetal.,2013)showingthatmaximalstrengthisnotasimportantformaximalspeedasrelativestrengthiswhenbodyweightistakenintoaccount(Turner,Tobin,&Delahunt,2015).Sprintcharacteristicsofrugbyunionplayers(Table2.8)showthatforwardsaregenerallyslowerthanbacksandfromapositionalaspectoutsidebacksarethefastestandpropsaretheslowestoveralldistances.Thiscouldbeexplainedbydecreasedbodymassbetweenthepositions,withpropsbeingtheheaviestandbacksbeingthelightest,thereforeillustratingthatdespitebodyweighthavinganinfluenceuponmaximalspeed,relativepowerisadeterminingfactorforspeed.Strongcorrelationsbetweenstrengthandspeedhavebeennotedinbothrugbyunion(Cunninghametal.,2013)andrugbyleague(Kirkpatrick&Comfort,2013)andareexaminedinmoredetailwithinChapter2.1.1.2.2.

2.1.1.2.1 StrengthandpowerofeliterugbyunionplayersNormativestrengthvaluesforprofessionalplayersinthepremiersouthernhemisphererugbycompetitionwerenotedbyAppleby,Newton,andCormie(2012).WhenassessingtwentyplayersoveratwoyearperiodApplebyetal.(2012)noted1RMforbenchpressrangingfrom132.5±14.0kgto146.8±11.5kgandsquat1RMrangingfrom164.6±31.5kgto179.1±26.7kg.AnotherstudyofinterestforpractitionerspresentingdatafromeliterugbyunionisthatbyArgus,Gill,Keogh,Hopkins,andBeaven(2009)where1RMbenchpress(141±22.5kg),1RMboxsquat(194±32.9kg)benchthrowpeakpower(1150W)andjumpsquatpeakpower(5190W)werereportedamongstthirtytwoprofessionalrugbyunionplayersfromaSuper14team.RecentlyreportedresearchassessingstrengthandpowerofeliterugbyunionplayersispresentedinTables2.6and2.7.

2.1.1.2.2 SpeedcapabilitiesofeliterugbyunionplayersInastudyassessingneuromuscularperformanceandrelationshipswithsalivaryhormonesbyCrewtheretal.(2009),thirty-fourprofessionalmalerugbyplayerswereassessedforrunningspeed,with10m(Forwards=1.85sBacks=1.73s)and20m(Forwards=3.16s;Backs=2.96s)sprinttimesbeingsignificantlydifferentbetweenforwardsandbacks.Similarly,Quarrie,Handcock,etal.(1996)reported30msprintvaluesforforwardsrangingfrom3.9-4.1s,andbacksrangingfrom3.7-3.28s.Superiorsprintingspeedinbackscomparedtoforwardswasnotedwithinotherresearch(Duthieetal.,2006),yettheinfluenceofthecombinationofspeedandbodymass,leadingtogreatermomentumwithinforwardsisapointforconsideration.AsnotedbyCrewtheretal.(2009)momentumhasadefinitiveadvantageinrugbyespeciallyduringbodycontactsituations.

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RecentresearchwithinprofessionalrugbyunionbyCunninghametal.(2013)highlightedtheimportanceofrelativestrengthandpoweruponspeedcomponents(accelerationandmaximumvelocity).Relativepowerinrugbyunionplayersisalsoadeterminingfactorinacceleration,withathletesthathaveagreaterpowerclean,broadjumpandtriplebroadjumpproducingquicker10msprinttimes.Thisincreasedpowercanbeexplainedbytheirabilitytoproduceforcequickly,thereforereducingfootcontacttimewiththeground,asisrequiredformaximalacceleration(Barr,Sheppard,Agar-Newman,&Newton,2014).TherelativepeakpowerduringahexagonalbarbelljumpsquathasalsoshownasignificantrelationshipbetweenCMJheightand10mand20msprinttimesinprofessionalrugbyunionathletesplayinginthePro12competition(Turneretal.,2015).PerhapsthemostinterestingrecentresearchassessingspeedqualitiesininternationalrugbyunionplayerswasthatbyCross,Brughelli,etal.(2015)showing10m(Forwards2.04±0.12s;Backs1.95±0.04s)20m(Forwards3.33±0.15s;Backs3.19±0.06s)and30m(Backs4.32±0.09s)times,withthesevaluesbeingquickerthaninternationalrugbyleagueplayerswithinthesamestudy.

Alongwithstraightlinespeed,rugbyisateamsportwhichrequireseffectivechangingofdirection(agility)qualitiestobeasuccessfulrugbyunionplayer(Greenetal.,2011).Researchintochangeofdirectionabilityofrugbyunionathletesiswelldocumented(Darrall-Jones,Jones,&Till,2015;Greenetal.,2011;Pienaar&Coetzee,2013)withstudiesusinganumberofdifferenttestswithdifferentcuttingandchangeofdirectiontestsimplemented(Table2.9).Similartorugbyunion,rugbyleagueplayersarerequiredtohavehighlevelsofagility(Gabbett,Kelly,&Sheppard,2008).Despitetheresultsbeingfromrugbyleague,Gabbettetal.(2008)foundinterestinginformationforpractitionersthatshowsthatthereisasmallyetnotsignificant(p>0.05,ES=0.28to0.32),differenceinchangeofdirectionabilitybetweenperformancelevels(higherandlowerskilled),withhigherskilledplayersperformingchangeofdirectiontasksquickerthanlowerskilledplayers.Additionally,itisofnotethatplayerswithfastersprinttimesover5,10and20mwerealsoshowntohaveagreaterchangeofdirectionability(Gabbettetal.,2008).RecentlyreportedresearchassessingspeedofeliterugbyunionplayersispresentedinTable2.8.

2.1.1.2.3 AerobicandanaerobicabilityofeliterugbyunionplayersMaximaloxygenuptake(VO2max)hasbeenproposedasanindicatorofaerobicfitnessinrugbyplayers(Duthieetal.,2003a)withfindingsthattheVO2maxofinternationalrugbyforwards(51.1±1.4ml/kg/min)(Warrington,Ryan,Murray,Duffy,&Kirwan,2001)beinglowerthanplayersfrommorerunning-basedsportssuchassoccer(57.8±6.5ml/kg/min)andfieldhockey(61.8±1.8ml/kg/min)(Duthieetal.,2003a).VO2maxvaluesarecommonlyexpressedabsolutelyaslitresperminute(l/min),orwhenexaminedinarelativeformat(wherebodymassisconsidered)iscomparedtobodymassperminute(ml/kg/min).ForwardshavebeennotedtohavesuperiorabsoluteVO2maxvaluescomparedwithbacks(Jardine,Wiggins,Myburgh,&Noakes,1988),yetconsideringthatbackstypicallycarrylessbodymassthanforwards,backsrelativeVO2maxvaluesaregreaterthanforwards.

VO2maxvaluesarenotcommonlyreportedinelitelevelrugbyunion,perhapsduetothecumbersomenatureoflaboratorytestingandthelimitedopportunitiesthatexisttoimplementsuchtestingwithinacompetitiveplayingseason.ResearchbyQuarrie,Handcock,etal.(1996)onaerobicperformanceineliteplayers,hasusedVO2maxtestingviaamulti-stageshuttlerun.Quarrie,Handcock,etal.(1996)reportedthatbackstypicallypossessgreaterlevelsof

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endurancefitnessthanforwards,whenassessedviaamultistageshuttleruntopredictVO2max.FromthisresearchbyQuarrie,Handcock,etal.(1996),hookerswerenotedashavingthehighestscore(58.7±15.2ml/kg/min),followedbythelocks(55.1±15.2ml/kg/min),looseforwards(55.1±15.2ml/kg/min)andprops(50.8±15.2ml/kg/min)withintheforwardsgroup.Forthebacks,theinsidebacks(62.5±16.9ml/kg/min)producedthehighestindicationofVO2max,comparedwiththemidfieldbacks(59.8±16.9ml/kg/min)andtheoutsidebacks(57.6±16.9ml/kg/min).Itis,however,importantforpractitionerstonotethatlaboratorybasedtestingmethodologyisperhapswarrantedinordertoassesspreciseVO2maxvalues,astheshuttleruntestisonlyapredictionofVO2maxratherthanadirectmeasurement.Itisthereforeapparentthatthiscomponentisoneofseveralrequirementsoftheoverallfitnessprofileofarugbyplayerandthatanaerobiccapabilitiesarethereforejustasimportantwithingamedemandsrequiredforallpositions.Consideringthatrugbyplayersarerequiredtoexecutetackles,scrummagingandruckinginvolvingaccelerationsanddecelerationsduringgameplay,playersneedtheabilitytoworkinintermittentmovementsthatareprimarilyanaerobicinnature.RecentlyreportedresearchassessingaerobicandanaerobicqualitiesofrugbyunionplayersispresentedinTable2.10

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Table2.6:Researchshowingassessmentofupperbodyandlowerbodystrengthcharacteristicsofdifferentrugbyunionplayinglevels

Author Subjects Playingstandard Results

Lombardetal.(2015)

453subjectswhorepresentedthejuniornationalSouthAfricanNationalTeambetween1998and2010

Under20internationals

BenchPressincreased40%overa13yearperiod(1998,89±18;2010,135±22kg)

McMaster(2015)

20subjects(age=21.2±3.0years;mass=94.9)

Semi-professionalplayers

1RMbenchpress133.9±9.6kgforforwardsand110.9±23.9kgforbacks(1.30kg/BMforwards;1.24kg/BMbacks)

Darrall-Jones,Jones,andTill(2015)

67players(under16s,n=29;under18s,n=23;under21s,n=15)

AcademyU21players

1RMbenchpressfor108.2±14.1kg(1.11kg/BM)

1RMfrontsquatforacademyU21players118.2±17.8kg(1.24kg/BM)

Smartetal.(2013)

1161NewZealandrugbyunionplayersfrom2004to2007

Amateurandprofessionalplayers

Forwardshadsmall(7.7%;99%confidencelimits±8.2%forbacksquat1RM)tomoderate(13.3%;64.8%forbenchpress1RM)

Cunninghametal.(2013)

20players(age,26.5±4.6years;height,180.0±10.0cm;mass,105.5±11.9kg)

Professionalplayers Squatstrength186.2kg±22.6

Applebyetal.(2012)

20players(12forwards;8backs)withresistancetrainingexperienceof10.5±3.3years

Professionalplayers 1RMbenchpressrangingfrom132.5±14.0kgto146.8±11.5kgandsquat1RMrangingfrom164.6±31.5kgto179.1±26.7kg

Argusetal.(2009)


Professionalplayers

1RMbenchpress(141kg),1RMboxsquat(194kg)

Kilduffetal.(2007)

33players(13seniorinternationalplayers)(age,24.0±3.4years;height,185.0±8.0cm;mass,97.4±13.4kg)

Professionalplayers 1RMforbenchpressof124±16kgto153±23kgandsquat1RM

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Table2.7:Researchshowingassessmentofupperbodyandlowerbodypowermeasurementcharacteristicsofdifferentrugbyunionplayinglevels


Woodetal.(2016)

89maleplayers(age,18.6±0.5years;height,Forwards185.0±6.0cm,Backs179.0±5.0cm;mass,Forwards96.8±9.0kg,Backs81.9±7.0kg)

Internationalunder18andunder19players

CMJheightForwards38.37±4.00cm,Backs41.31±4.44cm

TobinandDelahunt(2014)


Professionalrugbyunionplayers

CMJheighttobe43.95±5.43cm

Cunninghametal.(2013)


Professionalrugbyplayers

LowerbodypowerCMJbeing5476.1±616.4W

Argusetal.(2009)

32players(age,24.4±2.7years;height,184.7±6.2cm;mass104.0±11.2kg)

Professionalplayers

Benchthrowpeakpower(1150W)andjumpsquatpeakpower(5190W)

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Table2.8:Researchshowingassessmentofshortsprintcharacteristicsofdifferentrugbyunionplayinglevels


Woodetal.(2016) 89maleplayers(age,18.6±0.5years;height,Forwards185.0±6.0cm,Backs179.0±5.0cm;mass,Forwards96.8±9.0kg,Backs81.9±7.0kg)


10msprinttime(Forwards1.85±0.07s,Backs1.77±0.06s)

Lombardetal.,(2015) 453subjectswhorepresentedthejuniornationalSouthAfricanNationalTeambetween1998and2010


10msprinttimesrange(1998,1.86±0.10;2010,1.73±0.10s)

Darrall-Jones,Jones,andTill(2015)

67players(under16s,n=29;under18s,n=23;under21s,n=15)

U21Academyplayers Darrall-Jones,Jones,andTill(2015)withinresearchofU21Academyplayersnoted505left2.41±0.10s;505right2.37±0.15s

Cross,Brughelli,etal.(2015)

15players(Age;Forwards28±5;Backs24±3)(Height;Forwards1.90±0.1;Backs1.82±0.1)(mass;Forwards114.55±6.3;Backs92.64±4.9)

NewZealandinternationals

Cross,Brughelli,etal.(2015)noted10m(Forwards2.04±0.12s;Backs1.95±0.04s)20m(Forwards3.33±0.15s;Backs3.19±0.06s)30m(Backs4.32±0.09s)

Smartetal.(2013)

1161NewZealandrugbyunionplayersfrom2004to2007

Bothprofessionalandinternationalplayers

10msprint(Props1.85±4.7s;Hookers1.81±4.1s;Locks1.79±4.7s;Looseforwards1.76±4.5s;Insidebacks1.72±4.0s;Centres1.70±4.0s;Outsidebacks1.68±4.4s);20msprint(Props3.21±4.4s;Hookers3.14±3.7s;Locks3.13±4.2s;Looseforwards3.06±4.4s;Insidebacks2.96±3.5s;Centres2.95±4.6s;Outsidebacks2.89±3.3s)

Smartetal.(2013)showedbackshadsmall(1.9±1.5%for30msprint)tomoderate(4.5%;±1.7%for20msprint)differencesinallspeedmeasuresbetweenamateurandprofessionalplayers

Smalldifferencein20msprint(1.9%;62.1%forforwardsand2.2%;62.2%forbacks)betweenprofessionalandinternationalplayers

Westetal.(2013)


Professionalrugbyunionplayers

10msprinttime1.74±0.07sand30msprinttime4.19±0.19sinprofessionalrugbyunionplayers

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Table2.9:Researchshowingassessmentofagilitycharacteristicsofdifferentrugbyunionplayinglevels


Greenetal.(2011)

23players(Startersage,21.0±1.65years;height,181.0±5.9cm;mass,88.9±11.3kg)(Nonstartersage,18.1±1.22years;height,176.8±5.4cm;mass,81.2±10.1kg)

Semi-professionalplayers

Greenetal.(2011)semi-professionalplayersnotedanticipated45°cut2.09±0.11s;unanticipated45°cut2.35±0.22s

PienaarandCoetzee(2013)

40players(age,18.9±0.4years)

Collegiateplayers

PienaarandCoetzee(2013)notedT-Testvaluesof10.28±0.57swithincollegiateplayers

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Table2.10:Researchshowingassessmentofaerobicandanaerobiccharacteristicsofdifferentrugbyunionplayinglevels


Woodetal.(2016) 89maleplayers(age,18.6±0.5years;height,Forwards185.0±6.0cm,Backs179.0±5.0cm;mass,Forwards96.8±9.0kg,Backs81.9±7.0kg)


150mshuttletest,Forwards675.90±82.46m,Backs711.71±27.46m)

Lombardetal.,(2015) 453subjectswhorepresentedthejuniornationalSouthAfricannationalteambetween1998and2010


Backsassessedviamultistageshuttleruntest(1998,101±13;2010,102±12shuttles)

SparksandCoetzee(2013)

21players(weight97.6±12.9kg,height182.3±7.1cm,age22.2±1.2years)

Universityrugbyunionplayers

Bloodlactateof42.7±6.8mmol.lduringincrementalV02maxtesttothepointofexhaustioninuniversityrugbyunionplayers

O'Gorman,Hunter,McDonnacha,andKirwan(2000)

7players(weight93.8±3.7kg,height187.0±2.2cm,age22.3±0.3years)

Internationallevelrugbyplayers

Bloodlactatelevelsof18.8±0.3determinedfromindirectcalorimetryusinganincrementalprotocol

Deutschetal.(1998) 24players(weight88.7±9.9kg,height185.0±7.0cm,age18.4±0.5years)

Eliteunder-19rugbyunionplayers

Meanbloodlactateconcentrationdidnotdiffersignificantlybetweengroups(range:4.67mmol.lforoutsidebacksto7.22mmol.lforbackrowforwards;p<0.05)duringcompetitivematches

Quarrie,Handcock,etal.(1996)

94players(Props;weight102.8kg,height182.0cm,age25.0years)(Hookers;weight89.7kg,height178.8cm,age23.0years)(Locks;weight101.9kg,height191.8cm,age22.4years)(Looseforwards;weight96.3kg,height186.3cm,age21.1years)(Insidebacks;weight75.0kg,height172.7cm,age21.7years)(Midfieldbacks;weight85.9kg,height179.7cm,age21.4years)(Outsidebacks;weight83.4kg,height179.4cm,age22.5years)

Senior“A”malerugbyplayers

Anaerobiccapacity(sixrepeatedhighintensityshuttles)over70mshowingforwardsrangingfrom54.3to67.4s,andbacksrangingfrom39.8-57.8sonafatigueindexmeasurement

Table2.11:Researchshowingphysicalcharacteristicsofrugbyunionplayers

Author Subjects Physicalcharacteristics(Heightandweight)

Additionalinformation

Quarrieetal.(1995)Quarrie,Handcock,etal.(1996)

94seniorlevelrugbyplayers (Age-Forwards22.7;Backs21.9)

Height-Forwards186.0cm;Backs177.8cm;Mass-Forwards98.5kg;Backs81.8kg

Positionalcategorieswithintheforwardsdifferedsignificantlywithrespecttoheight,bodymass,mesomorphyandectomorphy,whilepositionalcategoriesofthebacksdifferedsignificantlyintermsofheight,bodymass,andperformanceontheaerobicshuttletest.

Duthieetal.(2003a) A meta-analysis reporting much of the studies above. Forwards are typically heavier, taller, and have a greater proportion of body fat than backs. Training should focus on repeated brief high-intensity efforts with short rest intervals to condition players to the demands of the game. Training for the forwards should emphasize the higher work rates of the game, while extended rest periods can be provided to the backs.

Belletal.(2005)

Data taken from 30 young adult Rugby Union players not professional players (15 forwards and 15 backs)

Forwardsexhibitedlargerabsolute(kg)offatmassandleansofttissuemassthanbacks

Backshadasignificantlylargerleansofttissuemass(%)thanforwardsatthearms(84.4vs.76.5%),legs(80.0vs.71.9%)andtrunk(89.2vs.79.0%),whereasforwardshadagreaterfatmass(%)thanbacksatthearms(18.7vs.10.6%),legs(23.1vs.14.7%),andtrunk(18.4vs.8.0%)

QuarrieandHopkins(2007)

Age-Forwards22.7;Backs21.9

PlayersamplesizeunspecifiedanddatatakenfromBledisloeCupmatchesbetween1972and2004

Height-Forwards190.1cm;Backs182.9cm;Mass-Forwards111.1kg;Backs95.7kg

Markeddifferencesinmatchparticipationtimesandplayersizewiththeintroductionofprofessionalismassociatedwithlargeincreasesinpasses,tackles,rucks,tries,ball-in-playtime,andbodymass.

Modificationstolawsandtheapplicationofexistinglawshashadanimpactuponmatchcharacteristics.

Argusetal.(2010) 33eliterugbyunionplayersfromaSuper14professionalrugbyteam[Age24.8±2.4(Allpositions)]

Height-186.1±0.06cm(Allpositions);Mass-102.3±10.3kg(Allpositions)

Datatakenfromashort-termpre-seasontrainingprogrammeassessingtheeffectivenessofatrainingprogrammeonthebodycompositionandanaerobicperformance

Zemski,Slater,andBroad(2015)

37internationalAustralianrugbyplayers

Height-Forwards191.0cm(187.7to194.3cm);Backs182.6cm(180.0to185.3cm);Mass-Forwards111.7kg(108.1to115.2kg);Backs91.7kg(89.1to94.3kg)

SignificantdifferenceswerealsoseenbetweenCaucasianandPolynesianforwardsinlegleanmass(31.4kgvs.35.9kg,p=0.014,d=2.4)andperipheryleanmass(43.8kgvs.49.6kg,p=0.022,d=2.4)

(Woodetal.,2016) 89maleInternationalunder18andunder19players(age,18.6±0.5years)

(Height-Forwards185.0±6.0cm,Backs179.0±5.0cm;Mass-Forwards96.8±9.0kg,Backs81.9±7.0kg)

Forwards(1.85±0.06mand96.88±9.00kg)(Backs1.79±0.05mand81.97±7.09kg)

2.1.1.2.4 BodymassandcompositionofeliterugbyunionplayersInastudyassessingrugbyunionplayers’physicalcharacteristicsinthesouthernhemisphere,playerswerereportedtohavebecomeheavierandbacksreportedtobetallerbetweentheperiod1972and2004(Quarrie&Hopkins,2007).Theadventofprofessionalismin1995andtheassociatedadvancesintrainingledtoanincreaseinpasses,tackles,rucksandballinplayduration.Meanparticipationtimebyplayersisalsoconsideredalargedeterminantoftheincreasedphysicalsizeofplayers,wherebyplayersareoftennotrequiredtocompletethedurationofagameandarethereforeconditionedaccordingly,includinganincreasedbodymass.Lawchangessuchastheintroductionofthelineoutgapin1972,theincreaseofpointsawardedforatryin1992,theapplicationofincreasednumberofreservespermittedtobeallowedonthefieldin1997andtheintroductionofyellowcardsin2002,havealsoaddedtotheincreasedspeedofthegameandsubsequentmodifiedphysicalcharacteristicsofamoderndayrugbyunionplayer(Quarrie&Hopkins,2007).QuarrieandHopkins(2007)notedthattherapidincreaseofbodymasscanbeattributedtopressureexerteduponplayerstocompeteatanincreasedsizethatsuitedtherevisedlawsofthegame.Theentitlementtoplayforlessthanthewholematchduration,duetosubstitutions,meantthatrelativeaerobicrequirementsofplayerswerereducedinfavourofincreasedanaerobicability,tomatchtheamendedphysicalcharacteristicsofarugbyunionplayerinearly2000’s.TheincreasingsizeofplayersisillustratedinTable2.11andcanalsobeattributedtogreaterfocusandknowledgeofresistancetrainingandnutritionalinterventionsthathelpaddleanbodymasstoplayers’physiques.Thisincreasedstatureofrugbyunionplayersisperhapsmostnotableinbackswheretheirphysiquesarenowcloselymatchedtolooseforwardsofthemid’1990’s,inthehopeofhelpingbackswithintheirincreasedroleofruckandtackleinvolvementsinthemoderngameofthelate2000’s(Noakes&DuPlessis,1996).DatafromtheaforementionedresearchbyApplebyetal.(2012)showedsumofskinfoldsrangingfrom71.1±16.9mmto65.7±16.1mmacrosstwentyplayersbetween2007and2009,withbodymassrangingfrom103.8±7.6kgto106.0±8.4kg.

2.1.1.3 Whichphysicalelementsenhancethelikelihoodofsuccessofanelitelevelrugbyunionplayer?

AsreportedinChapter2.1.1,thephysicalelementsthatdistinguishaneliteplayerfromasub-eliteplayerareapparent.Theelementsthatdistinguishasuccessfulrugbyunionplayerfromanunsuccessfulrugbyplayerarehoweverlessclear.Arugbyunionplayerthathastheabilitytoproduceelitelevelattributeswilladdtotheteams’chancesofsuccessingames.Otherfieldsportssuchasfootball,rugbyleagueandAustralianrulesfootballhavepresenteddatauponwhichplayercharacteristicsrelatetogamesuccess,thusprovidingpractitionerswith“goldstandard”valuestocomparetheirplayingrosteragainst.RecentresearchbySmartetal.(2014)assessingtherelationshipbetweenphysicalfitnessandgamebehavioursinrugbyunionplayersshowedthatsprinttimesover10,20and30mhadmoderatetosmallnegativecorrelationswithlinebreaks(r=-0.26),metresadvanced(r=0.22),tacklebreaks(r=0.16)andtriesscored(r=0.15).Smartetal.(2014)alsoshowedthattheaveragetimeoftwelverepeatedsprintsandpercentagebodyfatintheforwards,alongwithrepeatedsprintfatigueinthebackshadmoderatetosmallcorrelationswithameasureofactivityrateonandaroundtheball(r=-0.38,r=-0.17andr=-0.17,respectively).

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Consideringthepreviousreporteddatathatphysicalcapabilitiesofeliterugbyplayersdifferfromamateurplayers,withthedifferencesinstrengthandpowerbetweenlevelsofplayingbeinglikelyduetomaturation,trainingageandbodymass(Argus,Gill,&Keogh,2012),theroleofbodycompositionwithinsuccessfulperformanceisemphasised.RecentresearchinrugbyunionbySperanza,Gabbett,Johnston,andSheppard(2015)demonstratedthattheenhancementoflowerbodymuscularstrengthandpowercontributedtowardsimprovementsintacklingability,furthershowingtheinfluenceofphysicalcapabilitiesuponmatchperformance.Speranzaetal.(2015)notedacorrelationbetweenimprovementsin3RMsquatandtacklingability(p=0.04;ES>0.85)andasmallnon-significantdifferenceintacklingabilityandlowerbodypower(p=0.20;ES>0.56)intherespondersandnon-respondersfromtheresearchgroupinquestion.Similarly,inalongitudinalretrospectiveassessmentofjuniorplayersFontana,Colosio,DaLozzo,andPogliaghi(2016)notedthatalowerpercentagebodyfatandhighersprintspeedover15mwerethemostimportantpredictorsoflikelycareersuccess.Inrespectofsuccessfulmatchactivities,recentresearchinrugbyunion(Tierney,Tobin,Blake,&Delahunt,2016)assessedtherunningdemandsofsuccessfulandunsuccessfulteams,andreportedthatwhenforwardsachievedgreaterhighspeedrunning(HSR)intensityduringattacking22entriesanincreasedlikelihoodofsuccessoccurred.ThedifferencesinplayerintensitiesseeninthestudybyTierneyetal.(2016),showingsuccessfulattacking22entries(3.6m/min-1),comparedtounsuccessfulattacking22entries,illustratethephysicaldemandsrequiredforsuccess,andthereforesupportstheviewthatplayerswithhigherperformancemeasures(speed,strength,power,repeatedsprintabilityandbodycomposition)areabletoperformtoahigherlevelingamesituations.

2.1.2 TheuseofGPSdataforoptimalperformanceThedevelopmentofGPStechnologyisprovidingsportssciencepractitionerswithdetaileddatarelatingtospecificmovementdemandsofplayers,whilealsooptimisingsportspecifictraining.AcriticalappraisalofGPSmonitoringinteamsportswasconductedbyCummins,Orr,O'Connor,andWest(2013)withsixstudiesdetailedacrossvaryingplayinglevelsinrugbyunion,confirmingthephysicaldemandsplaceduponplayersandthespecificmetricsinvolved.GPSdataiscollectedthroughoutrugbyplayers’trainingweeks(microcycles)andlongitudinallyoveranentireplayingseasonwithmanystudiespublishedrecentlyongamedata(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011;Quarrieetal.,2013).DespiteGPSnotbeingatestingtoolregularlyusedinthefieldforassessingNMForreadiness,GPSdoeshelpguidepractitionersuponthevolumeoftrainingundertaken,whichcanbeinvaluableinformationforreadinessassessment,whencombinedwithmanyofthemonitoringtoolsdiscussedbelow(Chapter2.4).TheneedtoanalyseGPSdataandtheassociatedtrainingvolume(distances,speedsanddynamicstressloadforexample)hasbeenutilisedinanumberofrugbyunionstudies(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011)andisconsideredtobeanessentialtoolofmanyelitesportteampractitioners,givingdetailedinformationonbothexternalload(i.e.distance)andinternalload(i.e.HR),thusprovidingamoreglobalassessmentofexerciseintensity.

LimitationsofGPStechnologyexist,asrepresentedinareviewofGPSreliability(Buchheitetal.,2014)showingsubstantialdifferencesbetweendifferentmodels,withvariationsrangingfrom1%variationinmaximalspeedassessmentsand56%differenceondecelerationsbetweenGPSmodels.Theselargevariationsthereforequestiontheusefulnessofaccelerationanddecelerationmeasures,withBuchheitetal.(2014)stronglyadvisingpractitionerstoapplycare

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whencomparingdatacollectedwithdifferentmodels.Similarly,researchcollectedbyCouttsandDuffield(2010)advisedthatdifferentdevicesshouldnotbeusedinterchangeably,yetanacceptablelevelofaccuracyandreliabilitywasnotedfortotaldistanceandpeakspeedsinteamsportsettings.Thissameresearch,however,didfindpoorreliabilityforhigherintensityactivities(highintensityrunning>14.4km/h)andnotedbetteraccuracyoverlinearmovementsthannon-linearmovements.Itseems,fromthedatapresentedbyCouttsandDuffield(2010),thatGPSdevicesaremorereliableatmeasuringmovementsoveralowspeedandalinearform,comparedtorapidaccelerationsacrossmultipleplanesthatmaybedifficultfortheGPSdevicetodistinguishbetween.Itis,however,importanttonotethatthetechnologicaladvancesinGPStechnologyhavebeenvastsincetheresearchbyCouttsandDuffield(2010),meaningthatdiscrepanciesbetweenhighintensityactivitiesandnon-linearmovementsarelikelytohavebeenresolved,withfurtherevidencesupportingtheassessmentofmaximumvelocityusing10HzGPSunits(Roeetal.,2016).ThesamplingfrequenciesofthestudiesinquestionaredetailedinTable2.2andmayexplainsomeofthevariationindatacollected.Recentresearch(Scott,Scott,&Kelly,2016)assessingtheimportanceofsamplingfrequencyforimprovingGPSaccuracy,notedthat1Hzand5HzGPSunitswerenotaspracticalforuseinteamsports,comparedto10Hzand15Hzunitsforteamsportsimulatedrunningmovements.

2.1.3 TrainingweekstructureandRPEAsreportedbyTwistandHighton(2013)gamesinrugbyleaguearesupportedbyperiodisedtrainingweeks,whicharemanipulateddependinguponthenumberofdaysbetweengames.Practitionershaveusedmanymethodstoevaluatetrainingload(TL)usingbothinternalandexternalmeasurements(Killen,Gabbett,&Jenkins,2010;Lovell,Sirotic,Impellizzeri,&Coutts,2013).Oftenthemostfrequentlyusedformofevaluatinginternaltrainingloadofteamsportathletesiscalculatedviaheartrate(Coutts,Rampinini,Marcora,Castagna,&Impellizzeri,2009;Elloumi,Maso,Michaux,Robert,&Lac,2003),yetthemostcommonlyusedpracticewithinteamsportsthatassessexternalloadutilisesrateofperceivedexertion(RPE)onascalemeasuringfromonetoten(Fosteretal.,1995)andhasbeenusedinmanystudies(Comyns&Flanagan,2013;Impellizzeri,Rampinini,Coutts,Sassi,&Marcora,2004;Lovelletal.,2013;Wallace,Coutts,Bell,Simpson,&Slattery,2008),withtheintensityscoremultipliedbythedurationofthetrainingsession,providingasinglenumberrepresentingthemagnitudeofthattrainingsession.Monitoringtrainingloadusingnumberscalculatedtorepresenttrainingvolumecanbecomparedagainstotherperformanceparametersinordertogaugetheeffectofthetrainingweekandperhapsexplainchangesinperformance(Halson,2014).AsillustratedinrecentresearchbyThorntonetal.(2015)ineliterugbyleague,theeffectivenessofself-reportdatawhenutilisingTLandWBdataforpredictingillnessisevident(weekly-TL>2786;WB<7.25).Practitionerscanusetrainingloaddatatoexamineload-performancerelationshipsandplanfuturetrainingloadprescription,thusreducingtheriskofinjuryillnessandNFOR.

Previousresearchinbothteamsports(Couttsetal.,2009;Impellizzerietal.,2004;Lovelletal.,2013)andindividualsports(RodriGuez-Marroyo,Villa,GarciA-Lopez,&Foster,2012)haspresentedstrongcorrelationsbetweenHRandsessionRPE.Lovelletal.(2013)alsoreportedlargecorrelationsbetweensessionRPEandGPSderivedmeasuresofdistanceandhighspeedrunning.Incontrast,bodyloadmeasurementstakenfromGPShaveshowncontrastingcorrelationstosessionRPE,withGomez-Piriz,Jimenez-Reyes,andRuiz-Ruiz(2011)showinglowcorrelatingvaluesinsoccerwhileLovelletal.(2013)showedhighcorrelations.Aswould

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beexpectedontrainingweeksinteamsportsettingswheredaysbetweengamesarereduced,lowertrainingloadshavebeenprescribedinrugbyunionandthesessionRPEmethodutilised(Elloumi,Maso,Michaux,etal.,2003).Onweekswithfivedaysbetweengames,comparedtoweeksthathavemoredaysbetweengames(Killenetal.,2010;McLeanetal.,2010;McLellan,Lovell,&Gass,2011b;Twist,Waldron,Highton,Burt,&Daniels,2012),lowerweeklytrainingloadistobeexpected.Typically,atrainingweekbetweengamesentailstworesistancesessionsfocusinguponstrengthandpower,andthreefieldsessionswithfocusuponrugbyskillsandgameplans.Inappropriatetrainingloadshavebeenshowntohaveanegativeimpactuponplayerreadiness(McLeanetal.,2010).ResultsfromMcLeanetal.(2010)showedthatplacementandscaleofloadwithineachtrainingmicrocyclebetweengamesisimportantforrecovery,andthatitispossibletorecoverbothneuromuscularandperceptualmeasureswithinfourdaysafterarugbyleaguematch.Additionally,itisimportanttoconsideralltrainingloadmeasureswhenassessingtheintensityandsubsequentphysicalandmentalcostofatrainingsessionorgameuponanindividual.Forexample,inrugby,manytrainingsessionsinvolveahighwrestlingandcontactelementandarethereforephysicallydifficulttoundertake,yetmaynotdisplayhighHRexertionvaluesormetresperminuteasseenin“onfeet”rugbyorconditioningsessions.RecentresearchillustratingpoormanagementofthedaysbetweengamesinteamsportswaspresentedbyMaloneetal.(2015),whereonlythedaybeforeagamepresentedconsistentperiodisedtrainingload.Thispoormanagementoftrainingloadisamajorconcernforpractitionersandonethatwillresultinsub-optimalperformanceandthereforewarrantsfurtherinvestigationinrugbyunion.

2.1.4 SummaryFromtheresearchaboveitisclearthatmatchdemandsdifferacrossplayinglevelsandpositionalgroups,withtheintermittentnatureofrugbyunionmeaninglow-intensityactivityismixedwithboutsofanaerobichigh-intensitymovementsandpower-basedtasksduringmatchplay.Giventhegreatercontactloadsexperiencedbyeliterugbyunionforwardssustainedduringmatchplaytheloadduringmatchplaycomparedtobacks,priorresearch(Cahilletal.,2013;Quarrieetal.,2013;Smartetal.,2014)recommendedpractitionersprovideforwardswithmoretimetorecoverpost-matchthanbacks.InvestigationsassessingmatchdemandsusingthemostrecentadvancementsinGPStechnologyandvideofootagewouldprovideagreaterunderstandingtothephysiologicalcostexpectedfrommatchplayandtheresultantresponsethishasuponpositionalgroupsintheimmediatedayspost-match.AsseeninmanyelitesettingstheuseofGPS,sessionRPEandindividualtrainingprescriptionaidsinmanagingthetrainingweeksofteamsportsplayersandenablesthelikelihoodofoptimalperformancebetweengames,viamoreobjectivetrainingprescription.

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2.2 Methodsofstrengthandpowertrainingandassessmentinrugby

2.2.1 ResistancetrainingmethodsBothfieldbasedrugby-specifictrainingandgymbasedresistancetrainingcompletedinthedaysbetweenmatchesislikelytohaveaninfluenceuponplayerfatigue.Oneofthemostcommonlyusedmodernrugbyresistancetrainingmethodsincludecontrastandcomplex-training(Argus,Gill,Keogh,McGuigan,&Hopkins,2012;Comyns,Harrison,Hennessy,&Jensen,2007),withliftsprescribedatapercentageofthemaximalpossibleforonerepetition(1RM)andtheload-velocityrelationshipconsideredaccurateforloadprescription(Jidovtseff,Harris,Crielaard,&Cronin,2011).Contrastandcomplex-trainingaresimilarmethodsofresistancetraining,withcompoundtraininginvolvingheavyresistancedaysalternatedwithlighterresistancedaysandcomplex-traininginvolvingsetsofheavyresistanceexerciseimmediatelyfollowedbysetsoflighterresistanceexercise. Despiteevidencetosupportenhancedperformanceasaresultofeithercomplexorcontrast-trainingwithinrugbyunioncompetitionphasesbeinglimited;avastbodyofevidenceexistssurroundingtheeffectivenessofstrengthtraining(Argusetal.,2010;Baker,1998,2001b),withtheirinfluenceuponacutefatiguealsodiffering(Bevan,Owen,Cunningham,Kingsley,&Kilduff,2009).

Manypractitionersusecontrastorcomplex-trainingasitisconsideredatimeefficientmethodfortraininglargegroupsofteamsportathleteswithinbusytrainingdays,wherethemainfocusofthedaymaybetheonfieldsportspecificsessionandnottheresistancetrainingsession.ConsideringtheresearchbyBaker(2001b)hasshownthatlevelsofstrengthareoftenincreasedormaintainedthroughoutacompetitionperiodofaseason,yetin-seasonmaximalpowerwasreportedwithinthesamestudytodecrease,theneedforamixofresistancemethodsisfurtheremphasised.Inaddition,Applebyetal.(2012)confirmedpreviousviewsthatasaplayerstrainingageincreases,diminishingreturninstrengthbecomeapparent,meaningamixedfocustoresistancetrainingisagainrecommended.Amixedfocusapproachissometimesknownasamixedmethodandinvolvesavarietyofexerciseswithloadsof30-70%1RMtodeveloppower,andloadsof75%andgreaterusedforabsolutestrengthdevelopment(Haff&Nimphius,2012).Despitereportedsuccessofmixedmethodsapproach(Cormie,McGuigan,&Newton,2010b;Schmidtbleicher,1992);difficultyexistsforpractitionerstodeterminethebestapproachfordevelopingmaximalstrengthandpowerinteamsportsettings.Mixedmethodsapproachis,however,oftenusedwithinteamsportsettingstoensuredevelopmentofbothrateofforcedevelopmentandpoweroutput,whicharephysicalelementsofmovementandexplosivenessneededforsportssuchasrugbyunion(Haff,Whitley,&Potteiger,2001).Scientificsupportfortheuseofcombinedtrainingmethodsonrelationsamongforce,velocity,andpowerdevelopmentisnotedbyToji,Suei,andKaneko(1997)withfurthersupportfromHaffandNimphius(2012,p.7)inareviewoftrainingprinciplesofpowernotingthat“theuseofamixedmethodsapproachtooptimizepower-generatingcapacityallowsforasuperiorincreaseinmaximalpoweroutputandagreatertransferoftrainingeffectbecauseofamorewell-roundeddevelopmentoftheforce-velocityrelationship”.

2.2.2 StrengthandpowertrainingspecificallyThereportedincreasedstrengthandpowerofrugbyplayersdevelopedoverthepastfifteenyearshasincreasedattackinganddefensivecapabilities,increasingtheteam’schancesofwinningandimprovingthegameforaudiences(Argusetal.,2010).Thisincreasedneedfor

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developingstrengthandpowerinrugbyplayershasresultedintimebeingdevotedtostrengthandconditioningtrainingwithspecificattentionappliedtoresistancetraining.Varyingresistancetrainingmodalitiessuchasisokinetic,isometricandplyometricexistandhavebeenutilisedwithinrugby(Beaven,Cook,&Gill,2008;Harris,Cronin,Hopkins,&Hansen,2008;Kilduffetal.,2007;Tobin&Delahunt,2014)withconcurrenttrainingoftenprescribedduetoschedulingconstraintsforoptimaladaptationinthemanyphysicalaspectsrugbyplayersarerequiredtoperform.EvidencesupportingtherelevanceofpowermovementsupongameperformancewaspresentedbyHorietal.(2008),whonotedacorrelationbetweenhangpowercleanperformanceandjumping(r=0.41,p<0.05)and20msprinttime(r=-0.058,p<0.01).WhenconsideringtheresearchabovebyArgus,Gill,Keogh,andHopkins(2011)andtheinfluenceofpoweruponperformancenotedbyHorietal.(2008),itisclearthatarugbyplayersabilitytoproducehighpoweroutputsisdependentupontheindividualsoverallstrengthandpoweroutput.

Recentresearch(Cormie,McGuigan,&Newton,2010a;Cormieetal.,2010b;Haff&Stone,2015)supportedthenotionofdevelopinghighlevelsofstrengthbeforetargetingpowerdevelopingactivities,whenattemptingtoimprovepoweroutputsgeneratedandwarnedagainsttheimplementationofballisticstrengthtrainingaloneasdecreasesinmuscularstrengthhavebeenreported.InsteadresearchbyMcMaster,Gill,Cronin,andMcGuigan(2013)recommendedtheuseoftwoheavyloadedstrengthtraining(75-85%1RM)sessionsperweektocounteractdeclinesinstrengthforrugbyplayersin-season.Withinrugbyuniontheabilitytoproducehighlevelsofpowerareparamountforsuccessfulperformance,withahighlevelofmaximalstrengthbeingtheprerequisitetoproducethesepowerfulactions(Argus,Gill,&Keogh,2012).Despiteimprovementsinpowerasaresultofstrengthtrainingbeingwelldocumented(Argusetal.,2011;Baker,2001a;Cormieetal.,2010a),therelevanceofstrengthtrainingforadditionalphysicaladaptationsarequestioned(Cormieetal.,2010b).ThefindingsbyBaker(2001b),however,emphasisetheneedformorefocusonpowersolely,ratherthancomplexorcontrast-training,whenassessingeliterugbyplayers.Itis,however,importanttonotethattheresearchbyBaker(2001b)incorporatedsubjectsfrombothprofessionalandamateursettingsandisthereforelimitedinrelevancetoeliterugbyunion.

2.2.2.1 EffectofstrengthandpowertrainingonsubsequentperformanceUnlikeothersports,rugbyplayersarerequiredtotraininthedaysbetweenweeklygamesanddonottypicallyhaveanextendedperiodofrestpost-matchtopreparetacticallyforthenextoppositionandtocreateathleticdevelopmentspriortothenextgame.Instead,inthedaysbetweenrugbyuniongames,eliteplayerstypicallyperformoneortwogym-basedsessionsperweekwiththeaimofmaintainingathleticabilityandaddressingindividualanatomicalissuesinordertomaintaintheiravailabilityforselection.Thesegymsessionscancreatebothfatiguedskeletalmuscleandmusclethatcanbeconsideredpotentiated,withtheresultantcurrentperformanceabilityofthemuscledependinguponthebalancebetweenthesetwofactors.Thefocus,volumeandintensityofthesegymbasedsessionsisthereforeacarefulconsiderationforrugbystrengthandconditioningpractitionersinelitesettings,wheretheaimistotryandimproveathleticabilityoftheplayersthroughouttheirplayingcareer,whileworkingwithintheconstraintsofanine-monthplayingseasonwheregamesappearonaweeklybasis.

AllformsofresistancetrainingarelikelytocreateNMFiftheloadsmovedandthevolumesprescribedarelargeenoughtoinitiateadaptation.Itcould,however,bearguedthatpower

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training(typically2-5reps)wouldnotcreateasmuchNMFasstrengthorhypertrophytraining,which,asnotedabove,involvesmovementscomprisinghigherloads(%1RM)andmoreoverallvolume.Instead,powertraininginvolveshighintensitymovements,whichduetotheloadprescribedoftencreateslessfatiguethanstrengthorhypertrophyfocusedgymsessions.Strengthsessionswhichcontainheavyloaded(%1RM)squatmovementsarelikelytocreatemoreeccentricmuscledamagethanpowerfocusedsquatmovements,therebyhavingagreaterinfluenceuponsubsequentperformanceintheimmediatehoursanddaysfollowingthisgymsession.Thereis,therefore,acarefulbalanceneededwhenpractitionersprescribeappropriatetrainingmodalities(strength,powerorhypertrophy)inthedaysbetweengames.

Improvementsinbothstrengthandpowerabilitiesofrugbyplayersasaresultofapre-determinedtrainingprogramarecommon(Harrison&Bourke,2009).ThebenefitsofresistancetrainingforspeeddevelopmentinmalerugbyplayerswerereportedbyHarrisonandBourke(2009),whonotedsignificantdecreases(p=0.02)in5mand30msprinttimesforagroupthathadperformedresistancetraining,incomparisontoagroupthathadnot.FurtherevidenceforthebenefitsofstrengthtrainingexistfromresearchinrugbyunionplayerswithComynsetal.(2007),recommendingtheimplementationofheavyliftingtoencouragefaststretchshorteningcycleactivityandthereforesubsequentlyimproveperformance.MostsignificantlyperhapsistheresearchbyArgus,Gill,Keogh,etal.(2012)whonotedtheimportanceofin-seasontraininguponsubsequentperformanceinrugbyunionplayers,wherebyrecommendationsweremadeforplayerstoperformhighervolumecontrast-trainingincomparisontotheuseofpowertrainingaloneduringcompetitionphases.ResultsbyArgus,Gill,Keogh,etal.(2012)indicatethatCMJperformancewasimprovedtoagreaterlevelasaresultofthestrength-powerprogram(50kgCMJ11.7%±6.5)comparedtothespeedpowerprogram(50kgCMJ3.1%±4.8).Thisfurtheremphasisestheimportanceofconcurrenttrainingduringcompetitionphasesofplayingsessionswiththepotentialeffectitcouldhaveuponsubsequentperformance.

Itis,however,importantforpractitionerstoconsiderthat,aspreviouslymentioned,evidencebyArgusetal.(2009)notedthatmorethantworesistancetrainingsessionsperweekwereneededinordertoinitiatechangeinelitelevelrugbyunionplayers.Additionally,researchofinterestisthatbyHarrisetal.(2008)whonotedthatcombinationtraining(strengthandpowerdevelopment)increasedbacksquat(11.6%)anddecreased30msprinttime(1.4%)incomparisontothatofstrengthorpowertrainingalone.However,theabilityforpractitionerstoimplementmorethantworesistance-trainingsessionsperweekisdifficultduringcompetitionphasesineliterugbyunionsettings,whereplayersareaskedtoperformmanyfieldandgymbasedsessionsperweek.Combination-trainingalongsidetheotherelementsofstrengthdevelopmentarethereforerecommended,yettheimportanceofincorporatingstrengthelementsintothesesessionsiskey,consideringtheevidenceoutlinedbyMcMasteretal.(2013).Thisevidence,therefore,furtheremphasisestheneedforimplementationofgymbasedsessionsin-seasoninordertoattempttomaintainathleticability.Additionally,itemphasisestheneedtochooseappropriateexerciseselectionandsessionfocuswithingymsessions,consideringthelimitedwindowsofopportunitythatexist.

2.2.3 ImplicationsforpractitionersFromtheresearchabove,thatreportsincreasedplayersizeandphysicalcapabilitiesofplayers,itisevidentthatthegameofrugbyunionhasdevelopedgreatlyduetotheadventofprofessionalism.Asdiscussedabove,advancesintrainingpractices(bothonthetrainingfield

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andinthegym)haveresultedinincreasesinstrengthandpower,leadingtoenhancedorimprovedmatchperformance.Differingvolumesandintensitiesoftrainingprescribedinthedaysbetweenmatcheswillresultinvaryingtime-courseofrecovery,withthishavingmajorimplicationsforpractitioners’trainingselectioninthedayspostmatch.Additionally,whenconsideringtheanthropometricandphysicalperformancedifferencesnotedbetweenpositionalgroupsandplayinglevels(Belletal.,2005;Quarrie,Feehan,etal.,1996;Quarrie,Handcock,etal.,1996;Quarrieetal.,1995;Quarrie&Hopkins,2007),theneedtoselectappropriatetrainingmethodswhenconsideringthegoalsofeachindividualwithinaplayingsquadiskey.

2.2.4 SummaryFromtheevidenceaboveitisclearthatstrengthandpowertrainingiscommonlyusedwithinrugbytoenhancerugbyperformance,yetcontrastingresultsarepresentedsurroundingtheeffectivenessofstrengthtrainingmodalities.Despiteconflictingevidenceforthemostbeneficialmethodsofperformanceenhancementwithinrugbyunionexisting,theabilitytoproducehighlevelsofpowerisparamountforsuccessfulperformance,withahighlevelofmaximalstrengthbeingtheprerequisitetoproducethesepowerfulactionsandthereforerecommendedforimplementation.Practitioners,however,needtobesurethattheyareprovidingthecorrectfocusoftrainingandappropriatetrainingdoseinthedaysbetweengames,toenablecontinuedathleticperformancemaintenance,withoutaddingfatigueandsubsequentlyslowingrestorationofperformancepost-match.

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2.3 PerformanceTests,FatigueandAssociatedRecovery

2.3.1 TestsofPerformanceMethodsofmeasuringperformancearevastinquantityandinapplicabilitytothesportsettinginquestion,withmeasuresofneuromuscularfunction,hormonalmarkers,heartratederivedmeasuresandsub-maximaltestingallbeingutilised.Monitoringofspecificperformancemeasuresandtheassociatedweeklytrainingvolumecommonwithinteamsportscenariosisarecentareaofresearch.Researchthathasusedmoderntoolssuchas:GPS;playermonitoring[well-beingquestionnaires(WB)];biochemicalmarkers[creatinekinase(CK),cortisol(C),testosterone(T)];andperformancetests(ergometerandjumps),thatcanallreportaccuratedata,helptoaidscientificsupportforcorrectlydiagnosingperformance(McLellanetal.,2011b;Waldron,Twist,Highton,Worsfold,&Daniels,2011).Othermeasuresofneuromuscularfunction(performance)include:varyingformsofrunningtests;plyometricpush-ups;sprintperformances;andisokineticdynamometry(Duffield,Murphy,Snape,Minett,&Skein,2012;Johnstonetal.,2013;Twist&Sykes,2011).Themostcommonmaximalperformancemeasuresusedinpastresearchwithinteamsportsaremaximalstrengthassessments(Argusetal.,2009;Beaven,Cook,etal.,2008;Comyns,Harrison,&Hennessy,2010;Harrisetal.,2008).Inaddition,modernpracticeshaveincludedheartratederivedmeasurestoaidpractitionersattemptingtoquantifyloadandassessperformance(Bosquet,Merkari,Arvisais,&Aubert,2008).Manyoftheabove-mentionedperformancetestsareusedtoassessfatiguewithinelitesportsettings,wherelongseasonsandmultipletrainingsessionsoftenpresentplayersinfatiguedstates.Afatiguedstateisnotedas“exhaustionorlossofstrengthand/orendurancefollowingastrenuousactivity”(MedicalDictionaryOnline,2015).MethodsofassessingfatigueandrestorationareexaminedinmoredetailinChapter2.4,withtheirrelevancetoperformanceandspecifictestscommonlyutilisedcritiqued.

2.3.2 FatiguescienceOnenegativeconsequenceofphysicalactivityisfatigue,withexercise-inducedfatigueassessedbymeasuringadecreaseinmuscleforce-generatingcapacity.Fatigueiscommonlyknownasanyreductioninphysicalormentalperformance(Knicker,Renshaw,Oldham,&Cairns,2011)withthemechanismsforfatiguebeingtaskspecificanditsoriginspanningfromthecerebralcortextomusclecrossbridgecycling,asisdisplayedinfigure2.2.Sensationsoffatiguearemarkedlydifferentdependinguponthelengthandintensityoftheexhaustiveexercisebeingconducted.Themostcommonlyreportedcausesoffatigueinclude:energysystemdepletion;theaccumulationofmetabolites;nervoussystemcontrol;andthefailureofthemusclefibrescontractilemechanism(Costill,Gollnick,Jansson,Saltin,&Stein,1973).Thecausesoffatigueandtheirrelationshiptoeliterugbyareexaminedinmoredetailbelow,yetanimportantconsiderationforpractitionersisthatnoneofthesecausesandsitesoffatiguecanexplainallaspectsoffatiguecreated.

Currentliteratureislackinginitsknowledgeofthephysiological,biochemicalandpsychologicalfactorsthatdeterminefatiguepost-physicalexertion.AsreportedbyAbbissandLaursen(2005),whendiscussingmodelsoffatigue,sportsscientistsfromvaryingfieldswillviewfatigueinawaythatbestsuitstheirindividualdisciplines.Apsychologist,forexample,mayviewfatigueasamentaltirednesssensation,whileaphysiologistmayviewfatigueasthefailureofaspecificphysiologicalsystemtoperformatitsusuallevel.Physiologicalmodelscreatedtounderstandexercisefatiguearecommon,yettheirrelevancehasbeencritiquedbyNoakes

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(2000)who,whenassessingadaptationandenhancementofathleticperformance,questionedwhymodelsareunabletoexplainvoluntaryexercisetermination.AscritiquedinChapter2.3.2,themajorityofresearchintofatigueduringexercisehasfocusedupontheabilityofthecardiovascularsystemtoprovideenoughblood,nutrientsandoxygentotheworkingmuscles,ortheabilityoftheenergysystemstore-phosphorylateATPinsidethemuscle(Noakes,2000).Post-exercisethefatigueexperiencedbyathletescanbeneural,mechanicalandmetabolicinnatureandisnotsimplybeingtired;itisacombinationoffactorsthatincludebodilyprocessessuchasthenervoussystem,theautonomicsystem,hormonalsystem,andthemusclesthemselves.Recentresearch(Abbiss&Laursen,2005)hasdiscussedmodelsthatexplainfatigue,withtheproposednon-linearmodelssuchastheCardiovascular/Anaerobicmodel,EnergySupply/EnergyDepletionModelandtheNeuromuscularFatigueModelbeingdetailedinChapter2.3.3.2andinFigures1.1and2.1.Despitesignificantresearchintoexercisefatiguemodels,contrastingviewsexistandarerepresentedinreviewsassessingwelldocumentedfatiguemodels(Abbiss&Laursen,2005;Noakes,2000)andmorerecentlyassessingexerciseregulationandtheinfluenceofcentralcontrol(Noakes,2012;Noakes,Peltonen,&Rusko,2001).Asdiscussedinmoredetailbelow,Noakesetal.(2001)suggestedthatcentralskeletalmuscleactivationiscontrolledalongtheneuromuscularpathwayinordertoprotectvitalorgansfrominjuryanddamage.

Mostimportantly,whenassessingmodelsoffatigue,practitionersmustunderstandthedifferencesbetweenacutefatigue(hydrogenionaccumulationorglycogendepletion)(Jardineetal.,1988)comparedtochronicfatigue,whichmaystillincludesubstratedepletionbutismorelikelytorelatetomuscledamage(Alaphilippeetal.,2012).Bothchronicandacutefatiguearethefocusofthisresearch,withacutefatiguebeingmoreassociatedwithrestorationofperformanceonashorttermbasisduringgames(Lacome,Piscione,Hager,&Carling,2015)(asrepresentedbyreducedrunningperformancewithinrugbyunionmatchplay)andchronicfatiguesymbolisingreducedreadinessofarugbyplayertoperformtotheiroptimalpotentialoveralongitudinalperiod(Alaphilippeetal.,2012).Symptomsofacutefatigueinclude,firstly,physicalfactorssuchasanaccumulationofwasteproductsduetomusclecontractions(Deutschetal.,1998;Dochertyetal.,1988);and,secondly,mentalstressorboredom(Noakes,2012).Acutefatiguetypicallyrecoversfollowingashortperiodofrest(days)andenergysourcerestoration.Recentresearchwithelitesnowboardathletes(Gathercole,Stellingwerff,&Sporer,2015)illustratesCMJasasuitabletoolformonitoringbothacutefatigueandtrainingadaptation.Incontrast,symptomsofchronicfatigueincludegeneralfatiguethatisdisproportionatetotheintensityoftheeffortundertaken(Shephard,2001).Chronicfatiguehasbeenreportedtolastforuptosixmonths,withanegativeenergybalancebeingtheresultanteffect.Inanathleticpopulationchronicfatigueiscommon,butdifficulttodiagnose.Theacutefatigueresultingfromasingletrainingsessionisexpected,yetcanaccumulateoveralongerperiodtotimetocreatechronicfatigue.Thisthoughisnormalduringperiodsofhigh-volumetraining.Practitioners,however,needtobeabletodifferentiatebetweenthisphysiologicalfatigueandmoreprolongedseverefatigue,whichmaybeduetoapathologicalcondition.ThisclinicalapproachwasresearchedbyDermanetal.(1997).

Commonformsofassessingfatigueincludeelectromyography(EMG)andobservationsofcontractilefunctionwithelectrical(nerve)andmagneticstimulation(cortex),wheretheenvironmentwithinwhichtheathleteisexperiencingfatigueplaysaroleinthedepletionofenergysourcesoraccumulationofmetabolites(Rahnama,Reilly,Lees,&Graham-Smith,2003).

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Manyofthefirststudiesassessingfatiguewerelaboratorybasedwhich,asreportedbyGandevia(2001),includedattemptsbyMosso(1904,citedinGandevia,2001)tocomparefatigueinvoluntaryandelectricallyinducedcontractions.FurthertechnicaladvancesinfatigueresearchwereimplementedbyMerton(1954,citedinGandevia,2001),wheredevelopmentofsuperimposedtwitchinterpolationwaskeyinadvancingknowledgeinthearea.Usinganectograph,Mosso(1904,citedinGandevia2001)assessedthedistancemovedbythemiddlefingerwhenliftinga3kgweighteverytwosecondsbeforeandafterinstruction.SimilarresearchbyReid(1928,citedinGandevia,2001)comparedmaximalvoluntarycontractionoffingerflexionandforceproducedbystimulationofthemediannerveattheelbowunderisometricconditions,withReid(1928,citedinGandevia,2001)concludingthatlargeweightscouldbeliftedbyartificialelectricalstimulationandnotvolition,thereforequestioningtheroleoffatigueinterminationofexertiontasks.EvidencefortheinvolvementthatfatiguehasuponmaximaleffortsduringteamsportmatchplaywasnotedbyNagahara,Morin,andKoido(2016),whoshowedhighspeedrunning(asiscommoninmanyteamsportsperiodsofplay)inducedimpairmentofthemaximalvelocitycapabilitiesofplayers(asmeasuredviaspeedtestsbeforeandaftereachhalf)asasoccergameprogresses.Thisresearch,therefore,supportstheviewthatfatigueaccumulatesovertheperiodofmatchplayandthatthisresponsehasaneffectuponthemaximalefforttasksrequiredduringteamsportplay.

Despitetheaforementionedlimitationsoflaboratorybasedfatigueresearch,fatigueassessmentviasimulatedexerciseisoneareaofrecentfocuswithinteamsportresearch.Duetothedifficultyofinvestigatingmuscleactivitythroughoutteamsportmatchplay,laboratorybasedprotocols,withsurfaceEMGusedtocompareelectromyographicactivityduringsimulatedmatchevents(Rahnama,Lees,&Reilly,2006;Thorlund,Michalsik,Madsen,&Aagaard,2008).AswasnotedinChapter2,rugbyunionmatchdemandsinvolvemovementsatvaryingintensitiesandacrossmultipleplanesmeaningthatavarietyofmuscleactivitiesandassociatedfatigueresponsesarecreated.RecentresearchinrugbyunionbyMorel,Rouffet,Bishop,Rota,andHautier(2015)hasshownthatEMGleveldecreasesaftersimulatedscrumsandmauls(respectively20.8±3.2%and12.6±2.5%;p<0.0001),concludingthatagreaterleveloffatiguewasevidentwhencomparedtosprintsandthatalargermetabolicactivity(Bloodlactateaccumulation)alsoexisted(Scrums=7.8±0.6mmol.L-1;Mauls=7.2±0.6mmol.L-1;p=0.0086;Sprints7.1±0.5mmol.L-1;p=0.001).OtherresearchinteamsettingswaspresentedbyThorlundetal.(2008)wherebyquadricepsandhamstringmaximalvoluntarycontraction(28%,p<0.05)andpeakrateofforcedevelopment(-30%,p<0.05)wereaffectedconcurrently,withmarkedreductionsinmuscleEMGfollowingsimulatedhandballmatchplay.Itis,however,importantforpractitionerstonotethatlimitationsexistsurroundingthefatiguecreatedduringasimulatedsituation(e.g.stimulationofisolatedmuscles)orlaboratoryexercisemodels,anddonotrelatedirectlytowhathappensinsportcompetition,asnotedbyKnickeretal.(2011).

Althoughlaboratorybasedmethodsarepreciseandcontrollable,suchmonitoringisnotfeasibleinthe“realworld”teamsportenvironment,whichiswhyassessmentofisometricforceproductionviamoderntechnology(dynamometers)andjumpperformance(forceplateandopticalmeasurement)havebeenusedmorerecentlyinelitesettings.Additionally,itisimportanttoconsiderthatisolatedmuscleexaminationviaEMGdoesnotassessperformanceasawholeandonlydescribesthestateofthatspecificmuscle,thereforenotpresentinginformationupontheathlete’sabilitytoperformatask,andwhetherthischangeinabilityto

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performataskhasaneffectuponsubsequentgameperformance.Recentresearchassessingmonitoringtoolstounderstandfatiguehasusedbothexternalloadquantifyingandmonitoringtools(suchaspoweroutputmeasuringdevices,time-motionanalysis)andinternalloadunitmeasures(includingperceptionofeffort,heartrate,bloodlactate,andtrainingimpulse)(Halson,2014).MethodsforassessingfatigueareexaminedinmoredetailinChapter2.4,withisometricforceproductionandjumpperformanceexaminedinmoredetailinChapters2.4.1.1and2.4.1.2respectively.

Figure2.1:Schematicoffatiguemodels

Fatigueexperiencedduringexerciseisreversiblewithrest(bothshortandlongtermrecovery),withathletesabletomaintainlowerintensityexercisedespiteexperiencingfatigue.Identifyingthesiteoffatigueisacomplexprocess,yetonethatcanprovidepractitionerswithalargeamountofdetailonthespecificconditionofindividualathletes.Aspreviouslymentioned,commonsitesoffatigueincludeglycogendepletionandenvironmentalfactorsthatalteranathlete’sphysiology,suchasheatandhumidity(Costilletal.,1973).Environmentalissues,suchasthese,affectindividualhydrationlevelstherebycontributingtoadisturbanceofhomeostasis.Fatigueduringexercisewasnotedtobeinfluencedbyacomplexinteractionbetweentwocommonlyreportedthemesoffatigue;peripheralandcentral,witharecentstudyinsemi-professionalsoccer(Thomas,Dent,Howatson,&Goodall,2017)notingthatwhilecentralprocessescontributedtowardsthefatigueexperiencedinthedayspost-match,peripheralfatiguewastheprimarycontributortowardstheneuromuscularfatigueexperienced.Central

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andperipheralfatigueisexaminedinmoredetailbelowinChapters2.3.2.1and2.3.2.2andpresentedinFigure2.1.

Muchofthefatigueresearchtodatewithinteamsportshasincorporatedtheassessmentofmuscularfatigue,presentedasaresultofmatches,withevidencefromsoccerbeingcommon(Greig,2008;Rahnamaetal.,2003;Thomasetal.,2017),andresearchfromrugbynotsoprevalent(Duffieldetal.,2012;Ronglan,Raastad,&Borgesen,2006).Thefatigueproducedwithinateamsportsettinghascommonlybeenassessedbycomparingtheforceofmaximalvoluntarycontractionbeforeandafterexercise(Duffieldetal.,2012;Ronglanetal.,2006).TheoriginalmodeloffatiguebyHill(1914)proposedthatperformanceduringexerciseofhighintensitywaslimitedbyskeletalmuscleanaerobiosis,resultinginlacticacidaccumulation.However,theproposedtheoryofHill(1914)hasbeencritiquedanddevelopedandhasledtothe‘‘catastrophetheory’’(Edwards,1983),whichproposedthat“exerciseterminateswhenthephysiologicalandbiochemicallimitsofthebodyareexceeded,causingacatastrophicfailureofintracellularhomeostasis”(NoakesandGibson,2004,p.648).Morerecentcriticismof“catastrophe”modelsoffatiguehasbeennoted,withlittlepublishedevidencesupportingthistheorythatfatigueoccursonlyafterphysiologicalhomeostasisfails.Insteadananticipatoryresponsecoordinatedinthesubconsciousbrainisconsideredtobeamajorcontributortofatigue(Noakes&Gibson,2004;Noakes,Gibson,&Lambert,2005).ArecentareaoffocusinfatigueresearchincludestheserotoninhypothesistheorybyMeeusen,Watson,Hasegawa,Roelands,andPiacentini(2006).Thissuggeststhatanincreaseinratioofserotonintodopamineacceleratestheonsetoffatigue,whereasalowratiofavoursimprovedperformancethroughthemaintenanceofmotivationandarousal.

Figure2.2:SchematicofmusclefatiguemechanismsadaptedfromAbbissandLaursen(2005)

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2.3.2.1 CentralfatigueCentralfatigueisaprogressivereductioninvoluntaryactivationofmuscleduringexercise,resultinginneuralinhibition,meaningthatgreatervoluntaryeffortisrequiredtodriveanymotorunit.Centralfatiguehasbeenknowntomanifestitselfinseveralwaysincludingcentralnervoussystemfatigue,motivationandotherpsychologicalfactors.Inabilitytocontinueexerciseexperiencedbybothrecreationalandeliteathletesoftenoccursdespitefatiguebeingpresentwithinthemusclesthemselves,withpainfromcentralfatigueaffectingcentraldrivetocontinue.However,restorationofforceasaresultofexternalstimulationofmusclefibresindicatesacentralfatigueresponse,asthemuscleisabletocontinueactivitydespitefatiguebeingpresent.Reducedmotorunitfiringratehasbeenreportedduringcentralfatigue,suggestingloweredcentraldrive,yetconflictingevidenceof“musclewisdom”hasbeenreportedbyGarlandandGossen(2002),whereimprovementinperformanceunderseverefatiguehasbeennoted.

Psychologicalfatigueisalsoaconsiderationforpractitionersassessingfatigueduringsportingactivities,asathleteshavebeenknowntolearntominimisetheinfluenceofsensoryefforts,thusenablingthemtoapproachperformancelimitswithintheirselectedsport.Ifanathletereportsasfatigued,itismostlikelythatthisfatigueexperiencedisfromsomesensorymanifestationoftheneuralregulatorymechanisms,ratherthanbeingaconsequenceofaphysiologicalissue.Anotionoftheinfluenceofinhibitorycontrolandanabilitytoresistmentalfatiguewasnotedwithinarecentstudyinprofessionalcycling(Rattray,Argus,Martin,Northey,&Driller,2015),asmeasuredviaStrooptestandatimetrialonacycleergometer.TheeffectofpsychologywithincentralfatiguewasfurtheremphasisedbytheStechnovphenomenon,whichshowedfasterrecoveryofstrengthmeasureswhenimplementingdistractionor“activepause”strategiesduringrecoveryfromexhaustivetasks.WithintheresearchbyStechnovworkoutputappearedtobesignificantlygreaterafteranactivepauseimplementedbetweenexercisebouts,ratherthanafterapassivepause.

2.3.2.2 PeripheralfatiguePotentialphysiologicaloutcomesoffatigueincludereducedmuscleforce,reducedmusclevelocityandpower,aneedforprolongedrelaxationtimeafterfatigueandincreasedEMGasthemusclelookstorecruitmoremotorunits(Kent-Braun,1999).Thesemechanismsareconsideredtobeperipheralfatigue,which,incontrasttocentralfatigue,concernstheperipheralnervoussystem,withfactorsaffectingperipheralfatigueincluding:alterationswithintheexcitation-contractioncoupling(ECC)process;energysupplychanges;andreductioninforcegeneratingcapacity.EvidenceforperipheralfatigueincludesthatbyPetrofskyandLind(1980)showinglargeincreasesinEMGsignalwithnoincreaseinforcepresent.PetrofskyandLind(1980)investigatedEMGsignalinarectusfemorismuscleduringgradedcycleexercise.Thisresearchillustratesthat,athigherworkrates,theEMGsignalincreaseddisproportionatelyasfatiguedeveloped,withthemotorunitsoftherectusfemorisrecruitingadditionalmusclefibresastheworkoutputoffatiguingmusclesdeclined.AdditionalevidenceforperipheralfatiguewasnotedbyKent-Braun,Miller,andWeiner(1993)whenassessingthemetabolicphasesthatoccurduringprogressiveexercisetofatigue.Kent-Braunetal.(1993)useda4sMVCfollowedbya6srelaxationofthetibialisanteriormuscle,ineighthealthyhumanstodemonstratethatthreedistinctphasesofmetabolismoccurduringprogressiveexercise,allrelatedtotheperipheralfatigueresponsecreated.Thephasesincludedahighlyoxidativephase;anintermediatephase;andahighlyglycolyticphase,where,asnotedbyKent-Braunet

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al.(1993)fatiguebecomesnoteworthyduringthesephases.

Twotheoriesexisttoexplainperipheralfatigue;firstly,depletionofenergysubstratesandsecondly,accumulationofmetabolicbyproducts(Abbiss&Laursen,2005;Kent-Braun,1999).Depletionofenergysubstratesinvolvestheexhaustionofbiochemicalproductssuchasadrenosinetriphosphate(ATP),creatinephosphate(CP)andglycogen.Themostcommonformofmetabolicdepletionisphosphagendepletion,wherebyATPandCPdepleterapidly,withCPdepletionresultingintaskfailureduringhighintensityexerciseandATPdepletionpreservedasfatiguedevelops.DuetotherapiddecreaseofCP,itisnowcommonforCPsupplementationwithinmanyelitesportsettings,withmetabolicdepletiondiscussedfurtherinChapter2.5.1.7.Glycogendepletion,asrepresentedbycarbohydrate(CHO)withinmuscle,isanotherareaofinterestforpractitioners,especiallywithinprolongedsubmaximalsportsettingsthatlastlongerthanonehour(Noakes,2002).Withinteamsportsettingslikerugbyunion,intermittentactivitiesareperformedthroughoutgameplayatvaryingexerciseintensities(VO2max),meaningthatglycogendepletionmayoccurmorequicklythanduringsub-maximalsettingssuchasmarathonrunning.

Duetoglycogendepletion,anathlete’sabilitytogenerateATPisimpaired,withtaskfailurecommonatmoderateintensityactivities.CHOandtheeffectofglycogendepletionandpotentialsupplementationusedtodelaythefatigueresponsearediscussedinmoredetailinChapter2.5.1.7.Accumulationofmetabolicbyproductsincludeshydrogenion(H+),calciumcalcification(CA++)andphosphates(Pi),wherethefatiguecreatedislikelytobeacombinationofthebiochemicalproducts,alongwiththespecificconditionsoftheactivityperformed.PiintracellularaccumulationinvolvesATPdevelopingintoADP,duringwhich,whenthecellbufferingcapacityiseventuallyexceeded,acidosisdevelops.AsnotedbyRobergs,Ghiasvand,andParker(2004),inareviewofthebiochemistryofexercise-inducedmetabolicacidosis,lactateproductionisconsideredtobeaconsequenceratherthanacauseofthecellularconditionsthatcauseacidosis.Whenlactateproductionisgreaterthanlactateclearance,accumulationdevelopsandwhere,similarlytoPiaccumulation,inhibitionofphosphofructokinase(PFK),decreasedforceproductionandnauseaareperhapsthemostcommonlyseenresponses.

2.3.2.3 Biochemistryoffatigue

2.3.2.3.1 DepletionandfatiguePerhapsthemostresearchedareaexaminingcausesoffatigueisthatofenergysystems(Kent-Braunetal.,1993;Nicholas,Tsintzas,Boobis,&Williams,1999),althoughtheevidenceforenergysystemfatiguewithinrugbyunionspecificallyislacking.Muscleglycogendepletionisthemostimportantsubstrateforenergyproductioninteamsportsettings(Nedelecetal.,2012)andisamajorareaoffocusforpractitioners(Ortenblad,Westerblad,&Nielsen,2013).Breakdownofmuscleglycogeniscommonlyreportedtowardstheendofsoccergames(Krustrupetal.,2006;Mohr,Krustrup,&Bangsbo,2003),whichinvolvebothaerobicandanaerobicexercise.Muscleglycogendepletion,assessedoverathreegameperiod,wasnotedbyKrustrupetal.(2006),wherebymusclefibres(mean±SEM73±6%)whichwerefullpriortoasoccergame,wererecordedasbeinglower(p<0.05)inglycogenpost-match(mean±SEM19±4%).Itisalsoofnotewithinsoccerresearchassessingglycogendepletionthat,asreportedbyJacobs,Westlin,Karlsson,Rasmusson,andHoughton(1982),muscleglycogenconcentrationwithineightSwedishtop-levelplayerswasabout50%ofthepre-matchvalue

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twodaysafteramatch.Thisillustratestheprolongedaffectthatglycogendepletioncanhaveuponsubsequentperformance.Recentresearchinrugbyleague(Bradleyetal.,2016)has,however,notedthatprofessionalplayersutilise40%oftheirmuscleglycogenstoresduringmatchplay,regardlessoftheamountofcarbohydratesconsumedintheprevious36hours.Thisnotionwouldthereforesupporttheviewthatmuscleglycogendepletiondoesnothaveaninfluenceuponfatiguepresented.Nutritionalinterventionandtheinfluenceuponfatigueinthedayspost-matchareresearchedfurtherinChapter2.5.1.7below.

Phosphocreatine(PCr)depletionhasbeenarecentareaofinvestigationwithinteamsportsettings(Bangsbo,Iaia,&Krustrup,2007;Spencer,Bishop,Dawson,&Goodman,2005).Atexhaustion,ATPlevels,whicharerebuiltbytheuseofPCr,maybedepleted,withathleteslearningthroughexperiencetojudgetheoptimalpacethatensuresthemostefficientuseofPCrandATP.MuscleglycogenistheprimarysourceforATPsynthesisduringteamsportactivities,andtheexperiencesoffatigue,lackofenergyor“emptiness”maybeattributedtomuscleglycogendepletion.Infieldbasedteamsportsettings,evidenceforthecontributionofPCrwasnotedbyGaitanos,Williams,Boobis,andBrooks(1993),whofoundthatduringten6ssprintsPCrcontributed50%oftheATPproductioninthefirstsprintand80%duringthetenthsprint,despiteasignificantdeclineinPPObythefifthsprint.EvidencefromtheresearchbyGaitanosetal.(1993)showsthatthemajorityofPCrre-synthesisisnotcompletewithinshortrecoveryperiods,similartothoseassociatedwiththeintermittentnatureofrugbyunionmatchplaywherepassiverestperiodsareoftennotlongenoughtofullyre-synthesisePCr.

TheinfluenceofglycogendepletionwithinteamsportsettingswasfurtheremphasisedbyNicholasetal.(1999),wheretrainedgamesplayersingestedacarbohydrate-electrolytedrinkduringfifteenminutesofintermittentrunning,witha22%reductioninmuscleglycogenutilisationrecorded,therebyimprovingperformance.Duringnutrient-relatedfatiguebothslowtwitchandfasttwitchmusclefibresareinfluencedbyglycogendepletion,andtheindividualmusclefibresmostfrequentlyrecruitedduringthatexertionaretheonesthatwillbecomedepletedofglycogenmostrapidly.Typicallyduringfootballbasedsports(soccerandrugby),fasttwitchandslowtwitchmusclefibresareused,yetthefasttwitchfibresarerecruitedmorefrequentlyduringhighintensityeffortsandthereforedepletemorerapidlythanslowtwitchfibres.Fasttwitchfibresarealsonotedtohaveagreaterrelianceuponglycogen(Wilmore&Costill,1999).Duetotheabovementioneddepletionmechanisms,thefatiguesensationsexperiencedmayreflectmusclefibres’inabilitytorespondtotheexercisedemands.Refuellingandtheroleofglycogenwithinshortandlong-termrecoveryareexaminedinmoredetailinChapter2.5.1.7,andwheretheinfluenceandrelationshipofrecoveryfromfatiguearecritiqued.

2.3.2.3.2 Metabolicby-productsandfatigueThemostcommonby-productoffatigueislacticacid,withitsoccurrenceoftenappearingduringhighintensitymuscularefforts,asoftenseeninrugbymatchsituations.InresearchbyDeutschetal.(1998)forwardswerenotedtoexperiencehighermeanbloodlactateconcentrationsthanbacks(6.6vs.5.1mmol.l;p=0.063).Thesevaluesaresimilartothosereportedinotherteamsports(Couttsetal.,2009)(5.59±1.78mmol.l),withthegreaterresultantby-productscreatedduringteamsportmatchplayemphasised,whencomparingthesevaluesagainstthosetakenduringperiodsofrest.Atrest,anormalrangeforbloodlactatewasreportedbyGollnick,Bayly,andHodgson(1986)tobe0.5±2.2mmol.l,withsimilarrestvaluespresentedbyMazzeo,Brooks,Schoeller,andBudinger(1986)(0.33±0.01mmol.l).Itis

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important,however,forpractitionerstonotethatthepresenceoflacticacidshouldnotbeblamedforthefeelingsoffatigue(Mann,2007).Insteadtheprocessinvolveslactateaccumulation,resultinginaconditioncalledacidosis,duetoareducedcapacitytobufferhydrogenions.Acidosis,however,doesnotalwaysmeanthatexerciseisvolitionallyterminated,asathleteshavebeennotedtoexerciseatalactateleveleighttimesgreaterthantherestingvalueduringsemi-professionalrugbyleaguematchplay(Coutts,Reaburn,&Abt,2003)(7.2±2.5mmol.l).

2.3.2.3.3 Neuralfatigueandtheexcitation-contraction-relaxationprocessesAnothercommonlyreportedfactorthatmayberesponsibleforfatigueistheroleofanathlete’sinabilitytoactivatemusclefibres.Thisisperhapsthemostcommonmechanismresponsibleforfatigueinthedaysafterarugbymatch,andlieswithintheexcitation-contraction-relaxation(ECR)processes.Theexcitation–contraction–relaxationcyclewithinmusclesinvolvesactionalongthesarcolemmaofthetubularsystem,withrepetitiveexcitationofthemusclefibres,causingaprogressivedecreaseinthetrans-sarcolemmalgradientswithinthetubularsystem,whichmayresultinalessnegativerestingmembranepotentialanddecreasedfibreexcitability(Stephenson,Lamb,&Stephenson,1998).TherearemanystepswithinthecomplexECRcyclethatcanbeseenaspotentialsitesformusclefatigueandarethereforeofinteresttosportssciencepractitionerswhenassessingpostexerciserecoveryrates.AsnotedwithinresearchbyStephensonetal.(1998)itisimportanttoconsiderthattheECRcycleislesslikelytobecompromisedduringrepeatedcontractionsofslow-twitchmusclefibresandinsteaditismorelikelythatfast-twitchmusclefibreswouldreachastateofrigorfirst.Thenotionoflowfrequencyfatigue(LFF)responsecreatedbygameinvolvementassociatedwiththeECRcycle,wasfirstdiscussedbyEdwards,Hill,Jones,andMerton(1977)andsubsequentlynotedinrecentresearchbyMcLeanetal.(2010)tobeamaincontributortofatigueinthedayspost-exercise.BothLFFandhighfrequencyfatigue(HFF)resultinreducedforceproductionwithLFFlastingformultipledaysandHFFusuallydissipatingwithintwohoursoftheendofexercise(Raastad&Hallen,2000).ItisbelievedthattheseLFFresponsesarerepresentedbyperceivedfeelingssuchas“heavylegs”(Taylor,2012),withSSCexercisessuchasverticaljumpingbeingusedtomonitorlonglastinglowfrequencyfatigue.TheroleoftheECRcycleandtherelatedneuromuscularfatigueresearchareexaminedinmoredetailinChapter2.3.3.

InastudybyKent-Braun(1999),assessingcontributionstomusclefatigueinhumansduringsustainedmaximaleffort(fourminutemaximumvoluntaryisometriccontraction),itwasnotedthatapproximately20%ofmusclefatiguewasattributedtocentralfatigueandthattheremainderwasassociatedwithintramuscularfactors.Theseintramuscularfactorsincludemetabolicresponsesfromexercise,whicharecommonlyseeninprolongedlowintensityexercisesituations,wherefailureofECCisareasonformusclefailure.Highintensityexercise,incontrast,involvesaccumulationofintramuscularmetabolitesasdiscussedintheperipheralfatiguesection(Chapter2.3.2.2).Thecontributionofcentralandperipheralfatiguecanbeestimatedusingelectricalstimulatedforcemeasures,EMGandmagneticresonancespectroscopy(MRS).

2.3.3 Neuromuscularfatigue

2.3.3.1 MechanismsofneuromuscularfatigueMusclefatigueconcernsthedecreaseinperformancecapacityofmuscles;usuallyevidencedbyafailuretomaintainordevelopacertainexpectedforceorpower(Enoka&Duchateau,2008).

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AspresentedinChapter2.3.2,musclefatiguecanoccurintwobasicmechanisms:centralandperipheralfatigue.MuchoftherecentresearchinNMFconcernsperipheralfatigue,wherebylocalchangesintheinternalconditionsofthemuscleaffectneuromuscularstatus.NMFhasbeendescribedbyMcLellanetal.(2011b,p.1030)as“anyexerciseinducedreductioninthemaximalvoluntaryforceorpowerproducedbyamuscle,withthetypeofmusclecontraction,intensityanddurationofexercisebeingdeterminingfactors”.ModelsofNMFoftenrefertoareductionintheforceorpowerproductionofamuscle,withfewstudiesexaminingtherelationshipbetweenneuromuscularfunctionandrugby.AsnotedbyCairns,Knicker,Thompson,andSjogaard(2005)thechoiceofmodelutiliseddependsuponthesportinquestion,withsometimesmorethanonemodelbeingneededtoevaluatefatigueresponsespost-exercise.TwomaintheoriesexistaroundNMFincludingthecentralactivationtheoryandtheneuromuscularpropagationfailuretheory(Allman&Rice,2002),yetnoidealmodelthatstudiesNMFexists(Cairnsetal.,2005).AsreportedbyAbbissandLaursen(2005),centralactivationfailuretheoryinvolvesareductioninneuraldrive,whereastheneuromuscularpropagationfailuretheoryseesfatigueasaresultofreducedresponsivenessandconcernsperipheralmechanisms.Thisreducedresponsivenessinvolvestheabilityofthemuscletoproduceforceandislimitedbytheresponseofthemuscletoanelectricalstimulus. Itis,however,importanttonotethattheinformationpresentedonNMFbyAbbissandLaursen(2005)focusedoncyclingandnotonanintermittentcontactsportsuchasrugby,whereeccentricmuscleactionsandbluntmuscletraumaarethelikelycontributorstoNMF.Animportantconsiderationforpractitionersisthatthecentralfatiguecreatedbyexercisecouldbearesponsetoafferentinputfromperipheralorgans,withtheaimofpreventinginjuryordeathandresultinginareductionorterminationofexercise.Centralfatigueandtherelatedcentralgovernancetheoryarediscussedbelowwhenconsideringthementalresponseoffatiguecreatedinteamsportsettings.

Manystudies(McLeanetal.,2010;McLellan&Lovell,2012;Mooney,Cormack,O'Brien,Morgan,&McGuigan,2013;Twistetal.,2012)havefollowedthecommontrendofanalysingNMFthroughStretchShorteningCycle(SSC)exercises,asopposedisometric,eccentricandconcentricmovementpatterns(Hoffman,Ratamess,&Kang,2011;McLellanetal.,2011b).StrojnikandKomi(1998)notedthatNMFmechanismswouldvarybetweensub-maximalandmaximalexercises,meaningthatsportspecifictestsshouldbeadministeredtoassessNMF.Themaindifferencebetweensub-maximalandmaximaltestinginvolvestheintensityoftheexercisesprescribed;meaningthatsub-maximalisoftenpreferredwithintrainingsettingsasnofurtherfatigueisaddedthroughthetestingprotocol.NMFfatigueandassociatedexhaustionexperiencedduringorpostmaximal,ornear-maximal,isometriccontractionsisunlikelytobearesultofgeneraldepletionoftheenergy.InsteadthelikelycauseofNMF,fromaphysiologicalstandpoint,maybethehigh-energyphosphates,especiallyCP.DuringhighintensityexercisethereducedrateofenergytransferfromthestorestotheATPandCPcauseanincreaseinmusclelacticacid.InresearchassessingmusclefatigueinsportbyAsmussen(1979),itwasreportedthatlacticacidproductionwastermedas"fatiguesubstance”.ThisisthereforeanadditionalareaofconsiderationforpractitionersutilisingmaximalNMFassessmentwithinhighintensitysportingactivities.

2.3.3.2 ModelsoffatigueNumerouslinearmodelshavebeendevelopedtoexplainfatigue,withacomprehensivemodelofthephysiologicalresponsestotrainingstimulibeingthefitness-fatiguetheory(Figure2.2).

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Thistheoryinvolvesdifferenttrainingstressesresultingindifferentphysiologicalresponses(Banister,1991).EarlyfitnessandfatiguetheorywasdevelopedbyBanister(1975),whohypothesisedthateachtrainingboutproducedbothafatigueandafitnessimpulse(Calvert,Banister,Savage,&Bach,1976).Calvertetal.(1976)notedthatfatiguedecaysthreetimesfasterthanfitness,hencetheneedforpositivetrainingadaptationtoenhanceperformance.Thefitnessorfatiguecreatedcanpositivelyornegativelyinfluenceperformance,resultinginachangefollowingthestimulusandbeingdependantontherelativelevelsofbothvariables(Chiu&Barnes,2003).Research(Hellardetal.,2006)has,however,proposedthattheBanistermodelisinappropriateforuseinmonitoringthetrainingprocessineliteswimmers,asthe5%ConfidenceIntervals(CI)values(themostusefulparametersformonitoringtraining)werereportedtobetoowide.Thisview,whichquestionstheirrelevanceoftheBanistermodel,isthereforeafurtherconsiderationforpractitioners,whoneedtobesureofitsaccuracyinordertomakeinformedtrainingprescriptiondecisions.

InadditiontothemodelsoffatiguedisplayedinFigure2.1,modelsoffatigueareexaminedinmoredetailinTable2.12.Itis,however,importanttonotethatTable2.12includesmanymodelstoexplainfatigue,butdoesnotexplainfatiguecreatedasresultofmuscledamagefrommatchdemands.AsnotedwithinChapter2.1,thematchdemandsforrugbyunionplayersinvolvesmanycontactsituationswheremuscletraumadamageiscreatedalongsidethemuscledamageaccumulatedduetoeccentricandconcentriccontractions(microtrauma).Onecould,therefore,arguethatamuscledamagemodelshouldbeproposedwhenassessingthepossiblefatiguecausesassociatedwithrugbyunion.Inhibition,duetotheswellingthatcouldoccurwithmuscledamagecreatedbymomentsofphysicalcontactfromtrainingandgames,willaffectneuromuscularstimulationandthereforesubsequentperformancetestresults,despiteplayersperhapsnotpresentingasbeingfatiguedinotherperformancemeasures(Smith,Kruger,Smith,&Myburgh,2008).InthereviewofmodelsoffatiguebyAbbissandLaursen(2005),whichfocuseduponthesportofcycling,theycorrectlyidentifiedTypes1,2and3muscledamagecategories,withType1muscledamageencompassingswellingasaresultofexercise.ThisType1muscledamage,proposedwithintheresearchbyAbbissandLaursen(2005),does,however,notinvolvetraumaexperiencedbybodycontactsassociatedwithmanyteamspotssuchasrugby.Despitesomeresearchshowingtheeffectofdeliberatemuscledamageimposedonanimalsinthelaboratorysettings(Bunnetal.,2004;Rushton,Davies,Horan,Mahon,&Williams,1997),totheauthor’sknowledgetherearenostudiesthathavebeenpublishedinrugbyunionillustratingtheeffectofmuscledamagefromtrauma,ongeneralfatigue.This,though,isunsurprisingconsideringtheethicalissuesthatsurroundallresearchinhumans.

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Table2.12:Exercisefatiguemodelsandthetheoriesassociatedwiththem

Model Theory Additionalpoints

Thecardiovascular/anaerobicmodel

• Performanceisdeterminedbycapacityoftheheartwithtrainingincreasingcardiovascularfitness

• Thehearthasalimitingmaximumcardiacoutputthatisreachedattheonsetofa‘‘plateauphenomenon’’

• Insteadwhentheoxygensupplybecomesinadequate,itisprobablethattheheartbyhumandesignincludescontrolstoprotecttheheartfromeverenteringdangeroussituations

• Thecapacityoftheheartdoesnotlimitoxygenutilisationbytheexercisingskeletalmuscle,thereforethistheoryislimited

• Insteadtheheartreachesthelimitofitspowersearlierthantheskeletalmuscles,anddeterminescapabilityforexertion

• A“governor”existsinthecentralnervoussystem,whosefunctionislikelytopreventthedevelopmentofmyocardialischemia

Theenergysupplymodel • FatigueduringhighintensityexerciseresultsfromtheinabilitytosupplyATPatratessufficientlyfasttosustainexercise

• SuperiorperformanceoccurswhenagreatercapacitytogenerateATPinthespecificmetabolicpathway(s)isdeveloped

• ExerciseisterminatedbyacentralgovernorrespondingtofactorsotherthanskeletalmusclepH

• ATPconcentrationsare‘‘defended’’inordertopreventthedevelopmentofskeletalmusclerigor

• EvidencesuggeststhatcellATPrarelyfallsbelow70%ofthepre-exerciselevel,evenincasesofexercisefatigue

• Peripherallylocatedinhibitionofmuscularcontractioniskeytoexercisecessation

Theenergydepletionmodel

• Theenergydepletionmodelofexerciseperformanceisspecificforexerciselastingmorethan2-3hours

• Thehumanbodyhasalimitedcapacitytostorecarbohydrates

• Fatigueduringprolongedexerciseisassociatedwithdepletionofmuscleglycogenstores

• Theinfluenceofcentral(neural)fatiguelimitingprolongedexercisewhenmuscleglycogenconcentrationsarelowisunclear

• Delayingtheonsetofterminalmuscleglycogendepletionwillaidperformance

Themusclerecruitment(centralfatigue)/musclepowermodel

• Theprocessesinvolvedinskeletalmusclerecruitment,excitationandcontractionisthelimitingfactor

• Reducedcentralneuraldrivetomuscleafterfatiguingmusclecontractions

• Thebrainconcentrationofserotonin(andperhapsotherneurotransmitters,includingdopamine)altersthedensityoftheneuralimpulsesreachingtheexercisingmuscles,therebyinfluencingfatiguerate

Thebiomechanicalmodel

• Thegreaterthemuscle’scapacitytoactasaspring,thelesstorqueitmustproduceandhencethemoreefficientitis

• Themoreeconomicaltheathlete,thefastertheywillbeabletorunbeforereachingalimit

• Reducedtolerancetomusclestretchandadelayedtransferfrommusclestretchtomuscleshorteninginthestretch/shorteningcycle

Thepsychological/motivationalmodel

• Theabilitytosustainexerciseperformanceresultsfromaconsciouseffortandisoftenincludedasacomponentofcentralfatigue

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2.3.4 FactorsaffectedbyfatiguewhichareimportantforperformanceAnathlete’scurrenttrainingstatushasalargeeffectuponthemechanismoffatigueexperiencedduringmatchplay,yetinteractionbetweenmechanismsisoftenseenasamajorcontributor,aswasreviewedinresearchbyKnickeretal.(2011).Datafromrugbyleague(Kempton,Sirotic,Cameron,&Coutts,2013)assessingmatch-relatedfatigueduringeliterugbyleaguematch-play,notedreductionsinphysicalperformancetowardstheendofmatches,followingbriefperiodsofintenseexercise.Kemptonetal.(2013)alsonotedthatmatch-relatedfatigueduringeliterugbyleaguematchplay,showedsignificantreductionsinskillratingandthenumberofinvolvementsobservedinthefinalstagesofmatches,whichmaybeattributabletomatch-relatedfatigue.Withinsoccer,recentresearchbyKrustrup,Zeris,Jensen,andMohr(2010)reportedthatdecrementsindistancecoveredbysprintingandhigh-speedrunningtowardtheendofelitefemalesoccergamesarecausedbyfatigue.DevelopmentoffatigueduringsoccermatchwasalsoexaminedbyMohretal.(2003),withfatiguereportedasoccurringtowardstheendofmatches,aswellastemporarilyduringthegame.Additionally,withintheresearchbyMohretal.(2003)thetop-classplayerswerenotedtoperformbetter(11%;p<0.05;2.26±0.08km)ontheYo-Yointermittentrecoverytestthanthemoderateplayers(2.04±0.06km),despitethetop-classplayersperformed28%and58%more(p<0.05)high-intensityrunningandsprinting.Lastly,withinsoccer,evidencefortheeffectoffatigueupongameperformancewasalsonotedbyGreig(2008),whenassessingisometrictorqueofthekneeflexorsandextensors,withpeakeccentrickneeflexortorquesattheendofthegame(127±25N.m)comparedtothefirstfifteenminutes(161±35N.m,p=0.02).

2.3.5 AssessingfatigueWhenmonitoringfatigue,itisimportanttoconsiderthatfatigueoccursinthenervoussystemandmuscleatvaryinglevels,andtheratesatwhichfatiguedevelopsdependsontheactivityandintensityofthesportcompleted.Neuromuscularfunctiontestsareperhapsthemostcommonlyusedformsofassessingplayerfatigueinteamsportsettingsandinclude:varyingformsofjumptests;plyometricpush-ups;sprintperformances;sub-maximal(suchasheartraterecoverytests)andmaximalperformances;andisokineticdynamometry(Duffieldetal.,2012;Johnstonetal.,2013;Twist&Sykes,2011).Inthisreviewofbestpracticeforassessingfatigue,Taylor(2012)observedthat91%ofhighperformanceprogramsreportedusingsomeformofmonitoring,withthepredominantusagesbeinginjuryprevention(29%),monitoringeffectivenessofthetrainingprogram(27%),maintainingperformance(22%)andpreventingovertraining(22%).Consideringtheresearchabove,whichillustratestheaccumulationoffatigueandincompleterecoverycommonlyseeninrugby,theimportanceoffurtheremphasisonoptimisingpost-matchrecoveryperiodsisnoted,inordertoavoidadditionalcumulativeadverseeffectsongamesandtraining.

Fewstudieshaveusedmonitoringmethodsthatprescribefuturetraining,insteadpreviousresearchhasfocusedonadaptationtotrainingload(Aubert,Seps,&Beckers,2003;Hartwig,Naughton,&Searl,2009)andontheexistenceofovertraining(Halson&Jeukendrup,2004).OnestudythathasimplementedmeasurestoassessdeliberateoverreachinginRugbyLeagueplayersoverasixweekprogressiveoverloadperiod(Coutts,Reaburn,Piva,&Rowsell,2007),notedthatnosinglereliablebiochemicalmarkerwaspresentandalsothattheMultistageFatigueTest(MSFT)testmaybeausefulmeasureformonitoringresponsesinteamsportathletes.Coutts,Reaburn,Piva,andMurphy(2007)concludedthatmuscularstrength;powerandendurancewerereducedfollowingtheoverloadtrainingperiod,indicatingastateof

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overreaching.Restingmeasureofplasmatestosteronetocortisolratio,plasmaglutamate,plasmaglutaminetoglutamateratioandplasmaCKactivitydemonstratedsignificantchangesattheendoftheoverloadtrainingperiod(p<0.05).ThedecreasedperformanceintestssuchastheMSFTand3RMexercises,weremostlikelyaresultofincreasedmuscledamagecausedfromadecreaseintheanabolic-catabolicbalance.LaboratorymethodsforassessingNMFaremorecomplex,moretimeconsumingandmoreinvasivethanmeasurestypicallyusedwithinelitesportsettings.Adirectsummaryoftheathlete’sneuromuscularstatushasbeentheaimofpractitionersformanyyears,withreactiontestsandjumptestsbeingsomeofthemostusedprotocols(Waldronetal.,2011).

Arecentareaofinterestforpractitionershasbeentheuseofsubjectiveindicatorsofwell-beingandelectronicdevicestoassessoverallreadiness,which,whencombinedwithmoretraditionalmeasuresofNMFhavepresentedaddedvalue(Flatt&Esco,2013,2015;Tianetal.,2013).Readiness,assessedbybio-electricalcurrentwhichispainlessandsimpletoadministerisbecominganappropriatealternativeforpractitioners,withdirectelectronicassessmentsofNMFviadevicessuchasCheck,ithleteandOmegawavebeingreadilyused.Subjectiveindicatorsandprofileofmoodstates(POMS)questionnaireshavebeenusedinrecentresearch(Filaire,Bernain,Sagnol,&Lac,2001;Halsonetal.,2002).DespitebeingsensitivefordailyusewhencombinedwithmoretraditionalmeasurestoassessNMF(Schmikli,Brink,deVries,&Backx,2011),theiraccuracyhasbeenquestioned(Grove&Prapavessis,1992).ModernpracticesdesignedconsistentlytoproducevalidneuromuscularstatusutilisingNMFtestingviarecenttechnologicaladvances,arekeyareasoffuturedevelopment.Despitethefactthattheuseofwell-beingandelectronicdevicesthatassessoverallreadinessdonotactuallyassessNMF,thefunctionalstateassessmentthatthesemodernpracticesinvestigateisstillofinteresttopractitioners.Incontrasttoperformancetests,whicharemoreobjectiveinnature,suchfunctionalstateassessmentsdonotinvolveanypotentialinfluenceofathletecomplianceandthereforeparticipantscannotmanipulatedataproduced.RemovinganyobjectivediscrepanciesthatcanbeassociatedwithcommonNMFtestingpractices,suchaslackofmotivationfromathletes,iskey,whenconsideringtheeffectcomplianceissuesofplayerscouldhaveuponresults.

Inacriticalappraisalofmonitoringtoolstoassessrecovery,TwistandHighton(2013)notedthatmatchdemandsofrugbyleagueleadtoimmediateandprolongedpost-matchfatigue,duetoacombinationofmuscledamageandsubstratedepletion.Whenassessingperceptualmeasures,biochemicalmarkersandmuscularfunction,TwistandHighton(2013)notedasimplemeasureofmusclefunctionsuchasjumptestingtobethemostpracticalandappropriatemethodofdeterminingtheextentoffatigueexperiencedbyrugbyleagueplayers.ReducedperformanceduringpeakkneeextensiontorquetestingwasreportedtobeprolongedbyTwistandSykes(2011)forupto48hourspostsimulatedrugbyleaguegame;withWestetal.(2014)alsoreportingprolongedperformancereductionwhenassessingpeakpoweroutputfromCMJforupto60hourspostrugbyuniongame.DespitethefactthattheresearchbyTwistandSykes(2011)incorporatedmanymeasuresofperformance(perceivedmusclesoreness,CreatineKinase[CK]activity,isokineticstrengthandjumpheight)theRugbyLeagueMatchSimulationProtocol(RLMSP)involvedwithinthisstudyalongwiththelowplayingleveloftheparticipants,makethisresearchlimitedinvaluetoothereliterugbyunionresearchers.TheresearchbyWestetal.(2014),bycontrast,incorporatedassessmentofprofessionalrugbyunionplayerspostrealmatchsituationsandinvolvedtheuseofsalivaandforceplatetesting

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(lowerbodypeakpoweroutput).Resultsshowed,reducedNMFandhormonaldisruptionat36hourspostmatch,beforerecoveringat60hourspost-match,whileself-perceivedreductioninmoodwasnotedtohaverecoveredby36hourspost-match.Itis,however,importanttonotethatthedifferingtimepointassessmentsandmethodologicalinvolvementmentionedabove,withinthesetwostudies,couldperhapsexplainthedifferencesrevealed.RegardlessofthemethodusedtoassessNMF,itisimportanttonotethatheavytrainingofthelowerbodyhasbeenadvisedtobeavoidedinthe48hoursafterarugbyleaguegame(McLellanetal.,2011b).ThereliabilityofNMFtestingisdifficulttoascertain,asnostudyhascomparedmethodsacrossresearch,meaningthatcomparisonsbetweenresearchandresultsarelimited.

2.3.6 FatigueandrugbyResearchonplayerfatiguelevelsinrugbyiscommonlyreported(Alaphilippeetal.,2012;Kemptonetal.,2013)andtheassociatedphenomenonofburnoutisaconcernwithinthemoderngame(Cresswell&Eklund,2006).Withinrugbyunion,themyriadoffactorsthatcaneffectfitnessorfatigue(minutesplayed,injury,weatherandplayingstyle)createdbytrainingandgames,meansthattheBanistermodelisunlikelytobeaccurateandpotentiallydifficultforpractitionerstocontrol.FatigueisoftenrepresentedbytheinabilitytomaintainforceorpoweroutputattherequiredlevelandasnotedbyHalson(2014),fatigueismultifacetedinnatureandcanbeinfluencedbythetypeofstimulus,contraction,duration,frequencyandintensityoftheexercise.Duetotheseactivitiesandthelargevolumesofactivityfrombothtrainingandgamesoverthecourseofaplayingseason,rugbyplayersbecomefatigued(Argus,Gill,Keogh,etal.,2012;Cresswell&Eklund,2006;Fuller,Brooks,Cancea,Hall,&Kemp,2007).ThemostcommonlyusedfatiguemodelsandthetheoriesthatsurroundthemarereviewedinTable2.12,withnotestakenfromNoakes(2000).Whenconsideringthemodelsabove,itisclearthatallthemodelscontributetothefatigueresponsedevelopedfromexerciseandthat,withinrugby,afatigueresponseislikelytobecreatedbyacombinationofallmodelscritiquedabove.

UncertaintyexistsaroundtheinfluenceofrugbyspecificimpactsandmuscledamageonacuteNMFandassociatedrecoverypost-matchplayinrugbyunion.Todate,themajorityofresearchinrugbyunionandplayersreadinesshasfocuseduponmovementpatternsduringgames(Cahilletal.,2013),trainingworkload(Casamichana,Castellano,Calleja-Gonzalez,SanRoman,&Castagna,2013)andperformancefatiguemarkers(Coutts,Reaburn,Piva,&Rowsell,2007;Coutts,Slattery,&Wallace,2007)allofwhichwouldbetterprescribefuturetraining.AsseeninthestudybyMcLellan,Lovell,andGass(2011a),PRFDonaveragewas12653N.s-1acrossrugbyleagueplayers24hourspre-gameandonaverage9379N.s-124hourspost-match.Similarly,McLellanandLovell(2012)notedreductionsinpeakpowerof-10%forupto24hourspostrugbyleaguegame,beforerecoveringat72hours.Additionally,inanotherstudyassessingrugbyleagueplayers(McLeanetal.,2010),CMJflighttimeandrelativepowerweresignificantlyreducedinthe48hoursfollowingthematch.McLean(2010)reportedthatCMJvariablesreturnedtonearbaselinevaluesfourdaysaftermatches,whileWestetal.(2014)notedpeakpowermeasuredviaCMJrecoverednosoonerthan60hours(-7%for36hours).McLeanetal.(2010)notedthatdayoneCMJflighttimemeasuresweresignificantlylowerthandayfour(p<0.01,d=−1.06)andthedaybeforethematchattheendofthetrainingmicrocycle(p<0.05,d=1.06),withWestetal.(2014)notingNMFassessedbyCMJoutlastingmooddisturbancespostrugbyunionmatch.McLeanetal.(2010)notedthatCMJvalueshavebeenshowntobereliableandusefulindetectingLFFinteamsportathletes,withthisnotionsupportedbymanyotherresearchers(Cormack,Newton,McGuigan,&Cormie,2008;Cormack,Newton,McGuigan,&

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Doyle,2008).Itis,however,importanttonotethattheloadprescribedforCMJneedstocarefullyselected,asunderaloadLFFislessinfluencedduetotherelationshipthatexistsbetweenloadliftedandRFD(McLellan,Lovell,&Gass,2011d).

ResearchbyFowles(2006)showedCMJflighttimetobesensitivetoacutefatigueandCMJrelativepowertobemoresensitivetoaccumulatedfatigue.ThisnotionwasalsosupportedbyJohnstonetal.(2013),whonotedincreasedType2musclefibredisruptionandtheresultantchangesintheforce-velocityrelationship.Contrastingresultsdo,however,existshowingalackofsensitivityofjumpheighttofatigue(Cormack,Newton,&McGuigan,2008;Coutts,Reaburn,Piva,&Rowsell,2007).Itisimportantforpractitionerstonotethatmovementwithminimalloadingonthemuscles,suchasaCMJperformedatbodyweight,maybeimpairedtoalesserextentthanthosethatinvolvemaximalloads,suchasisometricstrengthtests,whichrelyonmaximalforceproductioninstead,asreportedbyTwistandSykes(2011).PrescriptionofCMJasatestingmeasuredoes,however,havelimitations,includingtechniqueandapparatusused(Glatthornetal.,2011;Markovic,Dizdar,Jukic,&Cardinale,2004).However,thisnotionthatCMJtestingisanunreliablemeasureforfatiguetestingwasdisputedbyTwistandSykes(2011)andsupportedbyotherresearch(Hamilton,2009;McLellan&Lovell,2012),whichshowedjumpingactivitiestobereliableandaccurateindeterminingneuromuscularfatiguepost-matchsituationsandinaidingthefatigue-recoverycycletimeline.JumptestingiscritiquedinmoredetailwithinChapter2.4.1.2,showingitsrelevanceasaperformancetestandasameasureoffatigue.

Accumulationoffatigueandincompleterecoverypostrugbygamehasbeenreportedbymanyauthors(McLeanetal.,2010;McLellan&Lovell,2012;Westetal.,2014),withneuromuscularfunction,biochemical,endocrineandperceptualmeasuresusedasmarkersoffatigue.Despiteavastamountofresearchuponfatiguepost-match,fewstudieshaveresearchedtheefficiencyofmethodsformonitoringrestorationofperformanceandoverallrecoverybetweengamesineliterugbysettings,whereplayersarecompetingonaweeklybasis(Taylor,2012;Twist&Highton,2013).BothMcLellanandLovell(2012)andMcLeanetal.(2010)utilisedCMJasatestofNMF,reportingcompromisedvalues(flighttime,peakpower,peakrateofforcedevelopmentandpeakforce)forupto48hourspost-match.Similarly,Westetal.(2014)notedreducedNMFinconjunctionwithhormonaldisruption,forupto36hourspost-match.CumulativefatigueoveraseasonhasalsobeenreportedbyGill,Beaven,andCook(2006)andwasillustratedbytheelevatedCKlevelspre-match.AlthoughvaryingdegreesofmuscledamagecanalterCKlevels,residualfatiguecarriedoverfromthepreviousmatchandthetrainingschedulethatfollowedthatmatchcanalsohaveaneffectuponthemuscledamagepresentandtheassociatedCKlevelsreported.Oftenthroughouttrainingweeks(microcycles)inteamsports,playersarerequiredtoreturntotrainingintheimmediatedayspost-match,asthepreparationforthenextmatchneedstocommence,yettheconsequenceofthesetrainingsessionsareanimportantconsiderationforpractitioners.Trainingstresscannotbeunderestimated,consideringtheevidencethatatypicallyusedstrengthandpowersessionresultedinreducedNMFfor48hourspostexercise(Geeetal.,2011),representedbyreducedCMJheight(3-10%)andincreasesinCKlevels(2hours:210±57U/L,24hours:413±205U/L,48hours:205±50U/L)comparedtobaselinelevelsbaseline(145±54U/L).

Significantcorrelationshavebeenreportedbetweenthetotalnumberofsevereimpacts(>10.1G)thatrugbyplayersareexposedto,theirpeakrateofforcedevelopment(PRFD)andtheirpeakpower(PP)valuespost-match(McLellan&Lovell,2012),withTwistandSykes(2011)

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showingevidenceofexerciseinducedmuscledamage(EIMD)forupto48hourspostsimulatedrugbyleaguegame.McLellanandLovell(2012)assessedtwenty-twoelitemalerugbyleagueplayers,overeightgames,usingGPStechnology(preandpost-game),inordertocomparechangesinvariableswhenassessingneuromuscularresponsestoimpactandcollisionsduringmatchplay.DatafromthestudybyMcLellanandLovell(2012),demonstratedthatneuromuscularfunctioniscompromisedforupto48hourspost-match,indicatingthatatleasttwodaysofmodifiedactivityisrequiredtoachievefullneuromuscularrecoveryaftereliterugbyleaguematchplay.Similarly,researchwithinrugbyleaguebyJohnstonetal.(2013)reportedthatcumulativefatiguefromrugbyleaguematchesresultsincompromisedhighspeedrunning,accelerationsandtackling,thusillustratingtheintensityofgames.TheresearchbyTwistandSykes(2011),incontrasttobothMcLellanandLovell(2012)andJohnstonetal.(2013),assessedmuscledamagepostsimulatedmatchsituationusingdifferingmeasuresofneuromuscularfunction(CKvaluesandkneeextensortorque).Theyperceivedsorenessmeasures,andsuggestedrecommendationsforadaptedtraininginthe48hoursfollowingagame.Resultsfromasimilarstudyinrugbyunion,assessingneuromuscularfunctionthroughoutaseason,showedanincreaseinCKlevelsduringthefirstthreetofiveweeksoftheseason,followedbyastabilisation(Alaphilippeetal.,2012).Withinanotherrugbyunionstudy,assessingchangesinstrengthandpowerthroughoutthecompetitivephaseofaseason(Argusetal.,2009),itwasnotedthatdecreasesinpowerwereduetocompromisedphysicaldevelopmentcausedbyfatiguefromweeklycompetitionandtrainingstress.

DatafromAlaphilippeetal.(2012)andArgusetal.(2009)demonstratetheneedforregularmonitoringofbothbiochemicalandneuromuscularmarkers,inordertoenableeffectivemanagementoffatiguethroughoutacompetitiveseason.Thedifferencebetweenphysical,biochemicalandendocrinetime-courseofrecoverypostrugbygame,havebeenillustratedbyresearchpresentedbyMcLellanetal.(2011b),whichnotedthatthebiochemicalmarkersdonotreflectthechangesinperformanceoverthesametimeperiod.Inaddition,positionaleffectuponrestorationtime-course,wasnotedinastudyassessingphysicaldemandsofrugbyunionandtheassociatedfatigue(Mashiko,Umeda,Nakaji,&Sugawara,2004b),whereitwasnotedthatbothphysical(biochemicalmarkers)andmental(ProfileofMoodStatesPOMS)measuresdifferedpost-matchandacrossplayingpositions.ThisresearchbyMashiko,Umeda,Nakaji,andSugawara(2004a),however,onlyinvolvedthirty-sevenuniversitystandardplayers,postasinglegame,thereforelimitingitsrelevanceandcomparabilitytoeliterugbyunion.

Consideringtheaforementionedpositionaldemandsinvolvedinrugby(backsandforwards)andthedifferencesinfatigueresponse(EIMD,reducedfunctionalperformancemeasures),post-matchareofnosurprise.AsreportedbyMashikoetal.(2004b),rugbyunionbacksdisplaymovementpatternsthataremorefocusedonhighspeedrunningandtackling,comparedtorugbyunionforwardswhotakepartinrunning,tacklingandanelementofmaulingandscrummaginginvolvingphysicalcontact.Althoughdatatakenfromrugbyleaguecannotbedirectlycomparedtorugbyunion,itisofinteresttonotethatTwistetal.(2012)reportedthatforwardsshowedgreaterperceptionofmusclesorenessintheimmediatetwodayspost-matchwhichcouldbeexplainedbythegreaternumberofcontactsexperiencedbyforwards.Similarly,asreportedbyMashikoetal.(2004b),theblunttraumaassociatedwithforwardplaymayproducelongerlastingmuscledamagethanthatexperiencedfromeccentricactions,whichbackswouldbemorelikelytoencounter,duetotheirgreaternumberofdecelerationsandaccelerationscompletedwithingamesituationscomparedtoforwards(Twistetal.,2012).

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Whenconsideringthefactthatforwardsplaylesstimeandcoverlessdistancethanbacks(yetexperiencelongermuscledamage),thedamagingeffectofthebluntforcetraumathatforwardsexperienceisfurtheremphasised.Recentdatafromrugbyunion(Jonesetal.,2014),supportstheviewthatthenumberofimpactsencounteredduringamatchrelatespecificallytothelevelsofmuscledamage(CK)experienced.Additionally,Jonesetal.(2014)reportedthathighspeedrunningwasapredictorofmuscledamageforbacks,withtailoredindividualrecoverystrategies,baseduponimpactsandhighspeedrunningdataderivedfromGPS,beingofinterest.

Theresearchassessingmuscledamagepostrugbyinvolvement(Mashikoetal.,2004b;Takarada,2003;Twistetal.,2012)isofsignificantrelevancetopractitionersanditcouldbearguedthattailoredrecoverystrategies,baseduponpositionaldemands(utilisingGPSdata),wouldprovideabetterunderstandingoffatiguepost-match.Itisalsoofnote,inthestudybyTwistetal.(2012)inprofessionalrugbyleague,thatbackspresentedgreaterdecrementinperformancecomparedtoforwards,whenassessingchangesinCK,perceptualandneuromuscularfatigueforupto48hourspost-match.Datafrompreviousresearch(Cunniffeetal.,2010;Smart,Gill,Beaven,Cook,&Blazevich,2008;Takarada,2003),alsoreportedpositivecorrelationsbetweenthenumberoftackleinvolvementsduringarugbyunionmatchandCK,suggestingthattissuedamageisproportionaltothenumberofbodycontactsaplayerexperiencesandthereforerelatedtopositionplayed.FurtherevidenceofmatchcontactsexperiencedandresultantfatiguewasnotedbyTwistetal.(2012),wheretotalcontactsforforwardswasreportedtocorrelatewithallmarkersofpost-matchfatigue(p<0.05)(r=musclesoreness0.62;perceivedfatigue0.69;CK0.74;jumpflighttime-0.55),butonlyflighttimewascorrelatedwithoffensivecontactsinbacks(p<0.05)(r=0.54).

Decrementinperformancemeasures(CMJflighttime)forbackscomparedtoforwardscouldbeassociatedwiththemuscledamagecommonfromeccentriclengtheningactionsandtheeffectthishasuponthestretch-shorteningcycleutilisedinjumptestingprotocol.ALFFmeasurement,hasbeennotedasanimportantvariableinmeasuringNMF(Fowles,2006),withthecausesofLFFbeingdifferenttothatofHFF.LFFiscommonlyseenpostheavytrainingperiodsandinvolvesimpairmentinexcitationcontractioncoupling,duetomicroscopicmuscledamagefromeccentricmuscleaction,asopposedtoHFF,whichinvolvesimpairedactionpotentialpropagationoverthesarcolemma(Jones,1996).Whenassociatedwithinagamecontext,LFFistypicallyillustratedbyreducedjumpperformanceinbacksandmaybeduetotheincreasednumberofaccelerationsanddecelerationsinvolvedinbacks’play,comparedtoforwards.However,Twistetal.(2012)arguedthatmoredecelerationscouldbeseeninforwardsduringgamesastheyapproachcontactsituations,comparedtobacks,whowouldexperiencelesscontactsituations.DespitethequantificationofdecelerationsintocontactnotbeingcategorisedwithinthemethodologyproposedbyTwistetal.(2012),thisisanareathatwarrantsfurtherinvestigation.Thesignificantlygreater(p<0.05)numberofcontactsforforwardscomparedtobacks(38.2±18.7;25.2±8.0),couldhavebeenattributedtoincreasedmuscledamageandperceptionoffatigue.Theresearchpresentedabovehighlightstheimportanceoflookingattherelationshipsbetweenhighlevelimpacts≥7Gratherthantotalimpacts,asthemuscledamageresponsecreatedfromimpactsarelikelytobepredominatelyasaresultofhighlevelimpacts.Impacts,therefore,aboveacertainlevelcouldactasmeasurementtoolforfutureresearch.However,thereliabilityandprotocolinvolvedinutilisingGPSimpactsasamonitoringtool,usedtoguidetrainingprescriptioninpost-matchsituations,alsoneedsfurtherexamination.

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2.3.7 RestorationofPerformanceResearchshowingincompleterestorationbetweenboutsofexerciseisvast,withRonglanetal.(2006)observingreduced20msprinttimeandCMJperformanceduringahandballtournamentandKraemeretal.(2001)notinginsufficientrestorationofmaximalstrengththroughoutawrestlingtournament.Plannedperiodisation,withoutconsiderationforrestorationofperformanceandtestingoftime-courseofrecoveryislikelytoputplayersatriskofsub-optimalperformance,ormoreseriouslyinjury.Rugbyunionhasbeenreportedtoinvolvebothintenseanaerobicexercise,interspersedwithlowerintensityboutsofaerobicexercise(Cahilletal.,2013).Duetotheseactivitiesandthelargevolumesofactivityfrombothtrainingandgamesoverthecourseofaplayingseason,rugbyplayersbecomefatigued(Argus,Gill,Keogh,etal.,2012;Cresswell&Eklund,2006;Fulleretal.,2007).

InresearchbyGilletal.(2006),assessingtheeffectivenessoffourrecoveryinterventionsupontherateandmagnitudeofmuscledamagerecoveryoftwentythreeeliterugbyplayers,itwasnotedthatmuscledamagewascarriedoverfrompreviousgamesand/ortraining,asrepresentedbyCKlevels,withincreasedlevelsoffatiguepresentastherugbyseasonprogresses.AsalsonotedbyGilletal.(2006),thegreatestphysicalstimuliofarugbyplayersweekisfrequentlythematch,althoughhightrainingloadscombinedwithmatchexertionsandinsufficientrecoveryinrugbyhavebeenreportedwhichoftenpushplayersintostatesofoverreaching(Coutts,Reaburn,Piva,&Murphy,2007).Theneedtorecoverbetweengamesandtorestoreperformancepriortosubsequenttrainingsessionsintheinterveningperiodsisofmajorimportancewithinprofessionalteamsports.Theriskofinjuryorsub-optimalperformance,resultingfrominsufficientrecoveryarepointstoconsiderforpractitioners,whilealsoconsideringtheaccumulationoftrainingand/ornon-trainingstress.AsnotedbyKreideretal.(1998),overreaching(OR)isanaccumulationoftrainingand/ornon-trainingstress,resultinginashorttermdecrementinperformancecapacity,inwhichrestorationofperformancecapacitymaytakefromseveraldaystoseveralweeks.Anaccumulationoftrainingstress,ifmanagedproperly,willhaveapositiveeffectupontheathlete.However,ifmanagedpoorlyandinsufficientrecoveryoccurs,overreachingcandevelopintothemoreseveretrainingresponsephenomenonofovertraining.

Long-termdecrementinperformancecapacityistheresultofimbalancebetweentrainingandrecovery;thisisknownasovertraining(OT).OTliesattheendofthetrainingstresscontinuum,andoccursiftrainingisnotprescribedaccordingtotherecoveryrequirementsofathletes(Halson,LancasterJeukendrupandGlesson,2002).Stressonathletes’bodiesinteamsportsisoftenmorefrequentlyaccumulatedbygamesituationswhereplayersareaskedtocompeteonaweeklybasis.AshypothesisedbyTwistetal.(2012),fromtheirpost-matchfatigueresearchinrugbyleague;teamsportpractitionersshouldpayspecificattentiontothe24hourspost-match,asthisisthemostchallengingperiodintermsoftrainingprescriptionbetweengames.OTandoverreachinghasbeenrecognisedasasignificantprobleminmanysports,includingrugbyunionandhasbeenregularlyresearched(Coutts,Reaburn,Piva,&Murphy,2007;Coutts,Reaburn,Piva,&Rowsell,2007;Halson&Jeukendrup,2004;Wallace,Slattery,&Coutts,2009).Applyingtheappropriatetrainingvolumepresentsamajorproblemformanycoachesaimingtoachieveoptimalsportingperformancewiththeirathletes.MorerecentdiscussionofOT(Lewis,Collins,Pedlar,&Rogers,2015),hasraisedthenotionofunexplainedunderperformancesyndrome,yetnoresearchtosupporttheirviewscurrentlyexists.Thetermunexplainedunderperformancesyndrome,relatedtoaperiodofunexplained

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underperformance,wherebyfatigueispersistentandmaladaptationtothetrainingprogrammesimplementedlikelytohaveoccurred.Itcouldbearguedthatitisperhapsunlikelythatthisnotionofunexplainedunderperformancesyndromewouldbeexplainedinthenearfuture,asdespiteitsrelevancetothemorecommonlyresearchedphenomenonofOT,theexactnatureofthissyndromeisunknown.UnexplainedunderperformancesyndromeisexpectedtoinvolvemanyofthemechanismsandlikelycausesassociatedwithOT,yetthemultifactorialnatureoftheconstructtowhichunexplainedunderperformancesyndromeinvolvesmeansthatitcannotbeexplainedbyanimbalancebetweentrainingandrecovery.

Whenassessingactivitiestobeperformedinthedayspostrugbymatch,TwistandSykes(2011)discussedthatactivitiesperformedshouldbeselectedcarefully.TwistandSykes(2011)notedthatresistancetraining,involvingmaximalstrengthemphasis,shouldbeavoidedinthe48hourspost-match,asthishasbeenreportedtoincreasechancesofinjury.McLellanetal.(2011b)did,however,noteintheirstudyofrugbyleagueplayersthatPRFDvalueswereacceleratedpost-match,whenresistancetrainingwasimplementedinthedayspost-performance.PRFDiscommonlyusedasmeasureofexplosivestrength.Whentestingfatiguefollowingagameofrugbythatinvolvesmanyactivitiesofanexplosivenature,PRFDisthereforeconsideredanappropriatemeasuretomonitorfatigueinrugbyspecifically.AreductioninPRFDpost-matchsituationsinteamsportshasalsobeenreportedinsoccer(Thorlund,Aagaard,&Madsen,2009),yetnotinastudybyHoffmanetal.(2011)involvingAmericanfootballplayers.McLellanetal.(2011b)notedthatthesecontrastingPRFDvalues,notedbyHoffmanetal.(2011),maybeexplainedbythereducedtotalnumberofcontactsandtheprotectivepaddingworninAmericanFootball.Inrugbyleague,significantNMFhasbeenreportedtobehighlydependentuponthenumberofheavycollisions>7.1G(McLellan&Lovell,2012).

2.3.8 RecoveringfromteamsportactivitiesFatiguecanbebothshortterm(recoveringwithinhoursordaysofexertion)orlonger-term,wherelongertermfatigueisconsideredabnormal.Distinctdurationalphasesoffatiguehavebeennotedbymanyauthors(Halson&Jeukendrup,2004;Meeusenetal.,2013;Schmiklietal.,2011;Tianetal.,2013),withvarioustheoriesdiscussed,includingfunctionaloverreaching(FOR),non-functionaloverreaching(NFOR)andOT.FORcanbeconsideredarequiredpracticeforinducingadaptationwithintheathlete(plannedandmanagedbythecoach)andiscommonplaceinmanyelitesportsettings.NFOR,bycontrast,involvespoormanagementoffatiguelevelsandwhenoccurringneedsanalterationoftrainingloadandtrainingplansoasnottoinduceanyfurthernegativeadaptation.OTSdevelopswhenlong-termdecrementinperformancecapacityexistsasaresultofimbalancebetweentrainingandrecoveryandisaconsequenceofnotreactingtoNFORsignals.Duethemultifacetednatureoffatigue,itsmonitoringormeasuringiscomplex,meaningthatprovidingaccuratereasonsforchangesinperformanceorassessingathletereadinessaredifficult.Manycoachesmonitorloadretrospectively,notonlyinordertoassesstheload-performancerelationship,butalsotoenablefutureplanningandtherebyreducetheriskofinjuryandNFOR.

Recoverypost-exercisecoversmanyfacetsofperformanceandisabroadtermreferringtorestorationofperformancecapacity,oftenwithbothshort-termandlongtermprocessespost-exercisereferredtoasrecovery.Afteraworkoutoneisfatiguedandperformancecapacityisreduced,andinthehoursanddaysaftertheworkoutone“recovers”withperformancecapacity

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returningtonormalwithinthisshort-termtime-course.Thetime-courseofrecoveryassociatedwithatrainingsessiondependsonmanyfactors,includinghowhardtheworkoutwas,with,intensity,duration,playercapacityandenvironmentalfactors,suchasaltitudeandheat,playingmajorrolesinthespeedatwhichplayersreturntopre-performancevalues.Acuteorrapidrecoverypost-exerciseisdifferentfromlong-termadaptationandassociatedfitnessfatiguemodels,withlong-termadaptationreferringtotheimprovementsinthemuscleandcardiovascularsystemthatwillultimatelyresultinimprovementsinperformance.Oftenresearchdiscussingrecoveryreferstorapidrecoveryinthehoursafterexerciseandsometimesreferstothelonger-termeffects.Bothshortandlongtermrecoveryarelinked,buttheyarenotthesame.Short-termrecoverytypicallylastsfor2-3mins,involvingrapiddeclineofVO2maxandbeingmorerelatedtointensityofexerciseratherthanduration.Duringshort-termrecoveryanelevatedmetabolicrateispresent:toreducecorebodytemperature;provideO2forenergycost;replenishglycogenandremovelactate.Thisresearchinvestigatesthelonger-termperiodofrecoveryinteamsportathletesbetweengamesandacrossplayingseasons,therebyexaminingrestorationofperformancetime-courseandperformancemarkersthatcanbeusedtoassessthislongertermrecoveryperiod.

Withinteamsportsettings,perhapsthemostimportantaspectofathletepreparationduringacompetitiveseasonisrecoverybetweenweeklygames,withtheextentoftherecoveryrequiredbeingdeterminedbythevolumeandmechanismsexperienced.ThemechanismsofEIMDcanbemechanical,metabolicoroxidative,withallofthesemechanismsevidentwithinacontactsportlikerugbyandduetobluntforcetrauma,distancescoveredandaccelerationanddecelerationsencountered(Alaphilippeetal.,2012;Johnstonetal.,2013;McLeanetal.,2010;McLellan&Lovell,2012;McLellan,Lovell,&Gass,2010;McLellanetal.,2011a,2011b;Twist&Sykes,2011;Westetal.,2014).ThemetabolicandmechanicalcostscreatedbyEIMD,meanthatmuscularfunctionisimpairedforupto48hours,yetthestressexerteduponmusclesisconsideredtobeanimportanttriggerrequiredforadaptationtooccur(Twist&Eston,2009).RecentresearchbyMinettandDuffield(2014),assessingtheroleofbothcentralandperipheralfactorsaffectingrecovery,suggestedthatthepotentialforotherdriversofrecoveryoutsideofperipheralfactors(muscledamageormetabolic)couldbeofsimilarimportance.Despitetheroleofthebrainasacontributortoneuromuscularrecovery(asrequiredfollowingcompetitionandtraining)remainingunclear,theelementsassociatedwithcentralfatigueareobviouswhenconsideringtheinfluenceofCNSinmotorunitrecruitmentduringexercise.Itisagreedthatmuchofthereductionofperipheralfatiguefromrecoverystrategiesisattributedtorecoveryofthebrain(Gandevia,2001),withapsychobiologicalmodeldiscussedbySmirmaul,Bertucci,andTeixeira(2013),whenassessingthepaucityofVO2maxtestingbeingmaximal.Practitionersareadvisedtoconsiderrecoverytobeamultifacetedprocess(DePauwetal.,2013).However,currentmethodsofassessingneurophysiologicalmeasures[computedtomography(CT),magneticresonanceimagingscan(MRIS)andelectroencephalography(EEG)]limititsappealforpractitionersintheelitefield,duetologisticalandbudgetrestrictions.Developinganunderstandingthatpost-exerciserecoverypracticesshouldnotsolelyfocusuponperipheralmechanismsoffatigueiskey.Furtherresearchintheareaofrecoverystrategiesthatimpactthebrainareneededtounderstandbettercurrentmethodsthatwouldminimisebrainfatigueandultimatelyimproveperformance(Minett&Duffield,2014).

Kellmann(2002)describedrecoveryasthecompensationoffatigueand/ordecreaseinperformancethatisatendencytostabiliseintheinternalenvironmentoftheathlete.Recovery

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isatermusedtodescribebothpositiveandnegativeadaptationstotheworkloadsthatathletesareexposedtofromtrainingandcompetition.Positiveadaptationinvolvesrestorationandregenerationofbothphysicalandpsychologicalcapabilities,whereasnegativeadaptationinvolvesafailuretorecoverfromtrainingandcompetition.Practitioners,inboththeeliteandamateurfields,needtohelpathletescreateahealthybalancebetweentraininghardandrecoveringwellinordertoensureoptimalperformance.Theprincipleofrecovery(fromasinglesession)asdisplayedinFigure2.2isconsideredoneofthebasicsoftraining,yetisonethatisoftenignoredbyathletesandcoaches(Rushall&Pyke,1990).Recoveryandadaptationfromexerciseareessentialforoptimisingperformance,withadaptationconsideredtobetheprocessofadjustmenttoaspecificstimulus.Repeatedstimuliareimplementedwithinateamsportathlete’sseasonandperiodisationisamethodforemployingsequentialorphasicalterationsintheworkload,trainingfocus,andtrainingtaskscontainedwithinthemicrocycle,mesocycle,andannualtrainingplan(Baker,1998).AsreportedbyBaker(2007),aperiodisedtrainingplanwithinteamsportsencompassesaproperlydesignedframeworkforappropriatetraining,sothattrainingtasks,content,andworkloadsarevariedatamultitudeoflevelsandinalogical,phasicpatterninordertoensurethedevelopmentofspecificphysiologicalandperformanceoutcomesatpredeterminedtime-points.

Figure2.3:TrainingadaptationtheoryadaptedfromBompaandHaff(2009)

Theabilityofathletestorecoverfromweeklycompetitioninteamsportenablesthemtobeabletotrainsoonerandwithbetterquality,thereforeimprovingthechancesofsuccessinthenextcompetitivematch.Thegoalofmanypractitionersworkingwithinteamsportsistorestoreplayerstopre-gamelevelsandintheshortestpossibletime,thereforeminimisingtheaforementionedsourcesoffatiguecreatedbygameplayandtrainingsessions.Trainingstimulusresponsivenessisanareathatpractitionersshouldpayattentiontowithintheirrugbyplayers,asinappropriateloadscanresultinplayersbeingillpreparedandinasub-optimalstatetoperformpre-game.Whenconsideringthattheindividualvariationinbothphysiologicalandpsychologicalresponsesfromtrainingandgamesarevariedacrossplayingpopulations(Elloumi,Maso,Michaux,etal.,2003;Hartwigetal.,2009),theneedtomanagetheindividualtrainingdoseisemphasised.Thedoseoftraininggiventoplayersisonlyeffectiveiftheindividualresponsivenesstotheloadappliedisconsideredandactedupon,infuturesessions,if

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needbe,inordertoenableoptimalperformance.Withthisindividualvariationinmind,itisimportantforpractitionerstoprescribetheappropriatetrainingsessionatthecorrectpointinthetrainingweek,asbothfieldbasedsessionsandgymbasedsessions(asexplainedinChapter2.2.2.1)imposevaryingresponsesuponathletefatiguelevelsandthereforesubsequentvariedrestorationofperformancepost-match.EvidenceaboveinChapter2.2illustratesthecommonalityofgym-basedsessionswithinrugbyteamsweeklytrainingschedulesandthebenefitsuchsessionshaveforimprovingsubsequentperformancearewelldocumented(Argusetal.,2009;Baker,2001b,2001c;Beaven,Cook,etal.,2008;Comfort,Haigh,&Matthews,2012;Pienaar&Coetzee,2013).Theresultanteffectoftrainingsessions(bothfieldandgym)inthedaysbetweengameshasproducedalargeamountofresearchtodate(Coutts,Reaburn,Piva,&Murphy,2007;Crewtheretal.,2013;Cross,Williams,Trewartha,Kemp,&Stokes,2015;Edmonds,Sinclair,&Leicht,2013;Elloumi,Maso,Robert,Michaux,&Lac,2003;Gaviglio&Cook,2014;Twist&Highton,2013),withthephysiologicalandpsychologicalresponsecreatedasresultofthesetrainingsessionsbeingapparent.Duetotheextensivelengthandintensityofaprofessionalrugbyplayingseason,alongsidetheaforementionedindividualfatigueresponsecreatedbytraining,thepractitioners’knowledgeoftheeffectofspecifictrainingsessionsuponplayersfatiguelevelsiskey.ResearchbyHowatson,Brandon,andHunter(2016)illustratedtheinfluenceofspecificresistancetrainingsessionsuponrecoveryinelitetrackandfieldathletes,where,intheimmediatehourspost-match,increasedlactatevaluespoststrengthtrainingincomparisontopowersessionswerenoted.Additionally,impairmentinmaximalstrengthonthedaypoststrengthtrainingwasnoted,thereforeillustratingtheneuromuscularandendocrineresponseassociatedwithvaryingtrainingstimuli.RecentresearchbyCook,Kilduff,Crewther,Beaven,andWest(2014)illustratedtheinfluenceofvaryingtrainingsessionsuponsubsequentperformance,showingadecreaseinsalivarytestosteroneconcentrationsintheafternoon,followingamorningspeedsession(-6.2±7.1pgml-1),incontrasttoaweightssession(-1.2±5.5pgml-1).FurtherresearchdemonstratingtheeffectofspecificloadinguponacuteneuromuscularandendocrineresponsewaspresentedbySchumannetal.(2013),whichalthoughnotinvolvingrugbyplayersandcombiningtrainingmodalitiesthatwouldnottypicallybeseenineliterugbysettings,providesfurtherknowledgetotheareaoftrainingsessionrecovery.TheresearchbySchumannetal.(2013),whichcomparedtheeffectofcombinedstrengthandendurancetrainingsessionswithstrengthandendurancetrainingsessionsprescribedindividually,notedthatthatendocrinefunction(decreasedconcentrationsofserumtestosterone),remainedelevatedafter48hoursofrecoverypostthecombinedstrengthandendurancesessions.Thesefindingsthereforeillustratethedifferingresponsescreatedbyspecifictrainingsessions.Otherresearchofinterestforpractitionersintheelitesetting,isthatbyBeaven,Gill,andCook(2008),whodemonstratedtheinfluenceofgymbasedsessionsuponresultantfatigueandidentifiedlargeindividualdifferencesintestosteroneresponsestofourdifferingresistanceexerciseprotocols.Theirrecommendationwasthemonitoringofhormonalresponsestogymbasedexercisestimuli.Whenconsideringtheevidenceoutlinedabove,whichillustratestheeffectofspecifictrainingsessionsuponratesofrecovery,onecouldthereforearguethatthelikelyrestorationofperformancerates,followingacombinationoffieldandgymsessions,wouldresultinalengthenedrecoveryperiodpost-sessionincomparisontoagymbased

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sessionalone.Additionally,whenconsideringtheviewofCook,Kilduff,Crewther,etal.(2014)thatresistancetrainingsessionsprovideawelcomedistractionforplayersfromrugbytraining,theroleofsuchgymbasedsessionsalongsidefieldsessions,arefurthersupported.WhencombiningtheseviewsofCook,Kilduff,Crewther,etal.(2014),withresearchshowingincreasedtestosteronelevelsasaresultofgymbasedsessions(Kraemer&Ratamess,2005),theneedforcarefulsessionprescriptionisevident.Anotherinterestingpotentialareaoffutureinvestigation,wouldbearecommendationfortheuseofmidweekmeasurementoftestosteroneandcortisolratioasapredictorofreadinessleadingintocompletionaspresentedbyGaviglioandCook(2014),whonotedthatthepertainingtestosteroneandcortisolratiowassignificantlylower(p<0.01)beforeawinthanaloss.Morerecentsupportfortheuseofcortisolmeasurementinthedaysprecedingrugbyunionmatcheswasillustratedby(Crewther,Potts,Kilduff,Drawer,&Cook,2017),whonotedalargemidweekriseincortisolpriortomatcheswhichwerewon,whereascortisoldecreasedbeforematchesthatwerelost.However,whenconsideringthelimitationsassociatedwithhormonaltestingoutlinedinChapter2.4.4.2thereliabilityandapplicabilityofsuchmeasuresintoelitesettingsisquestionable.Additionalimportantaspectstoconsiderwithintherecoveryadaptationprocessofrugbyplayerspost-matchandtrainingisfirstlythatfitterathletesareexpectedtorecovermorequickly,asreportedbyJohnston,Gabbett,Jenkins,andHulin(2015)whenassessingYo-Yointermittentrecoverytest(level1)(Yo-YoIR1),3RMbacksquatand3RMbenchpress.Whenassessingtheinfluenceofphysicalqualitiesonpost-matchfatigueinrugbyplayersJohnstonetal.(2015)notedthatstronger,fitterplayersrecoveredmorequicklythanweakerplayersevenifphysicalmatchloadsweregreater.Johnstonetal.(2015)concludedthatpost-matchfatiguewasreducedinplayerswithwell-developedhighintensityrunningabilityandlowerbodystrength.ResultsshowedlargerreductionsinCMJpowerinthelowYo-Yogroupatboth24(ES=-1.83),and48hourspost-match(ES=-1.33).ThisnotionthatfitterathletesrecovermorequicklyinteamsportsettingsissupportedbyHunkin,Fahrner,andGastin(2014),whonotedsmallerdisturbancesinCKvaluespriortoAustralianrulesfootballgamesalongwithsmallermetabolicdisturbancesfollowinghighintensityactivity.Inareviewofneuromuscularfunctionpost-EIMD,muscularstrengthhasalsobeennotedtoinfluencethefatigueresponseofplayerspostteamsportinvolvement,withgreaterstrengthaugmentingtheSSC,therebyplacinglessstressonthecontractilepropertiesofthemuscle(Byrne,Twist,&Eston,2004).Althoughcollisionsituationsinteamsportssuchasrugbyarethemaincontributortomuscledamage(Johnston,Gabbett,Seibold,&Jenkins,2014;Twistetal.,2012),enhancingtheabilityofmusclestomanageSSCactivitiesmaymoderatetheeffectsofthismuscledamageandthereforehastentherecoveryprocess.

2.3.9 Whatisreadiness?Throughoutthisthesistheterm‘readiness’isusedtodescribeathletepreparednessandoverallstateoffatigue,whichmayaffecttheirabilitytoperformatask.Withinthisresearchtheconceptofreadinessconcernsamoreholisticviewofrugbyplayers’preparednesstocompletetrainingtasksandoptimalgamedayperformance,withtheaforementionedfatigue,restorationofperformanceandNMF,beingimportantaspectsinassessingoverallreadiness.Adefinitionofreadinessis“thewillingnessorastateofbeingpreparedforsomething”(CambridgeDictionaryOnline,2015)andtheterm“readinesstotrain”hasbeenusedinrecentresearch(Cook,Kilduff,Crewther,etal.,2014;Mann,Lamberts,&Lambert,2014;Taylor,Cronin,Gill,Chapman,&Sheppard,2010)whendiscussingavarietyofsportsscienceandstrengthandconditioning

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topics.Readinessinpursuitofoptimalathleticperformanceshouldalsoconcernthestateofbeingprepared,yetinsportitconcernstheabilitytocompletetheathletictaskinquestion.Theimportanceofplayerreadinesswithinbothpreparation(pre-season)andcompetition(in-season)periodsisparamount.In-seasonassessmentofrugbyplayers’readinessconcernstheirpotentialtoperformtheirrolewithingamesituationstotheiroptimalability,whileinpre-seasonperiodsassessingplayerreadinessiskeytoenablingoptimalathleticdevelopmentduringtheseperiodsofintensetraining.ThelinkbetweenreadinessandfatigueisevidentwhenconsideringtheresearchinChapter2.3.Thefactorsthataffectfatigueandsubsequentperformanceinrelationtoreadinessarecritiquedinmoredetailbelow.

2.3.10 SummaryFatigueismorelikelywhenplayingexposureaccumulateswithoutsufficientrest(minutesandnumberofgamesplayedandtrainingvolume)andasgamescannotberescheduledduetothepresenceoffatiguethetrainingloadneedstobemanaged.Asisevidentfromtheresearchreviewedabove,manytestsofperformanceexistintheelitefield,yettheapplicabilityofthemeasuresforthesportinquestionisakeyconsiderationwhenaimingtomaximiseperformance.Muchofrecentperformancetestinghasfocuseduponattemptingtoquantifyfatigueandtheresultantreadinessforcompetition.Theneedforsuchtestingwithinteamsportsettingssuchaseliterugbyunionisparamountwhenconsideringthematchdemandsoutlinedinpreviouschaptersinadditiontothelargenumberofgamesplayedonaweeklybasisoveranine-monthperiod.Fatigueisexpectedpostrugbyunionmatchplayandtheabilityforpractitionerstomakeinformeddecisionsbaseduponfatiguetestingusingperformancemeasuresisthereforethegoal.Asnotedabove,themechanismsoffatiguearewiderangingandthespecificteststhatexaminealllevelsoffatigue(chronicandacute)thatmaybeexperiencedpostrugbyunionmatchplayneedtobequantifiedwithintheperformancetestsadministered.Ifmeaningfullevelsoffatiguearedetected,practitionersneedtobecarefulinselectingprescribedtrainingsessionsbetweengames,astheevidenceaboveillustratestheaffectthatsomeformsoftrainingmayhaveuponsubsequentratesofrecovery,duetothepotentialfatiguecreated.Reliableandapplicablemonitoringtools,whichassessrugbyplayerreadinessthroughoutaplayingseason,combinedwithappropriatetrainingprescriptionwillaidinenhancingthelikelihoodofoptimalperformance.

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2.4 MethodsofAssessingFatigue,RecoveryandReadiness

Readinessanditsimportancewithinexerciseprescriptioninthedayspost-competitionisdiscussedinmoredetaillater(Chapter2.6),yettheunderstandingofthetermreadinessneedsclaritybyevaluatingmanyofthemethodsofassessingrecoveryandrestorationdetailedbelow.Withinthisresearchreadinessisconsideredtobetheabilitytoperformwithoutimpairedperformance,andnotsimplyfullrecoveryfrommuscledamage,withthetermsreadiness,recoveryandrestorationofperformanceusedinterchangeably.IntheirreviewofcurrentmethodsformonitoringfatigueinhighperformancesportTaylor,Chapman,Cronin,Newton,andGill(2012)notedthat61%oftherespondentsintheirresearchreportedusingjumptests,submaximaltestsorsportspecificteststoassessreadiness,varyinginfrequencyfromweekly,tomonthlyordaily.Practitionersintheeliteteamsportsettingsarecommonlypresentedwiththequestionofhowfatiguedtheirathletesareandhowtheycanaccuratelyquantifyfatigue(Chiu&Barnes,2003;Twist&Highton,2013).Manyoftheperformancemeasuresusedtodiagnosefatiguetodatehaveused“timetofatigue”tests,withexerciseperformedatafixedintensitybeingusedasatoolagainstwhichtocomparesubstratekineticsandhormonalresponse.However,ascritiquedbelow,manyoftimetofatiguetestsinvolvemaximalefforts,usingperformanceteststhatarenotsportspecific,thereforecreatingunwantedadditionalfatigueandquestionableresults.

Duetothelimitationsassociatedwithmaximaltestingmentionedabove;requirementfornon-invasivemonitoringtoolsforassessingrecoverystatus(restorationofNMF)inathletesareneeded,withrecoverymarkersadvisedtobesensitivetodailyvariabilityintrainingload(Meeusen,Duclos,etal.,2006).Themonitoringtoolsandpracticeschosenwilloftenbedependentuponthesportinquestion,withmanymonitoringtoolsbeingutilisedwithinrugbyalongsideeachothertorepresentbestthefatigueandreadinessofplayers.Thefollowingsectionsdetailthemethodscommonlyusedformonitoringfatigueandreadinesswithinhighperformancetrainingenvironments,manyofwhicharerepresentedinTable2.13.Amajorpointofconsiderationforpractitionersisthatofreliabilitywhereitisseentovaryacrosstestingmethodused.Inaddition,therearesometestingmethods,suchasperceptualmethodsoffatigueassessment,whosereliabilityisdifficulttotest.Hopkins(2000)notedthereliabilityofperformancemeasurement,suchasjumptesting,occurredwhenthereisneithermarkedsystematicnorrandomvariationindataacrossdifferenttestingapparatus.Thereliabilityofperformancetestswouldthereforebemoreapparentifthereproducibilityofthemeasureofperformancewasconsistentwhenadministeredonseveraloccasions.

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Table2.13:Anoverviewofperformancemeasuresutilisedinrugby

Tool

Areasmeasured

Reliability(ICC/SDD/SWC)

Advantages

Disadvantages

Minimumrecommendationforuse

Questionnaire(McLean,2010;Johnston,2013;West2014)

MusclesorenessFatigueMoodAppetiteSleep

UnknownPerceivedmeasuresvalidityquestioned

CheapandeasytoadministerReportedtobesensitivetochangesinperformanceinteamsports

Subjectiveandcanbemanipulatedbyplayerperformance

Recorddailyasvariationmaybesmall

Bloodmarkers(Elloumi,2003;Maso,2004;Mashiko,2004;Crewther,2009Cunniffe,2010;Johnston,2013;West2014)

CreatinekinaseTestosterone:Cortisol

Varied(West,2014;CV<10%)(Elloumi,2003;CV<10.9%)(Maso,2004;CV<10.5%)(Crewther,2009;CV<10.5%)

Helpsdevelopanunderstandingofthephysicalfatiguemechanismviathevastnumberofmarkers

Costlyandinvasivemeaningdifficulttoimplementintotrainingprograms

Unrealistictoimplementdaily/weeklysoinvestigationWhenotherparametersshowreductionsoftenthebestoption

Neuromuscularperformance(McLellan,2012:McLean,2010;Duffield2012;Johnston,2013;Cadore,2013;West2014)

CMJMVCSingleJoint–KneeExtensorPeakpower

Good(Johnston,2013;ICC0.98PP,0.97PF)(Cadore,2013;ICC0.94RFD)

Anindirectmarkeroffatiguewhichcanbeimplementedintotrainingprogram

Difficulttoidentifymatchspecificfatigue

Recordweeklyonthesamedaypost-matchapplyinginterventionwhendroppingbelowbaselinevalues

Performancetests(Coutts,2007a;Lovell,2013)

RunningvelocityRPE&trainingloads

Good(Coutts,2007a;ICC0.93MSFT)

Helpsassessmatchfatigueandprovidesmoresubjectivemeasures

Timeconsumingandoftenaddsmorefatigue

Oftenbestusedduringpre-seasonperiodsorwhenreturningfrominjury–limiteddataonthismethod

Functionalstate(Edmonds,2013;Morales,2014;Buchheit,2010)

HeartrateHRV

Unknown(Morales,2014;ICC>0.81HRV)(Buchheit,2010;CV<10.5%)

Providesinformationonfunctionalstatewithoutfatigue

Expensivetoimplementandfewstudiesconfirmingreliability

Threeassessmentsaweekhavebeenrecommended–implementingthistoawholeteamsportplayingsquadisunrealistic(Plews,2014)

2.4.1 Maximalandsub-maximalperformancetestsSub-maximaltestsreportedtobeusedbypractitionersinclude;theheartrateintervalmonitoringsystem(HIMS),heartraterecovery(HRR)testingandYo-YoIR,withsub-maximaltestsnotedbyTayloretal.(2012)toaccountfor14%ofperformancetestsutilised.Maximaltestsincontrasttosub-maximaltestsinclude;Wingatecyclingtests,maximalstrengthtestingandjumptesting.Suchmaximaltestsincludeanyactivitywheretheparticipantisaskedtoengageinmaximaleffort.Whilethedesignofsub-maximalandmaximalperformancestestsspecifictothesportinquestionhavebeendeveloped,thespecificityofthemovementsinvolvedcanbequestioned(Coutts,Reaburn,Piva,&Murphy,2007;Coutts,Reaburn,Piva,&Rowsell,2007;Rowsell,Coutts,Reaburn,&Hill-Haas,2009).Consideringfatigue,whichwasdescribedinChapter2.3.2,asbeingtheinabilitytomaintainforceorpoweroutputattherequiredlevel,maximalperformancetestsareperhapsthemostappropriatemeasureofinthiscase.

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MaximalperformancetestshavebeenshowntobeadefinitivemarkerforNFORinteamsportathletes(Coutts,Reaburn,Piva,&Rowsell,2007;Krustrupetal.,2010).AdditionalsupportformaximaldecrementtestsispresentinthefindingsofCoutts,Reaburn,Piva,andRowsell(2007)whereMSFTperformanceandVO2maxtestingdecreasedfollowingsixweeksofintensivetraininginrugbyleagueplayers.FurthersupportformaximalperformancetestswasnotedbyKrustrupetal.(2010)withinfemalesoccerresearch,whichshowedsignificantinversecorrelationsbetweenYo-YoIE2testperformanceandfatigueindexduringtherepeatedsprinttestbothatrest(r=0.76,p<0.05)andafterthegame(r=0.66,p<0.05).However,maximalperformancetestingshouldbeadministeredwithcautionasitcancreateadditionalfatiguewithintheathlete.

Limitationsexistforsportspecificrunningtests.Firstly,fatigueasaresultofthetestingneedstobeconsideredandsecondly,alackofopportunitytoaddtestingtoweeklyscheduledtrainingprogramsmayhamperimplementation.Additionallackofsupportformaximaltesting,outlinedbyDarrall-Jones,Jones,Till,andRoe(2015),demonstratedthatsprinttestsineliterugbyplayersover10m,20mand30mwereincapableofdetectingsmallestworthwhilechangeinperformance.Despiteasub-maximalcyclingtests(usingHIMSorHRR)notbeingasspecifictoateamsportsettingsuchasrugbyasarunningbasedtestwouldbe,itcanbearguedthatitismoresuitabletothecompetitionandtrainingenvironmentthatexistswithinteamsplayingonaweeklybasis.Consideringthemultifacetednatureoffatigueresearchandthemanyconsequencesoffatigue,maximalperformancetestsareperhapsthemostlikelytoreplicatetheathletesevent,yetthelogisticalissuesandaddedfatiguesurroundingmaximaltestingwithincompetitionperiodsmakethisformoftestinglimitedinvalue.Similarly,whentestingwithinasportsuchasrugby,whererunningmovementsarerequired,runningspecificmaximaltestingwouldlikelybethetoolofchoiceformanypractitionerstoassessfatigueinrugby.However,runningspecificmaximaltestingareperhapsnotthemostlogisticallyviabletestingoptionduetotheadditionalfatiguethesetestscanaddandthetimeneededtoconductthem.

AsaresultofmaximalperformancetestsproducingdatathatrepresentsamorecomprehensivedescriptionofNMF,performancetestsincorporatingmaximaltestingareperhapsthemostvalidforuseinelitesettings.Questionablevalidity,however,existswithinsub-maximalperformancetests(Arteroetal.,2012;Murphy&Wilson,1996;Noonan&Dean,2000),withfutureresearchrecommendedforuseinelitesportsettings(Rampininietal.,2007).Duetothequestionablevalidityassociatedwithmaximaltestsandtheaddedfatiguethatmaximaltestscancreate,theuseofWingatecyclingtestsandmaximalstrengthtestingwereexcludedfromuseinfuturediscussionwithinthisresearch.Maximaljumptestswere,however,consideredapracticaltoolforusewithintheeliterugbysettinginquestion,astheycanbeeasilyimplementedintotrainingprogramsandaddnoadditionalunwantedfatigue.Themostcommonlyusedformsofsub-maximalandmaximalperformancetestsarereviewedbelow,tohelpexplaintheirinclusionorexclusionwithinfuturediscussionwithinthisresearch.Itis,however,importantforpractitionerstonotethatmaximaljumptestingandmaximalrunningtesting,forexample,arebothverydifferentinresponsetothephysicaldoseapplied.Whereasamaximaljumptestmayinvolvehighmuscularexertion,othermaximaltestvarietiesmayinvolvehighaerobicoranaerobicexertions,whichwillresultinadifferingphysiologicalcostfollowingtheirimplementation.

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2.4.1.1 MaximalstrengthtestingThemostcommonmaximalperformancemeasuresusedinpastresearchwithinteamsportsaremaximalstrengthassessments.Manymaximalstrengthassessmentshavebeenusedtomonitorprogressthroughouttrainingcycles(Argusetal.,2009;Beaven,Cook,etal.,2008;Comynsetal.,2010;Harrisetal.,2008),yetfewhavefocuseduponmaximalstrengthtestingtomeasurefatigue(Haffetal.,1997).Muchofthemodernresearchusingstrengthtrainingtoassessperformancehasrarelyusedstandardmeasuresofstrengthtraining,which,utilisepercentageofone-repmaximumcalculations(%1RM)andhasinsteadusedmaximalisometricvoluntarycontraction(MVIC).ThereasonMVIChasbeenpreferredto%1RMtestingisthatitdeterminesthevolitionalforce-generatingcapacityofamuscleunderrelativelystandardconditions,whereasstrengthtrainingdoesnot.RecentsupportfortheuseofMVCforassessingEIMDwaspresentedbyDamas,Nosaka,Libardi,Chen,andUgrinowitsch(2016)whonotedMVCtobethebestEIMDindirectmarker,whenresearchingretrospectivelyacross286athletes.Additionally,traditionalstrengthtestingisfatiguinginnaturewhileothermaximaltestingsuchasCMJandMVICarenotandarethereforeconsideredtobemoreapplicableforuseineliteteamsportsettings.MVICassessmentenablesgenerationofaforce-timecurve,whichcanidentifymultiplemarkersofneuromuscularperformance;yetcontrastingsupportfortheuseofmaximalstrengthassessmentexists.Cairnsetal.(2005)notedmaximalstrengthasaninvalidassessmentforfatigue,duetotheextenttowhichtheyreplicatethenatureofsportsactivitiesinquestion.ResearchbyVerdijk,vanLoon,Meijer,andSavelberg(2009),however,notedthat1RMstrengthtestsrepresentsavalidmeanstoassesslegstrengthinhumans,withrecommendationsforusing1RMtestingtoassesschangesinstrengthfollowinganexerciseintervention.Therelevanceofassessmentsofstrengthisthattheycouldbeappliedtothefatiguetestingproposedinthisresearch.

Aspreviouslydiscussed,reliabilityofperformancetestsareofparamountimportanceforpractitionersinordertoensurethatthedatacollectedisaccurateandvalid.Datawithinmaximalstrengthtestinghavepresentedcontrastingreliability,whichwasfurthersupportedbySoares-Caldeiraetal.(2009)whenassessing1RMtestsinadultwomen.Comfort,Jones,McMahon,andNewton(2015),bycontrast,notedhightest/retestreliabilityduringtheisometricmid-thighpull(IMTP),with>1.3%changeinpeakisometricforce,>10.3%inmRFD,>5.3%inimpulseat100ms,>4.4%inimpulseat200ms,and>7.1%inimpulseat300msbeingconsideredmeaningful,irrespectiveofpostureadopted.Furthersupportforthereliability(ICC>0.90)ofusingisometrictestingwasnotedbyBazyler,Beckham,andSato(2015)withisometricsquatnotedasprovidingastrongindicationofchangesinstrengthandexplosivenessduringtraining.RecentresearchbyHaff,Ruben,Lider,Twine,andCormie(2015)presentsanimportantconsiderationforpractitioners,asthemethodusedtoassesRFDduringanisometricmid-thighcleanpull(IMTCP)impactsonthereliabilityofthemeasure.Haffetal.(2015)did,however,acknowledgethereliabilityoftheIMTCP(ICC0.95,CV<4%),therebyfurthersupportingtheuseofisometrictesting.LastlyanisometricposteriorlowerlimbmuscletestwasreportedbyMcCalletal.(2015)tobeareliableandsensitivemeasuretotrackmatch-inducedfatigueinprofessionalsoccerplayers.Thisthreesecondisometriccontractionofthelowerlimbshowedhighreliabilityfordominantlegat90°(CV=4.3%,ICC=0.95,ES=0.15),non-dominantlegat90°(CV=5.4%,ICC=0.95,ES=0.14)andwassensitiveenoughtodetectreductionsinforcefordominantlegat90°(p=0.0006,ES>1)thatcouldpresentvaluableinsightsforfuturerecoverypracticesinelitesoccer.

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Limitedresearchexistsregardingthemagnitudeofchangeofstrengthmeasuresthatsignifyfatigue,andasdiscussedpreviously,maximalstrengthtestingislikelytoinducefatigueandthereforeshouldnotregularlybeimplementedintoelitesettings.RecentresearchbyComfortandMcMahon(2015)does,however,demonstratehighreliabilityformaximalstrengthimplementationofthebacksquat(ICC=0.994)andpowerclean(ICC=0.997)performanceinexperiencedlifters.FromtheresearchbyComfortandMcMahon(2015)practitionerswereadvisedtolookforachangeof>5%inordertoidentifymeaningfulchangeinmaximalstrengthbacksquatandpowerclean.Additionalsupportforresistancetrainingtomeasurereadinesswas,however,presentedbyCrewtheretal.(2013)whenassessingsalivarytestosteroneandcortisolresponsestoresistancetrainingworkouts.Theyclaimedthatfreetestosteroneresponsestoamidweekworkoutmightprovideanearlysignofteamreadinesstocompete.Despitesupportforthereliabilityofmaximalstrengthtestingtoassessfatigueinrugbyleagueplayers,contrastingevidenceexistsinresearchbyCoutts,Reaburn,Piva,andMurphy(2007),whoreportminimalreductionsin3RMbenchpressandsquatassessmentduringoverreachingperiods.Thisminimalchangeduringoverreachingperiods,therefore,demonstratesalikelylackofsupportfortheuseofstrengthtestingforassessingfatigue.ManyoftheothermethodsofperformancetestingcritiquedwithinChapter2.4.1.2and2.4.4(jumptestingandbiochemicaltesting)providemoredetailandspecificvaluesthatsignifymeaningfulchange,withrateofforcedevelopmentandvariabilityinhormonalprofileofrugbyplayersinthedayspost-matchprovidingmoreobjectivevaluesthanthosereportedformaximalstrength.

InareviewofmodelsusedtoevaluateNMF,Cairnsetal.(2005)discussedtheuseofmechanicalfatiguemeasuresusingMVIC,suchasisokineticdynamometerexercisesanddynamickneeextension,withresearchinrugbyspecificallyconductedbyCrewtheretal.(2009)illustratingsignificantrelationshipsbetweenneuromuscularperformanceandhormonesecretionpatternsineliterugbyunion.WithintheresearchbyCrewtheretal.(2009)concentricmeanandpeakpowerduringa70-kgsquatjumpmeanpower(r=0.41,p<0.05),50-kgbenchpressthrowPP(r=0.41,p=0.05),andestimated%1RMstrengthforaboxsquatandbenchpresswerepositivelycorrelatedwithsalivarytestosteroneandcortisolconcentrations.Anotherstudyusingstrengthtesting(3RMbenchpressandsquat)tomeasureperformanceandreadinesswasthatofCook,Kilduff,Crewther,etal.(2014)whonotedtestosteroneconcentrationstobeoffsetbymorningtraining,therebyrecommendingmorningbasedstrengthtestingtoimproveafternoonperformanceinrugbyunion.Additionally,Johnstonetal.(2013)supportedthenotionthatupperbodypowerisalsoagoodindicatorofNMFpostrugbymatchandthatupperbodyPPappearstobeasuitablemeasureforthespecificforcerelatedexertioninvolvedintackling.Itis,however,importanttonotethattime-courseandmechanismsoffatigueoftheupperbodydiffertothatofvelocitybasedlowerbodypowermovements.

FromtheresearchwithinthissectionitisclearthatquestionablevalidityandreliabilityexistwithinbothmaximalstrengthtestingandMVICtesting.Duetothesevalidityandreliabilityissues,alongwiththelackofaccesstofacilitiesandmanpowerneededonaregularbasisforbothmaximalstrengthandMVICtesting,theseperformancemeasuresareexcludedfromfutureusewithinthisresearch.Additionally,theequipmentrequiredfortestingisometriccontractions(isokineticdynamometers)arelargeinsizeandthereforecumbersomeandexpensivetouse.Addedtothefactthatadditionalfatiguecanbecreatedasaresultofboththeseformsofperformancetestingitisclearrationaletoexcludetheirusewithinthisresearch.

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2.4.1.2 MaximalJumptesting

2.4.1.2.1 CommonusesofjumptestingAnindividual’sabilitytogenerateforcequicklyisakeyperformancemeasurementforathletescompetinginmanyteamsports,hencejumptestshaveoftenbeenutilisedtomonitorpower(Markovicetal.,2004).Withthegoalofassessinglowerlimbpower,manyjumptestsincludingverticaljumphavebeendeveloped.Theverticaljumphas,however,beenreportedtorepresentaninaccuratemeasureofexplosivelowerlimbpowerduetothemorecomplexnatureofleg/armcoordination(Leardetal.,2007;Markovicetal.,2004;Young,MacDonald,Heggen,&Fitzpatrick,1997).JumptestscommonlyusedintheappliedsettingincludeCMJandsquatjump(SJ).CMJinvolvestheuseofthestretchshorteningcycle,wherebysubjectsperformadownwardmovementfromanerectstandingpositionuntiltheyfeelcomfortableandthenjumpforheightinanupwardmotion.SJisapuremeasurementofconcentricpower,wherebythesubjectisinstructedtosquatto90°,thenholdforthreesecondsatthebottomofsquatandjumponacommand.

Thejumpmodalitiesmentionedabovehavecomeunderscrutinybecauseofthetechniquemanysubjectsusedalongwithinconsistenttestingprotocol(Markovicetal.,2004).Testingirregularitiessuchasthesubject’sabilitytoswingtheirarmsforgreaterheightandtheeffectofpre-stretchingmeantthatrecentjumptestinghasfocusedsolelyontheSJandCMJ.Lees,Vanrenterghem,andDeClercq(2006)concludedthatarmswingcontributestojumpperformancebyaidingthestoringandreleaseofenergyfrommusclesandtendonsaroundtheankle,kneeandhipandbyinitiatingapullforceattheshoulderjoint,thusincreasingjumpheightby10%ormore(Lees,Vanrenterghem,&DeClercq,2004).Additionally,thisuseofarmsinverticaljumpperformancehasbeenreportedtoprovide10%meanincreaseintake-offvelocity(Carlocketal.,2004;Harman,Rosenstein,Frykman,&Rosenstein,1990).Thereforetheuseorexclusionofarmmovementneedstobestandardisedduringsuchassessmentsinordertoensurethattheyarecomparable.Duetotheaboveinaccuraciesdetailedregardingverticaljumps,theyhavebeenexcludedasareliabletestforjumpperformancefrommorerecentresearch(Acero,Sanchez,&Fernandez-del-Olmo,2012).

2.4.1.2.2 JumptestingtoolsInadditiontojumptestingprotocolsbeingscrutinisedforinaccuracies,specificjumpandpowertestingtoolshavealsocomeundercriticism.Numerousinstrumentsmeasuringjumpheightandcontacttime,utilisingdifferenttechnologiesandcalculations,haveprovidedvaryingresults(Markovicetal.,2004).Forceplateshavebeenconsideredtobethe“goldstandard”forthemeasurementofjumptests,havingbeenreportedtoprovideexcellentmeasurementaccuracyforestimationofpowerviaforwarddynamics,calculatedbytheforceappliedtothejumpingsurface(Walsh,Ford,Bangen,Myer,&Hewett,2006).Jumpinstrumentssuchasopticalmeasuringsystems,thatsolelyassessflighttimeanddonotdeterminejumpheightfromtheimpulse-momentumrelationship,asusedbyDomireandChallis(2007)areatriskofinaccuracy,assubjectscanalterjumptechnique,suchasaflexedfootonlandingtoincreaseflighttime.Bycontrast,whenusingforceplateassessmentmaximalverticalvelocityofthecentreofmassattake-offprovidesamoreaccuratemeasureofjumpheight,byusingaforwarddynamicsapproach.Cormack,Newton,McGuigan,andCormie(2008)highlightedtheimportanceofanalysingtheflighttimetocontractiontimeratioasameasuresensitivetofatigue,withthetimefrominitiationofthecountermovementuntilthesubjectleavesthejumpingsurfacebeingkey.Itis,however,importantforpractitionerstonotethatdespitethe

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researchbyCormack,Newton,McGuigan,andCormie(2008)reportingflighttimetocontractiontimeasthemeasureofjumpperformance,themethodologyusedactuallyassessesonlytheinitialmovementwhenutilisingvelocityofthecentreofmassjumptestingprotocol.MovementmayhavealsohaveoccurredintheupperbodypriortocontractionofthelowerbodyduringvelocityofcentreofmassassessmentusingtheprotocolbyCormack,Newton,McGuigan,andCormie(2008),andonecannotthereforeassumethattheinitialmovementreportediscontractiontime.Alsoofnoteforpractitionersisthat,despitetheresearchbyCormack,Newton,McGuigan,andCormie(2008)notstatingthesamplingfrequencyusedfortheforceplateassessment;typicalBallisticMeasurementSystemsuseafrequencyof40ms.Asaresult,itcouldbearguedthatthisdefaultsamplingfrequencyoptionmayproveinaccurate,whencomparedagainstresearchwhichinvolvedadifferentsamplingfrequency.Practitionersarethereforeadvisedtonoteboththethresholdssetfortheonsetofmovementandthecalculationusedforflighttime,asthismayhaveaneffectupontheresultantmeasurementvariablescollected.

Forceplateshavebeenshowntopossessexcellentreliabilityasperformancemeasuresforbothjumpingandlandingtasksandstrengthassessment(Cormack,Newton,McGuigan,&Doyle,2008;Cormie,McBride,&McCaulley,2007;Walshetal.,2006),whileuseofsalivatoassesshormonalresponsepostrugbymatchiscommonplace(Beaven,Cook,etal.,2008;Crewtheretal.,2013;Elloumi,Maso,Michaux,etal.,2003;Elloumi,Maso,Robert,etal.,2003;Maso,Lac,Filaire,Michaux,&Robert,2004;Westetal.,2014).Forceplatesusetheimpulse-momentumrelationshiptodeterminevelocity,whichcalculatespowerthroughtheforwarddynamicsapproach(Cormieetal.,2007).Previousresearchhasutilisedtheflighttimecalculationviatheheightofriseofcentreofmass(Frenchetal.,2004;McBride,Triplett-McBride,Davie,&Newton,1999,2002).Theverticaltake-offvelocityofthecentreofmassiscalculated,wherebyacceleration(a)isdeterminedbydividingverticalgroundreactionforces(F)bythemassofthesystem(SM)ateachtimepoint:

! = !/!"

Withjumpheightfromvelocityofcentreofmasscalculatedviathefollowingequation:

!" = (!^2)/(2 ! 9.81)

v=displacement/time

Thismethodofforwarddynamicscalculationhasbeenregularlyusedtoassessbodyweightjumpsinpreviousresearch(Frenchetal.,2004).However,themaindisadvantagesassociatedwithforceplatesarethattheyareexpensivetouseandoftenimpracticalinfield-testingscenarios(Casamichanaetal.,2013).Additionally,methodsofassessingpoweroutputviakineticmethodssuchastheforceplatehavebeenquestioned(Cormieetal.,2007),withforceplatemethodologytypicallyusedtocompareperformanceofbodyweightjumps,ratherthantomeasuretheinfluenceofloadsuponpoweroutput.DuringOlympicliftingmovements,forexample,thebarbellmovesatadifferingratetothatoftheparticipantscentreofmass(COM),asthebarbellstartsbelowthelifter’sCOMandfinishesabovetheirCOMmeaningthepowerappliedwilldiffer.OnsummarytheadvantagesofforceplatesoutweighthedisadvantagesmainlyduetothevastamountofdatathatforceplatescancollectincludingsuchparametersasPRFDandimpulse(McLellan&Lovell,2012;McLellanetal.,2011a,2011b;McLellan,Lovell,&Gass,2011c;McLellanetal.,2011d).

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Recently,contactmatsandopticalmeasuringsystemshavebecomecommonplaceforfieldbasedassessments(Bosquet,Berryman,&Dupuy,2009).CMJandSJperformedonacontactmatweredeemedreliableatestimatinganaerobicpowerinastudybyMoir,Button,Glaister,andStone(2004).Contactmatswerealsoconsideredpracticalforuseinlaboratoryandfieldsettings,forsquatjumpandCMJ(Markovicetal.,2004).Thiswasmainlyduetothenatureofthetestingprotocolinthefieldandtheabilityfordatatobeproducedrelatingnotjusttojumpheight,butalsotovariousotherparameterstoassesspower(Casartelli,Muller,&Maffiuletti,2010).Bosco,Luhtanen,andKomi(1983)werethefirsttoderivejumpheightfromflighttimeviaacontactmat,withinfraredopticaldevicenowreplacingcontactmatstomeasureflighttime.However,duetoerrorintimekeepingbysubjectstakingoffandlandingindifferentlocations,thismethodofcalculatingjumpheighthasbeenquestioned(Garcia-Lopezetal.,2005).Themaincriticism,thatcontactmatscauseinaccuracies,hasbeenbasedonthefactthatthesubject’sfeetarenotdirectlyincontactwiththespecificsportsurfaceinquestion,withtheresultthatathletesurfaceinteractionvaries(Markovicetal.,2004).Althoughthisinabilitytotestonspecificsurfaceisalsoseeninforceplates,theadvantagesofforceplatesoutlinedabovemeanthatthisisnotconsideredamajorconcern.

Ifmethodologicalprotocolisstandardisedthroughoutjumptesting,theeffectofdifferingsurfacesandotherdependentvariablessuchastechniqueusedwillbeminimised.AccuracyofdatacollectedoncontactmatswasresearchedandevidenceforitsusequestionedbyKlavora(2000),whofoundthatsubjectsrecordedhigherjumpscoreswithacontactmatthanajumpandreachstyletestasusedinNFLcombinetesting(Kuzmits&Adams,2008).Inrecentresearch(McMahon,Jones,&Comfort,2015)acommonlyusedcontactmat(JustJump)wascomparedagainstaforceplate,withsuggesteduseofacorrectiveequationwhenusingaJustJumpsystem,despiteICCdemonstratingexcellentwithin-sessionreliabilityofCMJheight(ICC=0.96,p<0.001).Jumpandreachtestshavealsocomeunderscrutinyasthetechniquesusedbyparticipants,asasubject-performingjumpandreachtestscanusethewallasanaidtoextendjumpheight.Harman(1990)reportedthatjumpingandtouchingawallduringaverticaljumpismorerestrictivethanjumpingstraightupanddown,hencetheirstudyfoundjumpheighttobe5.3cmgreaterwhenusingatotalbodycentreofmassdisplacement,comparedtothejumpandreachtest.Additionally,itisassumedthatparticipantsonajumpandreachtestwillmarkthewallordisplaceamarkingvaneatthepeakoftheirjump.AsreportedbyKlavora(2000)thisisoftennotthecase,thereforeinfluencingresultscollected.

Earlyresearch,assessingthevalidityandreliabilityofmethodsfortestingverticaljumpperformancearebeingquestionedduetomethodologicalconsiderations(Hatze,1998).IntheresearchbyHatze(1998)themethodologicallimitationsnotedinclude;invalidassumptionsregardingperformancecalculationsandthejumpingtechniqueutilised.Thisisdespitetheuseofforceplatemethodssupportedbyresearch(Walshetal.,2006).Jumpmats,forexample,useflighttimeasthecalculationofperformance,yetthiscalculationisanapproximation,asflighttimeisnodirectmeasurementofforce.Bycontrast,forceplatesgivedirectmeasurementofforcebasedupontheforwarddynamicsdiscussedearlier.Ifthecalculationsusedtoassessperformanceincorporatedisplacementtimedatainvolvingdirectmeasureofvelocity,itisimportantforpractitionerstoacknowledgethatthismeasureisanapproximationofforce,thereforeitsaccuracyshouldbequestioned.ThisviewwassupportedbyHatze(1998)whonotedthatthevalidityandreliabilityofthejumpingergometermethodforevaluatingcertainaspectsofathleticperformancearehighlyquestionable,duetothemethodsofcalculation

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identifiedabove.Morerecentresearchhas,however,shownjumptestingthatusesmodernmethodsasreliable(Markovicetal.,2004).Technologicaldevelopmentofcontactplatformsandmobiledevices(MyJump)hasbeenreportedtoproducereliableintraandinter-sessiondataduringdropjump,CMJandSJmovements(Gallardo-Fuentesetal.,2016).

2.4.1.2.3 Jumptesting–kineticandoutcomebasedmeasuresWhenconsideringthatPRFDisnotedbyMcLellanetal.(2011d)tobeaprimarycontributortojumpperformanceduringCMJ,theneedforvalidityofthismeasurefortestingperformanceisneeded.DespitedatashowingarelationshipbetweenRFDandCMJheightbeinglimited,eccentricmovementisgenerallyconsideredtobeafundamentalcomponentoftheSSCandis,therefore,importantforconsiderationwhenassessingCMJperformanceofteamsportathletessuchasrugbyplayers.Similarly,theabilitytodevelopforcerapidlyisaprerequisiteforexplosivestrength,yetascarcityofknowledgeregardingRFDcorrelationstoverticaljumpexists.RFDrelatestoshortcomponentsoftheSSCandarecharacterisedbysmallangulardisplacement(100to250ms)oftheankle,kneeandhipjointsduringCMJ.Theeccentricphaseconsistsofthepointinthedownwardmovement,wheretheforcebeingexertedintotheforceplateexceedsbodyweightuntilthepointofzerovelocityatthelowestpointofthecountermovement.EccentricRFDconcernsthepeakpowerexertedduringtheeccentricphaseoftheCMJandismeasuredinN.s-1,withtheabilitytohandlethemaximaleccentricforceintheminimaltimepossiblebeingatypicalindicatorofexplosivestrength.ResearchshowingrelationshipsbetweeneccentricRFDandCMJperformancearecontrasting,withMcLellanetal.(2011d)assessingtheRFDonverticaljumpperformanceonaforceplateandnotingpoorretestreliability(CV16.3%)intwenty-threephysicallyactivemen.McLellanetal.(2011d)did,however,notethatsignificantcorrelationsbetweenmaximumRFDandjumpheightcouldonlyexplain46%ofthevariancenotedinjumpheightandthattheothervarianceislikelytobeduetoinexperienceofthesubjectsinquestion.ResearchbyEbben,Flanagan,andJensen(2007)notednocorrelationbetweenRFDandCMJ(r=0.19,p=0.22)andthereforequestionedtheusefulnessofRFDforassessingCMJperformance.AswasarguedbyEbbenetal.(2007)andnotedwithinpreviousresearch(Haffetal.,1997),theuseofRFDmaybemoresuitedtohighloadactivitiessuchasmid-thighcleanpulls.

TheavailabilityofreliabilitystatisticsforeccentricRFDislimited,withMoir,Garcia,andDwyer(2009)reportingRFDvalues(CV17-21%),yetitmustbenotedthatthevaluespresentedbyMoiretal.(2009)arefromnon-elitemenandwomen.WithintheresearchbyMcLellanetal.(2011d)asignificantrelationshipexistedbetweenverticaljumpdisplacement(VJD)andPRFDfortheCMJ(r=0.68;p=0.001).Incontrast,anon-significantrelationship(r=0.65-0.74)betweenRFDandverticaljumpperformancewasnotedbyHopkins,Schabort,andHawley(2012),yetthelackofstatisticalsignificancewithinthatresearchislikelytobeexplainedbythepoorstatisticalpower(n=8).Additionally,theresearchofMcLellanetal.(2011d)showedthateccentricRFDdisplayedlowreliability,however,animportantpointforconsiderationwhencomparingtheresultsofMcLellanetal.(2011d)tootherresearchisthedifferingtestingapparatusused.WithintheresearchbyMcLellanetal.(2011d)asamplingfrequencyof1000Hzandacutofffrequencyof17Hzwasused,withthismethodologylikelytodifferacrossstudies.

Perhapsmostinterestingwithinfuturekineticmeasuresresearch,isthefindingsofGathercole,Sporer,Stellingwerff,andSleivert(2015a),who,whenassessingthereliabilityofCMJ,notedthatthevariableswithaCV>5%relatedtotheeccentricphaseoftheCMJ,whilevariableswith

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CV<5%includedthosethatrelatetotheconcentricoutcomeofthejumpperformance.Gathercole,Sporer,Stellingwerff,etal.(2015a)thereforearguedthatassessmentofCMJperformanceshouldincludebothvariablesthatassesschangesinoutcomeandvariablesthatdeterminethejumpstrategyemployedbythesubject,fortheretobeamoreinformedconsiderationofthemovementbehaviour.Inananalysisofmalecollege-levelteam-sportathletes,Gathercole,Sporer,Stellingwerff,etal.(2015a)notedthatmostkineticvariablestakelongertoreturntowardsbaselinevaluesat72hourspost-exercise,whencomparedtoCMJoutput(typicallyconcentricfocusedvariables),withtheseviewssupportedbyKennedyandDrake(2017b)inrugbyplayers,comparingisometricstrengthandCMJoutputvariables.Gathercole,Sporer,Stellingwerff,etal.(2015a)thereforerecommendedthatpractitionersconsiderNMFbyassessingchangesinbothoutputand/ormovementeconomy.Theresearchproposedbelowwillassessplayers’abilitytojumpashighaspossible,yetthekineticmeasuresthatareoftenusedwithinjumpperformanceassessmentneedalsotobeconsidered.Itcould,however,bearguedthatintermsofrestoringperformancepostrugbyunionmatchplay,assessmentofjumpheightisthemostessentialmeasureofperformance,asthisrelatesspecificallytotheplayers’abilitytooutjumptheiropponentsandwillthereforeresultinimprovedlikelyhoodofteamsuccess.However,therolethatkineticmeasuresplayintheassessmentofjumpperformancecannotbediscountedandisthereforeexaminedfurtherintheexperimentalChapter5below.

2.4.1.2.4 JumpperformancetoassessfatigueInadditiontousingjumpteststhatmeasurepower,velocity,force,contacttimeandrateofforcedevelopment;recentresearch(Hamilton,2009;Kennedy&Drake,2017a;Kennedy&Drake,2017b;Mooneyetal.,2013;Roeetal.,2015;Taylor,2012)hasfocusedonutilisingverticaljumpstoassessneuromuscularfatigue,witheffectivenessofCMJconfirmedbyGathercole,Sporer,Stellingwerff,etal.(2015a).ReliabilityofCMJanalysistoquantifyacuteNMFusingaforceplatewasalsoconfirmedbyGathercole,Sporer,Stellingwerff,etal.(2015a).CMJvariablesexhibitingintraday(n=20)andinterday(n=21)CVsof<10%wherereportedwhenassessedatzero,24and84hoursfollowingafatiguinghigh-intensityintermittent-exerciserunningprotocol.Additionally,effectsizeswerereportedtorangefromtrivialtomoderateineighteenCMJvariablesatzerohoursimmediatelypostexercisefatigue,furtherconfirmingCMJasareliablemeasureforNMF.Follow-onresearchbyGathercole,Sporer,Stellingwerff,etal.(2015a)showedhighrepeatabilityandimmediateandprolongedfatigue-inducedchangesdetectedbyCMJ(CV=3.0%),whencomparedtootherjumpmeasures(SJ=CV3.5%andDJ=CV4.8%)and20msprinttimes.ResearchbyMarkovicetal.(2004)alsoconfirmedreliabilityofCMJwithintraclasscorrelationcoefficients(ICC)being0.98,whilewithin-subjectCVinCMJwas2.8%,whichwasreportedaslowcomparedtootherverticaljumpssuchasSJandhorizontaljumps(standinglongjumpandstandingtriplejump).

OtherrecentresearchofinterestincludesthatbyRoeetal.(2015)whichsuggeststhatCMJmeanpower,peakforceormeanforcecanbeusedforassessinglowerbodyneuromuscularfunction,duetoboththeiracceptablereliabilityand(CV<5%)andgoodsensitivity(CV<SWC).Themeta-analysisofCMJanditsuseformeasuringNMFpresentedbyClaudinoetal.(2016)notedthatthemajorityofstudieshaveincorporatedhighestCMJperformancevaluesincontrasttotheuseofaveragevalues.However,Claudinoetal.(2016)reportedthattheaveragejumpperformancewasmoresensitivethanhighestjumpperformancewhenassessingfatigueandrecommendeditsapplicationinappliedsettings,as,statistically,researchershaveahigher

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probability(10-1)offindingthetruejumpperformancewhentheaveragevalueisusedinsteadofthehighestvalue.Despitetheserecommendationsforuseofaveragejumpmeasures,thehighreliabilitywithinandbetween-sessionreportedandtherecentsuccessusingCMJforassessingNMF,itcanbeconcludedthatCMJtestsappeartobeasuitableathlete-monitoringmethodforNMFdetection.Specificallyinrelationtorugby,furthersupportforjumptestingtomeasurefatiguewaspresentedbyTwistetal.(2012),whoreportedthatjumptestsprovidethemostappropriateindirectmarkeroftissuedamageandreductioninmuscleforcegeneratingcapacity.RecentresearchinelitesoccersettingsbyRusselletal.(2015)alsoreportedthatcreatinekinase(34.3%)demonstratedgreaterbetween-matchvariabilitythanjumptestingmeasuringpeakpoweroutput(9.9%).

Jumptestsareconsideredexcellentindicatorsofneuromuscularfunctionforathletes,duetothestretch-reflexinvolvingbotheccentricandconcentricactions,asseeninjumpingandhoppingactionswithinrugby.Jumptestshavecommonlybeenused,asjumpsareaconvenientexerciseforassessingNMFthatiseasytoimplementintoahighperformancesportsetting,whileprovidinggreatecologicalvalidity.Eccentricmuscledamage,asseeninrugbyunionmatchplay,hasbeennoted,withHarrisonandGaffney(2004)showingreductionsinmanyjumptestingmovementspost-matchexposure.RecentstudieswithineliterugbyleaguefoundthatCMJperformancewasimpairedforupto24hourspost-match,alongwithreportsof26%reductioninPRFD24hourspost-match(McLellanetal.,2011b;Twistetal.,2012).

2.4.1.2.5 TherelevanceofjumptestingineliteperformancesettingsTwistetal.(2012)reportedaninverserelationshipbetweencontactsandimpairedCMJflighttime,indicatingthatplayersthatareinvolvedinmorecontactsexperiencemoreloadingonthelowerlimbsmusculature.Thisdamagetolowerlimbmusclesfromcontactsituationscanbeattributednotonlytothenumberofcontacts,butalsothetothelargeaccelerationsanddecelerationsleadingintothecontactsituation.WhilemoststudiesassessingneuromuscularrecoveryhaveutilisedoneCMJrepetition,Cormack,Newton,McGuigan,andCormie(2008)usedfivecontinuousCMJmeasuringflighttime.SingularCMJflighttimehasbeenseentoshowmoresubstantialreductionsinperformancecomparedtofiverepeatedCMJ,suggestingthatitislessabletodistinguishbetweenlevelsofneuromuscularfunction,despiteitsreactivenatureandSSCinvolvement.Additionally,inresearchassessingmuscledamageonSSCfunction(Harrison&Gaffney,2004),CMJwasseentoshowreducedlevelsofdecrementcomparedtoSJ.ThefindingsbyJohnstonetal.(2013)suggestthatmaximalstrengthassessmentsarelessaffectedthanpeakpoweroutputs,meaningCMJflighttimeisperhapsmoreappropriateformeasurementofmuscledamagethanisometricmeasurementssuchasisolatedlegpress.Johnstonetal.(2013)alsoreportedthatCMJheightcorrelateswithsprintperformanceover5m,10mand30m.Hamilton(2009)notedasignificantdecline(p≥0.05)indropjumpreactivestrengthindex(DJ-RSI)foryouthsoccerplayersfollowingmatchplay.DespiteCMJassessingflighttimereceivingpraiseasamodalitytoassessNMF(Cormack,Newton,McGuigan,&Cormie,2008;Cormack,Newton,McGuigan,&Doyle,2008),Hamilton(2009)notedDJ-RSIasbeinganappropriatetestforuseinteamsportsettings.

InspiteofCMJbeingthemostcommonlyusedjumpmodality,criticismsurroundingCMJexistsandinsomeresearchhasbeenreplacedbyotherformsofjumps(dropjumpsandsquatjumps)(Hamilton,2009;Kamandulisetal.,2011).CriticismofjumptestingasaperformancemeasureformeasuringfatiguehasbeenillustratedbyKrustrupetal.(2010),whonotedthatjumptests

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hadnoimpactuponthetypeoffatiguepostfemalesoccergame.However,itshouldbenotedthattherearenoticeabledifferencesbetweenfemalesoccerplayersandmalerugbyunionplayersintermsofthenumberofimpactsencounteredinmatchsituationsandtheassociatedtraumaandmuscledamage.ConsideringthefindingsbyGathercole,Sporer,Stellingwerff,etal.(2015a),thatmeanpower,peakvelocity,flighttime,forceatzerovelocityandareaundertheforcevelocitytraceshowedchangesgreaterthantheCVinmostindividuals,CMJuseisfurtherquestioned.Impairedneuromuscularfunction,duetoutilisationofthemorespecificSSCnatureofdropjumps(DJ)andtherelativelyshortcontractiontimesinvolvedinthemovement,leadtomoresensitivemeasures.TheincreasedsensitivityassociatedwithDJ(reactivestrengthindex)isinpartduetoDJ’susingbothcontactandflighttimemeasures,whichasHamilton(2009,p.4)concludes“anytechnicalalterationsthatdeveloptofacilitateimprovedforcecapabilities”thatcanbeassociatedwithotherjumpmodalities.ThehighspeedandpowerqualitiesassociatedwithrugbyunionmatchplayperhapsdeemDJtobeamoreaccuratemeasureofanathlete’scurrentfunctionalstate,comparedtodatafrombilateraljumpssuchasCMJ.

CMJhashoweverpreviouslybeenreportedtomeasurefatigueaccurately(Duffieldetal.,2012),withreducedvaluesofCMJandmaximalvelocitycontractionofthekneeinanisometrictestshowntocorrelatematchplayingtimeundertakenbyplayersinrugbyleague.Additionally,CMJassessingNMFhaspreviouslybeenreportedtobereliableandvalidusingtheFT:CTcalculation(Argus,Gill,Keogh,etal.,2012;Argusetal.,2009;Baker,2001c;Cormack,Newton,McGuigan,&Cormie,2008;Cormack,Newton,McGuigan,&Doyle,2008;Mooneyetal.,2013).McLeanetal.(2010)recommendedweeklyCMJtestingtoanalysetheresults,alongwithpsychometricvaluestoassessneuromuscularreadiness.FindingssuchasthosefromDuffieldetal.(2012)illustratethatintermittent-sprintteamsportssuchasrugbyunionresultinpost-matchsuppressionofskeletalmuscleforce.InastudybyJohnstonetal.(2013),assessingcumulativefatiguethroughoutaperiodofthreegames,decrementsindefensiveperformanceseeningamethreecorrelatewithreducedCMJvalues,suggestingthatlowerbodypowerisaprerequisitefortacklingability.Similarly,inarecentstudyassessinganintensifiedfixturescheduleinprofessionalrugbyleague,cumulativeNMF(Match1vs.Match2-2.3%;-Match3-6.9%;Match4-2.9%)wasnoted(Twist,Highton,Daniels,Mill,&Close,2017).Lastly,aspreviouslystated,decrementinjumpperformancepost-matchsituationshasbeenreportedinmanystudies(McLellanetal.,2011b;Twist&Sykes,2011;Waldronetal.,2011),withdecreasedperformancereportedinaperiodofupto24hours.Importantlythough,prolongedincreaseinmusclesorenesshasbeenreportedtolastforlongerthanjumpperformancedecrement,lastingupto48hoursinsomestudies(McLellanetal.,2011b;Twist&Sykes,2011).Itisbelievedthatthisperceivedsorenesshasanimpactuponplayers’senseofeffortduringtraining,intheimmediatedayspost-match,therebyhavingimplicationsuponthequalityoftrainingthatcanbeperformedduringthisperiod.Potentially,however,jumpperformancevaluescouldstillbecollatedinordertoassessplayerreadiness.

Fromtheresearchaboveitisevidentthatjumptestingisaperformancetestthatwarrantsconsiderationforusewithinfuturestudiesinthisthesis.Jumptestingisarelativelyeasyandinexpensiveperformancetesttoimplementinelitesettings,withtheresearchaboveillustratingitsreliabilityandvalidityformeasuringperformanceandfatigue,especiallywhenastandardisedtestingprotocolisadministered.

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2.4.1.3 MaximalergometertestingAnotherformofmaximaltestingusesergometerstoassessreadinesswithoneofthemostwidelyusedanaerobictestsbeingtheAnaerobicCyclingWingateTest,whereparticipantspedalmaximallyagainstaconstantresistanceproportionatetobodymass.Wingatetestshavebeenshowntoprovidereliablemeasuresofpeakpower,meanpowerandfatigue(Bar-Or,Dotan,&Inbar,1977)andwhenoneconsidersthatmaximalcyclingtestsarenotsolelylowerbodypowerassessments,supportformaximalcyclingtestsisunsurprising.Bakeretal.(2002)concludedthatalargecontributiontothepeakpoweroutputismadebythemuscularskeletalcomponentsoftheupperbody,suggestingthatacyclingergometertestmightbeawholebodyexercise.TheanaerobicnatureofWingatetestsandtheresearchpreviouslyreferredto,furthersupporttheuseofmaximaltestsasameansforassessingrugbyplayers.Anaerobicfatigueisatopicthathasreceivedaconsiderableamountofattention,withanaerobicandrepeatedsprintperformancetestsprovidinganindexofanaerobicendurance.Thepercentagedeclineinpower,relativetothepeakvalue,representsthemaximalcapacityforATPproductionviaacombinationofintramuscularphosphagenbreakdownandglycolysis(McArdle,Katch,&Katch,2005).

Maximalcyclingeffortshavebeenadministeredinrugbyleaguetoassessoverreaching,withadeclineinpeakpowerduringatensecondsprintaftersixweeksofintensivetrainingreported(Coutts,Reaburn,Piva,&Murphy,2007;Coutts,Reaburn,Piva,&Rowsell,2007).Thisdecreasedperformancewasattributedtoincreasedlevelsofmuscledamage.An“offfeet”testthatdoesnotinvolve“onfeet”runningmechanicsisoftendeliberatelychosenasafatiguetest,post-gameinrugbyunionplayers,usingthereliabilityofWattBiketesting(Drilleretal.,2014;Driller,Argus,&Shing,2012).Currentlyunpublisheddata(Grainger,Ripley&Comfort,InReview),utilising6”peakpowertestingonaWattBikeineliterugbyunionplayers,hasrecommendeditsuseforassessingrestorationofperformancepost-matchsituations.“Offfeet”testsareconsideredtobeamoresensitiveandpracticaltesttoadministeronrugbyplayerspost-match.Theaforementionedbluntforcetraumaandhighrunningvolumesassociatedwithrugby,alongwiththelargebodymassofplayers,meanthatrunninginthedayspost-matchwouldpresenttheplayersatanincreasedinjuryrisk.Thisincreasedinjuryriskwouldbeaccentuatedbythenatureofthemaximalrunningtests;meaningthatan“offfeet”testwouldbemoreapplicable.Itcouldalsobearguedthatanindoortestonastationarybikewouldbemorereproduciblethanarunningtestperformedoutside,whichcouldbeaffectedbyweatherandgroundconditions,therebycreatinginaccuracies.

2.4.2 RunningspecificperformancetestsforfootballcodesAreliableandrobustmeasureoftheperformanceofarugbyplayerforuseasatoolforadjustingtrainingscheduleshaslongbeenrequired.Performancemeasuresinmostfootballcodesettings(soccer,rugbyunionandrugbyleague)seekingtoreplicatethemovementsofthesportgenerally,involverunningspecificactivitywhichischallengingtoimplementandperhapsimpossibletomakeaccuratejudgementsupon.Typicallymaximalrunningtestshavebeenusedinrugbyleague(Coutts,Reaburn,Piva,&Murphy,2007;Coutts,Reaburn,Piva,&Rowsell,2007)withoverreachingathletesidentifiedviaaMSFTfollowinganintensifiedtrainingperiod.DespiteCoutts,Reaburn,Piva,andMurphy(2007)reportingonthestateofoverreaching,theynotedthatthemostlikelyexplanationforthedecreasedperformanceisincreasedmuscledamage,viaadecreaseintheanabolic-catabolicbalance,inadditiontopoormanagementofthetrainingadaptationprocess.Inanotherstudyexaminingperformancetestsforrugby(Austin,

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Gabbett,&Jenkins,2013)itwasnotedthatrepeatedsprintabilitytestsalonemayunderestimatetherepeatedhighintensityeffortsseeninrugbymatchplayandalsotheassociatedfatiguethatthiscreates(Johnston&Gabbett,2011).However,Austinetal.(2013)concludedthatthefindingsfromtheirrepeatedhighintensityexerciseperformancetestwereadequatelysensitivetodetecttraininginducedchangesinrugbyleagueandrugbyunion.WithintherugbyleagueandrugbyunionresearchbyAustinetal.(2013)varyingreliabilitywasnoted,withICCfortotalsprinttimebeingmoderatetohigh(0.82,0.97,and0.94)andCVlow(4.2,1.4,and0.6%)forthebacks,rugbyleagueforwards,andrugbyunionforwardstests,respectively.Additionally,thereliabilityofrunningspecificperformancemeasureswasquestioned,whenconsideringthatsprintperformancedecrementscoreswerelow,withICCandCVof0.78,0.86,and0.88and49.5,48.2,and35.8%forrugbyleagueandrugbyunionbacks,rugbyleagueforwards,andrugbyunionforwards,respectively.

Onecouldarguethattheserunningspecificperformancetestsandtheirassociatedtraininginducedchangescouldpresentgreaterunderstandingasregardsdatauponwhichtoassessplayerfatigueandoverallreadiness.Within“realworld”eliterugbysettingsitisunrealistictoaskplayerstocompleterugbyspecifictestingmeasures.Attimesmultipleplayersmayberequiredtoperformacontactsituationdrillthatreplicateselementsofthegame(tomaketheperformancemeasurementsasspecifictotherugbytasksinquestionaspossible),yetthedrillisforthesolepurposeofassessingoneplayer’sfatigueorreadiness.Thisfurtherhighlightstheunrealisticexpectationsofsuchrugbyspecificperformancetests“onfeet”.Addedtotheimpracticalityofusingspecificrugbytests,theextrafatiguethatthesetestingpracticeswouldinducemaketestingforreadinessusingrugbyspecificmeasureslessappropriateforuseinelitesettings,wherethedaysbetweengamesareshortandanalreadybusytrainingschedulemakestheeliteplayerscompliancetosuchtestingunlikely.Duetotheimpracticalityofusingrugbyspecificperformancemeasuresforassessingreadiness,themonitoringofcurrentfunctionalcapacityhasfocuseduponindirectmarkersofperformancesuchasalternativeformsofmaximalandsubmaximaltestingandotherrelevantphysiologicalandpsychologicalassessments.

Cormack,Smith,Mooney,Young,andO'Brien(2014)assessedloadperminute(LPM)viaGPSdatacollectionasameasureofexerciseintensity.LPMwascalculatedviaaccumulatedaccelerationsmeasuredbytri-axialaccelerometers,withCormack,Monney,Morgan,andMcGuigan(2013)concludingthat,whenconsideringLPMinconjunctionwithNMFdataassessedviaCMJ,itisapparentthatLPMmeasuresareacutetoefficiencyofmovementperformed,duetoreducedneuromuscularfunctionandwouldthereforebeanotherperformancemeasureuponwhichtojudgeplayerreadiness.TheseGPSvaluessuchasLPMdo,however,needtobevalidatedforreliability,despiteMooneyetal.(2013)showingsimilarGPSefficiencywhenassessingCMJperformance,Yo-YoIRtestingandsubjectivecoaches’voting.OnecouldarguethatjumptestingcouldmeasuretheSSCofathletesbutwouldnotprovideaglobalmeasureofplayerfatigueinrugbyunion.Itwasarguedthataplayercouldperformamaximaljumpdespitebeingfatiguedandthereforeshownosignsofdecrementintheirjumpperformance.Whereasamaximaleffortperformancemeasuretest;suchasMSFTor(Coutts,Reaburn,Piva,&Rowsell,2007)Yo-YoIntermittentEnduranceLevel2Test(Yo-YoIE2)(Krustrupetal.,2010),wouldpresentmoreobjectivedatauponthewholeathlete,asregardsneuromuscularfunctionandcardiovascularreadiness,ithasbeenshowntobeadefinitiveperformancemarkerforNFORinteamsportathletes.However,manyrunningspecifictests,

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althoughnotmaximalinnature,arehardertoimplementlogisticallythanjumptesting,forexample,andcanaddtothetrainingvolumeandsubsequentfatigueoftheathlete,meaningthatitmaynotbethebestperformancemeasureformanysportingscenarios.

Sub-maximalrunningtestsarecommonlyusedwithinteamsportsettings(Buchheitetal.,2013;Cornforth,Robinson,Spence,&Jelinek,2014),withheartratederivedmeasuresusedtoassessreadinessandgeneralfatigue.Heartraterecovery(HRR)andheartratevariability(HRV)aretwosuchperformancemeasuresandtheycanbeusedwithinsub-maximalexerciseprotocolasperformancemeasuresforfatigue.HRRandHRVarethereforeconsideredforusewithinfuturestudieswithinthisresearchandarecritiquedinmoredetailwithinChapter5.5.

2.4.3 Perceptualfeelingsofwell-beingPerformancetestsprovideagoodindicatorofanathlete’sphysicalandpsychologicalwell-being;yetasmentionedpreviously,oftenaddfatiguetoparticipantsandarethereforeimpracticalfordailyimplementation.Thegoalofmanysportpractitionersistoprovideastimulusthatimprovesprospectiveathleticperformance,withmanypractitionersapplyingwell-being(WB)questionnairesasameasureoffindingoutbothhowtheirplayersfeelandhowtheyarehandlingthetrainingvolume(Coutts,Wallace,&Slattery,2007;Halson,Lancaster,Jeukendrup,&Gleeson,2003).SupportfortheuseofmonitoringtoolssuchasWBquestionnairesisvast(Coutts,Wallace,etal.,2007;Elloumi,Maso,Michaux,etal.,2003;Johnstonetal.,2013;Slattery,Wallace,Murphy,&Coutts,2006),withcoefficientvariantforsubjectivemoodstatebeing9-12%(Hooper&Mackinnon,1995).Despitethis,researchintotheeffectofteamsuccessuponmoodisstillunclear(Gonzalez-Bono,Salvador,Serrano,&Ricarte,1999).Mooddisturbances,asassessedviaquestionnaire,havebeenreportedtoincreaseinaprogressivemannerastrainingloadincreases(Filaireetal.,2001;Saw,Main,&Gastin,2016),whilemoodwasnotedtooutlasthormonalresponsespostrugbyunionmatch(Westetal.,2014).Subjectivemarkersoffatigueinclude;theProfileofMoodStates(POMS)questionnaire,theTotalQualityRecoveryScale,thePassiveand/orActiveRecoveryScaleandtheDailyAnalysisofLifeDemandsforathletes’questionnairehavebeenutilisedinteamsportstudiesoftrainingeffectandreadiness(Filaireetal.,2001;Kentta&Hassinen,1998;Sheareretal.,2016).FurthersupportforWBquestionnairescomesfromKillenetal.(2010)whoreportedatrendtowardshigherinjuryratesandnoticeablechangesinpsychologicalwell-being.Whenconsideringthatsensorypsychologicalinhibitionpost-exerciseisperhapsthemaincauseoffatigueduringperiodsofhightrainingvolume(asillustratedinChapter2.3.2)furtherevidencefortheuseofWBmeasures,thatcanassesspsychologicalreadinessinthedayspostrugbygame,arefurtheremphasised.

Asmentioned,supportfortheuseofmonitoringtoolssuchaswell-beingquestionnairescomesfromSlatteryetal.(2006).TheyclaimedthattheRESTQ-76Sportquestionnaireprovidedapracticaltoolformonitoringoverreachingintriathletes.Recentresearchinteamsportsettingshasalsosupportedtheimportanceoffrequentmonitoringofrecoveryandstressparameterstolowertheriskofinjuriesinprofessionalfootball,withtheRESTQ-Sportquestionnairepredictinginjuriesinthemonthaftertheassessment(Laux,Krumm,Diers,&Flor,2015).TwistandHighton(2013)studiedrugbyleagueplayers’functionalstateinpost-matchsituationsandconcludedthatamultidimensionalapproachshouldbeadministeredinordertotestandmanagefatigue,asanalteredsenseofeffortwaspresent,bothwhenfatiguedandduringperformingtesting.Whenanimpairedpsychologicalstateormentalfatigueisapparent

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participantsmaydownregulatetheirexercisecapacity.Thisisthereforeapointtoconsiderforanyfutureperformancetestingunderastateoffatiguepost-match.ThisnotionwassupportedbyJohnstonetal.(2013)whonotedthatanincreaseinperceivedmusclesorenessmightperhapsincreaseperceivedeffort,therebyreducingarugbyplayer’sabilitytoperformoptimally.

Subjectivemeasureshavebeenusedtomonitorfatigueinrugby,withpreviousresearchincludingself-reportwell-beingquestionnaires,showingreducedperceptionofreadinessacrossalongitudinalperiod(Cresswell&Eklund,2006).Evidencefortheuseofwell-beingquestionnairesinrugbyunionwassupportedbyTwistandHighton(2013)whofoundalterationsinperceivedfatigueandmusclesorenesstooutlastdeductionsinneuromuscularandbiochemicalmarkers.Fatigueanddiminishedperformancethroughoutarugbyseasoniscommon,withpreviousresearchinrugbyunion(Argus,Gill,Keogh,etal.,2012)reportinga3%decreaseinlowerbodypeakpowerduringacompetitivephaseinrugbyunion,whileastudyassessingin-seasonstrengthandpowercharacteristicsinrugbyleagueshowedadecreaseof1%inlowerbodymeanpower(Baker,2001b).EvidenceforthisresultantfatigueandreducedperformancecapacityhavebeenrepresentedbycorrelationsbetweenOTscoresassessedviaquestionnaireandalteredCKvalues.ThisevidenceisapparentinthestudybyAlaphilippeetal.(2012)assessingbiochemicalmarkersoveralongitudinalperiodinrugbyunion.Inrugbyspecifically,perceptualfatigue(assessedviaquestionnaire)wasreportedtolastuptofourdayspost-match(Johnstonetal.,2013).TwistandHighton(2013)reportedachangeofapproximately1to2onascaleof1to5inmusclesoreness,fatigueandattitudetowardstraininginthe48hourspostrugbyleaguegamewhenassessingviaaLikertscale.Nicholls,Backhouse,Polman,andMcKenna(2009)notedthatrugbyunionplayersdescribedmanyself-reportstressorsasbeing“worsethannormal”thedayafteramatch,incomparisontodaysprecedingandincludingmatchday.

Musclesorenesspost-matchhasbeeneffectivelyresearchedinpreviousrugbyunionresearch(Gilletal.,2006;Takarada,2003)andwasconsideredanappropriatemeasureuponwhichtoassessrecovery.Whenanimpairedpsychologicalstateormentalfatigueisapparent,participantsmaydownregulatetheirexercisecapacity.Aswasdiscussedinrecentresearch(Marcora,Bosio,&deMorree,2008;Marcora,Staiano,&Manning,2009;Twist&Eston,2009),perceivedmusclesorenessandtheeffectthishasuponincreasedperceivedexertionareimportantconsiderationsforwell-beingassessment.Ithasbeenreportedthatalterationsinperceivedfatigueandincreasedmusclesorenessareknowntooutlastreductionsinneuromuscularperformanceandbiochemicalmarkersinrugbyleague(Twist&Highton,2013;Twistetal.,2012).Thisprolonged,lastingalterationinperceivedfatiguesupportstheargumentfortheuseofwell-beingquestionnaires,yetalsoillustratestheimportanceofintegratingperformancemeasuresassessingNMFandwithself-reportmeasures.RecentresearchineliterugbyunionbyShearer,Kilduff,etal.(2015)furtheremphasisedtheuseofWBmonitoringasameasureofrecovery,viaTheBriefAssessmentofMoodquestionnaire(BAM)(ashortenedversionofPOMS),althoughitdidrecommendeditsusealongsideendocrinemeasuresandpoweroutput.

Despitewell-beingratingsbeingcommonpracticeintheelitefieldandbeingrelativelyeasytoadministeratminimalcost,cautionshouldbetakenwheninterpretingresults.Limitedevidenceexists,regardingtherelationshipbetweenwell-beingquestionnairesandchangesinperformance,withcompliancefromathletesdecreasingifdatacollecteduponthetrainingdose-

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responserelationshipisnotactedupon.RecentresearchbyRoeetal.(2015)presentedaCVof7.1%forWBquestionnairesineliteyouthmalerugbyplayers,whichdespitebeinglowerthanthe<10%CVrecommendedbyBuchheit,Lefebvre,Laursen,andAhmaidi(2011),showsthedifficultyofassessingWBscoresandthereforewarrantsconsiderationwhenusedtoassessfatiguepostrugbyunionmatchplay.Practitionershavebeennotedtogatherdataonrecoveryviacustom-madequestionnaires(Rowselletal.,2009)anditisbelievedthatwell-beingquestionnaires,designedapplicabletothesportinquestion,providemoreinformativedataontheresponseoftheindividualthanagenericwell-beingquestionnaire.Onecouldthereforearguethattheuseofwell-beingquestionnairesinteamsportsettingsareespeciallyimportant,consideringthateachindividualmightrespondinadifferentmanner,asaresultofthetrainingdoseadministeredbythecoaches,aswasfoundinthestudybyLovelletal.(2013)assessingfactorsaffectingRPEinrugbyleague.

Inadditiontodesigningbespokequestionnairesforathletes,thequestionnairelengthandfrequencyofadministrationshouldbeconsideredassupportedbyHalson(2014)inordertomaximisecompliance.Saw,Main,andGastin(2015)recommendedamultifactorialandmulti-levelapproachtobeimplantedintoathleteself-reportmeasures,toimproveefficacy.Inadditiontotheaforementionedconsiderations,practitionersshouldbeawarethatathletescouldmanipulatewell-beingdata,basedupontheirestimationofthetrainingloadanddesiretomanipulateanyfuturetrainingplanned.Additionally,anathlete’ssleepisoftenratedwithinfatigueresearch,yetthereliabilityofsuchmeasuresisoftenquestioned,asthelengthandqualityofsleep,forexample,aredifficulttomeasureviaperceptualmeasures,despitetheimportanceofameasuresuchassleepbeingusedtoassessanathlete’sreadiness.Thevalidityofsomeoftheperceptualmeasuresusedbypractitioners(suchasself-reportwell-beingandrateofperceivedexertion)intheresearchoutlinedinTable2.13isthereforequestioned.

2.4.4 BiochemicalmarkersAssessingfatigueviaperformancetestssuchasjumptests,submaximaltests,orsportspecifictestsiscommonplacewithinelitesettings,yet,asconcludedbyTwistandHighton(2013),performancetestsshouldonlybeusedwhenothermarkers(biochemicalandperceptualmeasures)suggestfatigue.Itis,however,importanttonotethatmanyteamscannotaffordtoimplementbiochemicaltestingandthattheythereforeutiliseperformancetesting(sub-maximalormaximal)asanalternativemeansofassessingfatigue.Hormonalconcentrationsduringtherecoveryperiodpost-trainingorcompetitionprovideimportantdataforpractitionerswhenassessingrestorationofperformanceandassociatedreadiness.Neuroendocrineresponsetoexerciseiswelldocumented(Cunniffeetal.,2010;Lindsay,Lewis,Scarrott,Gill,etal.,2015),yetthefindingsontheresultantfatiguestatearecontrasting(Cormack,Newton,&McGuigan,2008;Filaire,Legrand,Lac,&Pequignot,2004).

Manystudieshavereportedtheuseofbiochemicalandendocrineanalysisduringteamsportsseasons(Alaphilippeetal.,2012;Crewtheretal.,2009;Cunniffeetal.,2010;Hoffmanetal.,2002),reflectingthestressandmuscledamagethatoccurspostmanyteamsportmovements,withareviewofthepotentialuseofurineandsalivatoolsnotedas“thefuture”inarecentreviewofnon-invasivebiomarkers(Lindsay&Costello,2016,p.11).Crewtheretal.(2009)analysedneuromuscularchangesandassociatedchangesinbiochemicaldatapost-trainingforthirty-fourprofessionalmalerugbyplayers.Correlationswerefoundbetweensalivarytestosteroneandcortisolvaluesandspeed(10m,20mor30msprints;r=0.65,p<0.05);

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power,concentricmean(r=0.41,p<0.05),duringa70kgSJand50kgpeakpowerbenchpressthrow(r=0.41,p=0.05);andstrengthmeasures(estimated1RM)strengthforaboxsquat(r=0.39,p=0.05)andbenchpress(r=-0.42,p<0.05).Morerecentresearchinrugbyunion(Westetal.,2014)has,however,notedthatnorelationshipsexistbetweenchangesinCMJ,biochemicalmarkers(testosteroneandcortisol)andmood.Thesefindingshaveimplicationsforthepost-matchrecoverymodalitiesimplementedandthehormonesecretionpatternsexpected.Itis,moreover,importanttonotethatpractitionersshouldbeawarethatthepossiblereasonsforthecontrastingresultsbetweenstudiesthatassessuseofbiochemicalmarkersinrugbymightbebaseduponmethodologicaldifferences.Forexample,thestudybyWestetal.(2014)incorporatesdatapost-match,whereasthestudybyCrewtheretal.(2009)assessespost-trainingacrossdifferingtime-points,withdifferentperformancemeasurescorrelatedtobiochemicalmarkersbeingevidentwithinboththestudies.Thefollowingsub-chapterscriticallyassesscommonlyusedbiochemicalmarkersutilisedbyteamsportpractitionersandtheirpracticalityforusewithineliterugbysettings.

2.4.4.1 MuscledamageandbiochemicalresponseResearchinbothrugbyleagueandrugbyunion(Cunniffeetal.,2010;McLellanetal.,2011b;Takarada,2003)hasshownthatthenumberofcollisions/tacklesthatoccurduringmatchescorrelateswithmuscledamagemarkers,whileinsoccerthevolumeofhighintensityefforts,manyofwhichincludeeccentricloads,relatesspecificallytofatigueandmuscledamage(Crewtheretal.,2009;Proske&Morgan,2001).Takarada(2003)notedthatthedegreeofmuscledamageinrugbyunionrelatesdirectlytothenumberofcollisionsexperienced,withMcLellanetal.(2011b)notinga25%reductioninPRFDand20%reductionassociatedwitha51%increaseinsalivarycortisolconcentrations,ineliterugbyleagueplayers. McLellanetal.(2011b)reportedthatCKvaluesremainedelevatedforuptofivedayspost-matchandthatsignificantcorrelationswereseenbetweenCKvaluesandPRFDandcortisolandpeakforcePFmeasuredviaCMJ.Itis,however,importantforpractitionerstounderstandthattherearedifferencesinthemethodsusedtocollectandanalysethebiochemicalmarkersmentionedabove.Forexample,bloodsampleswereusedtoassessimmuneendocrinemarkerspost-matchplaywithintheresearchbyTakarada(2003)andbyCunniffeetal.(2010),yetintheresearchbyMcLellanetal.(2011a)theyincorporatedbothbloodandsalivameasurements.Despitedatatakenatsimilartime-pointsacrossalltheaboveresearch,disparitiesinresultstakenfrombothbloodandsalivaareexpected,thereforeemphasisingtheneedtocompareonlydataacrosssimilarmethodologicalprotocols.Reliabilityofbothsalivameasureshavebeenreported,withDabbs(1990)presentingr=0.64acrosstwodaysandr=0.52acrossseven-eightweeksusingsalivatestosteronemeasurements.Theimportantconsiderationhereforpractitionerstonoteisthemethodologyused.Cautionisadvisedwhencomparingresearchwhere,forexample,Coutts,Reaburn,Piva,andMurphy(2007)usedplasmatestosteronetocortisolmeasures,whereasWestetal.(2014)usedsalivarymeasuresacrosssimilareliterugbyplayingpopulations.

Duffieldetal.(2012)andTwistandHighton(2013)discussedstudieswheresignificantpost-matchincreasesinmuscledamagewereobservedthroughCKandmyoglobinanalysis.SimilarsupportfortheuseofCKanalysisinrugbyunionhasbeenreportedbyAlaphilippeetal.(2012)andinmanyrugbyleaguestudies(Johnstonetal.,2013;McLellanetal.,2011b;Twistetal.,2012),withincreasesinCKvaluesfollowingsixweeksofdeliberateoverreachinginrugbyleague(Coutts,Reaburn,Piva,&Rowsell,2007).AnincreaseinCKhasbeenquantifiedasa

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reliablemarkeroftissuedamagepost-matchplayinrugbyleagueandhasbeenrecommendedasamarkertomonitorrecovery(McLellanetal.,2011a),aswellastrainingprescriptioninvolvinghormonemonitoring(Crewtheretal.,2009).SomeresearchhasreportedCKrequiring72hourstoreturntobaselinevaluespost-rugby(Minett,Duffield,&Bird,2010;Takarada,2003).Varyingresultshave,however,beenreportedforCK,withaCVof26.1-27%reportedbetweentestingdays(Roeetal.,2015;Twist&Highton,2013;Twistetal.,2012).TwistandSykes(2011)commentedthatmyofibrillardisruptionhasbeenreportedinsomestudies(Cunniffeetal.,2010;Takarada,2003),yetthismeasureofmuscledamageprovidesnoclearindicationofmusclefunctionanditismorelikelythatforcegeneratingcapacityprovidesthemostappropriateindirectmarkerofmuscledamage.

Despitealargeamountofrecentresearchincorporatingsalivatestingthatassessestime-courseofchangesinimmuneoendocrinemarkersinteamsports(Beaven,Cook,etal.,2008;Beaven,Gill,etal.,2008;Cormack,Newton,&McGuigan,2008;McLellanetal.,2010),variedreliabilityandvalidityhasbeennoted(Coad,McLellan,Whitehouse,&Gray,2015;Dabbs,1990).Thispoorreliabilityandsubsequentlackofmeaningfulimpactofsalivatestingis,therefore,apointtoconsiderforpractitionersintheelitefield,whenmakingdecisionsaboutwhichtestingmeasureswouldbebesttoimplement.

2.4.4.2 HormonalresponseTandCareconsideredreliablemarkersofareturntoendocrinehomeostasispost-competition,withTbeingthedominantanabolicmarkerofproteinsignallingandCbeinganimportantstresshormonethatworksagainstT(Cormack,Newton,McGuigan,&Cormie,2008;Elloumi,Maso,Michaux,etal.,2003).Arugbymatchisknowntoalterthecatabolic/anabolic-relatedhormonalhomeostasistowardsapredominantcatabolicresponseduringthefirst48hoursoftherecoveryprocess(McLellanetal.,2010).McLellanetal.(2010)alsoreportedthatreturntonormaltestosteronetocortisolbalance(T:C)isexpectedwithin48hoursofrugbyleaguematchplay.Cunniffeetal.(2010)reportedT:Clevelsrisingabovepre-gamevaluesandElloumi,Maso,Michaux,etal.(2003)notedthatT:Cratioincreasedabovebasallevelsforuptofivedayspostinternationalrugbygames.Cormack,Newton,McGuigan,andCormie(2008)discussedtheanabolic-catabolicT:Cratioandreportedaratiodecreaseof30%asbeinganaccurateindicatorofovertrainingandthatChadasmallrelationshiptoperformancewhenassessedalongsideCMJflighttime.Filaireetal.(2001),however,didnotethatcautionshouldbeusedwhenusingtheT:CratioforNMFassessmentastheirresultsdidnotrelatetoreducedperformanceordiagnosedOTwhenusingprescribed70-75%ofVO2maxphysicaltrainingsessions.Conversely,someresearch(Alaphilippeetal.,2012;Coutts,Reaburn,Piva,&Murphy,2007)reportedthatlargetrainingloadswithinsufficientrecoverycausedreductioninT:Cratio,increasedCKactivityanddecreasedglutaminetoglutamateratio.

Buchheitetal.(2013)notedthattrainingload,heartratedataandwellnessmeasuresviaquestionnairesshouldbeusedtomonitorrecoverystatus,butnotthesalivarycortisolmeasurescommonlyusedtoassesshormonalbalance.Whenexaminingtheusefulnessofselectedphysiologicalandperceptualmeasurestomonitorfitness,fatigueandrunningperformanceduringatwoweekpre-seasontrainingcampinAustralianrulesfootballers,Buchheitetal.(2013)notedsignificant(p<0.001forall)day-to-dayvariationsintrainingload(CV=66%),wellnessmeasures(6-18%),HRex(3.3%),LnSD1(19.0%)whenutilisingaYo-YoIR2test(pre-,mid-andpost-trainingcamp).Buchheitetal.(2013)didnoticethatsalivary

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cortisolmeasuresdidnotshowpracticalefficacy(20.0%,p=0.60),furthersignifyingtheneedforcautionwhenimplementinghormonalmeasurestoassessreadiness.Inadditiontoday-to-dayvariationsthatexistwithinsalivarycortisol,Hayes,Sculthorpe,Young,Baker,andGrace(2014)reportedthatalargemagnitudeofchangeforsalivarycortisol(90%)andsalivarytestosterone(148%)exists,thereforesuggestingabiologicallysignificantmeanchangeisdifficulttoassess.Filaireetal.(2001)similarlyreportedthatdecreasedsalivaryT:Cratiodoesnotleadtoadecreaseinteamperformance,orperceivedwellness,oftheplayersassessedviaquestionnaireinprofessionalsoccer,whilemorerecentresearch(Sheareretal.,2016)hasnotedvarianceinCKcorrelationwithBAMscoresineliteunder21academysoccerplayers.ThisisincontrasttopreviousresearchthathasreportedsignificantchangesinCpostteamsportgames(Cormack,Newton,McGuigan,&Cormie,2008;McLeanetal.,2010).Datafrombothsoccerandcyclingendurancetests(Filaire,Lac,&Pequignot,2003;Gastmann,Petersen,Bocker,&Lehmann,1998)wouldsuggestthatinsteadoftheT:CratiobeingawarningsignforOTS,itisperhapsonlyanindicatorofshorttermphysiologicalstressfromtrainingorcompetition.TheaforementionedresearchbyFilaireetal.(2001)illustratestheinaccuracyofTandCassessmentwhenusingtheT:CratioforNMFassessment,astheirresultsdidnotrelatetoreducedperformance.Whenconsideringthetimeconsumingnatureofmanagingbiochemicalessays,alongsidetheinconclusiveaccuracyofTandCtestingalone,therationalefortestingtheT:Cratioisfurtherquestioned,demonstrating,perhaps,thatidentificationofasinglebiochemicalvariablewouldbemorerealisticforuseinteamsportsettings.Biochemicaltestingwithineliterugbyenvironmentsonaregularbasisisthereforeconsideredimpractical,duetothetimecommitment,cost,circadiandisturbancesandlackofrapidfeedbackinvolvedwithinsuchbiochemicaltestingprocedures.

2.4.4.3 MetabolicresponsetorugbygameplayMetaboliccostofexerciseandtheassociatedEIMDhavebeenresearched(Tee,Bosch,&Lambert,2007),aswellasinflammatoryresponsetolowfrequencyneuromuscularfatigue(Twist&Eston,2009).Mashikoetal.(2004b)notedthatrugbyunionforwardsaccumulateacatabolicdegenerationofmuscletissueduetocontactsituations,incontrasttobackswheremetabolismandenergyconsumptioninducesfatigue.McLellanetal.(2011b)reportedthatimmediatereductioninneuromuscularfunctionpost-match,whenassessingjumpperformanceandassociatedSSC,shouldbeattributedtothemetabolicaccumulationanddepletionofenergysourcesduringperformance.Additionally,secondaryreductioninNMFwasnotedbyMcLellanetal.(2011b)tobemorelikelytobeattributedtotheinflammatoryprocessesaccumulatedasaresultofSSCexercises.Thesevaryingformsoffatiguehavebeenreportedtorequiredifferingingestionofrecoveryenergysourcespost-match,whereforwardsarerecommendedtoincludeanincreasedsourceofproteininordertoacceleraterecovery(Mashikoetal.,2004b).Ingestionofenergysources(carbohydrates,fatsandproteins)hasbeennotedtospeedrecoveryinpost-matchsituations,aidinginthereplenishingofglycogenstoresandrepairofmuscledamageandthereforespeedingrestorationofperformance(Howarth,Moreau,Phillips,&Gibala,2009;Minettetal.,2010;Mooreetal.,2009).ThisisdiscussedinmoredetailinChapter2.5.1.7.Bothsubstratedepletionandmuscledamageareconsideredtobemajorinhibitorsofhastenedrestorationofperformanceandgeneralfeelingofrecoverypost-rugby(Casiero,2013)andarethereforeanareaofimportanceforpractitionersworkingwithteamscompetingonaweeklybasiswheretheneedtohastenrecoveryandimprovereadinessforthenextmatchareessential.

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IthaspreviouslybeenreportedbyBangsbo,Iaia,andKrustrup(2008)thatfatiguetowardstheendofsoccermatchplayismuscleglycogendepletionrelated.Itcould,however,bearguedthatthisglycogendepletionwouldnotaffectjumpperformanceimmediatelypost-matchandthatinsteaditismorelikelythatmuscularfatiguefrommovementpatternscompletedwithingamesituationswouldaffectjumpperformance.Theexercisedurationassociatedwithrugbyunionmatchplayistooshortforanyglycogeniccontributiontoberequiredandhencejump-testmarkersarelikelytobeaffectedbyglycogendepletionfatigueimmediatelypost-match,thereforeemphasisingtopractitionersthatotherareasoffatiguepost-match,suchasmuscledamage,warrantmoreinvestigationthanmetabolicresponses.Glutaminetoglutamateratioisonebiochemicalmarkerthathasbeenconsideredtobeagoodindicatoroftolerancetotrainingassessingfreeaminoacidconcentrations,showingareductioninglutamine/glutamateratiothusrepresentingitstrainingintoleranceinrugbyleague(Coutts,Reaburn,Piva,&Rowsell,2007).Totheauthor’sknowledgenodatahasbeenreportedonoptimalglutamine/glutamateratiosinteamsportssuchasrugby,althoughHalsonetal.(2003)haveobservedathresholdof<3.58asbeingindicativeofoverreachingincycling.Itisofimportanceforpractitionerstonotethatfactorssuchasnutritionaldietanddeliberateglutaminesupplementationcouldaffectresultantfreeaminoacidconcentrations.Therefore,cautionshouldbeadvisedwhenusingglutamine/glutamateratiostoassesstrainingtoleranceinteamsportsettings.

2.4.4.4 ConsiderationsforbiochemicaltestingAlthoughbiochemicalmarkersoffatigueprovidemoreobjectivemeasuresofhomeostaticdisturbances,theexpenseassociatedwithhormonaltestingandtheexpertiseneededtoperformsuchtestsmakethemunrealisticforassessmentinmanyclubrugbyunionteams.Onecouldalsoconcludethathormonalmarkersasmeasuresforassessmentinrugbyunionarenotpracticalinateamenvironment,wheredailytrainingandthelargenumberofplayersinaplayingroster,wouldinhibithormonalmarkertestingonaprogressivebasis.Anotherimportantconsiderationforpractitionersisstandardisationofbiochemicaltestingprotocol.Commonissuesthatareknowntobeutilisedandtoaffectthereliabilityofbiochemicaltestinginclude;ambienttemperature,hydrationstatus,diet,glycogencontent,previousexerciseandsamplingprocedures.TheseissuesaresummarisedbyHalson(2014,p.143)whonotes“theuseofbiochemical,hormonaland/orimmunologicalmeasuresasindicatorsofinternalloadiscurrentlynotjustifiedbasedonthelimitedresearchinthisarea”.Whenconsideringthelowreliability(Hoffmanetal.,2002)andlargeintra-individualdifferences(Masoetal.,2004)associatedwithbiochemicaltesting,practitionersshouldinsteadfocusuponmarkersfromperformancetests,whicharespecifictothetaskcompletedandaremorepracticalinnature.

FurtherlackofsupportforbiochemicaltestingarisesfromresearchassessingbiochemicalandhormonalresponsesduringanintercollegiateAmericanfootballseason(Hoffman,Kang,Ratamess&Faigenbaum,2005,p.1237),whereplayerswerenotedtodevelop‘‘contactadaptation’’astheyprogressthroughthecompetitiveseason.AssupportedbyTwistandHighton(2013),duetotheinhibitiveandexpensivenatureofbiochemicaltestingamoreroundedappraisalofplayerfatigueandsubsequentreadinesstotrainisrecommendedforuseinmanysportingenvironments.Consideringthatitisnotuncommonforhormonalandneuromuscularfactorsnottocorrelatewithperformancetestssuchasthosedetailedabove,practitionersshouldperhapsusebiochemicaltestinginconjunctionwithmovementdata(GPS)andheartratedata,whichhavebeennotedtohavehighvalidityandreliability(Casamichanaetal.,2013)inadditiontoperceptualmeasures(RPE)whichwouldthereforeaidinbetter

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quantifyingglobalfatigue.

2.4.5 HeartratederivedmeasuresAchangeinheartrate(HR)duetoautonomicnervoussystemresponseisapossibleindicationofadaptationtotrainingstress.Asacoach,asimpleandeffectivemeansofassessingplayerreadinessisparamount,withheartratederivedmeasuresprovidingrecentliteraturetoaidpractitionersattemptingtoquantifyload(Bosquetetal.,2008).Trainingloadassessmentviaheartratemeasuresiswell-documentedandvalidatedinendurancesports(Plews,Laursen,Kilding,&Buchheit,2012;Plews,Laursen,Stanley,Kilding,&Buchheit,2013),yetthismethodofassessmenthasonlybeenresearchedinafewteamsportscenarios(Buchheitetal.,2013;Couttsetal.,2003).MostHRdatafromrugbyconcernsmatchsituations,wheredatahasbeenusedtodescribetheintensityandenergyexpenditureofplayersthroughoutgames,therebyhelpingtoguidepractitionersintrainingprescription.Recently,however,manypractitionershaveusedheartdatatoguiderecoveryandrestorationpost-performance(Cornforthetal.,2014).

2.4.5.1 RestingheartratePerhapsthesimplestheartratederivedmeasureoffatigueisthatutilisingrestingheartrate(RHR),withoverreachingineliteathletesnotedtocorrelatewithincreasedRHR(Kuipers&Keizer,1988)whenreviewingeliteathletecasestudies.LackofsupportfortheuseofrestingheartratecomesfromBosquetetal.(2008),whonotedtrivialincreasesinRHRasanindicatorofoverreaching,whenconductingameta-analysisupontheeffectofoverloadtrainingonRHR.Bosquetetal.(2008)did,however,observelargerincreasesinRHRpostshort-termtrainingloads,thereforerepresentingRHRasavalidindicatorofshort-termfatigue.DespiteRHRbeingarelativelysimplepracticetoimplement,itsuseinteamsportsettingsislimitedandrequiresfutureresearchtoconfirmvalidity.RecentresearchbyPlews,Laursen,Kilding,andBuchheit(2013),evaluatingtrainingadaptationandcomparingmethodologicalpracticesfromheart-ratederivedmeasures,recommendthepracticeofaveragingweeklyRHRvalueswhenassessingadaptationtotraining.

2.4.5.2 HeartratevariabilityOneofthemostincreasinglyusedmethodsofassessingcardiacreadinessviaheartratemeasuresistheapplicationofheartratevariability(HRV)assessment,whichwasfirstusedinclinicalpracticealmostfortyyearsago.HRVassessmenthasreceivedsignificantpraiseinrecentyears(Bosquetetal.,2008;Stanley,Peake,&Buchheit,2013)andhasbeenappliedinmanyelitesportingsettings(Buchheitetal.,2013;Plews,Laursen,Stanley,etal.,2013;Tianetal.,2013),withitsreliabilityconfirmedinastudybyParradoetal.(2010).However,themeta-analysisprovidedbyBosquetetal.(2008)notedday-to-dayvariabilityofHRVmeasures,withcontrastingevidencepresentedforitsaccuracyandpracticalitytoreflectchangesinperformanceinelitesportsettings(Buchheitetal.,2013;Plews,Laursen,Stanley,etal.,2013;Tianetal.,2013).Additionally,inamorerecentsystematicreviewofHRVuse(Bellengeretal.,2016),itwasnotedthatalongsidepostexerciseHRVassessmentdemonstratingpositiveadaptationstotraining,increasesinHRVcanalsooccurinresponsetooverreaching.

Modulationoftheheartandtheassociatedchangeinintervalbetweenheartbeatsiscontrolledbytheautonomicnervoussystem(ANS),withR-Rintervalusedasanindexofautonomicnervoussystemresponsiveness.Thecardiovascularsystemcanbeviewedasawell-structuredfunctiondesignedtoachievedynamicstabilityoftheheart.HRVmeasuresfluctuationsinHR,

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withahighvariabilityinHRsignalinahealthyindividualsuggestingwell-functioningautonomiccontrolmechanisms(Pumprla,Howorka,Groves,Chester,&Nolan,2002).Conversely,alowervariabilityoftheheartisoftenanindicatorofinsufficientadaptabilityoftheautonomicnervoussystem,thereforepotentiallyimplyingcompromisedhealthinanindividual.CardiovascularstabilityisachievedbytheautonomicsystemcontrollingHRandotherfactors,byreactingtoeventssuchasischemiaandchangesinphysicalormentalactivity.Inthecaseofsport,ischemiaispresentduetoarestrictionofbloodtothetissuesduringexertionandmeansthatheartratehastoadjustaccordingly.Withinthedynamicstabilityoftheheartmentionedabove,parasympatheticactivationslowsdowntheheart,whilesympatheticactivationresultsinanincreaseinHR.HRVisaffectedbythebalancebetweenboththesympatheticandparasympatheticresponsesandtheeffectthishasuponthenervoussystems.HRVrepresentsthecontinuousoscillationoftheR-Rintervalsarounditsmeanvalue,providingnon-invasivedataabouttheautonomicregulationoftheheartinreallifesituationsandismostcommonlyassessedinrestingstates(TaskForceOfTheEuropeanSocietyOf,TheNorth,SocietyOf,&Electrophysiology,1996).ThefrequencybandsassociatedwithHRVanalysesviaECGcorrespondtodifferingfrequencylevelswithlowfrequency(LF),withsympatheticactivityoccurringbetween0.04-0.15Hzandhighfrequency(HF)parasympatheticactivityoccurringbetween0.15-0.4Hz.

ContrastingfindingshavebeenreportedregardingHRVduringOTperiods(Aubryetal.,2015),withbothincreasesanddecreasesobserved.ManyauthorshaverecommendedtheuseofweeklyandrollingaveragesofHRVdata,whenassessingautonomicbalanceandassociatedplayerreadiness(Daanen,Lamberts,Kallen,Jin,&VanMeeteren,2012;Halson&Jeukendrup,2004;Plewsetal.,2012;Plews,Laursen,Stanley,etal.,2013).Tianetal.(2013)reportedtwodistinctHRVfluctuationpatternswhenassessedagainstthetrainingloadprescribed,intheirstudyinvolvingoverreachinginfemalewrestlers.Firstly,theynotedthatwhenHRVindiceswerereduced,theLF:HFratiowassignificantlyincreased,representingaperiodwheretrainingloadwastoohighandrecoverytimetoosmall.Usingtime-domainanalysis,SDNN(standarddeviationofthenormaltonormalintervals),RMSSD(thesquarerootofthemeansquareddifferencebetweenadjacentN-Nintervals)andHFcanberecordedforstatisticalandgeometricalanalysisofR-Rintervaldata.Secondly,Tianetal.(2013)reportedthatwhenHRVindicesincrease,thewrestlerswerereportedtobeundertoomuchpsycho-emotionalstress,demonstratingthatbothphysicalandpsychologicalstimulineedtobeconsideredwhenassessingathletereadiness.ItcanthereforebeconcludedfromtheresearchbyTianetal.(2013)thatNFORcanbebothsympatheticallyandparasympatheticallydriven,givingcoachesgreaterinsightintoathletesphysicalandemotionalcurrentfunctionalstate.However,limitedresearchillustratingtheeffectivenessofHRVmeasuresthatassesschangesinperformanceinteamsportsettingsexists.

Manyteamsportstrainingweeksinvolveworkoutsthatdoincorporateacardiovascularresponseandinsteadfocusonstrengthandpowerelements,manyofwhicharebasedinthegymnasium.DespiteHRVmeasuresbeingshowntoreflectacutefatigue(Mourot,Bouhaddi,Tordi,Rouillon,&Regnard,2004),thelackofcardiovascularresponseandassociatedlackofresearchinHRVpracticesinteamsportsettingsmeansthatHRVuseinrugbyislimited.ManyteamsportpractitionershavereliedupontheaforementionedneuromuscularfunctiontestssuchasCMJandtrainingloadmonitoring,insteadoftheuseofHRV,orotherHRderivedmeasures.SomeHRVresearchinrugbyuniondoesexist.Forexample,Edmondsetal.(2013)

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notethatparticipantsintheirrugbyleaguestudywhoexhibitedgreatercardiacrandomnessmightbeabletotraintoahigherworkloadinfuturetrainingweekscomparedwithplayerswithreducedcardiaccontrol.Itcould,however,bearguedthatthereweremultiplelimitationstothestudybyEdmondsetal.(2013),asthesamplesizewassmallandthesubjectswereallyouthteamplayerswhomightexhibitdifferentHRVresponsestothatofelitefull-timeprofessionalrugbyplayers,whohavegreatertrainingageandassociatedmatchfatigue.Additionally,withinthestudybyEdmondsetal.(2013)themonitoringperiodwaslimitedto4-5days,meaningexactmeasuresofHRVdatacannotbecomparedtootherstudiesthatwouldincorporatelongerresearchperiods.

Bara-Filhoetal.(2013)concludedthatHRVvalueswereaneffectivemeansofassessingadaptationtoatrainingschedulewithastableorincreasingHRVindicatinggoodrecoveryandmaintenanceoftrainingvolume.Buchheit(2014)recommendsthataconsiderationandunderstandingofthecontextoftrainingloadimposedontheplayersinteamsportscenariosisimportant.Incontrasttoendurancerelatedsports,whereHRderiveddataandbloodlactatelevelsarecommonplace(Plews,2014),theimpactoftrainingloadonHRresponseisstilltobeexamined.Inteamsports,“theloadarisesfromamyriadsofbiologicalsystemsstressedsimultaneously”(Buchheit,2014,p.8),thereforeemphasisingtheneedforfurtherinvestigation.TheneedforrepeatedmeasuresanalysisofHRVdataincontrasttoisolatedmeasureswasemphasisedinrecentresearch(LeMeuretal.,2013;Plews,Laursen,Kilding,etal.,2013),withaminimumofthreeHRVassessmentsperweekrecommendedforaccurateassessmentoftrainingstatus.CorrelationshavebeenreportedinenduranceathletesbetweenHRVindices,runningperformanceandathletesidentifiedasoverreached(Leti&Bricout,2013).Buchheit(2014)alsorecommendedonlyconsideringchangethatispracticallymeaningfulandclearlygreaterthanthesignificantworthwhilechange(SWC).ThecalculationofmagnitudeofSWCassociatedHRmeasuresarelessstraightforwardthanotherperformancetests,duetotheindividualnatureofHRderiveddataandtheassociatedtrainingloadwhichhasperhapsinitiatedtheHRchange.ThischangeinHRindicescouldderivefromisolatedtrainingsessionsorperhapsbeinresponsetoawholetrainingphase,furtheremphasisingtheindividualisednatureofHRdata.AnotherfactorthatmayinfluenceuseofHRVrecordingsistherecommendationbyPlewsetal.(2014)thatlessertrainedindividualsrequiremorefrequentHRVrecordings(>5days),asCVwasshowntobe10.1±3.4%forrecreationalrunnerscomparedto6.7±2.9%fortriathletes.

Inordertoadapttrainingbaseduponmeasurementsrequiresconfidenceinthedata,meaningthatrecentresearchhasfocuseduponday-to-dayvariationsofindices.ThestudybyEdmondsetal.(2013)usingrugbyleagueplayersisbelievedtobethefirsttoexaminetheinfluenceofdailytrainingandmatchesonday-to-dayvariationsinHRVwithinacompetitiveplayingseason.ThisstudybyEdmonds,etal.,(2013,p3)reportedthatduringanormalweekoftraining,includingacompetitivematch,participants“exhibitedashiftincardiacautonomicbalancetowardslowerHRVongameday,reducedHRVandpredominantsympatheticmodulationsfor1-2dayspost-match,andareducedsupine-tostandingHRVresponseforuptofourdaysafteragame.”ThisresearchshowsthatrugbyplayersexperienceHRVfluctuationsthroughoutatrainingweekandmaintainsignificantcardiovascularstressforuptofourdaysafteramatch.HRVdatapresentedfromrugbyplayerspost-matchshouldthereforebeconsideredforsubsequentplanningoftrainingweeks,asHRVresponsescouldsignificantlyaffectfuturegameperformancethroughoutacompetitiveseason.TheresearchbyEdmondsetal.(2013)and

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McLeanetal.(2010)supportedsuppressedmetabolicandcardiacsystemsrespectivelyforatleasttwodayspostrugbyleaguegame.Asmentionedabove,Edmondsetal.(2013)concludedthatHRVmeasuresfromsupinetostandingremaineddepressedfortwodayspost-matchandthatthisorthostaticanalysismayprovidemoreaccurateandinsightfulmeasuresofcardiacautonomicreactivityandrecoverycomparedtoabsoluteHRVmeasures.

Arecentcontactsportstudyassessingjudoathletes(Moralesetal.,2014)utilisedHRVformonitoringstress,presentinginterestingresults.SimilarlytorugbyunionMoralesetal.(2014)notedthat,injudo,difficultyariseswhenattemptingtoquantifytrainingloadbecauseofthecharacteristicsofthesport.Thesamedifficultiesareapparentinrugbyunion,whereopponents,weather,volumeofcontacttrainingcompletedandintensityofgamesalladdtothequestionablequantificationofthetrainingloadcompleted.Someaspectsofarugbyplayer’strainingweekareeasiertoquantify,suchasstrengthandconditioningsessions,yetthesesessionswouldnotrepresentthewholetrainingweekprescribedtotheplayerwiththeassociatedeffectthiscanhaveuponHRV.Moralesetal.(2014),therefore,recommendfurtheranalysisofHRVtrainingloadresponsesinsportssuchaswrestling,rugbyandothercontactsports.

Stanleyetal.(2013)notedthatindividualswithgreaterfitnesslevelsshowmorecardiovascularresiliencetotrainingstress,withperiodsofsupercompensationbeingtheoptimalperiodforgreatestperformancegain.Stanleyetal.(2013)alsonotedthatdataonthecardiacparasympatheticresponsefollowingstrength/resistancetrainingislimited,asaspectssuchasmusclesorenesscannotbetrackedbycardiacparasympatheticactivity.Itwas,therefore,proposedbyStanleyetal.(2013)thatthelevelofperceivedneuromuscularandmusculoskeletalstraininducedbythetrainingsessionshouldbeincludedwithintherecoveryperiod.Chenetal.(2011),however,notedthatparasympatheticreactivationoccurredataslowerrateamongstweightliftersthanwasseenforendurancetraining(Iellamo,Pigozzi,Spataro,Lucini,&Pagani,2004).Chenetal.(2011)commentedthatthisdiscrepancyisprobablyduetoweightliftingbeingasportthatinvolvesmoremuscletraumathanendurancesport.Theanaerobicnatureofweightliftingmeansthatneuromuscularrepairaftertrainingcandemandmoreenergyandthereforeasubsequentlylongerrecoverytime.

Rugbyunioncouldbeconsideredasportthatinvolvesbothaerobicandanaerobicaspectsfrombothtrainingandgamesperspectives;withtheresultanteffectthishasuponparasympatheticandsympatheticresponsepost-matchandtrainingbeingasignificantareaofinterestforfutureresearch.OnemonitoringtoolthatdoesclaimtoincludeHRVanalysisalongsideCNSandmetabolicreactionindex(MRI)(whichisreportedtobeinfluencedbymuscledamage)istheOmegawave.Iftheclaimsarevalid,amonitoringtoolsuchasOmegawavewouldpresentamoreholisticviewofarugbyplayer’sreadiness(consideringtheassociatedaerobic,anaerobicandblunttraumaaspects)andreflectchangesinperformance,thenitspracticalityandusefulnessineliteteamsportsettingswillbedifficulttoignore.

2.4.5.3 HeartraterecoveryIncontrasttoHRV,whichprovidesinformationonthemodulationofHR,heartraterecovery(HRR)isconsideredamarkerofparasympathetictonewithDaanenetal.(2012)recommendingitasatrainingmonitoringtooltoaccesschangesinhighintensityexerciseperformance(Vernilloetal.,2015),thusassessingcardiacparasympatheticactivityintheimmediateminutespost-exercise.However,inarecentinvestigationoftheminimalexercise

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intensityrequiredforHRRassessment,LeMeur,Buchheit,Aubry,Coutts,andHausswirth(2016)recommendedsub-maximalintensityformonitoringenduranceathletes’responsestotraining.WhileHRduringexercisemeasurescardiacload,HRRreflectsautonomicnervoussystemfunction,indicatingthebody’scapacitytorespondtoexercise.HRRmeasurestherateatwhichHRdeclinesatthecessationofexercise,withHedelin,Kentta,Wiklund,Bjerle,andHenriksson-Larsen(2000)notingthatassessingmaximalHRduringanincrementalruntestisaneasywaytodetermineovertrainingrelatedvariationsinmaximalperformance.SupportforHRRguidedtrainingprogramswaspresentedbyBuchheitetal.(2008)whonotedHRRtobemoresensitivetotraininginducedchangesthanHRVindices,andrecommendeditforcombinedusewithHRVanalysisinordertoassesspost-exerciserecovery.Despitepreviousresearch,assessingHRR,showingconflictingresults(Vicente-Campos,Lopez,Nunez,&Chicharro,2014),BuchheitandGindre(2006)proposedan8±5bpmdifferenceinHRRrecordedoverthe60secondperiodpostexercisetobemeaningfulforinvestigation.

Asreportedinpreviousresearch(Buchheitetal.,2008)themostcommonwayofassessingHRRwastoassesstheabsolutedifferencebetweenthefinalHRatexercisecompletionandtheHRrecordedafter60sofrecovery(HRR60s).Aubertetal.(2003)describedthat,duringexercise,heartrateincreasesduetobothaparasympatheticwithdrawalandanaugmentedsympatheticactivity.InarecentreviewofHRRandchangesintrainingstatus(Daanenetal.,2012),itwasproposedthatalthoughHRRimproveswithtrainingstatus,itremainsunchangeduntilaperiodofdecreasedtrainingisimplemented.InastudybyBuchheitetal.(2013)examiningselectedphysiologicalandpsychometricmeasuresformonitoringfatigue,asubmaximalfive-minuterunningandrecoverytestwasutilisedatthestartofeachtrainingsession.Inthisstudy,involvingelitesoccerplayers,trainingloadvariationswereseentocorrelatewithheartrateexertion(HRex)andvagalrelatedHRindex(LnSD1)measuresandHRexwereseentodecreaseastheplayersprogressedthroughthepre-seasonperiod,demonstratingthattheeffectivenessofasubmaximalperformancetestwaswarranted.Itis,however,importanttonotethattheregularimplementationofafive-minuterunningandrecoverytestwouldbeimpracticalinmanyteamsportssettings,duetologisticalconstraints.

PreviousstudiesinteamsportssettingsutilisingHRRhaveproducedcontrastingresults(Daanenetal.,2012;Lamberts,Swart,Capostagno,Noakes,&Lambert,2010;Lamberts,Swart,Noakes,&Lambert,2009,2011;Vicente-Camposetal.,2014),mainlyduetothewidevariationinbaselinefitnessofathletesmeasuredandexerciseprotocolsused.MethodologiescurrentlyusedtomeasureHRRincludemeasuringthenumberofbeatsrecoveredwithinagiventimeperiod(e.g.60s)andsignalmodellingvialinearmodels.OthermethodologiesusingHRderiveddatatomeasurefatigueincludeintervalrunningtestsandtheZoladztest(Schmiklietal.,2011),whereelevatedHRandperformancedropwereindicatorsofoverreaching.LimitationsofHRRuseandthevariablesandmethodologyusedwithinit,includesignalmodellinglimitationsandtheneedforsoftwarethatisoftenunavailabletopractitioners.MonoexponentialmodelinghasbeenreportedtocapturemoreeffectivelytheoverallHRresponse,withcorrelationsnotedinenduranceperformancechangewhenassessingHRRvariables(Daanenetal.,2012).Bycontrast,teamsportchangesinHRRhavenotcorrelatedwithperformanceandhavepresentedcorrelationsoflowermagnitudethanobservedinHRexertion(Buchheit,2014).FurthersupportforHRRwaspresentedbyCornforthetal.(2014)whereHRRshowedanincreaseinfitnesscorrelating(p=0.016)with2kmtimetrialresultsimprovingineliteAustralianRulesfootballplayers.Reliabilityofpost-exerciseHRVmeasurementswasnotedbyBuchheitetal.

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(2008),withanSEMof14.2msforpost-exerciserMSSD,whileHRRshowedaSEMof12.6ms(Buchheit,Papelier,Laursen,&Ahmaidi,2007).Cornforthetal.(2014)reportedthatHRRwasareliable(r=0.92)andvalidfortheassessmentoftrainingloadwithlowintra-individualvariation,whileLambertsetal.(2010)notedaCVof95%whenassessingHRR%.AddedtothisCornforthetal.(2014)notedthatanadaptedversionoftheHeartrateIntervalMonitoringSystem(HIMS)testhassufficientprecisiontodetectchangesinfitnessandtrainingloadstatusinAustralianRulesfootballers.ThisresearchbyCornforthetal.(2014)supportstheviewsofpreviousresearchers(Buchheit&Gindre,2006;Lambertsetal.,2009)thattrainingloadinfluencesHRRandthataerobicfitnesscontributestoanincreaseinHRR%.

2.4.5.4 ConsiderationsforheartratederiveddataandresponsestoexerciseDespiteHRderiveddatabeingoneofthemosteasilyaccessiblephysiologicalmeasuresavailable,changesinHRandHRRareinaccurate(Bagger,Petersen,&Pedersen,2003)withdailyvariationinHRreportedtobeupto6.5%forsubmaximalHRandnotedtobeaffectedbyfactorssuchashydration,caffeineintake,environment,stressandmedication(Vukovich,Schoorman,Heilman,Jacob,&Benowitz,2005).ResultantchangesinHRasaconsequenceofexercisecanrepresentbothapositiveandnegativetrainingresponse,therebysupportingtheviewthattheuseofHRforassessingreadinessandpossiblemaladaptationtotraining,yetalsoemphasisingthedifficultyforinterpretation.DuetothereluctanceofmanypractitionerswithinteamsportsettingstoadministermaximalHRmeasuresduringcompetitionphasesoftheseason,moreresearchisneededintowhatconstitutesmeaningfulchangeinsub-maximalHRperformancetests.Fromtheresearchaboveitisevidentthatheartratederivedmeasuresholdthepotentialtoassessaccuratelyinternalload.Heartratederivedmeasureswerethereforeconsideredforfutureusewithinthisresearch,withtheperformancemeasureimplementedlikelytobethemeasurethatismostapplicabletotheeliterugbysettinginquestion.

2.4.6 SummaryInconsiderationofalloftheaboveperformancetests,methodologicalandlogisticalconsiderationsoftendictatethechoiceofassessment.Despiteperformancetestsbeingeasytoimplementinordertoassessindividualtrainingresponse,themainlimitationofsomeofthesetestsisthattheinformationobtaineddoesnotexplainthereasonfortheperformancereduction.Inlightoftheperformancetestsreviewedabove,jumptesting,“offfeet”maximaltestsonacyclingergometerandheartratederivedmeasures(HRRandHRV)seemthemostapplicableforfurtherstudywithinthisresearch.Jumptesting,forexample,needsfurtherinvestigationinordertoascertainwhichparametersaremostinformativewhenmonitoringfatigue.Whensportspecificparameterssensitivetofatigueareidentified,fromperformancemeasuressuchasjumptesting,themeaningfulchangeandexpectedtypicalerrorwillfurtherguidepractitionersonthemeaningoftestresults.Incontrasttojumptesting,maximalandsub-maximalperformancetests(“offfeet”and“onfeet”)arelessfrequentlyusedwithinteamsettingsandreliabilityofsuchtestsarethereforelacking.Itis,however,expectedthatasfuturesportspecifictechnologicaladvancesforreadinesstestingaredeveloped,thefocusoffatiguemeasurespostgamewillcontinuetoinvestigatetheuseofoverground“onfeet”andgymbased“offfeet”performancetests,alongsidetheimplementationofjumptesting.Similarly,theuseofheartratederivedmeasures,willlikelycontinue,asunlikejumptestingandmaximalandsub-maximalperformancetests,heartratederivedmeasurespresentatruerepresentationofinternalloadandthereforemaybeofmoreinteresttopractitioners.

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2.5 StrategiesusedtoEnhanceRestorationofPerformanceandRecovery

Duetothematchdemandsoutlinedaboveandtheneedtoattempttorestoreperformanceassoonaspossiblepost-match,anecessityexiststoutilisestrategiesthatwouldenhancerestorationofperformanceinthedayspost-match.Asexaminedbelow,manyshort-termfatiguemanagementstrategiesexistthatenhancerestorationofperformanceinthedayspost-exercise,wheretherelevanceandeffectivenessofeachmodalitydependsuponthesportinquestion,thepracticalabilityofthepractitionerstoimplementsuchstrategieswithintheenvironmentandthecomplianceoftheathletes.

2.5.1 CommonlyusedrecoverymodalitiesSportsscientistsandphysiologistshaveroutinelypushedtheboundariesofscienceinelitesportbyimplementingrecoverystrategiesdesignedtoimprovereadiness(Gilletal.,2006).Abalancebetweentrainingorcompetitionstressandrecoveryneededtomaximiseperformanceisoneofthemostresearchedareasinmodernsportsscience,withcontrastingevidencefortheuseofvaryinginterventionstrategies(Crystal,Townson,Cook,&LaRoche,2013;Dawson,Gow,Modra,Bishop,&Stewart,2005;Rowselletal.,2009).Shortturnaroundtimesbetweengames,themultifacetednatureofprofessionalteamsportathletes’training,matchandcommercialrequirementsallmeanthatthereisconsiderabledemandonplayers’time.Knowledgeofprovenandtime-efficientrecoverystrategiesandprotocolsare,therefore,paramount.AsmentionedbyCook,Kilduff,andJones(2014),duringcompetitionphases,teamsportathletesareinacyclicstateofadaptationandrecoverybetweengamesandtraining.RecoverymodalitieshavesubsequentlybeenusedtohastentherecoveryprocessoutlinedinFigure2.2,yetasexplainedabove,consideringthatrecoveryisareturntorestingfunctionandphysicalperformance,thisissometimesunrealistic.

Althoughrecoveryisconsideredofextremeimportancewithinteamsportsettings,bothpractitionersandathletesoftenignoreit.Thehighlevelofimpactsandthemetaboliccostinvolvedinasportsuchasrugby,aresomeofthelikelycontributingfactorstothephysiologicalandmechanicalstressassociatedwithEIMD.Manyteamsportsconductrecoverysessionsthedayafteramatch,yettheprotocolandpreferredmodalityforasportsuchasrugbyunionvaryconsiderably.Nedelecetal.(2013)concludedthatscientificevidencetosupporttheuseofmanyrecoverystrategiesislacking.Difficultiesindeterminingefficacyofrecoverystrategiesaremainlyduetomethodologicalissues,yetresearchbyLindsay,Lewis,Gill,Gieseg,andDraper(2015)notesthatimmediatepost-gamerecoveryintervention,followingagameofprofessionalrugbyunion,maybethemostimportantaspectofpsychophysiologicalplayerrecovery.Despitea57%increaseinsalivarycortisol(p<0.001),notedbyLindsay,Lewis,Gill,etal.(2015)whenassessingtheeffectofvariedrecoveryinterventionsonmarkersofpsychophysiologicalstressinprofessionalrugbyunionplayers,nodifferencewasobservedintheinflammatoryresponse36hourspost-matchbetweendifferentprotocols,yettheeffectivenessofimmediatepost-matchrecoveryinterventionwasconsideredkey.Theneedtoresearchrecoverypracticesinrugbyunionisthereforeofimportancetopractitionersaimingtoimproveplayerreadinessbetweengames,wheresupposedalteringofmuscletissuetemperatureandincreasedbloodflowaidrecoveryfromEIMDandrelatedmusclesoreness.

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2.5.1.1 IcebathsandcontrastwatertherapyTheuseofwatertherapytoaidrecoveryisprobablythemostcommonlyusedrecoverymodality,withbothcontrastwatertherapy(CWT)andcoldwaterimmersion(CWI)usedbymanysportsteams(Webb,Harris,Cronin,&Walker,2013).Exposureofathletestocoldwateraidsinreducingoedemathroughthevasoconstrictionandvasodilationresponseofbloodvesselstothechangesintemperatureexperienced.Thebenefitsofwatertherapyaremostlikelyduetoacombinationofthewatertemperatureandhydrostaticwaterpressure.Inanextensiveliteraturereview,Nedelecetal.(2013)proposedthatCWIisaneffectiverecoverystrategyduringacuteperiodsoffixturecongestioninsoccer.FurthersupportforCWIasamodalitytoprovidebeneficialeffectsonperformancewasnotedbyPournot,Bieuzen,Duffield,etal.(2011),whenassessingitsinfluenceonbloodmarkers(inflammatorymarkers,haematologicalprofileandmuscledamage)postrunningtreadmillexercise.Inaddition,perceptionsoffatigueandlegsorenesswerereportedasreducedwiththeuseoficebathsthroughoutasoccertournament(Rowselletal.,2009),whenassessedviaquestionnaire.Additionally,researchbyAlHaddad,Parouty,andBuchheit(2012)reportedthebenefitsoficebathsuponsubsequentsleepfollowingintensetrainingdaysandemphasisedthatCWIwasnotjusttobeusedtoreduceDOMS.However,thesmallsamplesize(n=8)andthecollectionofsleepdataviasubjectivequestionnaireswithintheresearchbyAlHaddadetal.(2012)canbequestioned.

RecentliteratureinvolvingtwostudiesassessingmuscleadaptationasaresultofCWIhasemerged(Roberts,Raastad,Cameron-Smith,Coombes,&Peake,2014;Yamane,Ohnishi,&Matsumoto,2015).ThesestudieshavedoubtedtheeffectsoficebathsorCWIonlong-termmuscularperformanceandattenuatedlong-termgainsinbothmusclemassandstrength.Bluntedactivationofkeyproteinsandsatellitecellswasnotedinskeletalmuscleforuptotwodaysafterstrengthexercise,highlightingthisasanareaofmuchneededfutureresearch,especiallyinrugbyunionwheremusclehypertrophyiskeytomaintainingmusclemass.Itis,however,importanttonotethatthesestudiesonlyanalysedresistancetraininginactive,butnotelitesubjectsandthereforemoreresearchisnecessarybeforeconclusionscanbedrawnontherelevanceofCWIineliterugbysettings.Withinarecentsystematicreviewandmeta-analysisofcoldapplicationsforrecoveryinadolescentathletesbyMurrayandCardinale(2015),itwasproposedthatpositiveeffectsofCWItoreduceDOMSarescarce,withmoreworkwarrantedtoassesseffectiveness.ThislackofsupportforCWIwasalsonotedineliteweightliftingsettings,whereSchimpchenetal.(2016)displayednosignificantdifferencesinasnatchpullmovement,bloodparametersorsubjectiveratingsoffatiguewhenusingarandomisedcross-overstudydesign,thereforeagainquestioningCWIuseinelitesettings.Schimpchenetal.(2016)did,however,notethatinter-subjectdifferencesdoexistasaresultofCWI,andthatitsapplicationshouldbeconsideredonacase-to-casebasis.

Inacriticalappraisalofthreedifferentrecoverystrategiespostrugbyleaguegame,Webbetal.(2013)reportedthatCWIandCWTrecoveredjumpheightperformance,reducedmusclesorenessandreducedCKlevelspost-match,whencomparedwithactiverecovery.Higgins,Heazlewood,andClimstein(2011)notedthebenefitofCWTforenhancingrecoveryinrugbyunion,asrepresentedbysubjectivewell-beingreports.ContrastingviewsuponcoldwatertherapiessuchasCWIandCWTareshownbytheresearchofMontgomeryetal.(2008)whonotedCWIassuperiortoCWT,whereas,conversely,Webbetal.(2013)notedCWTassuperiortoCWI.Inameta-analysisofCWI(Leeder,Gissane,vanSomeren,Gregson,&Howatson,2012),

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littleeffectwasshownforstrengthexercises,yetapositiveresponsewasnotedforexercisesthatinvolvedstretch-shorteningmovements.Specificallyinrugbyunion,icebathsprescribedascoldtherapytoenhancerecoverybetweengameshaveillustratedcontrastingresults(Bleakleyetal.,2012;Higginsetal.,2011;Takedaetal.,2014),withnegativeeffectsofCWIreportedbyHigginsetal.(2011)andthepositiveeffectsofCWTreportedbyGilletal.(2006).Gilletal.(2006)reportedenhancementofCKclearancewiththeuseofCWTwhilerecommendationsforrepeatedapplicationofCWIwasreportedbyMontgomeryetal.(2008)asthemostbeneficialresponse.Bycontrast,Higginsetal.(2011)notedadetrimentaleffectoficebathsonplayersperformancewhenrecoveringfromtrainingandcompetition.Theseresultsillustratetheconflictingevidenceforicebathsandcontrastwatertherapy.However,consideringthesimplicityandlowcostwithwhichthisinterventionstrategycanbeimplementedthismodalitywill,likely,continuetobeutilisedfrequentlywithinrugby.

2.5.1.2 WholeBodyCryotherapy(WBC)WBCisacoldexposurerecoverystrategythat,althoughinexpensiveinnatureanddifficulttoadministerisbeingusedbymanyathletesthroughouttheeliteandrecreationalsportsworld(Hausswirthetal.,2011;Pournot,Bieuzen,Louis,etal.,2011).WBCwasproposedoverthirtyyearsagoforuseastreatmentformanyinflammatorydiseases,withasignificantvolumeofrecentliteraturedetailingthetopic(Bleakley,Bieuzen,Davison,&Costello,2014;Costelloetal.,2015;White&Wells,2013).Thistherapyconsistedofexposureto extremelycoldairmaintainedat-110°Cto-140°Cinspecialtemperature-controlledcryochambers,generallyfortwominutesandtypicallyinitiatedwithin24hoursofexercisecompletion.Theuseofcoldmodalitiessuchasicepacksandthephysiologicaleffectsofsuchpracticesarewellestablished(Costello,Algar,&Donnelly,2012).InelitesporttheuseofWBChasgainedsignificantpraise(Gallieraetal.,2013)asamethodtoimprovemusculoskeletaltraumafollowingtrainingormatchplayscenarios.AdditionalrecentsupportfortheuseofWBCwasnotedbySchaaletal.(2015)whereteneliteswimmersreportedreducedsignsofFOR,suchasreducedsleepqualityandincreasedfatigue,andwhereWBCwasthereforerecommencedduringperiodsofintensecompetitionpreparation.

ThepositiveeffectsofWBChavebeenreportedinaliteraturereviewbyBanfi,Lombardi,Colombini,andMelegati(2010)andWBCisthereforeconsideredbymanypractitionerstobeaprocedurethatfacilitatesathletes’recoveryandcarriesnoknownnegativeeffects.WBChasbeenreportedtoinfluencehormonalmodifications,wherethebody’sadaptationtothecoldstressappliedorexperienced,showsanincreaseinnoradrenaline(norepinephrine)(Banfietal.,2010).Physiologicalchangeshavebeenreportedinimmunology(venousbloodsamples)andanaerobiccapacity(20sWingatetest)(Klimek,Lubkowska,Szygula,Chudecka,&Fraczek,2010),yettheseformsofphysiologicaladaptationrequireasufficientnumberofsessions(atleastten)forchangetobeseen.Additionally,Schaaletal.(2013)reportedpositiveeffectsofWBCuponparasympatheticreactivation(measuredviaHRV),whichsuggestssystemicrecoveryfromthetrainingstressimposed.Fewstudieshave,however,justifiedtheeffectivenessofWBCasarecoverymodalitythatpositivelyinfluencesathletereadinesstotrain.Recentresearch,promotingtheuseofCWIinsteadoftheapplicationofWBCwhenassessingitsinfluenceuponacceleratingrecoverykinetics(Abaïdiaetal.,2016).Bleakleyetal.(2014)concludedthatdespiteWBCbeingregardedasasuperiormodeofcooling,duetotheextremetemperaturesinvolved,thereisnoevidencetosuggestthatWBChasanyadvantagesoverotherformsofcryotherapy.Bleakleyetal.(2014)notedthatthepoorthermalconductivityofair

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preventssubcutaneousandcorebodycooling.Inaddition,WhiteandWells(2013)notedthattheeffectivenessofWBCremainsambiguous,asthemethodologyused,protocolundertakenandperformancemeasuresassessedthroughoutWBCstudiesaresovariedinnaturethatnoclearagreementcanbeconcluded.

2.5.1.3 CompressiongarmentsCompressiongarmentshavebecomeincreasinglyprevalentinteamsportsettings,withtheaimofenhancingrecoveryinthedayspost-trainingandgames(Davies,Thompson,&Cooper,2009).Thesecompressiongarmentsareoftentightfittingelasticfabricsthatareexpectedtoenhancemusclerecoverybyexertingpressureonlimbscoveredbythegarments,byimprovingbloodflowandreducinginflammation.Despiteconflictingresults,compressiongarmentsareusedtolimitthedamagecreatedbyexercise,withreducedpainreliefandalteredinflammatoryresponsesbeingthefocusofadministration(Daviesetal.,2009;Jakeman,Byrne,&Eston,2010).SupportfortheuseofcompressiongarmentscomesfromJakemanetal.(2010),withperceivedreductioninmusclesorenessasaresultofwearingcompressiongarmentsbeingclaimedtobeasignificantfactorwhenrecoveringfromEIMDinyoung,activefemales.

Incontrasttothepositiveevidenceabove,Montgomeryetal.(2008)notedthattheapplicationofcompressiongarmentshadlittleadvantageinenhancingmuscledamageinthedayspostbasketballtournament.Additionally,noperformanceimprovementswerenotedwithinrecentresearch,neitheruponpeakpoweroutput(Duffieldetal.,2008)followingintermittentexercisenoruponCMJperformance(Daviesetal.,2009)followingdropjumptraining.However,inasystematicreviewandmeta-analysisconductedbyHill,Howatson,vanSomeren,Leeder,andPedlar(2014),evaluatingtheefficacyofcompressiongarmentsacrosstwelvestudies,amoderateeffectwasnotedonmeasuresofDOMS(95%CI0.236to0.569,p<0.001),muscularstrength(95%CI0.221to0.703,p<0.001),muscularpower(95%CI0.267to0.707,p<0.001)andCKpresence(95%CI0.171to0.706,p<0.001),thereforeindicatingthepotentialeffectivenessofcompressiongarmentsinenhancingrecoveryfrommuscledamage.Inamorerecentsystematicreviewandmeta-analysisbyMarqués-Jiménez,Calleja-González,Arratibel,Delextrat,andTerrados(2016)itwasnotedthatcompressiongarmentshadnoeffectuponCK(standardmeandifference=-0.98),whereasincontrast,bloodlactateconcentrationwasimprovedduetocompressiongarmentadministration(standardmeandifference=-0.52),thereforeillustratingtheneedforfurtherresearch.

InrugbyunionspecificallyenhancedCKclearancewasreportedbyGilletal.(2006)asaresultofplayerswearingfulllegcompressiongarmentsfor12hourspost-matchincontrasttousingpassiverecoverymethods.Itisalsoofimportancetonotethattheuseofcompressiongarmentsalongsideelectrostimulationimprovedperceivedrecovery,comparedtowearingcompressiongarmentsalone(Beavenetal.,2013).Currentresearchintotheuseofcompressiongarmentsshowsnobeneficialeffectswhencomparedtoactiverecoveryandcontrastwatertherapy(Gilletal.,2006),yetcompressiongarmentsareamodalitythatprovidesaneasytoadministerstrategyinteamsportenvironmentswhererecoverytakesplacewhiletravellingtoandfromgames.Consideringthepossibleplaceboeffectofimprovedperceptualfeelingasaresultofwearingcompressiongarments,alongwiththerelativesmallcostimplicationsofimplementingcompressiongarmentuseintoteamsportsettings,thisisarecoverymodalitythatshouldpotentiallybeincludedwithinarugbyplayer’srecoverystrategy.Itis,however,advisedthatcompressiongarmentsshouldbeadministeredalongsideotherrecoverystrategiesandincorporatedwhenappropriatewithinthehoursanddayspostexertion(Hamlinetal.,2012).

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2.5.1.4 Activerecovery

InanattempttoreduceDOMS,manysportingteamscommonlycompleteapost-match“activerecovery”sessionincorporatinglightaerobicactivity(Kinugasa&Kilding,2009;Nedelecetal.,2012,2013).Thesesessionsoftenincludelightstretchingandmovementtohastenrestorationofperformanceinthedayspost-matchandpriortothepreparationforthenextmatchcommencing.Theincorporationofactiverecoverypracticesisconsideredtobeaprocessthatacceleratestheremovalofmetabolitesandincreasesbloodflow,thereforereducingpost-matchrecoverytime(Calder,2000).Themostcommonlyusedactivitiesforrecoverysessionswithinteamsportsare;low-intensityswimming,walkingandcycling,whicharebelievedtoincreasetheremovalofmetabolicwasteproductssuchaslactate,hydrogenionsandpotassiumproducedduringexercise(Fairchildetal.,2003).However,theefficacyofactiverecoveryforimprovingsubsequentperformancewasquestionedbyRobson-Ansley,Gleeson,andAnsley(2009)intheirreviewoffatiguemanagementstrategies,duetothenotionthatthatactiverecoveryprotocolwouldslowglycogenresynthesispostexercise.Whencomparingtheeffectivenessofrecoverystrategiesinrugbyunion(CWTandcompressiongarments)twentyminutelowintensityrecoverysessionswerenotedbyGilletal.(2006)asaneffectivemeasuretoreduceinflammationandremovemetabolites.Morerecently,Peakeetal.(2016)recommendedactiverecoveryasbeingjustaseffectiveatreducinginflammationorcellularstressinmuscleafteraboutofresistanceexerciseasCWI.Inastudyassessingtheintensityatwhichbloodlactatedisappearsfollowinga50secondmaximalcyclingtest,moderateintensityrecoverysessionswerenotedasmoreeffectivethanpassiverecovery,yetacombinationoflowandhighintensityrecoverypracticeswereconsideredtohavenomoreeffectthanalowintensitysessionthatinvolvesactivitieslessthan35%V02max(Dodd,Powers,Callender,&Brooks,1984).

Lum,Landers,andPeeling(2010)notedthepositiveeffectsofswimmingbasedrecoverysessionsonsubsequentrunningperformance,whileSuzukietal.(2004)reportedreductionsinpostrugbymatchpsychologicalstressasaresultofswimrecoverymethods.However,thestudybyLumetal.(2010)usedtriathletesduringamaximalruntesttenhoursposthighintensityrunningtomeasuretheeffectivenessofswimrecoveryandthisisthereforelimitedinrelevancetorugbyunionwheremaximaltestinghasalreadybeenidentifiedaboveasunrealisticforuseineliterubysettings.DespitethestudybySuzukietal.(2004)involvinguniversitylevelrugbyplayers,itsrelevancetoeliterugbyunionisevident.Physiological(bloodbiochemistry)andpsychological(POMSscores)wereusedtoassessrecoveryinthedayspost-match,showingnoadversephysiologicaleffectofswimrecoveryimplementationandanincreasedpsychologicalrecoveryduetoenhancedrelaxation.Hydrostaticpressurefromwaterpressingagainstmuscletissue,involvedwithinswimsessionsisbelievedtorestoreperformanceatagreaterratethanotherformsofactiverecovery,withevidencepresentedbyLumetal.(2010)showingthatlevelsofC-ReactiveProteininbloodsamplesdecreasedasaresultofswimbasedrecoverysessions.Itis,however,importanttonotethatsupportforactiverecoverymethodsareconflicting,withalackofsupportpresentedbyChoi,Cole,Goodpaster,Fink,andCostill(1994).Usingthree,1-minexerciseboutsatapproximately130%VO2maxperformedinterspersedwith4-minrestperiodsbetweeneachworkboutofvaryingintensitytojudgetheeffectivenessofpassiveandactiverecoverymodalities,theyreportedthatactiverecoverymaydelaymuscleglycogenreplenishmentafterhigh-intensitycyclingperformance.

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Inadditiontothevalueoflowintensityactivitiessuchasswimmingandcyclingforrecovery,stretchingisakeycomponentofthedailytrainingplanforathletesandplaysanimportantroleintherecoveryprocesswiththeaim,ultimately,toprepareathletesforthenexttrainingsession.Stretchingincreasesbloodflowtomuscles,stimulatesthepassageofaminoacidsintomuscles,acceleratesproteinsynthesisincells,andinhibitsproteinbreakdown.Stretchingaspartofrecoverycanalsoreducethechanceofinjury(Herman,Barton,Malliaras,&Morrissey,2012)andincreasethechancesofoptimalperformance(Turkietal.,2011).Cautionwasrecommendedforstretchingaftereccentricactions(Lund,Vestergaard-Poulsen,Kanstrup,&Sejrsen,1998)asitwasreportedtoleadtodelayedonsetofmusclesoreness.ThisconclusionbyLundetal.(1998)highlightedthegreaterdecreaseinbothconcentricandeccentricquadricepsstrengthfollowingtheuseofeccentricexerciseandstretching,incomparisontousingeccentricexercisealone.Thisisanimportantconsiderationforpractitionersworkinginrugby,whereeccentricactionsarecommonlyperformedandresultantmusclesorenessreported(McLellan&Lovell,2012).Additionally,whenutilisingactiverecovery,practitionersshouldbecautiousnottoaddmorefatiguetotheathletesinthehourspost-match,byincorporatingrecoverysessions.Theintensityofsessionsshouldbelowandadecisionuponwhethertheactiverecoverysessionwillaidrestorationandrecovery,orhinderit,needstobemade.Athletecomplianceinthehourspost-matchisoftendifficulttoguaranteeastheyareoftenemotionallyandphysicallydrainedfromperformance,meaningthatperhapscompleterestisthebetteroptionforbeginningfatiguereversal.

2.5.1.5 SportsmassageMassagehasbeenusedforgeneralrelaxationofthemuscularskeletalsystem,withsportsmassagedirectedintolocalareasbeingoneofthemostcommonlyusedrecoverymodalitiesinteamsportsettings(Hongsuwan,Eungpinichpong,Chatchawan,&Yamauchi,2015;Nedelecetal.,2013).Sportsmassageispossiblytheoldestmethodoftreatingfatiguedmusclesandisperformedonathletestoaidrecoveryortotreatpathologywheretypeanddurationofmassagehavevariedconsiderably.Bothpositiveeffectsofsportsmassage(Micklewright,Griffin,Gladwell,&Beneke,2005)andnegativeeffects(Jonhagen,Ackermann,Eriksson,Saartok,&Renstrom,2004)arewelldocumented,withadaptationandrecoveryfromDOMSreported(Andersenetal.,2013).ThestudybyMicklewrightetal.(2005)reportedenhanced30sWingateperformanceasaresultofmassage,yettherelevanceoftheresultstoeliterugbyarequestionable.Inarecentmeta-analyticalreviewofmassageandperformanceinvolvingtwenty-twostudies,Poppendiecketal.(2016)reportedthatlimitedpositiveeffectsofmassageexistasarecoveryinterventionforcompetitiveathletes.ResultsfromtheresearchbyPoppendiecketal.(2016)showedatendencytowardsmorepositiveresultsamongstuntrainedathletes(ES=0.23)incomparisontotrainedathletes(ES=0.17),withresultsalsofavouringmixedexerciseapplication(ES=0.61),ratherthanstrength(ES=0.18)orendurance(ES=0.12)forms,whenassessedbyeffectsizesusingHedges’gvalues.

Inaliteraturereviewofsportsmassage,musclesorenessassociatedwithDOMSandthepotentialbenefitsofmassagewerenotedbyMoraska(2005),yettheaffectthatmassagehasuponforcerecoverywasconcludedasunclear.Changeinperformanceasaresultofsportsmassageisalsolesswellreported(Robertson,Watt,&Galloway,2004),withnomeasurablephysiologicaleffectsoflegmassagenotedcomparedtopassiverecovery,posthighintensityexercise(30scycling).Hemmings,Smith,Graydon,andDyson(2000)reportedscientificsupportfortheuseofmassagetoimprovepsychologicalstate,yetalsoraisequestionsaboutthe

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benefitofmassageforphysiologicalrestorationandrepeatedsportsperformance.Bycontrast,Micklewrightetal.(2005)notednoimprovementinmoodstatefollowingmassage,butdidnote30sWingateperformancewasimprovedfollowingmassagecomparedtorest.Additionally,itisinterestingtonotetherecentresearchbyAndersenetal.(2013)showingthatthepositiveeffectsofmassage,whichoccurduringthefirst20minutesaftertreatment,infactdiminishwithinanhour.ThestudybyAndersenetal.(2013)illustratedtheacuteeffectsofmassageoractiveexerciseinrelievingmusclesorenessandconcludedthateitheractivewarm-upormassagecanbeusedtoreduceDOMS.However,itcouldbearguedthattheeccentriccontractionsoftheuppertrapeziusmuscleonaBiodexdynamometerutilisedinthisstudytoassesseffectivenessofmassagearenotofrelevancetorugbyresearch,wherethewholebodyisexposedtoischemiaandbluntforcetrauma.Theaboveresearchintosportsmassageillustratesthecontrastingevidenceformassageasarecoverytool.Yet,ifmassageisaregularfeaturewithinaspecificathlete’s“recoverytoolbox”,thenitbesttoleavethisinplaceandmonitortheresultanteffect,ratherthanremoveitfromanathlete’sdailyroutine,despiteitsusepossiblybeingbaseduponresearchirrelevanttothesportinquestion.Moreresearch,incorporatingwell-designedresearchstudiesinvolvingteamsports,isneededtoconcludewhetherornotmassagefacilitatesrecoverypostrugbymatchplay.Theextenttowhichmassagecanbeneficiallyaffectarugbyplayerpost-matchmaybesignificantlydifferenttothatofothersportsconsideringthevariationsinactionsperformed.

2.5.1.6 SleeptoaidrecoverySleepisconsideredtobeacomplexandphysiologicalphenomenonthathastwoclassifiedstates;rapideyemovement(REM)andnon-rapideyemovement(NREM),withtheprimaryneedforsleepbeingneuralbasedratherthanamechanismnecessaryfortissuerepairalone.NREMconsistsoffourstagesofprogressivelydeepersleepandisassociatedwiththereleaseofgrowthhormone,whichisimportantforoptimalsportingrecovery.Twomainmethodsareusedtoassesssleep;onebeinganon-invasiveACTigraphandtheotherbeingpolysomnographywhichisconsideredtobethe“benchmark”forassessingsleepqualityandquantity.Researchupontheeffectofsleepdeprivationinsportsperformanceiswelldocumented(Mejrietal.,2014;Oliver,Costa,Laing,Bilzon,&Walsh,2009;Skein,Duffield,Edge,Short,&Mundel,2011;Skein,Duffield,Minett,Snape,&Murphy,2013),withtheresultanteffectuponpost-matchrecoveryaffectingmanyperformancemeasures.Sleepisconsideredtobethepremierrecoverytoolformanyeliteathletesduetotheanabolicprocessesthatoccurduringperiodsofsleep,therebyaidingathletestoprepareandrecoverfromtrainingandcompetitiondemands(Halson,2008).Inarecentreviewofsleepanditsinfluenceuponperformance,negativeeffectsofsleeplosswereassociatedwithphysiological,psychologicalandimmunesuppression(Fullagaretal.,2015).TheacuteresponseofsleepdeprivationwasillustratedbyKiller,Svendsen,Jeukendrup,andGleeson(2015)whonotedprogressivedeclinesinsleepquality,moodstateandexerciseperformanceduringaperiodofshort-term,intensifiedtrainingineliteathletes.FurtherevidencefortheimportanceofqualitysleepduringintensivetrainingperiodswasshownbyKöllingetal.(2016),whonotedimprovedrecoveryandstress(p<0.1)followingadditionalsleepopportunitiesforrowersduringtrainingcamps.Resultsfromthisstudyshowedimprovedsubjectivefeelingsofwell-beingasaresultofextendedsleepperiods,withsleepnotedasbeingasimpleandeffectivestrategytoenhancerecoveryandstressrelatedratings.

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ResearchbyLeeder,Glaister,Pizzoferro,Dawson,andPedlar(2012)acrossmultipleOlympicsportsnotedthattheaveragesleeptimeofathletesis8:36±0:53hr:minandthatasleepperiodsoflessthanthisrangearenotrecommended.Whenconsideringthattraveldemands,unfamiliarsleepenvironmentsandpre-competitionstresscanoftenaddtoanathlete’ssleepdisruption,theneedtomaximiseandmonitorsleepresponsesare,therefore,paramount.Thedeepestandmostrestorativesleepoftenoccursfrom10pmuntil2am,thereforehavingimplicationsforathleteswhoplayinnightgames.Wheneveninggamesoccurathletesareunlikelytobeintheirbedsuntil2am,duetopost-matchinvolvementssuchasgettingshowered,conductingmediaobligationsandrefuelling.Inaddition,perhapsthemostunderestimatedfactoraffectingeveningpost-matchsleepcommencingistheinabilitytofallasleepaftertheexcitementofperformance.EvidencesupportingthisnotionwaspresentedbyEagles,McLellan,Hing,Carloss,andLovell(2014),whonotedthatthetimetosleepongamenightswassignificantly(p<0.05)laterthanonnon-gamenightsinprofessionalrugbyunionplayers.Thisexcitementpost-performance,combinedwithergogenicaidssuchascaffeine(outlinedinChapter2.5.1.7below),meansthatathletesunderstandablystruggletorelaxpost-match,therebyimpactingupontheirpost-matchrecovery.Whenconsideringandcombiningthesedifficultpost-matchrelaxationlogistics,includingtheneedforathletestotravelimmediatelypost-match(oftenacrosstimezones)andcompeteagaininashortnumberofdays,theimpactthiscanhaveuponrestorationofperformanceinthedayspost-matchisfurtheremphasised.

AsrecommendedbyHalson(2014),monitoringofsleepquantityandqualityasisoftenincludedwithinaforementionedwell-beingquestionnairesandtheirresultscanalsobeusefulforthemonitoringoffatigue.Theearlydetectionofovertrainingviatheuseofwell-beingquestionnaires,however,isunclear(Halson,2008).WithinrugbyspecificallytwentyeightmalerugbyunionplayershadtheirsleeppatternsassessedoverafourgameperiodviaanACTiwatch,withresultsdemonstratingthatsleepwasdeprivedpost-matchandthatthismayhavehadadetrimentaleffectupontherecoveryprocess(Shearer,Jones,Kilduff,&Cook,2015).Additionally,inanassessmentofsleepincollisionsportathletes(Swinbourne,2015),itwasreportedthatcollisionsportathletesexperiencedreducedsleepqualityduringintensetrainingphases.However,perhapsmostimportantfromtheresearchbySwinbourne(2015),wasthefindingthatasleepextensioninterventionelicitedasignificantmoderate(-0.65;±0.99)improvementinthepercentagechangeinsleepqualityscorescomparedtothecontrol(-24.8%;±54.1%).Thisnotion,therefore,supportstheviewsthattheimplementationofasleepextensionwithrugbyplayersislikelytobeworthwhileforreducingthereportedrisesincortisollevels(-18.7%;±26.4%)andsmall(-0.44;±0.31)resultantimprovementsinreactiontimes(-4.3%;±3.1%)demonstratedbySwinbourne(2015).

2.5.1.7 NutritionalinterventionstoaidrecoveryRehydrationduringandposttrainingorcompetitionisthefirstkeynutritionalinterventionthatpractitionersshouldfocusupontofastenareturntohomeostaticbalance.Fluiddeficitsof2-4%arecommonfollowingteamsportexercise(Maughan&Shirreffs,2010;Shirreffs&Sawka,2011),withphysiologicalchangesnotedsuchaschangesinextracellularosmolaritythatissuggestedtoinfluenceglucoseandleucinekinetics(Keller,Szinnai,Bilz,&Berneis,2003).Rehydrationpost-sessionhasbeenshowntoeffectsubsequentsessionspositively(Shirreffs,Taylor,Leiper,&Maughan,1996),allowingadaptationandregenerationforthenextsessiontobeadvancedasaresultofstrategiesimplementedinthehourspost-exercise.Researchinto

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rehydrationstrategiespostrugbymatchplayislacking,althoughtheuseofabodymassurinespecificgravityrefractometerwasrecommendedbyHolwayandSpriet(2011)inordertohelpidentifyteamsportathletespronetodehydration.Anadditionalconcernregardinghydrationthatpractitionersshouldtakenoteof,asnotedbyMaughanandShirreffs(2010),isthat,duringcompetitionperiods,manyathletesreportfortraininginahyper-hydratedstate,whichcanbejustasdetrimentaluponperformanceasadehydratedstate.

Alongsiderehydrationpostexercise,foodsconsumedintheimmediatehourspost-exercisemakealargecontributiontotherecoveryprocess,withrestorationofmuscleglycogenreportedlyremainingattenuatedfor2-3days(Nedelecetal.,2012,2013).Adequatemuscleglycogenreplenishmentandahealthydietwillaidindividualsinrecoveryduringperiodsofexcessivetraining,speedingtissuerepairandpromotingadaptationstotraining.InareviewofnutritionalstrategiestomaximiseperformanceinrugbyCasiero(2013)recommendedintakeofappropriatenutritionalrefuellinginthehourspost-exerciseinordertoenhancerecovery.Repairandre-synthesisofmusclecellsiskey,withthesizeofthesnackormealdependinguponthetype,lengthandintensityoftheexerciseundertaken.Specificguidelinesregardingwhenandwhattoeatpostteamsportsvary(Mujika&Burke,2010),withanathlete’soverallnutritionalaimsguidingtheirrefuellingprocesspost-exercise.Theneedtorefuelisalwaysofimportance,althoughcalorierestrictionshouldalsobeconsideredwithinothertime-periodsofanathlete’sday,ratherthanintheimmediatehourspost-exercise.Effectivenutritionalrecoverymaintainsenergyandlimitstissuebreakdown,especiallyduringperiodsofhighvolume/highintensitytraining,withbothcarbohydrateandproteinbeingessentialtotheplan(Macnaughtonetal.,2016).Oneofthekeyfactorstokeepinmindisthatthe“windowofopportunity”formaximisingglycogenrepletionstartstocloseassoonasexercisestopsandlastsforaboutuptofourhours(Mujika&Burke,2010).

Carbohydratesareprobablythemostresearchedformofrecoverystrategypost-exercise,withtheutilisationofcarbohydrateduringexercisebeingrecommendedforsustainedperformance(Jentjens&Jeukendrup,2003).ThisreviewbyJentjensandJeukendrup(2003),however,outlinestheuseoffoodsourcespost-exercisetoenhancerecovery,withteamsportactivitiesreportedtodepletefuelsourcesduringcompetition(Costilletal.,1973).Carbohydrateformsthemajorityoffoodintakepost-exercise,withfoodsourceswithahighormoderateglycaemicindex(GI)recommendedforrapidreplenishmentofglycogenstoresintheliverandmuscle.Sincecarbohydratesaretheprimarysourceofenergyintrainingandcompetition,itisimportantthattheselossesarereplacedbeforethenextexertion.Research,reportingthatduringasoccermatchmuscleglycogenstoresusuallydepletebyupto75%duringamatch(Bangso,2000),alsoprovidesguidelinesforcarbohydrateintakepost-gameasbeing1-1.2gperkgofbodymass.Asmentionedpreviously,morerecentresearch(Bradleyetal.,2016)intorugbyleaguehassubsequentlyreviewedmuscleglycogenstoresandfatigueresearch,withglycogenpoolsnotedtoaffectmusclecontractilityandfatigability.Inrelationtocarbohydratereplenishmentpost-matchplay,perhapsmostinterestingfromtheresearchbyBradleyetal.(2016),isthatrugbyleagueplayerswerenotedtouse<40%oftheirglycogenduringacompetitivematchregardlessoftheircarbohydrateconsumptioninthepreceding36hours.ThisevidencebyBradleyetal.(2016)doesnotdisputetheimportanceofcarbohydratesduringandafterexercise,butitdoespresentapointforconsiderationforpractitionerswhenusingnutritionalinterventionstohastenrecoveryandrestorationpostrugbymatchplay.

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Researchassessingtheinfluenceofresistancetrainingandtimingofproteiningestionisalsowelldocumented(Tiptonetal.,2001),yettheinfluenceofproteinpost-rugbyisunclear.Proteinintakewithcarbohydratesisrecommendedespeciallyafterhardtrainingsuchasweights,sprintingorwhenimpactactivitieshavebeenundertaken(Howarthetal.,2009;Minettetal.,2010;Mooreetal.,2009).Proteinisespeciallyimportantformuscleregenerationandthepreventionofexercise-relatedanaemiaandisthereforeacommonlyusedfoodsourceformanyrugbyplayers(Casiero,2013).Rugbyplayersareadvisedtoincludesomeproteinalongsidetheircomplexcarbohydrateswithintheirpost-exercisemeal.Aratioof4:1isagoodrecommendation,withguidelinesforproteinintakepost-gamebeing0.3-0.4gperkgofbodymass(Casiero,2013).

Withinteamsportsettingswhereactivitiesdifferfromresistancetraining,activerecoverysessionsand“onfield”teamactivities,theguidelinesforpost-activitynutritionmayvary.Thenatureofindividualtrainingdayswithintheteamsportsettingmayguidethefoodandfluidintake.Forexample,aplayermayfueldifferentlyafteranintensetrainingdaycomparedtoalighttrainingday,typicallythedaypriortoagame.Oneaspectthatshouldremainconstantthroughout,though,isthatfoodandfluidreplenishmentshouldbeanintegralpartoftheteam’srecoverystrategyaftergames.Withinelitesport,supplementshavebecomearegularadditiontoanathlete’spostexercisenutritionstrategy.Althoughawell-balanceddietisconsideredappropriateforoptimalrecovery,manyrugbyplayersusesupplementsforlogisticalpurposesandtoaddcaloriestoadailydietwheretheyareconsiderednecessaryduringperiodsofintensetraining,orperiodswhenaddedleanmusclemassisthegoalofthetrainingstrategy(Robertsetal.,2011).Manysupplementsarenowincludedwithinanathlete’sdailyroutine,includingtheuseofdietarynitrates(Jones,2014)andtartcherryjuice(Bell,Walshe,Davison,Stevenson,&Howatson,2015)bothofwhichhavereceivedsignificantpraisefortheiruseduetotheirabilitytoincreaseantioxidativecapacityandenhancerecovery(Howatsonetal.,2010).Foodsandfluidsare,however,consideredtobeapreferredoptiontosupplements,astheycontainmanynutrientsthatsupplementscannotsupplythusencouragingamorebalancedroutinewithinanathlete’sdailylife.

Anadditionalpointtoconsiderforpractitionersregardingfoodandfluidintakeintheimmediatehourspost-gameisalcohol.InastudyassessingalcoholusewithinrugbyunioninNewZealand,Quarrie,Feehan,etal.(1996)notedpatternsofthesamplegroup’salcoholuseasbeingofconcernandemphasisedtheirpotentialimpactuponperformance.Theeffectofalcoholduringrecoveryperiodspost-exercisehasbeenshowntobedetrimental(Barnes,2014),withtheconsumptionof1gofalcoholperkgofbodymassnegativelyaffectinglowerbodypoweroutputpostsimulatedrugbymatch(Barnes,Mundel,&Stannard,2012).Withinrugbyleaguealcoholwasalsonotedtohavedetrimentaleffectsuponpeakpower,measuredviaCMJandcognitivefunction(modifiedStrooptest)inthehourspost-game(Murphy,Snape,Minett,Skein,&Duffield,2013).Thisthesis,however,focusesmoreupontheNMFelementsofrestorationofperformance,ratherthanthelackofmacronutrientsupplementationpost-exercisetorestoreperformance.

2.5.1.8 RestanddayswithouttrainingPerhapsthemostunderresearchedandleaststrategicallyimplementedstrategytoenhancerecoverypost-exerciseisrestdays.Despiterestbeingthemostobviousstrategytoimplementpost-exertioninordertomanagefatigue,itcouldbearguedthatfewpractitionersdeliberately

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putrestintotheirperiodisedtrainingplansandinsteadreacttotheresponsecreatedfromtraining.Ofthelimitedresearchthatdoesexistregardingrecommendedrestdaysforathletes,Bruin,Kuipers,Keizer,andVanderVusse(1994)inastudyofadaptationandovertraininginhorses,reportedthattheabsenceofarecoverydaywasrelatedtotheonsetofsignsofoverreachingandunderrecovery.Replenishmentofsubstratesandtherepairofmuscledamageinducedbytrainingandcompetitionarethemostlikelyreasonforrestdayimplementationineliterugbyunionsettings.Withouttheadditionofrestdaystoenablethereplenishmentofsubstratesandtherepairofmuscledamage,rugbyplayersarelikelytoproducesub-optimalperformance.Whenconsideringresearchthatreportedtime-courseofrestorationandsubstratedecrement(Bradleyetal.,2016;Casiero,2013;Cunniffeetal.,2009;Lindsay,Lewis,Scarrott,Gill,etal.,2015;Minettetal.,2010),theimplementationofrestdayswherefatigueisdissipatedisthereforepotentiallymoreadvantageousthandaysthatinvolvetraining.

Itisalsoimportantforpractitionerstounderstandthatrestdaysarenotsolelyputinplaceforphysicalrecoverybutalsowiththeaimofpositivelyimpactingmentalrecovery.Dayswithouttrainingprovideathleteswithadistractionfromthedailyroutineoftrainingandinadditionwillreduceperceptionofmentalfatigueduetotimeawayfromorganisedtrainingevents.Itcouldbearguedthatpsychologicalrecoveryachievedviarestdaysisjustasimportantasphysiologicalrecovery.Whenconsideringthatphysiologicalstressisdifficulttoidentifyandvariantinmechanism,perhapstheattentionofpractitionersshould,insteadfocusuponinvestigatingpsychologicalrecoveryalongsidephysiologicalelementsasrecommendedbyRattrayetal.(2015).Despitelimitedresearchexistingasregardspsychologicalstresspost-exercise,psychologicalstressis,perhaps,amoreeasilyinvestigatedareaincomparisontophysiologicalstressandthereforewarrantsattention.

Alongsidephysiologicalstress,rugbyunionmatchplaydemandshighlevelsofcognitiveactivityandmostlikelywillhaveacostuponsubsequentrecovery.Theneurologicalfatiguecreatedfromexertioncanbereducedbytheimplementationofrestdaysfromtraining,which,ifplannedappropriately,willhaveapositiveinfluenceuponadaptation.Itis,however,importantforpractitionerstonotethatsomephysiologicalfocusedrecoveryinterventions(massage,forexample)alsopotentiallyencompassapsychologicalrestorativeelement(Poppendiecketal.,2016),wherebytheindividualperceivescareandconsiderationfortheircurrentphysiologicalandpsychologicalstatetobepresent.Thesamenotioncanperhapsbesaidforactiverecoverysessions(swimrecovery,forexample).Thelikelihood,however,ofthisbeingtrueformodalitiessuchasCWIimmersion(whichtypicallycarrylesscompliance)canbequestioned.Itisimportantthatpractitionersnotethepotentialnegativepsychologicalinfluencethatarecoveryinterventionmighthave,evenifthismodalityhasbeendeliberatelyimplementedintoanathletestrainingschedulealongsideapre-plannedrestday.IfamodalitysuchasCWIisnotenjoyed,ornotperceivedasbeneficialbyindividuals,thiscouldbehavinganegativeeffectupontheglobalrecoveryresponse,whenconsideringtheinfluenceoftheaddedpsychologicalstress.Insummary,theabilityofpractitionerstoimplementrestdays,attheappropriatetimeandfortheappropriatenumberofdays,ismainlyduetocommonsenseand“coachingart”.Experiencedcoacheswilllikelyrecogniseperiodsoffatigueusingsomeoftheobjectivetrainingloadmanagementmethods(GPSandHR)andsubjectivemeasures(WB)ofassessmentoutlinedinChapter2.4.Coachesare,however,advisedtousetheircoachingexperienceandtheir

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knowledgeoftheindividualstheyoverseetoimplementrestdayinterventionswhereappropriate.

2.5.1.9 SelectingtheappropriaterecoverymodalityAsproposedinresearchfromYamaneetal.(2006)themicrodamage,cellularandhumoraleventsinducedbyenduranceandstrengthtrainingareimportantaspectsoftheadaptiveprocesswhichleadtoimprovedperformance.Thisadaptiveprocessis,therefore,contrarytotheapplicationofrecoverymodalitiesthathastentherecoveryprocess.Recoveryinterventionsgobeyondthenaturalmechanismsinvolvedwithinthephysiologicaltrainingadaptationprocessandasreportedaboveareregularlyimplemented.Fromtheevidencepresentedabove,itisclearthat“recoverytraining”inteamsportsisanaspectofimportance.Selectingtheappropriaterecoverymodalityis,therefore,akeydecisionforpractitionersandisdependentuponmanyfactors,includingtherecognitionthatwhathasfatiguedtheathlete,isofprimeimportance.Notonlydothemechanicalmovementsperformedaffecttheresponsecreatedbutthenatureofthemovementsalsoaffectsthefatigueoutcome.Forexample,ifmetabolicfatigueiscreatedthenperhapsreplenishmentoffluidandfuelstoresneedtoadministered,whereasifthemovementinvolvedexplosiveexercises,thenthefatiguemaybemorepsychologicalinnatureandthereforeanotherrecoveryinterventionmaybebettersuited.Regardlessofthefatiguemechanismcreated,enhancedrecoveryfollowingcompletionofanathletictaskiscrucialforfutureperformanceformanyathletes,althoughreliableandspecificscientificevidencetosupportrecoverystrategieshasyettobefound.Itis,however,importantforpractitionerstonotethatthepoorevidencetodateforassessingtherecoverystrategiespostexerciseexertion,ispartiallytheresultof;alackofdiagnostictoolsavailabletoassesseffectiveness,largevariabilityofresultsofresearchstudiesandalackofwellcontrolledstudies.

Individualisationofrecoverystrategiesbypractitionersisrecommendedduetotheindividualnatureofrecoverypostcontactsports(position-specific)andtherequirementtomonitortheindividualresponsestointerventionsrequiredtoassessingeffectiveness.Anotherconsiderationwithinteamsportsettingsisavailabilityofresources,withapragmaticapproachoftenconsideredbestwhenchoosingtheinterventiontoimplement.Withinteamsportsthenumberofathletestorecoverislarge,meaningthatlogisticalconsiderationsandtimeconstraintsareofimportance.Thecostofselectedmodalitieshasimpacteduponcommonlyusedpracticesinteamsports,withtechniqueswhichcanbeself-administeredandincurnocostoftenbeingthemodalitiesmostreadilyused.Sustainabilityandmanageabilityareconsideredimportantforathletecompliance,asrecommendedbyCook,Kilduff,andJones(2014),withsleepandnutritionbeingidentifiedasthetwomostcriticalelementsoftherecoveryprocess.Despitemanypractitionershopingtouseexpensiveandcuttingedgetechnologieswithintheirrecoveryprocess,budgetrestrictionsoftenlimittheuseofmodalitiessuchasWBC,whichincuragreatertimeandfinancialinvestment.Aholisticapproachtoarugbyplayersdailyandweeklyscheduleshouldbeusedsothatphysicalstress,psychologicalstressesandoff-fielddemandsaremanaged.

Withintheprofessionalteamsportenvironmentitisnotsolelythecoaches’responsibilitytomanagetherecoveryprocess.Theabilityofpractitionerstomakeathletesaccountableandself-awarewithintheirtrainingandrecoveryprocesswillincreasecomplianceandsubsequentrecovery.Ifathletes,however,arenotcompliantordonotlistentotheirbodiesthroughouta

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competitiveseasontheywillstruggletocopewiththeworkloadandmaladaptationcouldpotentiallyoccur.

2.5.2 SummaryContrastingevidencesupportingtheeffectivenessofmanyrecoverymodalitiesexists,mainlyduetothemethodologyused,protocolundertakenandperformancemeasuresassessedbeingsovariedinnaturethatnoclearagreementcanbeconcluded.Theneedtoresearchrecoverypracticesinrugbyunionisthereforeofimportancetopractitionersaimingtoimproveplayerreadinessbetweengames,wheresupposedbenefitsneedtobeconsideredagainstthefinancialandpracticalimplicationsthateachmodalityassumes.Modalitiesthatprovidesimplicityofadministrationandlowfinancialcost,willmostlikelybetheinterventionstrategyimplementedwithinmanyeliterugbysettings.Asoundrecoverytheorywithconsistencyofadministrationandplayereducationembeddedintodailylifestylechoicessuchassleepandnutrition,isconsideredaneffectivestartingpointforenhancingratesofrecoverypostrugbyunionmatchplayandtoimproveplayercompliance.Thechoicesofadditionalrecoverymodalitiesbeingusedbyeliteclubs,alongsideimprovedlifestylechoicestoenhancerecovery,arelikelytobescenariospecific.Itis,however,importantforpractitionerstonotethatmanagementoffatiguedoesnotalwaysrequiretheuseofrecoverymodalitiesandthatinsteadcoachesshouldlooktomanagefatiguebymonitoringreadiness(usingmethodsoutlinedinChapter2.4),alongsidecontrollingthevariablesthattheyhavethepowertomanipulate(intensity,volumeandrestdays).

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2.6 Relevanceofreadinessandrestorationresearch

AswasrecommendedbyPyneandMartin(2011),asystemsbasedapproachthatintegrateswell-chosendiagnostictoolsisconsideredtobethefutureforfatiguemanagementinelitesport.Theabovediagnostictoolsandrecoverymodalitiesneedtobeselectedbaseduponthemovementsandactivitiesofthesportandthefatigueresponsecreated.Asaresultofusingasystem-basedapproachthatencompassesrecoveryandrestorationofperformancemonitoring,overallplayerreadinesscanbebetterassessed.Theincreasingamountofcommerciallyavailableathletemonitoringsystemsineliterugby(RugbySquad,Egde10,ApolloandKitManLabs)makeintegrationofperformancemonitoringdatawithintheathlete’strainingregimemoreeasilyaccessibleandenablebettermanagementandreporting.Itisimportanttonote,however,thatdatacollectedwithinaneliterugbysettingshouldnotbeusedsolelyforresearchpurposesandshouldinsteadbeprioritisedforusetoimproverugbyplayers’dailytrainingandplayingreadiness.

2.6.1 TheimportanceofreadinessNMFisperhapsatermthatcouldbeperceivedashavinganegativeconnotationbysportscoaches.Therefore,sportssciencepractitionersshouldperhapsusetheterm“neuromuscularreadiness”,asthisislesslikelytobeconstruedasaperformancetestthatcanonlydetectfatigueinanegativecontext.Instead,readinessassessmentwillaidsportspecificcoachestounderstandthemechanismandcausesofthefatigueandguidepractitionersinchoosingaspecificreadinessassessmenttoolforthesportinquestion.Theterm“readiness”hasbeenusedinvariousrecentstudies,rangingfromPlews,Laursen,Stanley,etal.(2013)mentioningreadinesswhenusingHRVandtrainingresponse;GaviglioandCook(2014)usingtestosteroneandcortisoltomeasurereadinessleadinguptogamesinrugbyunion;Duffieldetal.(2008)whenmeasuringtheeffectsofcompressiongarmentsandMyer,Paterno,Ford,andHewett(2008)using“readiness”terminologywhendiscussingreturntoparticipationcriteriapostanteriorcruciateligamentinjury.Readinesshasbeendescribedas“thecurrentfunctionalstateofanathletethatdeterminestheabilityofanindividualtoeffectivelyachievetheirperformancepotential”(FominandNasedkin,2013,p.5).Itcouldbearguedthatreadinessin-seasonrelatestorestorationofperformancevaluesandthatduringpre-seasonreadinessrelatestotheaforementionedFORtheory.Hightrainingvolumesduringeliterugbyunionpre-seasonperiodsaredesignedtocauseapositiveplayeradaptationtoatrainingdosestimulusandwillthereforehaveadifferingimpactuponreadinessthanatypicalin-seasontaperedtrainingweekasagamedayapproaches.Basedupontheconceptofreadiness,recenttechnologicaldevelopmentshaveenabledobjectivefeedbackonchangestakingplaceasaresultoftrainingandcompetitionexposure,meaningevaluationofplayerreadinesshasbecomemorequantifiable(Fomin,Grainger,Nasedkin,Bork,&Huttunen,2015).Onecouldarguethatthegoalofeverycoachshouldbetoimprovethemanagementofthefunctionalstateofanathlete,withthemostimportantmarkerofthisbeingreadinesstotrainandplay.Readinessis,therefore,theresultofmanydifferentstimuliappliedtotheathletefrombothtrainingandnon-trainingstressors,andisanaccurateindicatorofanathlete’sabilitytorealisetheirperformancepotential,whenconsideringcardiacpulmonaryreadiness,autonomicnervoussystemreadinessandreadinessoftheneuromuscularsystem.Reducedreadinesswhenassessedviaaccuratemeasuresshouldprovidecoacheswithcuestoaltertrainingload,asaresultoftheadaptiveresponsesoftheathlete’sorganismtothestimuliapplied.

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Readinesstotrain,fromasportscoach’sperspective,surroundstheinfluenceoftrainingprogramdesignandmanagementandtheimpactthishasuponathletefatigue.AsillustratedinFigure2.2,manycoachesfollowtheoverloadingtrainingstimulusresponse(supercompensationmodel)fortrainingadaptation,whereanathleteisexposedtoanoverloadingtrainingstimulusthatcausesfatigue,withthebodythenreorganisingitscapacitiessothatthenextexposuretothesamestimuluscauseslessstrain.Thedisplacementinhomeostasiscausedbytheoverloadwillresultinadaptation,withtherecoverytimebetweenexposuresbeinglongenoughforthenexttrainingstimulustocreateafurtherpositiveadaptationfromhomeostasis.Theaccumulationoftrainingeffectandpossibletrainingstress,wheretherecoveryperiodsbetweenexertionsarenotsufficient,willresultininadequateadaptation.Monitoringofanindividualathlete’sresponsestothetrainingeffectimposedisthereforeofsignificantimportance,inordertoavoidmaladaptationandimprovedailyreadinesstohandlingtrainingexposures.

Readinessassessmentbypractitionerscanresultintheloadbeingappliedatanappropriatetimewithinthetrainingprocess.Thisutilisationof“windowsoftrainability”enablescoachestoprescribespecificsessionswiththeappropriateload,withtheaimofproducingoptimalperformance.Inessence,readinessassessmentenablescoachestomanageathletepreparationbaseduponreadinessmeasures,whichassessNMFandtheathletes’overallfunctionalstate.Itiscommonpracticeforcoachestodesignlong-termtrainingprograms,withouttakingintoaccounttheresponseoftheathletetotheloadimplemented.Readinessassessmentcouldbeconsideredtobeamoreathlete-focusedapproachtooptimaltrainingthanthemorecommonlyusedtraining-focusedprocess.Concurrentalterationstoalong-termperiodisedplanusingreadinessassessmentincreasesthechancesofoptimalperformance,whileavoidingmaladaptationorpotentialinjury.

2.6.2 MeaningfulchangeCoacheswanttoknowthattheirathleteshaverecoveredfromtrainingorgameexertion.Often,though,playerswillnothaverecoveredcompletelyfromtrainingandgames,yethavetocompeteagain.Thisinsufficientrecovery,priortocommencinganothertrainingsessionorgame,iscommoninmanyteamsportenvironmentswheretimebetweengamesislimitedandtheneedtoprepareforandcompetewithinthenextgameareessential.Practitionersneedtoascertainwhethertheyshouldbelookingforfaultsinplayerperformancethroughtesting,orbealerttocluesthatshouldbeinvestigatedfurthertoassessreadiness.Onecouldarguethatreadinessdoesnotmeancompleterestorationofperformancetopre-gamelevels,asoftenthisisunrealisticinrugbywherethenumberofdaysbetweengamesaresmall.Thislackofrestorationofperformancetopre-gamelevelsdoesnotmean,however,thatoptimalperformancecannotbeattained,andshould,perhaps,notbeconsideredtoomuchofaconcernintheelitesetting.

Incompleterecoveryisthereforeascenariothatshouldbeconsideredwhenpreparingathletes,althoughitthatshouldnotcausetoomuchconcern.Amorespecificconcernshouldbethelevelofperformancedecrement,ratherthanthatthereisadecrementinthefirstplace.AsmentionedinChapter2.3.6,performancedecrementiscommonlyseen,especiallyinthelaterperiodsofplayingseasonswhencumulativefatigueisafactor.Theabilitytoidentifydecrementinperformanceandassociatedreadinessisonlyonetaskforstrengthandconditioningcoaches.Thedecisionoverwhentoactuponthischangeandimplementinterventionfortheplayerinquestionisthekeyareaoffuturefocusinreadinesstotrain.AssupportedbyTwistandHighton

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(2013),moreresearchneedstobeconductedtounderstandmoreclearlywhatmeaningfulchangerepresents,forselectedmonitoringtools,beforeanyinterventionsaremade.Moreinformeddecisionscouldbemadeuponreadinesswhenknowledgeofperformancestandardsinthetestscritiquedaboveiscombinedwithacoach’sinstinctiveunderstandingoftheirplayers.ThiscombinationofobjectiveandsubjectivemeasureswasrecommendedbyTwistandHighton(2013),whoidentifiedthatlargechangesinperformance,combinedwithanincreaseinperceptualfatigue,couldaidcoachesinmakingdecisionsuponreadinessusingassessmentssuchasCMJ,HRVandself-reportwell-being.

Theimportanceofindividualisedmonitoringiskey,withresearchbyPyneandMartin(2011)illustratingtheneedforasystem-basedapproachthatintegrateswell-chosendiagnostictests.Itcouldbearguedthatoneathlete’sreadinessdatacannotbecomparedtoanother,asreactiontothetrainingdose-responserelationshipisbespoketotheindividual.Individualrugbyplayersareexpectedtohavedifferingcapabilitiestoadapttothesametrainingload,withthephysiologicalandpsychologicalbufferzonesdeterminingtheresultantfatigueresponse.AsreportedbyTwistandHighton(2013),themultifacetedelementsoffatigueandthephysicalandmentalresponsethatindividualsathletesdemonstrate,meanthatsinglebiochemical,hormonalorperformancetestsdonotpresentaclearpictureofathletereadiness,butinsteadmeanthatathletesshouldbemonitoredwithinamulti-methodindividualisedapproach.Additionally,TwistandHighton(2013)discouragetheuseofarbitrarycut-offpointsacrossmeasurementtoolswhenalterationsinperformancearereported.Previousresearchhasinvestigatinginter-dayreliabilityofmeasureforeachindividual,byassessingrepeatedmeasures.TwistandHighton(2013),whenassessingchange,reportedmultiplyingfactorsof0.3,0.9and1.6todeterminewhatwouldbesmall,moderateandlargechanges,whileHopkins(2004)proposedtheimplementationofSWCvalueswithinperformancetesting,inordertodeterminewhetherornotameaningfulchangehasoccurred.AmeaningfulchangewasnotedtooccurwhenCVerrorbarslayoutsideoftheSWCthreshold,withthismethodproposed,therefore,forusebypractitionersinassessingreadinesstotrain.

Thecollectionofaveragescoresforindividuals,onselectedperformancemeasuresassessingfatiguepostperiodsofrestorperceivedoptimalstate,iskey.Theaimforpractitionersistoestablishastablevalueforeachindividualthatcanbeusedtoserveasacomparisonastheseasonprogresses.Itcouldbearguedthatthemostimportantcomparisonisintra-individual,yetitisrecommendedthatpractitionerspayspecificattentiontothecomparisonofacuteandchronictrainingalongsideindividualfatigueresponsesasrecommendedbyHulin,Gabbett,Lawson,Caputi,andSampson(2016).Theabilityofpractitionerstobeabletomakeinformeddecisionsbaseduponfatiguedata(irrespectiveofthetestingvariableused),whilealsoconsideringtheacuteandchronictrainingresponsewilltakealargeamountofdatacollectionandanalysis.However,ifreliabilityvalues(CV%)andSDDaredetectedpriortocollationofdata,thiswillbeofbenefitforinformeddecision-makingmovingforward.ThisnotionofindividualisedmonitoringwithinrugbyunionwasfurthersupplementedwiththerecentapplicationofbespokehighspeedrunningvaluesbyReardon,Tobin,andDelahunt(2015).Reardonetal.(2015)recommendedtheuseofpositionalsub-categorieswheninterpretinghighspeedrunningdemands,toenablemakingmoreinformeddecisionsonthedatacollected.

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2.6.3 ImprovingreadinessIfpractitionersareconfidentinmakinginformeddecisionsbaseduponreadinessoftheirathletestoperform,improvedperformanceandreducedpresenceofinjuryfromtrainingandcompetitionseemlikelytooccur.Thisassumptioncouldbemadeformanysportswherecoachesareoftenunsureoftheappropriatetrainingdoseneeded.Inadditiontopractitionersbeingabletomakeinformeddecisionsoverwhetherornotathletesshouldtrain,perhapstheareathatelitepractitionersshouldbefocusinguponistheneedtoimprovereadiness,ifrequired,andhowbesttodoso.Specificrecoveryprotocolsandadjustabletrainingschedulesonthedaypost-performanceareofsignificantimportance.Athleteinvolvementandfeedbackinthemonitoringprocessarevaluable,astheempowermentandsenseofownershipgiventotheplayerswillenhancetheprocess.

Theabilitytoquantifydecrementinkeyperformanceindicatorsandassociatedreadiness,orneuromuscularfunctionfromafunctionaltestsuchasjumpheight,isakeyareaoffocusforfutureresearch,especiallyduringperiodsofintensetrainingorplaying.ConsideringtheresearchbyGabbettandJenkins(2011),whonotedarelationshipbetweenathletefatigueandinjuryratesinprofessionalrugbyleague,pre-seasonperiods(whenplayerloadishigh)arepotentiallyofmostsignificance.IncreasedtrainingloadsandincidenceofinjurywerestudiedbyKillenetal.(2010),withnosignificantrelationshipobservedinprofessionalrugbyleague,yetthepre-seasonperiodwassignifiedasakeytimeforinjurytooccur.Despiteinjuryandtrainingloadbeinginterlinkedandthereforebeingofimportancetopractitioners,theareaoffocusforthisresearchdoesnotincludeinjury.Injury’srelationshiptoreadiness,however,couldbeconsideredasafutureareaofstudyforreturntoplayprotocol.Inananalysisofreturntoplay(RTP)protocolpost-injurybyReidetal.(2013)inelitelevelrugbyunion,aprogressiverugby-specifictrainingprogramwasrecommendedbasedonaplayer’spositionaldemands.Duetothefrequency,intensity,anddurationofrunningeffortsbyeachplayingpositionbeingvastlydifferentduringgames,asdetailedinChapter2.1,position-specifictrainingprogramsinvolvingRTPprotocolarecommonpractice(Reidetal.,2013).TheuseofGPSdatainconjunctionwithfatiguemonitoringmeasures,asdiscussedinChapter2.1.2,willprovidepractitionerswithmoreinformeddecisionsthroughouttherehabilitationperiodpost-injury.

TwistandHighton(2013)notedthatperformancetestdataassessingneuromuscularfunction,combinedwithperceptualdatafromquestionnaires,wouldprovideamoreaccurateunderstandingofplayerfatigue.Thisnotionisfurtherendorsedbymorerecentresearchassessingmeasurementsensitivityofmonitoringtools(Crowcroft,McCleave,Slattery,&Coutts,2016).Aspreviouslydiscussed,TwistandHighton(2013)notedthemultifacetedelementsoffatigueandthephysicalandmentalresponsethatindividualathletesdemonstrate,withamulti-methodapproachthatassessesanychangebelowbaselinerecommendedforimplementation.PractitionersusingjumptestingtoassessNMF,forexample,shouldquestionatwhatpercentagejumpperformancereductionwarrantsalteredtrainingvolumeorintensity.Belowbaselinechangeplustheabilitytohaveobjectivemeasuresofreadinesstotrainarethereforeparamount,sothataplayerknowswhentoreturntofulltraininginsteadofholdingbackbaseduponthereportedalteredsenseoffatigue(McLellanetal.,2011b;Sykes,Nicholas,Lamb,&Twist,2013).Consideringthatplayersoftenresumeresistancetrainingintheimmediatedaysafteramatchandoftenbeforeanyfieldsessions,theviewsofJennings,Viljoen,Durandt,andLambert(2005)areofnote.Jenningsetal.(2005)indicatethatresistancesessionscouldperhapsprovidetheopportunityforcoachestomonitorpoweroutputduringexercisessuchas

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benchpress,priortothemaintrainingsessioncommencinglaterintheday.Gymnasiumbasedsessionsonthemorningofatrainingdayarecommonwithinbothrugbyleagueandrugbyunion,enablingpractitionerstoassessplayersreadinesstotraininsubsequentsessionsthatday.Duringtheearlypartoftheirtrainingday(inthegymnasium),decisionscouldbemadebasedupontheresultsofthemorningsreadinesstesting,thusprovidingbetteroverallmanagementofdailyplayertrainingprescription.

2.6.4 LimitationsoftheresearchtodateEquipmentavailableforuseinassessingperformancemeasuresandthetimeavailabletoperformthetestingwerealsolimitingfactorswithinthisresearch.AlthoughforceplateswouldhaveprovidedmoredetailedanalysisofplayerperformancewhenassessingCMJ,thelogisticalandfinancialinvolvementofforceplatetestingmadethisunrealistic.Additionally,theshortperiodsoftimeavailableonatypicaltrainingdaytocollectperformancemeasuresmeantthatoftenfewerindividualsthandesiredwereassessedonadailybasis.Thissmallersamplesizecollected,therefore,presentedalessdetailedanalysisofperformanceacrossthewholerugbyplayingsquad,yetthetimeconstraintsinvolvedareconsideredtobea“realworld”scenariowithineliterugbyuniontesting,whereplayers’andpractitioners’timeislimitedwithinbusytrainingdaysintheleaduptocompetitivegames.

Anotherlimitationofthisresearchexistswithinthegamedatacollectedwhere,althoughthisresearchassessedthedemandsofplayeractionsduringgamesituations,itdidnotconsidertheeffectimpacts(measuredviaGPS)fromcontactsituationshaduponplayers,aswasresearchedbyMcLellanandLovell(2012)duringrugbyleaguematchplay.WhenassessingneuromuscularresponsestoimpactandcollisionsduringeliterugbyleaguematchplayMcLellanandLovell(2012)reportedimpacts>7Gasbeingasignificantinfluenceuponneuromuscularfatigue.ThisresearchbyMcLellanandLovell(2012)doesnotincludethemovementclassificationofimpactsexperiencedandinsteadsimplyfocusesuponthevolumeofimpacts.Thislackofdetailsurroundingthemagnitudeofimpactsexperiencedisanobviouslimitationinthisresearchandonethatwouldbeamendedinfuturestudytoguidepractitionersmoreclearlyonthetypicalrestorationofperformancetimingsforpositionalgroups.

Lastly,alimitationofthisresearchalsosurroundsrugbycoachesmakingdecisionsonwhentotrainandwhentorest,withnoconsiderationfortheevidencecollected.Although,inthisrespect,guidancecanbegiventosportspecificcoachesfromsportssciencepractitioners,therugbycoachesandnotthesportssciencepractitionersoftenmakethefinaldecision.Thisnotion,thatsportspecificcoacheshavethepowertooverrulesportssciencepractitionersandmedicalpersonnel,uponwhentotrainandwhentorest,isacommonlyreportedissueineliterugby.Althoughthisnotionoftherugbycoachesmakingill-informeddecisionsuponindividualplayertrainingavailabilityisnotidealforbestpractice,thisprocessofplayermanagementissimplea“realworldconsequence”ofelitesport,wherethepressurestosucceedarehighandtheemphasistopushplayerswhenperhapsilladvisedisacommonlyseenphenomenon.Decisionsregardingweeklytrainingstructure,andconsequentlyindividualplayermanagement,areoftenguidedbyexternalfactorssuchasweatherandinstinctive“coachingart”,ratherthanbeingdrivenbyscientificdataaimedatenhancingperformance,whileincorporatingrestorationofperformancemeasuresandassociatedreadiness.Basedonthesefindingsitistheauthor’sbeliefthat“coachingart”and“performancescience”,deliveredbypractitionerstorugbycoaches,whilekeepinginmindlogisticalissuesregardingplayermanagement,wouldbethebestcombinationtoforachievingoptimalresults.

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2.7 Summaryofresearchproposed

Insummary,theaboveliteraturereviewhasledtotheconclusionthatreadinesstesting,assessingrestorationofperformancelevels,isessentialwithineliterugbyunionsettings.Although,implementingperformanceteststhatfitwellwithinateam’sdailyandweeklystructure,thatwouldbenefitdecisionmakingoverplayerpreparedness,ismoreproblematic.Theoverallaimofthefollowingresearchchaptersis,therefore,toidentifyamonitoringtoolthatcouldeffectivelyassessrestorationofperformancepostrugbyunionmatchplay.

Firstly,aspecificobjectiveofthisresearchwastoascertainthematchdemandsexperiencedbyeliterugbyunionplayers.ViaanalysisofmatchdatatakenGPS,assessingmovementrequirements,matchloadexperiencedbyplayerswillberevealed.Aspreviouslystated,thenovelaspectofthisresearchincomparisontothatofpreviousstudy(Cahilletal.,2013;Quarrieetal.,2013),isthatthisresearchencompassesplayerswhoplaylessthan80minutesofarugbymatchandtherebyrepresentatruereflectionofcurrentelitepositionaldemands.Secondly,anotherobjectiveofthisresearchassociatedwiththecollectionofmatchdemandsdata,encompassesassessmentofperformanceteststhatidentifythematchcharacteristicsthataffecttime-courseofrestoration.Althoughthisresearchwillnotassesswhichmatchcharacteristicsinfluencerestorationofperformancetoagreaterdegreethanothers,anunderstandingofthesensitivityofselectedperformancetestswillbeascertained.Matchcharacteristicsthatimposeagreaterlevelsoffatiguewithresultantlongerperiodsofrestorationofperformanceareofsignificantinteresttotherugbyclubsandcouldhelpthemplansubsequenttrainingsessionspost-game,forbothpositionalgroupsandindividuals.

InadditiontoassessmentofGPSmatchdata;afurtherobjectiveofthisresearchwastoidentifyameasurementtoolthatwouldassessrestorationofperformanceandreadinessfortrainingandmatchplaywithinrugbyunion.Thismeasurementtoolhastobeaccurate,reliableandfeasibleforusewithineliterugbyenvironments,wheretimeandbudgetconstraintsexist.Thetoolsproposedforassessmentofreadinessare,therefore,theCMJtestandtheself-reportwell-beingquestionnaire.Thesetoolsareusedtoassesspreandpost-matchchangesinperformance,withrestorationofneuromuscularfunctioncollatedviaCMJperformancetests,andthemoresubjectivenotionsofrecoverycollectedviaself-reportwell-beingquestionnaires.CMJandWBquestionnaireswereidentifiedforusefromtheliteraturereviewabove;duetotheeasewithwhichtheycanbeimplementedandthelogisticalissuesthatsurroundthesettinginquestion.Previousmatchcharacteristicresearchandtheeffectthatmatcheshaveuponrestorationofperformancehavepredominatelyfocuseduponrugbyleague(Johnstonetal.,2013;McLellanetal.,2011b;Twist&Highton,2013;Twistetal.,2017;Twistetal.,2012),withlimitedresearchintorugbyunionspecifically(Crewtheretal.,2009;Westetal.,2014).Thisresearchaimstoaddtotheknowledgeofperformancemeasuresthatcandetectameaningfulchangeinneuromuscularfunctionasaresultofspecificmatchcharacteristicsinrugbyunion.

Lastly,anotherobjectiveofthisresearchwastoassessthefrequencyandmagnitudeofimpactsexperiencedbyplayersduringeliterugbyunionmatchplay,usingbothvideofootageandGPSdata.Thiscombinationofmethodologieswillprovidepractitionerswithgreaterinsightintoeliterugbyunionimpacts,asthefootageandGPSdatacombinedwillprovidemoredetailthanearlierresearch(Cahilletal.,2013;Coughlanetal.,2011;Venter,Opperman,&Opperman,2011).ThestudiesbyCunniffeetal.(2009)andCahilletal.(2013)didnotinvolveanalysisofimpacts,whiletwostudiesthatdoconsiderimpactswithinmatchanalysisassessment

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(Coughlanetal.,2011;Venteretal.,2011)involvesmallersamplesizesandlessextensiveanalysisofimpactacrosspositionalgroups.Amoredetailedanalysisofwhereimpactsoccurduringmatchplaywillfurtherhelpquantifythedemandsexperiencedbyplayersandwillprovideadditionalinformationabouttheeffectofspecificmatchcharacteristicsupontime-courseofrecoveryforpositionalgroups.TheGPSdatacollectedwithinthisstudywillidentifythematchintensityexperiencedbytheplayers(illustratedbyGPSvariables),whilethevideofootagewillactasareferencefileagainstwhichtocomparetheGPSresultsdata.Thiscombineddatacollectionwillhelptoascertainmatchinvolvementsandtheirassociatedimpacts.

Thenovelapproachoutlinedwithinthisresearch,incorporatinggreateranalysisofmatchdataandmorespecificuseofthemethodsofneuromuscularassessmentpresentedinTable2.13,willenableamoreglobaloverviewofplayerreadiness.ThisisincontrasttoresearchbyMcLeanetal.(2010)andMcLellanetal.(2011b)whoonlyusedCMJ,biochemicalandWBvaluesanddidnotprovideanyimmediatefeedbacktoplayersorpractitioners,withtheresultthatconcurrentinterventionscouldnotbeimplemented.Todate,methodsusedinthekeyresearchbyMcLellanetal.(2011b)includedquestionableCMJprotocolswhere,forexample,subjectshandswerenotplaceduponhipsduringthejump.Thisprotocolhasbeenshowntobeinaccurate(Domire&Challis,2007)wherearmswingallowsgreatermuscularforcetobegenerated,thereforeillustratingthatsomeoftheresultspresentedmaybedifficulttocompare.

2.7.1 Researchquestionsproposed• Dothephysiologicalrequirementsofeliterugbyunionplayersdifferacrosspositional

groups,irrespectiveofdurationplayed?o Dobackscoveragreaterdistanceacrossalldistancezonescomparedto

forwards?o Areforwardsinvolvedinagreaternumberofimpactsacrossallimpactzones

comparedtobacks?o Arebacksinvolvedinmoreaccelerationsanddecelerationscomparedto

forwards?o Dobackscompletegameactivitiesatagreaterintensitythanforwards?

• Whichjumpmodalityismorereliablewithinandbetweensessionsineliterugbysettings?

o Arebilateraljumpsmorereliablethanunilateraljumps?o IsCMJmeasurementanaccurate,reliableandfeasibletaskforusewithinelite

rugby,toassessrestorationofperformance?• Doestime-courseofrecoveryofeliterugbyunionplayerspost-matchdifferacross

positionalgroups?o AreCMJperformancesandWBscoresrestoredwithin60hourspost-match?o DoforwardstakelongertorestoreCMJperformanceandWBscoresduetothe

greaternumberofimpactstheyexperienceduringgames?o Domanyoftheimpactsexperiencedfromplayersduringmatchplayoccuronly

duringcollisionsituations?

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3 MatchCharacteristicsinanEliteRugbyUnionPlayingSeason

3.1 Abstract

Anunderstandingofthephysicaldemandsplaceduponeliterugbyplayersduringmatchplayisimportant,inorderforpractitionerstoprescribeappropriatetrainingplansforpositionalgroups.Thepurposeofthisstudywastoquantifythematchcharacteristicsofeliterugbyunionplayersacrossacompetitiveplayingseasonandtoidentifywhetherposition-relateddifferencesexist.Thirty-eightplayersfromoneEnglishPremiershipClubweretrackedusingGPSduringthirty-twogamesplayedthroughoutthe2014/2015playingseason(462datasets).Thisstudyinvolvedninepositionalgroups,whichweredefinedas:backs(n=220)orforwards(n=242);andfurthersubdividedintoprops(n=62),hookers(n=30),locks(n=59),backrows(n=95),scrumhalf(n=34),outhalf(n=33),centres(n=59),wings(n=62)andfullbacks(n=27).Thematchcharacteristicsrevealedasignificantlygreater(p<0.001)distancecoveredforbacks(5918±1206m)comparedtoforwards(5035±1157m),inconjunctionwiththebacksplayingatasignificantlyhigherintensity(70.9±7.4m/min)comparedtotheforwards(64.0±6.3m/min)(p<0.001).Additionally,backsconductedasignificantlygreater(p<0.001)numberofaccelerations(32.2±10.6)comparedtoforwards(22.0±11.9)andasignificantlygreater(p<0.001)numberofdecelerations(41.9±12.3)comparedtotheforwards(30.8±14.4),whileforwardsexperiencedagreater,yetinsignificant(p>0.05)numberofimpacts>Zone3(229±160)comparedtothebacks(226±151).Withintheninepositionalgroups,manydifferencesinmatchdemandswereidentified,withfullbackscoveringthegreatestdistance(6904±740m)comparedtothelowestbeingprops(4285±893m)(p<0.001).CentresperformedthehighestdistancecoveredinD1(2405±256m),fullbacksthefurthestinD2(2078±275m)andD5(429±118m),scrumhalf’sthefurthestdistancecoveredinD4(1009±214m),whilewingerspresentedthefurthestdistancecoveredinD6(139±72m).Impactzonesfortheninepositionalgroupsshowedthatpropstypicallyexperiencedthelowestnumberofimpactsinthelowerimpactzones(Im1,Im2andIm3),yetexperiencedalargenumberofimpactsinthehigherimpactszones(Im4,Im5andIm6).Fullbacksshowedalargelevelofimpactsonbothlowandhighimpactzones,yetthepositionsofprop,hookerandbackrowillustratedhighIm6valueswhencomparedtothevaluestheyexperiencedatthelowerimpactzones.Resultsfromthisstudyhelpguidecoachesuponwhateachpositionalgroupshouldcompletewithintheteam’splayingstructureandenablecoachestomakemoreinformeddecisionsuponwhetheranindividualplayercanperformsucharolefortheteam.Specifictrainingrecommendationsresultingfromthisstudyare,firstly,thathighlevelsofaerobicfitnessarerequiredtocompletematchdistances,andsecondlythathighmusclemassandstrengthareneededtocopewithmatchimpactsexperienced.Finally,implementationofmatchcharacteristiccomparisoncouldhelpguidethefutureofstrengthandconditioningtrainingprescriptioninordertoimproveindividualreadinesstotraininthedayspost-match.

3.2 Introduction

Rugbyunion,likemanyotherteamsports,isasportofintermittentperiodsofbothhighandlowintensityactivity,withmanygaitchangesduringgamephases(Austinetal.,2011a;Quarrieetal.,2013).Theabilitytoidentifyandunderstandthespecificdemandsplaceduponsportperformersduringmatch-playhaslongsincebeenrecognisedasacrucialfactorindeveloping

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appropriatetrainingandrecoveryprogrammes,whichmightelicitimprovedperformance(Coughlanetal.,2011;Quarrieetal.,2013;Robertsetal.,2008).Increasedcommercialinterestinrugbyunion,sinceitbecameprofessionalin1995,hasresultedinmatchesreportedasbecomingfaster,containingmorephasesaswellasinvolvingbigger,faster,morephysicalplayers(Quarrieetal.,2013).Additionally,thedevelopmentofGPStechnologyisprovidingpractitionerswithdetaileddatarelatingtothespecificmovementdemandsandworkratesofplayers.Acompetitivegameofrugbyunionlastsforapproximately90minutesandinvolveshighintensityactivitiesincludingbluntforceimpact(forwards≤838impacts;backs≤573impacts)andsprinting(>24km/h;forwards60±32m,backs143±67m,backs)(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011;Deutsch,Kearney,&Rehrer,2007).

DatafromarecentstudyfromtheEnglishPremiershiprugbyunionleague(Cahilletal.,2013)reportedthatmatchdistancespergame,averagedacrossaseason,weresignificantlylowerforforwards(5850±1101m)comparedtobacks(6545±1055m),withhighintensitybouts(sprinting,tackling,staticholdsandscrummaging)(Austinetal.,2011a)andhighimpactforces(>10G)(Venteretal.,2011)beingamajorsourceofcumulativefatiguethroughoutagame.Inarecenttime-motionanalysisstudybyQuarrieetal.(2013)involving763players,itwasclearthatvaryingdemandsareplacedupondifferingpositions(forwards5040±874m;backs5800±822m).Thedistancescoveredbypositionalgroupsatvaryingspeedintensitieswasthekeyfinding,implyingthatdifferingconditioningandrecoveryprogramsshouldbeimplementedtoprepareplayersmosteffectively(forwards44±32times>8m/s;backs104±54times>8m/s).Robertsetal.(2008)foundplayerstocoverdistancesof5408–6190monaveragedependingonthepositionalrole,withbacksgenerallycoveringthegreaterdistances,madeupofsprinting,jumpingandchangeofdirectionatvariousvelocities.Inastudyinvolving2008and2009Super14rugbyuniongames,Austinetal.(2011a),reportedthatthemaximumdistancecoveredinagamebyfourpositionalgroupswere:frontrowforwards(4662±659m),backrowforwards(5262±131m),insidebacks(6095±213m)andoutsidebacks(4774±1017m).AnadditionalstudythatwarrantsattentionisthatbyVenteretal.(2011)whichshowedconflictingdata.Venteretal.(2011)notedthatplayersonaveragecoveredatotaldistanceof4469±292m,withfrontrowforwardscoveringthegreatesttotaldistance4672±215,followedbyoutsidebacks4597±210m,insidebacks4307±214mandthenbackrowforwards4302±529m.Itis,however,difficultforcomparisonstobemadewiththeresearchbyVenteretal.(2011),asitinvolvedasmallsamplesize(n=23)ofsemi-professionalunder19players,whoplayfor60minutesratherthan80minutes.Playerpositions,theirrolesandthephysicalcharacteristicsassociatedwitheachpositionwithinrugbyunionaredetailedwithinTable2.1andTable2.11(Chapter2.1)oftheliteraturereview.Reportedworktorestratios,ofbetween1:4and1:6forvaryingpositionsexist,withtheaveragenumberofsprintsduringamatchbeingtwenty(Robertsetal.,2008).Austinetal.(2011a)alsoreportedworktorestratiosofbetween1:4and1:6forvaryingpositions,withbackrowforwardsspendingthegreatestamountoftimeinhighintensityexercise.Itis,however,importantforpractitionerstonotethattheseworktorestandsprintvaluesdonotreflecttheactualmovementpatternsduringintenseperiodsofmatches(includingrepeatedhighintensityefforts)andare,therefore,onlyaveragevaluesacrossthegame.Asreportedinrecentrugbyleagueliterature(Gabbett,2013),preparingforthe“worstcasescenario”(worktorestratio3:1)isrecommended,insteadofthe“average”reportedmeasuresofgamedemands(worktorestratio1:5),withpositionaldifferencessurroundingthisnotionnotedbyReardon,

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Tobin,Tierney,andDelahunt(2017).Additionally,itisimportantforpractitionerstonotethattheresearchbyQuarrieetal.(2013)wastakenfromtime-motionanalysisassessmentsandnotfromGPSdata.ThedifferenceinmatchdemandintensitybetweenpositionalgroupswasfurtheremphasisedinrecentresearchbyCunninghametal.(2016)whonotedthatforwards(5370m)coveredlessdistancethanbacks(6230m)andtypicallyperformedtheseatlowerspeeds(ForwardsHSR284m;BacksHSR656m).DespitetheresearchbyCunninghametal.(2016)beingcollateduponagegrade(under20)internationalsandthereforeill-advisedforcomparisonagainststudiesusingseniorprofessionals,itisofinterestforpractitionerstonotethatforwardsexperiencedgreatercontactloadsthanbacks.However,theassessmentofcontactloadswithintheresearchbyCunninghametal.(2016)doesnotincorporateGPSmeasurementsforimpactsandthereforecanbequestioned.InsteadtheresearchbyCunninghametal.(2016)utilisedearlierresearch(Cahilletal.,2013;Dochertyetal.,1988;Quarrie&Wilson,2000),toexplainitsviewthatforwardsexperiencedgreatercontactloadsthanbacks,withthereducedlocomotivepatternsinforwardsbeingdue,potentially,totheirprimaryroleofcontestingpossession.

Inanotherstudyinvolvingsouthernhemisphererugbyunionitwasreportedthatrugbyunionplayersperformedmostoftheirsprintsoverdistancesbetween10mand20m,withforwardssprintinglessoften,onaverage,thanbacks,highlightingtheimportanceofspeedtrainingforsomepositionalgroups(Duthieetal.,2006).Studiesusingtime-motionanalysisfoundthatsprintingoccurredonaverage16±15and23±19timesforforwardsandbacksrespectively,lastingonaverage1.2±0.2s(Robertsetal.,2008).Itis,however,importanttonotethatmanyofthestudiesconsideredabove,assessinggamedemandsinrugbyunion,incorporatedonlytheplayersthatplaythefullgameandthereforedonotrepresentthefullspectrumofplayingpositionsandtheirrequirements.Asiscommonlyseenwithinelitemodernrugby,manypositionalgroupsrarelycompletethefulldurationofthegameandinsteadaresubstitutedinapre-determinedformat,meaningthattheseplayerscanbeconditionedspecificallyfortheseparticularmatchdemands.RecentevidenceillustratingthisnotionwaspresentedbyLacomeetal.(2015),whonotedthat85.2%ofsubstitutionsweremadefortacticalreasons,withthemeanperiodfornon-injurysubstitutionsvaryingbetweenpositionalgroups(Forwards50-65mins;Backs70-75mins).AlsoofinterestfromtheresearchbyLacomeetal.(2015),assessinginternationalplayersusingtime-motionanalysis,wasthepositiveimpactofsubstitutionsuponmatchplay(asrepresentedbyimprovedrunningperformance;ES0.2-0.5),thereforesupportingtheuseofsubstitutionsinordertoimprovematchoutcome.

Austinetal.(2011a)notedthatforwardwalkingandforwardjoggingcomprised65%ofthetotaldistancecoveredbyfrontrowforwards,comparedto63%forbackrowforwards,56%forinsidebacksand58%foroutsidebacks.Thisamountoftimeeitherwalkingorjoggingillustratesthenatureofrugbyunionasanintermittentsport,withshortperiodsofhighintensityactivity.Stridingandsprintingaccountedfor31%,32%,38%and33%respectivelyfortheabovepositions;withinsidebackscoveringthegreatestdistanceatsprintingspeedsandfrontrowforwardsthesmallest.Highintensityrunsareperformed41±16and59±28timesforwardsandbacksrespectivelylastingonaverage1.3-1.5s(Robertsetal,2008).Ameasureofintensityisheartrate,whereitwasreportedthathighdemandsareplacedonaplayer’scardiovascularsystemwhenplayersarerequiredtoreach86%oftheirmaximalheartrate(Cunniffeetal.,2009).Anotherperformanceaspectthataddstothematchdemandstowhichplayersareexposed,isthatof“staticholds”.Thescrum,maulandruckelementsofrugbyunion

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werecategorisedbyAustinetal.(2011a)as“staticholds”andtheyreportedthatfrontrow(11±8s)andbackrow(15±9s)forwardsspentsignificantlymoretimeinstaticholdpositionscomparedtotheinsideandoutsidebacks.Forwardsperformhigh-intensitystaticexertionforlongerperiods,spendingeightminutesinintensescrummaging,eachlasting5-20sand5minutesinrucksandmaulscontributingto15%oftotalgametime,comparedto4minutesofhigh-intensitystaticexertionbythebacks.

Distancescoveredandintensityofefforthavebeenreportedtohaveincreasedinrugbyunionsincetheadventofprofessionalismin1995,withdistancescoveredinexcessof5m.sappearingmorefrequentlyintheinternationalgame,comparedtootherformsoftheprofessionalgame(Quarrieetal.,2013).DatafromAustinetal.(2013)showedchangesof2%increasedsprintingtimeanda7%decreaseintimestandingduringmatchplay,whencomparingdatawiththatofDuthieetal.(2006),collectedfromSuper12rugbysixyearsearlier.Cunniffeetal.(2009)revealedthattheaveragenumberoftotalimpactsinagamewas>1000pergameandMcLellanandLovell(2012)notedcorrelationsbetweenthetotalnumberofimpactsexperiencedwithineliterugbyleaguematchplayandcompromisedneuromuscularfunctioninthe48hourspost-match.Takarada(2003)concludedthatalthoughthedirectimpactoftacklesonthebodywasconsideredtobethemajorcauseofmuscledamage,repeatedintermittentsprintingwasalsoamajorcontributor.Researchinrugbyunionhasnotedthatcreatinekinase(CK)values(anindicatorofmuscledamage)relatespecificallytophysicalimpactsfromgames,withCKvaluespost-matchperhapsprovidingabasisforrecoverystrategies(Smartetal.,2008).Itislikelythatimpactsduringgametime,identifiedfromGPSunits,donosolelyarisefromcollisionsbutinsteadfromacombinationofmovementandcollisions,meaningthatlowerlevelimpactscanbearesultofactivitiessuchasdeceleration,changeofdirectionandlandinginalineout.McLellanandLovell(2012)noted“veryheavy”(8.1-10G)and“severe”(>10.1G)impactstobesignificantlycorrelatedwithneuromuscularresponses(peakrateofforcedevelopmentandpeakpower)24hourspost-match.Itis,however,importantforpractitionerstonotethata4Gclassificationfromacollisionoccurringduringatackle,forexample,mighthaveaverydifferentneuromuscularresponsetothatofa4Gclassificationfromachangeofdirection.AcriticalappraisalofGPSmonitoringinteamsportswasconductedbyCumminsetal.(2013),withsixstudiesdetailedacrossvaryingplayinglevelsinrugbyunion,confirmingthephysicaldemandsthatareplaceduponplayersandthespecificmetricsinvolved.GPSdataiscollectedthroughoutrugbyplayerstrainingweeksandlongitudinallyoveranentireplayingseason,withmanystudiespublishedrecentlyongamedata(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011;Quarrieetal.,2013).TheneedtoanalyseGPSdataandtheassociatedtrainingvolume(distances,speedsandimpactsforexample)hasbeenutilisedinmanystudiesofrugbyunion(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011)andisconsideredanessentialtoolofmanyelitesportteams.Thedetailedinformationcollected,onbothexternalload(i.e.distance)andinternalload(i.e.heartrate),providesamoreglobalassessmentofexerciseintensity.Itis,however,ofnotetopractitionersthatthesamplingfrequencyusedwithinresearchvaries,potentiallyresultingindifferingvaluesformanymatchdemandmetrics.

Theaimofthisstudyistodevelopagreaterunderstandingofmatchdemandswithineliterugbyunionandtoidentifydifferencesbetweenpositionsandpositionalgroups.Thenovelaspectofthisresearchisthatthedatausedtomeasurematchcharacteristicsincludesmatchdatacollectedforplayerswhoplayedlongerthan30minutes,unlikeearlierresearch,whichonly

104

focuseduponmatchcharacteristicsfromplayersthatplayedtheentirematch.Itcouldbearguedthatsolelyassessingdatainvolvingplayerswhoplayedtheentirematchlimits“realworld”application.Implementationofthefindingsfromtheassessmentofmatchdata,whichonlyencompassestheentirematch,wouldperhapsunderprepareplayersforthepeakintensitiesexperiencedduringmatchplay,astherelativemetrics(suchasintensity)arelikelytobehigheramongstplayerswhoperformsubstituteroles.Inlinewithearlierresearch(Austinetal.,2011a;Cahilletal.,2013;Cunninghametal.,2016),itwashypothesisedthatdistancecoveredwithingameswouldbegreaterforbacksthanforwardsandthatbackswouldcompletetheiractivitiesatagreaterintensity.Itwasalsohypothesised,thatforwardswouldexperienceagreaternumberofimpacts>Zone3inmatchsituationscomparedtobacksandthatbackswouldconductagreatervolumeofaccelerationsanddecelerationscomparedtoforwards.Additionally,aswasseeninpreviousresearch(Austinetal.,2011a;Cahilletal.,2013),itwashypothesisedthatoftheninepositionalgroups;fullbacks,wingersandscrumhalves,wouldcoverthegreatestdistancesandworkatthehighestintensities.Lastly,inasimilarveintopreviousfindings(Coughlanetal.,2011;Venteretal.,2011),itwashypothesisedthatoftheninepositionalgroups,backrowforwardswouldexperiencethehighestnumberofimpacts>Zone3andthatprops,hookersandlockswouldexperiencethehighestmagnitudeofimpacts(measuredinG-forces).Theresultsfromthisstudy,showingvaryingmatchcharacteristicsacrossavarietyofmatchminutes,willhelpguidepractitionersupontherequiredmatchdemandsofallninepositionalgroups.Theadditionalknowledgegainedasaresultofthisstudy,surroundingtheinfluenceoftacticalsubstitutionsandlikelymatchdemandsuponpositionaldemands,willalsohelpguidefuturepracticeinmodernrugbyunion.

3.3 Method

3.3.1 ExperimentalApproachTheassessmentperiodcoveredthirty-twogamesandwascollectedthroughoutacompetitiverugbyunionplayingseason.Datawascollectedfromthirty-eightprofessionalplayers,includingdatafromsomeplayerswhodidnotcompeteineverygame;meaningthat462setsofgamedatawereassessed(age26.4±4.7years,height182.3±30.2cm,mass100.0±11.0kg,trainingage7.8±4.6years).AdetailedbreakdownofpositionsisincludedinTable3.1below.TheGPSunitsusedbytheplayerswereworninbespokepocketsincorporatedwithintheirplayingjerseys.Theywerepositionedonthethoracicspinebetweenthescapulaeinordertoreduceunnecessarymovementduringmatchplaythatmightinfluencedatacollected.

Table3.1:Physicalcharacteristicsofplayersassessed

Position n Age Height(cm) Bodyweight(kg) TrainingAge(years)Allpositions 462 26.3±4.8 187.4±6.4 100.1±11.1 7.7±4.6Forwards 242 27.5±5.0 189.4±6.5 109.0±8.0 8.9±5.1Backs 220 25.2±4.4 185.4±5.9 91.3±5.3 6.5±4.4Prop 62 27.2±5.5 184.7±1.2 115.2±9.8 7.0±4.6Hookers 30 23.6±3.5 184.3±4.0 106.3±1.5 5.3±4.0Locks 59 31.0±4.8 197.2±2.8 116.5±5.0 13.0±4.8BackRow 95 27.3±5.0 189.8±6.4 103.1±3.8 9.2±5.1ScrumHalf 34 26.3±5.5 179.6±2.8 85.3±3.2 8.3±5.5OutHalf 33 25.5±2.1 184.0±1.4 88.5±4.9 7.5±2.1Centre 59 24.3±5.4 185.8±7.1 95.3±5.88 4.6±3.9Wing 62 26.1±4.2 187.1±6.1 91.3±3.6 7.6±3.2FullBack 27 23.5±4.9 189.5±2.1 91.5±3.5 5.5±4.9

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Participantswereadvisedtomaintaintheirusualrecoveryprocesspost-matchduringthetestingperiod,includingnutritionalinterventionsoractiveswimrecoverysessions.Onaverage,eachweekconsistedoftworesistancetrainingsessionsandfiverugbysessions,withthetrainingvolumetaperingonaweeklybasisasgamedayapproached(Table3.2).ThisstudywasconductedinaccordancewiththeDeclarationofHelsinkiandwasapprovedbySalfordUniversityInstitutionalReviewBoard.Allparticipantsprovidedwritteninformedconsenttoparticipateinthisstudy.Table3.2:Exampletrainingweek

Microcycleandtimeofday

GAMEDAY +1 +2 +3 +4 +5 +6

AM

ClubPrescribedRecoverywithTeam

RestDay Weights&UnitsRugby

RugbyTeamSession

RestDay RugbyTeamSession

PM Game RugbyTeamSession

Weights

3.3.2 MatchanalysisAllmatcheswithinthisstudywereplayedduringthecompetitiveplayingseasonofanEnglishPremiershipRugbyUnionteamoveraperiodofninemonths,withdataonlyincludedwhenplayersplayed≥30minutes.Therationalefortheinclusionofdatawhenplayersplayed≥30minutes,wasthatthisistypicallythesmallestnumberofminutesplayedconsideredlargeenoughformeasurement.Playerswhoplayedlessthan30minuteswereconsideredasnothavingcompletedtypicalmatchdemandsandwouldthereforerepresentaninaccuratemeasureofmatchcharacteristics.Whencombiningthisviewwiththecommonlyseenpracticewithinprofessionalrugbyunionofsubstitutingplayersataroundthe50minutetime-point,fortacticalreasonsratherthaninjury,furtherrationaleforselectingplayerswhoplayed≥30minutesforanalysisisevident.

Measurementswereconductedonplayersfromoneclubwith10HzGPSunits(StatSportsViper,NorthernIreland)beingusedthroughoutallgamestoassessmovementpatterns.ReliabilityofGPSanalysisinteamsportsettingshasbeenconfirmedinmanypreviousstudies(Coutts&Duffield,2010;Cumminsetal.,2013;Johnston,Watsford,Kelly,Pine,&Spurrs,2014;Varley,Fairweather,&Aughey,2012),withCouttsandDuffield(2010)reportingtotaldistancebeingstablebetweenmatchvariationsinrugbyleague(<5%CV),whileJohnston,Watsford,etal.(2014)showedalargerdegreeofbetweenmatchvariabilityforhigherspeedactivities(TEM=0.8-19.9%)alsoinrugbyleague.

Playerpositionsweredefinedas:backsorforwards;furthersubdividedinto;props,hookers,locks,backrows,scrumhalf,outhalf,centres,wingsandfullbacks.Thematchcharacteristicsassessedincluded[gametime,distancecovered,intensity,accelerations,decelerations,impacts>Zone3,DistanceinZone1(D1),DistanceinZone2(D2),DistanceinZone3(D3),DistanceinZone4(D4),DistanceinZone5(D5),DistanceinZone6(D6),ImpactsinZone1(Im1),ImpactsinZone2(Im2),ImpactsinZone3(Im3),ImpactsinZone4(Im4),ImpactsinZone5(Im5)and

106

ImpactsinZone6(Im6)].ThespecificcategorisationofthespeedandimpactzonesaredetailedinTable3.3below.

ThedependentvariablesassessedfromtheGPSdatawere;totaldistancecovered,gametimeplayed,intensity,accelerations,decelerationsandGPSimpacts.Intensitywasmeasuredasaveragemovementvelocityacrossthegame(m/min).TheGPSdevice(whichincludesa100Hz3-Daccelerometer)measuresGPSimpactswhenvaluesareabove2Gina0.1secondperiod.Impactsareinstantaneousmomentsthroughoutatrainingormatchsituation,measuredinG-forcesandexpressedasaquantity,withanumberofimpactsateachofthe6zonescategorisedintheVipersystem.Itisimportanttonote,thatGPSimpactsareacombinationofcollisionandimpactscreatedfrommovement(stepping,jumping,anddecelerations).Thenumberofaccelerationsanddecelerationswasmeasuredviatheaccelerometer,withindividuallyprescribedzonescategorisedforeachindividualregardsspeedaidingtosignifyaccelerations,decelerationsanddistancecoveredinspeedzones.

Table3.3:Categorisationofdistancescoveredandimpacts

Zone1 Zone2 Zone3 Zone4 Zone5 Zone6Speed(m/s)Speed(km/h)

0–1.5 1.51–3.0 3.01–4.0 4.01–5.5 5.51.–7.0 7.01+0–5.40 5.41–10.80 10.81–14.40 14.41–19.80 19.81–25.20 25.21+

ImpactsinZones(G) 3-5 5–7 7-9 9-11 11-13 >13

3.3.3 StatisticalAnalysesStatisticalanalysiswasperformedusingSPSSVersion20(IBM),withanapriorialphalevelsetatp<0.05.NormalityofanalysedvariableswasassessedusingShapiro-Wilkstestbetweenpositionalgroups(forwardsandbacks)andacrosspositions(props,hookers,locks,backrows,scrumhalf,outhalf,centres,wingsandfullbacks).Absolutevaluesforallpositionswereassessedinordertodeterminetheinfluenceofpositionsoneachofthematchcharacteristics,regardlessofthenumberofminutestheyplayed.DifferencesbetweenforwardsandbacksweredeterminedusingWilcoxonsignedrankstests.

Non-parametricFriedmantestswereconductedinordertodeterminedifferencesbetweeneachpositionforeachvariable,withmultiplepairwisecomparisonsperformedusingWilcoxonstests,includingsubsequentBonferronicorrection,inordertoassesswherethedifferenceoccurred.Cohen’sdeffectsizes(ES)wereusedtoassessthemagnitudeofanyeffectinaccordancewithRhea(2004)andinterpretedasfollows;trivial=<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.Post-hocstatisticalpowerwascalculatedusingGPower3.1(Faul,Erdfelder,Buchner,&Lang,2009).

3.4 Results

3.4.1 MatchcharacteristicsbetweenforwardsandbacksShapiroWilkstestsofnormalityrevealedthatallmatchcharacteristicsforforwards,(excludingintensity,Im1andIm2),werenotnormallydistributed(p>0.05).Forbacks,ShapiroWilkstestsofnormalityrevealedthatallmatchcharacteristics,(excludingintensity,accelerations,decelerationsandD5),werenotnormallydistributed(p>0.05).

TheWilcoxonstestsshowedthatbacksplayedatasignificantly(p<0.001)greaterintensity,withalargeeffectsizereported.BacksalsodemonstratedagreaternumberofimpactsinZone

107

1comparedtotheforwards,althoughthedifferencebetweenpositionswassmall(Table3.4andTable3.5).Additionally,Wilcoxontestsshowedthatforwardsperformedasignificantly(p<0.001)greaternumberofaccelerationsanddecelerations,withamoderatedifferencenoted.BackscoveredmoredistanceinD5comparedtoforwards,withalargedifferencebetweenpositionalgroups.Wilcoxontestsidentifiedthatbacksperformedsignificantly(p<0.001)moregametime,distancecoveredinD1,D4,D6,comparedtoforwards(Table3.4),withamoderatetolargedifferencebetweenpositionalgroupsnoted.

Table3.4:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals),effectssizesandstatisticalpower,acrossdistancedataforforwardsandbacks

Position Forwards Backs Cohen’sd Effect StatisticalPower

GameTime(mins) 66.6±14.8(CI64.8-68.5)

71.6±13.0*(CI69.9-73.3)

0.35 Small 1.00

Distance(m) 5035±1157(CI4890-5179)

5918±1206*(CI5758-6078)

0.74 Moderate 1.00

Intensity(m/min) 64.0±6.3(CI63.2-64.8)

70.9±7.4*(CI69.9-71.8)

1.00 Moderate 1.00

Accelerations 22.0±11.9(CI20.5-23.5)

32.2±10.6*(CI30.8-33.6)

0.90 Moderate 1.00

Decelerations 30.8±14.4(CI29.0-32.6)

41.9±12.3*(CI40.3-43.6)

0.82 Moderate 1.00

DistanceZone1(m)

1898±450(CI1443-1555)

2195±542*(CI2123-2267)

0.59 Moderate 1.00

DistanceZone2(m)

1499±494(CI1836-1960)

1558±399(CI1505-1610)

0.13 Trivial 0.88

DistanceZone3(m)

914±264(CI881-947)

904±243(CI871-936)

0.04 Trivial 0.23

DistanceZone4(m)

531±232(CI502-560)

804±245*(CI771-836)

1.14 Large 1.00

DistanceZone5(m)

153±97(CI141-165)

322±119*(CI306-338)

1.07 Large 1.00

DistanceZone6(m)

14±19(CI12-17)

77±66*(CI68-86)

1.29 Large 1.00

*p<0.001

Table3.5:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals),effectsizesandstatisticalpower,acrossimpactzonesforforwardsandbacks

Position Forwards Backs Cohen’sd Effect StatisticalPowerImpacts>Zone3 229±160

(CI209-249)226±151(CI206-246)

0.01 Trivial 0.10

ImpactsZone1 1836±604(CI1760-1911)

2054±546*(CI1981-2126)

0.37 Small 1.00

ImpactsZone2 811±243(CI781-841)

857±297(CI817-896)

0.16 Trivial 0.97


312±154(CI292-333)

0.07 Trivial 0.50


118±79(CI107-128)

0.05 Trivial 0.28


47±38(CI42-53)

0.02 Trivial 0.13


59±40#(CI53-64)

0.16 Trivial 0.97

*p=0.001#p=0.03

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3.4.2 MatchcharacteristicsbetweentheninepositionalgroupsShapiroWilkstestsofnormalityrevealedthatallmatchcharacteristicswerenotnormallydistributed(p<0.05)acrosstheninepositionalgroups.Friedmantestsshowedsignificantdifferencesbetweenpositionalgroupsforallthematchcharacteristicsvariables,excludingD3,wherenosignificantdifferenceswereobserved(p>0.05).

Pairwisecomparisonsdemonstratedthatgametimewasthegreatestamongthefullbacksandthatthiswassignificantlygreatercomparedtoprops(p=0.003,d=1.37),hookers(p=0.010,d=1.55)andscrumhalves(p=0.015,d=1.32),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Bycontrast,hookersdemonstratedthelowestvaluesforgametime,whichwassignificantlylowerthanlocks(p=0.036,d=0.99),backrow(p=0.011,d=0.92),centres(p>0.001,d=1.43),wing(p=0.001,d=1.08)andfullback(p=0.010,d=1.55),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups(Table3.6).

Fullbacksdemonstratedthegreatestintensityduringmatchplay,whichwassignificantlygreatercomparedtoprops(p=0.001,d=2.88),hookers(p<0.001,d=1.71),locks(p<0.001,d=1.53),backrow(p<0.001,d=1.94),outhalves(p=0.036,d=0.76)andwingers(p=0.036,d=1.15)althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Incontrast,propscompetedatthelowestintensity,whichwassignificantlylowerthanhookers(p=0.001,d=1.377),locks(p<0.001,d=1.133),backrow(p<0.001,d=0.945),scrumhalves(p<0.001,d=2.476),outhalves(p<0.001,d=2.341),centres(p<0.001,d=1.234),wingers(p<0.001,d=1.587)andfullbacks(p=0.001,d=2.881)(Table3.6).

Outhalvesperformedthemostaccelerations,whichwassignificantlygreaterthanprops(p<0.001,d=2.71),hookers(p<0.001,d=1.58),locks(p=0.006,d=1.11),althoughnotsignificantlydifferent(p>0.05)comparedtobackrow,scrumhalves,centres,wingersandfullbacks.Incontrast,propsdemonstratedthelowestvaluesforaccelerations,whichwassignificantlylowerthanlocks(p<0.001,d=1.57),backrow(p<0.001,d=1.02),scrumhalves(p<0.001,d=1.97),outhalves(p<0.001,d=2.71),centres(p<0.001,d=1.94),wingers(p<0.001,d=2.18)andfullbacks(p<0.001,d=2.61),althoughnotsignificantlydifferent(p>0.05)comparedtohookers(Table3.6).

Fullbacksperformedthemostdecelerations,whichwassignificantlygreaterthanprops(p<0.001,d=2.91)andhookers(p<0.001,d=1.57),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Incontrast,propsdemonstratedthelowestvaluesforaccelerations,whichwassignificantlylowercomparedtolocks(p<0.001,d=1.51),backrow(p<0.001,d=1.20),scrumhalves(p<0.001,d=1.72),outhalves(p<0.001,d=2.17),centres(p<0.001,d=2.48),wingers(p<0.001,d=2.05)andfullbacks(p<0.001,d=2.91),althoughnotsignificantlydifferent(p>0.05)comparedtohookers(Table3.6).

Table3.6:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossselectedmatchdemandsdataforallpositions

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackGameTime

(mins)

61.2±14.2

(CI57.7-

64.8)

56.6±16.8

(CI50.6-

60.5)

70.6±10.8

✚û(CI67.7-

73.4)

70.9±14.3

û✚(CI68.0-

73.8)

63.7±11.8

(CI59.5-67.8)

66.3±14.2

(CI64.1-71.3)

76.0±9.4

Ψα

(CI73.5-

78.4)

73.2±13.9

μţ

(CI69.7-76.7)

77.0±8.0

μ ✚ ★(CI73.8-80.1)

Intensity

(m/min)

59.6±5.4

(CI58.2-

60.9)

66.7±4.9

μ

(CI64.9-

68.4)

66.5±6.7

Ψ

(CI64.7-

68.2)

64.8±5.6

Ψ

(CI63.6-

65.9)

74.4±6.5

Ψα®ν

(CI72.1-76.6)

71.9±5.1

Ψ®ţŵ

(CI70.1-73.7)

68.1±8.1

Ψ

(CI65.9-

70.2)

69.0±6.4

Ψξ

(CI67.4-70.7)

76.2±6.1

Ψα®¥Ω♮(CI73.8-78.6)

Accelerations 13.6±7.0

(CI11.9-

15.3)

21.5±9.9

(CI18.0-

25.0)

26.6±9.3

Ψ

(CI24.1-

29.0)

24.7±13.6

Ψ

(CI21.9-

27.4)

31.5±10.7

Ψ✚(CI27.7-35.2)

37.5±10.3

Ψαν

(CI33.9-41.1)

29.2±8.9

Ψ

(CI26.9-

31.5)

34.1±11.3

ΨανΑ

(CI31.2-37.0)

32.6±7.5

Ψ✚(CI29.6-35.5)

Decelerations 20.3±7.7

(CI18.4-

22.2)

28.9±11.8

(CI24.7-

33.1)

34.5±10.8

Ψ

(CI31.6-

37.3)

36.0±16.7

Ψ

(CI32.6-

39.4)

35.1±9.4

Ψ

(CI31.8-38.4)

43.4±12.9

Ψţ

(CI38.8-47.9)

43.6±10.8

Ψνţ

(CI40.8-

46.5)

42.8±13.4

Ψα★ŵ(CI39.4-46.2)

46.0±9.8

Ψα

(CI42.1-48.9)

Keyforpvaluesfallingwithinthefollowingranges:Ψsignificantlygreater(p<0.001)comparedtoProps

μsignificantlygreater(0.001≤p<0.01�comparedtoProps

ûsignificantlygreater(0.01≤p<0.05)comparedtoProps

αsignificantlygreater(p<0.001)comparedtoHookersţsignificantlygreater(0.001≤p<0.01�comparedtoHookers

✚significantlygreater(0.01≤p<0.05)comparedtoHookers

¥significantlygreater(p<0.001)comparedtoLocksνsignificantlygreater(0.001≤p<0.01�comparedtoLocks

ŵsignificantlygreater(0.01≤p<0.05)comparedtoLocks

®significantlygreater(p<0.001)comparedtoBackRow

ξsignificantlygreater(0.001≤p<0.01�comparedtoBackRow

Αsignificantlygreater(0.01≤p<0.05)comparedtoBackRow ★significantlygreater(0.01≤p<0.05)comparedtoScrumHalves

Ωsignificantlygreater(0.01≤p<0.05)comparedtoOutHalves

♮ significantlygreater(0.01≤p<0.05)comparedtoWings

110

Fullbackscoveredthegreatestdistance,whichwassignificantlygreatercomparedtoprops(p<0.001,d=3.19),hookers(p<0.001,d=2.39),locks(p<0.001,d=1.60),backrow(p<0.001,d=1.55),scrumhalves(p=0.001,d=1.73)andouthalves(p=0.003,d=1.33),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Incontrast,propscoveredthelowestdistancewhichwassignificantlylowerthanlocks(p<0.001,d=1.31),backrow(p<0.001,d=1.10),scrumhalves(p=0.002,d=1.20),outhalves(p<0.001,d=1.23),centres(p<0.001,d=1.89),wingers(p<0.001,d=1.48)andfullbacks(p<0.001,d=3.19),althoughnotsignificantlydifferent(p>0.05)comparedtohookers(Table3.7).

CentrescoveredthegreatestdistanceinZone1(D1),whichwassignificantlygreatercomparedtoprops(p<0.001,d=1.28),hookers(p<0.001,d=2.10),locks(p<0.001,d=0.94),backrow(p=0.001,d=0.77)scrumhalves(p<0.001,d=1.69)andouthalves(p=0.78,d=3.193),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Incontrast,hookersdemonstratedthelowestvaluesforD1,whichwassignificantlylowerthanbackrow(p=0.002,d=1.24),centres(p<0.001,d=2.10),wingers(p=0.001,d=1.72)andfullback(p<0.001,d=2.12),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups(Table3.7).

FullbackscoveredthegreatestdistanceinZone2(D2)whichwassignificantlygreatercomparedtoprops(p<0.001,d=3.47),hookers(p=0.003,d=1.79),locks(p=0.036,d=0.98),backrow(p=0.005,d=1.24),scrumhalves(p<0.001,d=2.39),outhalves(p<0.001,d=2.34),centres(p=0.001,d=1.63)andwingers(p=0.003,d=1.484).Incontrast,propsdemonstratedthelowestvaluesforD2,whichwassignificantlylowerthanhookers(p=0.036,d=1.11),locks(p<0.001,d=2.00),backrow(p<0.001,d=1.76),scrumhalves(p=0.002,d=1.27),outhalves(p=0.002,d=1.34),centres(p<0.001,d=1.61),wingers(p<0.001,d=0.83)andfullbacks(p<0.001,d=3.47)(Table3.7).

LockscoveredthegreatestdistanceinZone3(D3),whichwassignificantlygreater,comparedtoprops(p=0.002,d=0.75),andcentre(p=0.004,d=0.82),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups.Incontrast,centresdemonstratedthelowestvaluesforD3,whichwassignificantlylowerthanlocks(p=0.004,d=0.82),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroups(Table3.7).

ScrumhalvescoveredthegreatestdistanceinZone4(D4)whichwassignificantlygreatercomparedprops(p<0.001,d=3.51),hookers(p<0.001,d=2.16),locks(p<0.001,d=1.84),backrow(p<0.001,d=1.87),outhalves(p=0.036,d=0.72),centres(p=0.002,d=1.28)andwingers(p=0.010,d=1.35),althoughnotsignificantlydifferent(p>0.05)comparedtofullbacks.Incontrast,propsdemonstratedthelowestvaluesforD4,whichwassignificantlylowerthanlocks(p<0.001,d=1.02),backrow(p<0.001,d=0.87),scrumhalves(p<0.001,d=3.51),outhalves(p<0.001,d=2.48),centres(p<0.001,d=2.19),wingers(p<0.001,d=1.69;)andfullbacks(p<0.001,d=3.45),althoughnotsignificantlydifferent(p>0.05)comparedtohookers(Table3.7).

FullbackscoveredthegreatestdistanceinZone5(D5)whichwassignificantlygreaterthanprops(p<0.001,d=3.36),hookers(p<0.001,d=3.96),locks(p<0.001,d=3.12),backrow(p<0.001,d=1.91),scrumhalves(p=0.002,d=1.49)andouthalves(p=0.001,d=1.49),

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althoughnotsignificantlydifferent(p>0.05)comparedtocentresandwingers.Incontrast,hookersdemonstratedthelowestvaluesforD5,whichwassignificantlylowercomparedtoprops,(p<0.036,d=0.87),locks(p<0.001,d=1.36),backrow(p<0.001,d=1.42),scrumhalves(p<0.001,d=3.29),outhalves(p<0.001,d=2.83),centres(p<0.001,d=3.01),wingers(p<0.001,d=2.73)andfullbacks(p<0.001,d=2.59)(Table3.7).

WingerscoveredthegreatestdistanceinZone6(D6)whichwassignificantlygreaterthanprops(p<0.001,d=2.28),hookers(p<0.001,d=2.62),locks(p<0.001,d=2.59),backrow(p<0.001,d=2.21)scrumhalves(p<0.001,d=1.99),outhalves(p<0.001,d=1.69)andcentres(p<0.001,d=1.49),althoughnotsignificantlydifferent(p>0.05)comparedtoandfullbacks.Incontrast,hookersdemonstratedthelowestvaluesforD6,whichwassignificantlylowerthanprops(p=0.007,d=0.73),backrow(p=0.010,d=0.87)scrumhalves(p<0.001,d=1.76),outhalves(p<0.001,d=1.51),centres(p<0.001,d=1.53),wingers(p<0.001,d=2.62)andfullbacks(p<0.001,d=2.69),althoughnotsignificantlydifferent(p>0.05)comparedtolocks(Table3.7).

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Table3.7:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossdistancedataforallpositions(symbolspresentedonTable3.8)

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackDistance(m) 4285±893

(CI4065-4505)

4469±1238(CI4029-4908)

5517±979Ψ(CI5259-5774)

5411±1134Ψχ(CI5181-5641)

5408±978#(CI5067-5750)

5583±1191#(CI5167-5999)

6043±966ΨΓ(CI5791-6295)

5926±1295Ψ₠(CI5597-6255)

6904±740Ψ₠⌃$£€(CI6617-7191)

DistanceZone1(m)

1799±487(CI1679-1919)

1474±429(CI1322-1627)

1963±479(CI1837-2089)

2043±482Γ(CI1945-2141)

1692±381(CI1559-1825)

2029±499(CI1855-2203)

2405±456Ψ₠⌃℗ξ∨(CI2286-2524)

2337±562ΨΓŵ£♮(CI2194-2480)

2328±371₠#ŵ£(CI2184-2472)

DistanceZone2(m)

1043±319(CI965-1122)

1451±410û(CI1306-1597)

1748±383Ψ✪(CI1647-1849)

1663±382Ψ★(CI1586-1741)

1421±273#(CI1325-1716)

1439±269#(CI1345-1533)

1574±338Ψ(CI1485-1662)

1446±400Ψ(CI1344-1548)

2078±275Ψ℗¤Γ✪ξuϖ(CI1971-2185)

DistanceZone3(m)

847±210(CI795-899)

926±296(CI821-1031)

1046±306#u(CI965-1127)

863±244(CI814-913)

971±217(CI895-1047)

948±228(CI869-1028)

824±225(CI766-883)

861±263(CI794-928)

1042±199(CI965-1119)

DistanceZone4(m)

394±124(CI364-425)

536±223(CI457-615)

589±240Ψ(CI526-580)

568±254Ψ(CI517-620)

1009±214Ψ₠⌃$u®∨(CI934-1084)

848±227⌃ΨΓ(CI769-927)

748±191Ψξχϖ(CI698-798)

708±230Ψ(CI650-767)

922±177Ψ₠⌃(CI853-991)

DistanceZone5(m)

118±56χ(CI104-131)

73±47(CI57-90)

142±54₠(CI127-156)

202±119₠#(CI178-226)

281±76Ψ₠⌃♮(CI254-308)

273±88Ψ₠⌃(CI242-304)

322±107Ψ₠⌃$(CI294-350)

346±113Ψ₠⌃$(CI317-374)

429±118Ψ₠⌃$£€(CI384-475)

DistanceZone6(m)

17±23Γ(CI11-23)

4±10(CI1-8)

6±9(CI3-8)

20±24ŵχ(CI15-25)

33±21⌃₠(CI25-40)

43±35⌃₠û(CI31-55)

51±42$Ψ₠⌃(CI40-62)

139±72Ψ₠⌃$℗¤Α(CI120-157)

101±50Ψ₠⌃$£∨(CI82-121)

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Table3.8:KeyfordescriptivedistancedatainTable3.7

Keyforpvaluesfallingwithinthefollowingranges:Ψsignificantlygreater(p<0.001)comparedtoProps#significantlygreater(0.001≤p<0.01)comparedtoPropsûsignificantlygreater(0.01≤p<0.05)comparedtoProps₠significantlygreater(p<0.001)comparedtoHookersΓsignificantlygreater(0.001≤p<0.01)comparedtoHookersχsignificantlygreater(0.01≤p<0.05)comparedtoHookers⌃significantlygreater(p<0.001)comparedtoLocksŵsignificantlygreater(0.001≤p<0.01)comparedtoLocksϖsignificantlygreater(0.01≤p<0.05)comparedtoLocks$significantlygreater(p<0.001)comparedBackRowξsignificantlygreater(0.001≤p<0.01)comparedtoBackRow♮significantlygreater(0.01≤p<0.05)comparedtoBackRow

℗significantlygreater(p<0.001)comparedtoScrumHalves£significantlygreater(0.001≤p<0.01)comparedtoScrumHalves★significantlygreater(0.01≤p<0.05)comparedtoScrumHalves¤significantlygreater(p<0.001)comparedtoOutHalves€significantlygreater(0.001≤p<0.01)comparedtoOutHalves∨ significantlygreater(0.01≤p<0.05)comparedtoOutHalvesΑsignificantlygreater(p<0.001)comparedtoOutHalvesusignificantlygreater(0.001≤p<0.01)comparedtoCentre✪significantlygreater(0.001≤p<0.01)comparedtoWingers®significantlygreater(0.01≤p<0.05)comparedtoWingers

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Impacts>Zone3showedthehighestvaluesamongthefullbackswhichwassignificantlygreatercomparedtolocks(p=0.001,d=1.84),backrow(p=0.003,d=0.68),outhalf(p=0.036,d=1.24)andwingers(p=0.036,d=0.76),althoughnotsignificantlydifferent(p>0.05)comparedprops,hookers,scrumhalfandcentres.Incontrast,locksdemonstratedthelowestvaluesforImpacts>Zone3,whichwassignificantlydifferenttohookers(p<0.001,d=1.25),scrumhalves(p=0.002,d=1.10)andfullbacks(p=0.001,d=1.84),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,backrow,outhalves,centresandwingers(Table3.9).

Im1showedthehighestvaluesamongthefullbackswhichwassignificantlygreaterthanprops(p<0.001,d=3.24),hookers(p=0.009,d=1.38),scrumhalves(p=0.036,d=1.03),outhalves(p=0.036,d=0.98)andwingers(p=0.012,d=1.26),althoughnotsignificantlydifferent(p>0.05)comparedtolock,backrowandcentres.Incontrast,propsdemonstratedthelowestvaluesforIm1,whichwassignificantlylowercomparedtohookers(p=0.001,d=1.43),locks(p<0.001,d=2.41),backrow(p<0.001,d=2.08),scrumhalves(p<0.001,d=1.79),outhalves(p<0.001,d=1.99),centres(p<0.001,d=2.28),wingers(p<0.001,d=1.68)andfullbacks(p<0.001,d=3.24)(Table3.9).

Im2showedthehighestvaluesamongthescrumhalveswhichwassignificantlygreatercomparedtoprops(p<0.001,d=1.81),locksp<0.001,d=0.72,backrow(p=0.009,d=1.20),centres(p=0.030,d=1.18),wingers(p=0.002,d=1.47)andfullbacksp=0.030,d=0.097),althoughnotsignificantlydifferent(p>0.05)comparedtohookersandouthalves.Incontrast,propsdemonstratedthelowestvaluesforIm2,whichwassignificantlydifferenttolocks(p=0.013,d=0.65),scrumhalf(p<0.001,d=1.81),outhalf(p=0.015,d=1.02)andfullback(p=0.036,d=0.98),althoughnotsignificantlydifferent(p>0.05)comparedtotheotherpositionalgroupshookers,backrow,centresandwingers(Table3.9).

Im3showedthehighestvaluesamongthescrumhalveswhichwassignificantlygreaterlocks(p<0.001,d=1.68),backrow(p=0.004,d=1.02),outhalves(p=0.009,d=1.03)andwingers(p=0.008,d=1.17),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,hookers,centresandfullbacks.Incontrast,locksdemonstratedthelowestvaluesforIm3,whichwassignificantlylowerthanprops(p<0.001,d=0.87),hookers(p=0.001,d=1.19),scrumhalf(p<0.001,d=1.68),outhalf(p=0.005,d=0.84)andfullback(p=0.003,d=1.30),althoughnotsignificantlydifferent(p>0.05)comparedtobackrow,centresandwingers(Table3.9).

Im4showedthehighestvaluesamongthescrumhalveswhichwassignificantlygreatercomparedtobackrow(p=0.036,d=0.69),outhalf(p=0.036,d=0.86)andcentres(p<0.001,d=0.55),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,hookers,locks,wingersandfullbacks.Incontrast,locksdemonstratedthelowestvaluesforIm4,whichwassignificantlylowercomparedtohookers(p<0.001,d=1.24),scrumhalf(p<0.001,d=1.43),outhalf(p=0.004,d=0.91)andfullback(p=0.001,d=1.66),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,backrow,centresandwingers(Table3.9).

Im5showedthehighestvaluesamongthefullbackswhichwassignificantlygreatercomparedtolocks(p=0.001,d=1.78),backrow(Im5p=0.003,d=0.75),outhalves(Im5p=0.036,d=1.22)andwingers(Im5p=0.036,d=0.77),althoughnotsignificantlydifferent(p>0.05)

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comparedtoprops,hookers,scrumhalvesandcentres.Incontrast,locksdemonstratedthelowestvaluesforIm5,whichwassignificantlylowercomparedtohookers(p<0.001,d=1.25)andfullback(p=0.001,d=1.78),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,backrow,outhalves,centresandwingers(Table3.9).

Im6showedthehighestvaluesamongthefullbackswhichwassignificantlygreatercomparedtolocks(p=0.006,d=1.73),backrow(p=0.030,d=0.74),scrumhalves(p=0.005,d=1.29),outhalves(p=0.001,d=1.92)andwingers(p=0.011,d=0.85),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,hookersandcentres.Incontrast,outhalfdemonstratedthelowestvaluesforIm6,whichwassignificantlylowercomparedtohookers(p=0.003,d=1.41),backrow(p=0.007,d=1.07),centres(p=0.003,d=0.72)andfullback(p=0.001,d=1.92),althoughnotsignificantlydifferent(p>0.05)comparedtoprops,locks,scrumhalvesandwingers(Table3.9).

Table3.9:Descriptivestatistics(mean±standarddeviations;CI=95%confidenceintervals)acrossimpactsdataforallpositions

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackImpacts>Zone3

259±250(CI198-321)

291±145εΨ(CI239-342)

157±40(CI146-167)

225±109(CI203-247)

274±145θ(CI223-324)

186±77(CI159-213)

229±186(CI180-278)

197±155(CI158-237)

296±99θΨΠΩ(CI257-334)

ImpactsZone1

1178±313(CI1100-1255)

1820±549⌃(CI1625-2015)

2232±533¢(CI2092-2373)

2019±476¢(CI1922-2115)

1998±566¢(CI1800-2195)

2042±528¢(CI1857-2226)

2053±441¢(CI1938-2168)

1901±521¢(CI1768-2033)

2553±510¢¤vΩΨ(CI2355-2751)

ImpactsZone2

716±195(CI668-764)

900±326(CI785-1016)

845±201α(CI792-898)

815±259(CI762-868)

1107±234¢ερσΑ¶(CI1025-1188)

948±255⌃(CI859-1038)

762±337(CI674-850)

748±252(CI684-812)

902±182α(CI832-973)

ImpactsZone3

323±128ε(CI292-355)

379±158θ(CI323-435)

231±76(CI211-251)

294±135(CI267-322)

449±166ερχσ(CI391-507)

307±102θ(CI271-343)

274±177(CI228-320)

273±132(CI239-307)

341±92θ(CI306-377)

ImpactsZone4

130±114(CI102-158)

148±79εΨ(CI120-176)

75±25(CI69-82)

112±59(CI99-124)

162±82εΠΩ(CI133-191)

106±41θ(CI91-120)

111±101(CI85-138)

100±73(CI82-119)

142±51θ(CI122-162)

ImpactsZone5

57±67(CI40-73)

62±35εχσΠ(CI49-75)

30±9(CI28-33)

46±26(CI41-51)

58±37ε(CI45-72)

37±20(CI29-44)

48±48(CI35-61)

41±37(CI31-50)

66±27θρΩΨ(CI55-76)

ImpactsZone6

70±74(CI51-88)

80±33θχσv(CI68-92)

49±15(CI45-53)

67±27χω(CI61-72)

52±27(CI43-62)

42±19(CI36-49)

66±43Ω(CI54-77)

53±49(CI40-65)

87±27θτχΠΨ(CI76-97)

Keyforpvaluesfallingwithinthefollowingranges:¢significantlygreater(p<0.001)comparedtoProps⌃significantlygreater(0.001≤p<0.01)comparedtoPropsαsignificantlygreater(0.01≤p<0.05)comparedtoProps¤significantlygreater(0.001≤p<0.01)comparedtoHookersεsignificantlygreater(p<0.001)comparedtoLocksθsignificantlygreater(0.001≤p<0.01)comparedtoLocksωsignificantlygreater(0.01≤p<0.05)comparedtoLocksρsignificantlygreater(0.001≤p<0.01)comparedtoBackRowΠsignificantlygreater(0.01≤p<0.05)comparedtoBackRow

τsignificantlygreater(0.001≤p<0.01)comparedtoScrumHalvesvsignificantlygreater(0.01≤p<0.05)comparedtoScrumHalvesχsignificantlygreater(0.001≤p<0.01)comparedtoOutHalvesΩsignificantlygreater(0.01≤p<0.05)comparedtoOutHalves¶significantlygreater(0.01≤p<0.05)comparedtoCentreσsignificantlygreater(0.001≤p<0.01)comparedtoWingersΨsignificantlygreater(0.01≤p<0.05)comparedtoWingersΑsignificantlygreater(0.01≤p<0.05)comparedtoFullBacks

3.5 Discussion

Positionaldifferencesinmatchdemandswereidentified,ashypothesised,withagreater(p<0.001,d=0.74)distancecoveredforbacks(5918±1206m)comparedtoforwards(5035±1157m),inconjunctionwiththebacksplayingatahigherintensity(70.9±7.4m/min)comparedtotheforwards(64.0±6.3m/min;p<0.001,d=1.00).Aswasalsohypothesised,forwardsexperiencedagreaternumberofimpacts>Zone3(229±160)comparedtothebacks(226±151),althoughthiswasnotsignificantlydifferent(p>0.05,d=0.01).Additionally,itwascorrectlyhypothesisedthatbacksconductedagreaternumberofaccelerations(32.2±10.6)comparedtoforwards(22.0±11.9;p<0.001,d=0.88)andagreaternumberofdecelerations(41.9±12.3)comparedtotheforwards(30.8±14.4;p<0.001,d=0.82).

Withintheninepositionalgroups,differencesinmatchdemandswereidentified,ashypothesised,withagreatestdistancecoveredbyfullbacks(6904±740m)comparedtothelowestbeingprops(4285±893m)(p<0.001,d=3.19).Itwas,however,importanttonotethatcentres(6043±966m)coveredagreaterdistancethanwingers(5926±1295m)(p>0.05,d=0.10)andscrumhalves(5408±978m)(p>0.05,d=0.65),unlikewhatwashypothesised.Additionally,fullbacksplayedatthehighestintensity(70.9±7.4m/min)comparedtotheprops(64.0±6.3m/min)(p<0.001,d=1.00),whoplayedatthelowestintensity,withouthalves(71.9±5.1m/min)surprisinglyworkingatagreaterintensitythanwingers(69.0±6.4m/min)(p>0.05,d=0.50),unlikewhatwashypothesised.Lastly,conflictingwiththehypothesis,scrumhalves(274±145),hookers(291±145)andfullbacks(296±99)experiencedthehighestnumberofimpacts>Zone3.Backrow(225±109)experiencedthefifthhighestnumberofimpacts>Zone3andtheforthmostIm6(67±27),behindfullbacks(87±27),hookers(80±33)andprops(70±74).

Distancescoveredinthisstudywerelowerthanpresentedinpreviousresearch(Cahilletal.,2013;Coughlanetal.,2011).Cahilletal.(2013)reporteddistancesof5850mand6545mfortheforwardsandbacksrespectively,whileCoughlanetal.(2011)noteddistancesof6427mfortheforwardsand7002mforthebacks.Thegreaterdistancecoveredbybackscomparedtoforwardsinthisstudywasexpected,becausebackstendtocompletemoreopenfieldrunning,ashasbeenreportedinpreviousresearch(Cahilletal.,2013;Quarrieetal.,2013).Whencomparingresultsfromtheninepositionalgroupswithpreviousresearch(Cahilletal.,2013),itwasapparentthatdistancescoveredacrosspositionalgroupswerelowerforallpositionsexceptfullback.Thisstudyshowedfullbacks(6904±740m)tocovergreaterdistancethanthatrecordedbyCahilletal.(2013)(6489±1572).Onfurtheranalysisofthefullbackposition,thiswasthepositionthatrecordedthehighestmeandurationofminutesplayedwithinthedatasetandthereforelikelyexplainsthehighdistancescoveredcomparedtotheothereightpositionalgroupswithinthisresearch.ThevaluesreportedbyCahilletal.(2013),forfullbacksarelikelytobeexplainedbytheseplayersplayingfewerminutes.However,asCahilletal.(2013)doesnotquantifyminutesplayedwithintheirresearch,thisnotionissomewhatquestionable.

Aspreviouslymentioned,sincetheadventofprofessionalismthegamehasbecomemoreintense(Quarrieetal.,2013),withoneoftheconsequencesbeingthattacticalsubstitutionsaremadetoensurethatplayersarefreshtoperformtheirtask.Consideringtheresultsabove,thevariationsseeninthematchcharacteristicdataforthisstudyandthatofpreviousresearch(Cahilletal.,2013;Coughlanetal.,2011)maybeexplainedbytheminutesplayedbyindividuals.Coughlanetal.(2011)examinedonlyplayerswhoplayedfor80minutesand

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Cahilletal.(2013)onlyincludedplayerswhoplayedlongerthantheaveragesubstitute’sgametime.Itcould,however,bearguedthatthisstudyisperhapsmorerepresentativeofmodernrugbyunion,whereplayersareoftenaskedtoplaylessthanthefullmatchduration,withthereducedvolumeofplayingminutesexpected,potentially,toresultinamorefastpacedandexplosiveperformance.AswasnotedwithinthisstudyandtheresearchbyLacomeetal.(2015),forwardsgenerallyplayedfewerminutesthanbacks.Positionalgroups,especiallyintheforwards,areoftensubstitutedfortacticalreasonsanditisnowcommonplace,inmanyeliteteams,toseeforwardsnotplayingthefulldurationofthegame.Duetothereducedgametimeperformedbyplayers,positionalgroupsareoftenconditionedforsubstitutionroles,whichappeartoinvolvegreaterintensityofmovementsandactivitiesovershorterplayingtimes.Therefore,excludingplayerswhodonotplaythewholedurationofthegameisshortsightedanddoesnotguidepractitionersuponthegamedemandsplaceduponspecificindividuals.

Intensity,inthisstudy,(Forwards64.0±6.3m/minandbacks70.9±7.4m/min)displayedslightlysmallervaluesincomparisontoCahilletal.(2013)(Forwards64.6±6.3m/minandbacks71.1±11.7m/min),withsimilarfindingspresentedbyCoughlanetal.(2011),whoreported66.7m/minforforwardsand71.9m/minforbacks.ThisissimilartotheresearchbybothReardonetal.(2015)andLindsay,Draper,etal.(2015),whonotedaverageintensityof77m/minand81m/min,respectively.Itis,however,importanttonotethatthevaluesfrombothReardonetal.(2015)andLindsay,Draper,etal.(2015),weretakenfromdistancepergametimeminutes,andthereforepossiblyaccountforthehigherintensityvaluesdisplayed.Asnotedabove,individualswhoplayshorterdurationsarelikelytoplaywithgreaterintensitythanindividualswhoplayedforthefull80minutedurationofamatch,aspacingstrategieswould,potentially,notbeadopted.Thisstudyshowedthathookers,locks,wingsandfullbacksplayedatahigherintensitythanthatreportedbyCahilletal.(2013),yetprops,backrow,scrumhalves,outhalvesandcentreswerereportedtoplayatahigherintensityinthestudybyCahilletal.(2013).Asthisstudyusedplayerswhoplayeddurationsrangingfromthirtytoeightyminutes,itissurprisingthatsomepositionalgroups’intensityvaluesaresmallerwhencomparedtothoseinpreviousresearch(Cahilletal.,2013;Coughlanetal.,2011),particularlyastheyinvolvedplayerscompetingforlongerdurations.Itis,however,importanttoconsiderthatthestudybyCoughlanetal.(2011)istakenfrominternationalrugby(involvingonlytwosubjects),whereonewouldexpectahigheraverageintensity,comparedtothatofthedomesticlevelprofessionalrugby,asitisconsideredtobealowerplayinglevel.

OnanalysisofthedistancecoveredinspeedzonesitwasapparentthatbacksspentlongerinD1(2195±542m)andD6(77±66m)comparedtoforwards(D11898±450m;D614±19m),butthatforwards(914±264m)spentlongerinD3comparedtobacks(904±243m).AbackspendingalongertimeinbothD1andD6isnotsurprising,consideringtheyarerequiredtoperformmorehighintensitymovementsthanforwardsandarereportedtohavelongerworktorestratiosthanforwardsduringmatchplay(Austinetal.,2011a).Accelerationsanddecelerationsassessedwithinthisstudyarealsohighestamongstbacks(Accelerations32.2±10.6;Decelerations22.0±11.9),comparedtoforwards(Accelerations22.0±11.9;Decelerations30.8±14.4),supportingtheviewthatbacksworkatahigherintensity,buthavelongerrecoveryperiodsbetweenefforts.Thisnotionisfurthersupportedwhenconsideringtheaforementioneddistancecoveredineachdistancezone.

AsreportedbyCoughlanetal.(2011),75%oftotalrugbyunionmatchdistance,isperformedatlowintensity(0-3.6m/s).Thisstudyalsoshowsthemajorityofmatchdistancecoveredas

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beingoflowintensity(95%)(D1,D2,D3andD4)anditisperhapssurprisinghowlittleoftheactualdistancecoveredisofhighintensity(D5andD6),whencomparingvaluestothatofpreviousresearch.Practitionersare,however,guidedtoconsidertheintensityvalueswithcautionasthedistanceinzonecategorieswithinthisstudydiffertothatofpreviousresearch(Cahilletal.,2013;Coughlanetal.,2011)andinadditiontheclassificationofwhatisregardedhighintensityalsodiffers.Thisresearchclassifiedhighintensityworkasmovementabove19.8km/h,whereastheworkbyCahilletal.(2013)notedhighintensityworkatdifferingvalues.Cahilletal.(2013)notedthatallpositionscoveredatleast80%oftheirtotaldistanceatthefollowingcategories<20%Vmax(standingandwalking),20–50%Vmax(jogging).Also,insteadofusingdistancecoveredinspeedzonestoclassifylowandhighintensitywork,theauthorsreportedrelativespeedclassificationsthatwerebaseduponunclassifiedindividualmaximumsprintspeeds.

Oncloserexaminationofthedistancecoveredathighintensitywithinthisstudy,forwardsperformed3%oftheirdistanceathighintensity(>D4),whilebacksperformed6%oftheirdistanceathighintensity(>D4).Cahilletal.(2013)notedforwardsperformed6%(369m)oftheirdistanceathighintensity(>81%Vmax),whilebacksperformed4%(323m)oftheirdistanceathighintensity.Thissmallamountofhighintensityworkhasalsobeenreportedwithinmanytime-motionanalysisstudies(Austinetal.,2011a;Deutschetal.,2007;Quarrieetal.,2013)andGPSstudies(Cunniffeetal.,2009),illustratingthatrugbyunionisasportofintermittentactivitywithcontactsituationsandhighworktorestratiosrepresentingalargeproportionofthematchdemandstowhichplayersareexposedto.Withintheninepositionalgroupsassessednoclearpatternemerged,withmanypositionssharingthefurthestandshortestvaluesforthedistancecoveredwithinzones.ScrumhalvespresentedthefurthestdistancecoveredinD4(1009±214m),whichconsideringtheirrolewithinthegameasthelinkbetweentheforwardsandbacks,isperhapsnotsurprising.Theyarerequiredtoperformmanymetresatmoderatepaceandattendeverycontactsituationinordertodistributetheball.Additionally,ofnotewithinthedistancezoneswasthedatashowingthatfullbackspresentedthefurthestD2(2078±275m)andD5(429±118m),whichsignifythatfullbacksarerequiredtocoveravastamountofdistanceatbothlowandhighintensity,tofollowplayinthebackfieldduringbothattackinganddefendingsituations.Alsoofinterestwasthedataforcentres,whichillustratedthesignificant(p<0.001)amountoftimespentinD1(2405±256m),wheretheyaremostlikelytobeengagingincontactsituations(attackinganddefending),asiscommonwithintheirpositionalrole.Thisisalsoevidentinthehightotalnumberofimpactsrecordedforcentrescomparedtotheotherbacks(excludingfullbacks).Lastly,itisofnote(Table3.7)thatwingersperformthefurthestdistanceinD6(139±72m),whichwouldbeexpected,consideringtheirphysicalcharacteristicsandtheirmainrolewithintheteamasanattackingthreattoscoretries,asdetailedwithintheliteraturereviewofthisresearch(Table2.1andTable2.11).

Aspreviouslymentioned,fewearlierstudiesinrugbyunionhaveincorporatedGPSdataonimpacts,meaningthatvaluesuponwhichtodrawcomparisonwithinthisstudyarelimited,thereforeaddingtothenoveltyofthisstudy.Cunniffeetal.(2009)revealedthatforwardswereinvolvedin60%morehighlevelimpacts(>8G)thanbacks,butthatbacksproducedmarginallymoreworkthanforwards.InthestudybyCunniffeetal.(2009)itwasalsorevealedthatforwardsexperiencethirteen“severe”impacts(10+G)pergamecomparedtobacks,whowerenotedtoonlyencounterfour“severe”impactinstances,althoughtherelevanceofthisdatacanbequestioned,consideringthatitwasbasedononlythreeplayers.Recentresearchby

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Schoemanetal.(2015),assessingdifferencesbetweenplayingpositionandcollisionrateswithinprofessionalrugbyunion,addedtotheknowledgeofimpacts,notingsignificantdifferencesbetweenforwardsandbacksregardingcollisionrates(p≤0.05).Thisisincontrasttotheresultspresentedwithinthisstudy,whichidentifybacksasexperiencingmorecollisions.Itis,however,importanttonotethattheresearchbySchoemanetal.(2015)wastakenfromtime-motionanalysisandthereforedoesnotidentifythemagnitudeofimpactsfromGPSanalysis(betheseimpactsfromcollisionsornot).Aneedforcautionwhencomparingtheresultsfromthisstudytothatofanyprevious,orfuture,researchintheareais,however,advised.

RecentresearchusingGPSmethodsuponwhichtocomparethefrequencyofimpactsreportedwithinthisstudydoesexist(Tee&Coopoo,2015),whereitwasrevealedthattherewasnodifferenceinthetotalnumberofimpacts(>5G)experiencedbybacks(9.5±3.2)orforwards(10.0±3.0)(>5G.min-1),orthefrequencyofhigh-intensityimpacts(>8G.min-1)(Backs1.1±0.4;Forwards1.1±0.5).Thisis,however,incontrasttotheresearchbyLindsay,Draper,etal.(2015),whonotedforwardsasexperiencingmoreimpactsperminutethanbacks(0.56±0.23;0.36±0.17).Despitethisstudyshowingthatbacksexperiencedagreatertotalnumberofimpactsthanforwards(Forwards3176;Backs5501),incontrasttotheirhypothesis,thisstudydoessupporttheviewthatforwardsareinvolvedinmore“heavy”impacts(>Zone3).Impacts<7Ginthisstudy(Forwards229±160;Backs226±151)werelowerthanthosereportedbyCoughlanetal.(2011)(Forwards670;Backs466).However,theGPSunitsusedbothwithinthisstudyandthatofCoughlanetal.(2011)dovary,thereforepotentiallyexplainingthedifferingresultsregardingimpacts.ItisalsoimportanttonotethatforwardsexperiencedasignificantlygreaternumberofIm6whencomparedtobacks(p<0.03),whichwhenconsideringtheseIm6instancesrepresenta13-15Ginvolvement,theresultantphysicalinfluencethismighthaveupontheplayersinvolvedisapparent.Furthersupportfortheeffectofhighmagnitudeimpactsuponresultanttime-courseofrecoverypost-matchplaywasnotedwithinsimilarresearchinrugbyleague(McLellanetal.,2011a),whereitwasreportedthatsignificantskeletalmuscledamagewashighlydependentonthenumberofheavycollisions>8.1G,asillustratedbyincreasedCKandCvalues.AnothercomparisonofinterestwhenassessingsimilarresearchisthattheaccelerometerintheStatSportsdeviceusedwithinthisstudyclassifiedimpactsiftheywereabovethe3Glevel,meaningthatmanyso-called“impacts”frommatchsituationswerepotentiallyduetomovements,ratherthanphysicalcontactwiththeoppositionortheplayingsurface.Incontrast,Coughlanetal.(2011)reportedlightimpactsas5.0–5.9G,thereforeexcludingmanyimpactswhichcouldbeaccountedforbymovementratherthancontact.Thevaryingimpactsvaluesdisplayedinthisstudy,could,therefore,beaccountedforbythedifferingclassificationofimpactzones.

Propstypicallyexperiencedthelowestnumberofimpactsinthelowerimpactzones(Im1,Im2andIm3),yetexperiencedalargenumberofimpactsinthehigherimpactszones(Im4,Im5andIm6),whencomparedtootherpositions(locks,scrumhalfandouthalf).Theresultsfromthisstudy,therefore,differfromthatofSchoemanetal.(2015),whonotedpropsandlocksexperiencingsimilarcollisionrates(Propsp=0.07;Locksp=0.62).However,asnotedabovetheresearchbySchoemanetal.(2015)wastakenfromtime-motionanalysisresearchandnotGPSassessment,meaningthatcomparisonsshouldbecautionedagainst.Fullbacksshowedasignificantlevelofimpactsonbothlow(p<0.001)andhighimpactzones(p=0.006),yetthepositionsofprops,hookersandbackrowillustratedhighIm6valueswhencomparedtothevaluestheyexperiencedatthelowerimpactzones.Itisimportantforpractitionerstonote,

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that,ashypothesised,thisresearchdoesnotsupporttheviewthatprops,hookersandlocksexperiencethelargestnumberofhighmagnitudeimpacts.However,thedurationofminutesplayedbyeachpositionshouldbeconsideredbeforecomparisonismade.

Anewfindingofthisresearchisthetotalnumberofimpactsandthewiderangeofimpactsexperiencedbyfullbacks.Itis,however,importantforpractitionerstonotethatthehighnumberoflowlevelimpacts,couldperhapsbeexplainedbythedistance,speedsandintensityatwhichfullbacksarerequiredtowork,asevidencedwithinthisstudybytheamountoftimefullbacksspendinallspeedzones.ThelowlevelimpactsassignedtoZones1m1,Im2andIm3aremostlikelytobecollectedbytheGPSunitduringlocomotivetasks,ratherthanduringcontactsituations(withtheoppositionandtheground)meaningthat1m1,Im2andIm3donotprovideatruereflectionofplayerimpactloadexperiencedviacontact.However,thenumberofhighlevelimpacts(Im6)forfullbacksisanewfindingfromthisstudy,whichalthoughcautionstillneedstobeconsideredwhencomparingpositionswithinthisresearch,isanareaofpotentialfutureinvestigation.Priorresearch(Tee&Coopoo,2015)hasalsoreportedthatoutsidebacks(1.2±0.4,ES0.2-1.4)werethepositionsmostlikelytobeinvolvedinhigh-intensityimpacts(>8G.min-1)andtheresultsfromthisexperimentalstudywouldsupportthis.Whenconsideringthatoutsidebacksarecapableofperforminghigh-speedmovements,resultinginapreponderanceofhigh-speedcollisions,thesefindingsarenotunexpected.Thedistancescoveredwithinthisexperimentalstudyarenotsurprising,consideringthosepresentedinpriorresearchoutlinedintheChapter1(Austinetal.,2011a;Cahilletal.,2013;Cunniffeetal.,2009;Jonesetal.,2015;Lindsay,Draper,etal.,2015;Venteretal.,2011).Importantly,however,highintensityeffort,suchasthefrequencyofaccelerations,decelerationsandimpactswiththeirlikelyinfluencetheyuponrestorationofperformance,shouldbeaconsiderationforfutureresearch.

FutureinvestigationofGPSimpactsdataperhapsneedstoassesscriticallyandinmoredetailtheexactloadbeingplaceduponplayersduringimpacts,withtheaimofclassifyingtheminto“heavy”and“veryheavy”valuesasoutlinedbyCoughlanetal.(2011).Additionally,theincorporationofvideoanalysisalongsideGPSdatawouldbetterinformpractitionersuponwhichmovementormatchinvolvementiselicitingtheseimpacts.Asexplainedabove,manyoftheimpactsexperiencedbysomepositionalgroups,withinthisresearch,mayhavebeenasaresultofvaryingmatchdemands(landingfromjumps,changingdirectionorskillinvolvements)andnotsolelyfromcollisioncontactswiththeopposition.Thisfurtherlevelofimpactsanalysiswouldhelpguidepractitionersonthemagnitudeofimpactsandtheeffecttheseimpactshaveuponplayers.Baselinevaluesoftheamountofimpactsexperiencedbypositionalgroups(props,locks)andthemagnitudeoftheseimpactsmayaidfutureprescriptionofpositionalspecifictrainingprogrammesforrugbyunionplayers.Althoughthisstudydoesnotinvestigatethenumberofcontactsituations(scrum,ruck,tackleandmaul)experiencedbyplayersduringgamesofrugbyunion,onecouldarguethatthatthecontactelementsofrugbyunionaresointensethat,althoughsmallinactualnumber,arehighinoverallloaduponplayers.Despitetheeffectthatcontactsituationsanalysiscouldhaveupontheresultsfromthisstudy,thecomplexityofassessingstaticexertionsmeantthatthisresearchonlyassessedthedynamicinvolvementsofmatchplayandimpactsclassifiedfromGPS.Loadanalysis,assessingcontactsituationinvolvement,wouldrequiretime-motionanalysisresearch,asseeninthestudybySchoemanetal.(2015)assessingcollisionrates.Thecombinationoftime-motionanalysiswithGPSdatawouldprovideagreaterlevelofdetailregardingcontactload,whichis,therefore,afurtherpotentialareaoffuturedevelopment.

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Fromthisresearchitisclearthatbacksperformatahigherrelativeintensitythanforwardsandthatbackscompeteoveralongertimeperiodthanforwards.Thegreaterintensitytowhichbacksareexposedwouldlikelyhaveaneffectupontheirneuromuscularperformancepost-match,assupportedbytheaforementionedresearchofMcLellanetal.(2011b).Despiteforwardsexperiencingonlyaslightlyhighernumberofimpacts>Zone3comparedtobacks,theimpactstheyexperiencearemostlikelytobearesultofthegreatervolumeofcontactsituations,ratherthanfromthejumpingandlandingimpacttasksthatthebacksexperience.Theimpactsexperiencedbyforwardscomparedtobacksarelikelytoaddsignificantfatigueandneuromuscularresponsetoforwards’post-match.ThisnotionissupportedbypreviousresearchbyDuthieetal.(2006),whonotedthatsprintingrepresents4%ofthegamemovementsfortheforwardsand25%forthebacks,yettherelativeeffectthatsprintshaveuponfatigue,comparedtothatexperiencedasaresultofcollisions,couldbequestioned.Thequestionableeffectsonfatigueofdistancecoveredandneuromuscularresponsepost-match,is,perhaps,anareapractitionersshouldfocusupon,withrelativeintensityandrelativeimpacts(impactsperminute)usedaspossibleguidelinesforjudgingtheloadexerteduponrugbyunionplayersduringmatches.

Thisgreaternumberofimpactsexperiencedbypositionalgroups,withinbothpreviousresearchandthisstudy,wasnotedasimportantforfutureconsiderationbyQuarrieetal.(2013),whereforwardsrequirealongertimetorecovery,duetothegreatercontactloadexperienced.Theeffectthatthislargervolumeofimpactshasonforwards,incontrasttobacks,isanotherpossibleareaofinvestigationforthefuture,wheremusclesorenesspost-matchinforwardsisoftentheconsequence.Itcouldalsobeimportanttoconsiderbacks’musclesoreness,incontrasttoforwards’,whodespitecompletinggreatermatchdistances,areexposedtoalowernumberofimpacts.Thislowerlevelofmatchimpactsforbacks,maymeanthattheyhavemoreopportunitiesforpassiverecoverywhiletheywalkorjogbetweenplays.Thislongertimebetweenefforts,therefore,potentiallyenablescreatinekinaseclearance,subsequentlyenhancingrecovery(Cunniffeetal.,2009).Theseresultantmovementpatternsandtimetoworkratiosforpositionalgroupscouldperhapsfurtherexplainthedifferencesseeninmusclesorenesspost-matchandthereforecouldaidpractitionersinprescribingfuturetrainingprogrammes.Performancetestingisnowcommonplaceinmanyrugbyunionsettings,yetGPSdatashouldbethemainstayuponwhichtocomparetestingdatainthedayspost-match.Datafromthisstudy,showingforwardscoveringlessdistanceandexperiencingmoreimpactsthanbacks,providesfurthersupportforpositionspecificconditioningprogrammes,withrecommendationsforcoachesregardingmatchdemands.Futureplanningisrecommendedforcoaches,wheretrainingprescriptioncanbebaseduponaplayer’srecenttraininghistory,comparingprevioustrainingcyclestoconcurrentdataandthematchdemandspresented.

3.5.1 LimitationsofthisstudyAllofthevariablesreportedwithinthisresearchrepresentabsolutevalues(excludingintensity),makingtherelevanceofcomparingtheninepositionalgroupssomewhatquestionable.Aspreviouslyargued,analysingdatafromplayerswhoplayedbetween30and80minutes,addsweighttothenoveltyandrationaleforthisresearch.However,comparingandcontrastingpositionsiscautionedagainst.Insteadpractitionersshouldperhapsconsiderrelativedata(variableperminute)forsomeofthematchdemandsassessedinordertoobtainatruerepresentationofpositioncomparisons.Practitionersare,therefore,advisedtoconductfurtherresearchintothecomparisonofabsoluteandrelativemethodsofmatchdemands

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analysis.Relativedatawillaidinidentifyingwhydifferencesmightoccurbetweenpositions,whileabsolutevaluesareusefulinunderstandingtherealdemandsofeachposition,astheyrecordwhattheplayerssufferasatotalloadthroughoutthematch.Absolutevaluesare,therefore,animportantconsiderationandassuchshouldnotbediscounted.Forexampleaplayermightperformatahighintensity(variableperminute)duringtheirtimeonthefield,yetiftheirminutesonthefieldaresmall,therelativevaluestheyexperienceareperhapsnotasimportantforconsiderationwhencomparedtoanotherplayerwhohasplayedthefulldurationofthegame.Aplayerwhoplaysthefulldurationofthegameislikelytohavelowerrelativevaluesacrossmanymatchdemands,yetalsolikelytohaveveryhighabsolutevalues,thereforewarrantingconsiderationwithinpostmatchanalysis.

Whenconsideringtheclaimabovethatbothabsoluteandrelativemeasuresareofinterest,itispotentiallyalsoimportantforpractitionerstoconsideranalysistobepositionrelated.TherelativevaluesforforwardsareperhapsofmoreinterestthanthebackswhenassessingthedataaboveinTables3.4-3.9.Somevariablesmightpresentmoreinformationfromarelativeview,ratherthananabsolute,consideringthereducedminutesplayedbymanyofthepositionswithintheforwards,comparedtothoseofthebacks.Despitenodataexistingtoshowthereducedminutesplayedbyforwardsincomparisontobacksacrossmanyleaguesandteams,thisviewisconsidered“realworld”.Theplayingpositionsthatexperienceboutsofimpactswithinashorterperiodoftime(impactsperminute)areperhapsbetterassessedfromarelativeview,withtheresultanteffectofclusteredimpactboutsuponrestorationofperformancepost-matchwarrantingfutureinvestigation.However,anindividualthatplays29minutescouldinfactbeexposedtoalargematchdemandandtheprocedureforinclusionwithinthisresearchwouldnotallowsuchexamplesthuslimitinganalysispotential.A“cutoff”point,nevertheless,hadtobesettoensureclarityandavoidunstructureddatacollection.

Asaresultofthedatawithinthisresearchbeingprovidedbyonlyoneteamovertheperiodofaplayingseason,itcouldbearguedthatthisdatadoesnotpresentafullpictureofthematchdemandsofplayerswithinthenorthernhemisphere,insteadonlyrepresentingthematchdemandsfortheteaminquestion.Playingstyles,tacticsandleaguepositioncouldallbemajorfactorsintheminutesplayedbypositionalgroupswithinthisteamandinthetasksthattheyareaskedtoperform.Additionally,itisimportantforpractitionerstonotethatdifferencesinfindingsbetweenstudies(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011)might,inpart,beduetothecontrastingstylesofplaybetweennorthernandsouthernhemisphereteams,asimpactedbyweatherconditions,refereeinterpretationandstrengthandconditioningpractices(Jones,Smith,Macnaughton,&French,2017).Despitethedatacollectedaddingtotheknowledgeofmatchdemandswithinrugbyunioninthenorthernhemisphere,thelimitationofusingdatafromonlyoneteamonlyisapointforpractitionerstoconsiderwhentheyareexaminingtheresults.Onepotentialwayofovercomingsamplesizeand“oneteam”limitationsistocombinedatafrommultipleteams,similarlytotheresearchofCahilletal.(2013).However,theelementofdirectcompetition,inherentinEuropeanteamgames,meansthatsharingofdataisandwillcontinuetobeunlikely.

Differencesinmethodologyarealsoapointtoconsider,assomepreviousstudiesutilisedGPStomeasuremovement,whileotherssolelyusedtime-motionanalysismethodsfromvideoreview.ConsideringthatboththestudiesbyCoughlanetal.(2011)andCahilletal.(2013)used5HzGPSunits,incomparisontothe10Hzunitsusedinthisstudy,thisisamajorpointofconsiderationwhencomparingGPSdata.AswasillustratedbyJohnston,Watsford,etal.(2014),10HzGPSunitsaremorereliablethan5HzGPSunitsandthereforearerecommended

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foruseinfutureresearch.Anotherpossibleexplanationforthedifferencesindataisthatrugbyunionintheprofessionaleraisgettingfaster.EvidenceforevolvingmatchcharacteristicsisillustratedbyRobertsetal.(2008)whofoundthattheaveragenumberofsprintsduringagamewas20.ThisisincontrasttodatafromAustinetal.(2011a)showinganaverageof40sprintsacrossallplayingpositions.ThedisparitiesinGPSvalues,seeninthisstudyandsimilarresearchbyTwistetal.(2014)betweennorthernandsouthernhemisphere,does,however,addecologicalvaliditytothecurrentbodyofresearch.

3.6 PracticalApplications

Thedatafromthisstudyaddstotheknowledgeofwhataretypicalmatchcharacteristicsforprofessionalrugbyunioninthenorthernhemisphere,helpingguidepractitionerstoassessthematchdemandsrequiredforpositionalgroups.Basedupontheresultsofthisstudy,coacheswillbemoreinformeduponwhateachpositionalgroupisrequiredtocompletewithinaneliteteam’smatchsituations.Theabilityofcoachestomakedecisionsuponwhetheranindividualplayercanperformaspecificrolefortheteamisimportantforfuturepractice.Whennewmatchcharacteristicdataiscollecteditcanbecomparedagainstpreviousmatchdataandthepotentialneuromusculareffectthatgamesmighthavehadontheindividualplayerscanbeassessed.

Whenassessingthedemandsofthesport,specifictrainingrecommendationsthatshouldbeconsideredforelitelevelrugbyunion,are,firstlythathighlevelsofaerobicfitnessarerequiredtocompletethedistancesnotedwithinthisresearch.Secondly,thathighmusclemassandstrengtharerequiredtocopewiththeimpactsillustratedwithinthisstudy.Theaerobicfitnessandabilitytowithstandimpactforcesvaryacrossallninepositionalgroups,yettheneedforbothofthesecomponentsofphysicalpreparednessisevidentfromthedatacollated.Asaresultofthisstudy,itcouldbeconcludedthatthephysicalstatureofeachpositionalgroupguidesthematchdemandsexpectedandthataerobicfitnessandstrengthprogrammingshould,therefore,beprescribedrelativetoposition.Additionally,frommatchcharacteristiccomparison,futureplanningcanbeimplementedintostrengthandconditioningprogrammesinordertoimproveindividualreadinesstotraininthedayspost-match.

Lastly,asmentionedpreviously,acombinationofvideoanalysiswithGPSdatawouldhelpguidepractitionersonthenatureoftheimpactsexperiencedwithinmatchsituations.Adeeperlevelofassessmentisneeded,whenconsideringthattheresultsfromthisresearchshowthehighlevelofimpactsexperiencedbypositionssuchasfullback.Despitebacksexperiencingagreaternumberofimpacts,manyoftheseimpactsarelikelynottobefromcollisionsandcould,asaresultofthematchdemandsconducted,resultinadifferentneuromuscularresponse.

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3.7 Implicationsofexperimentalchapter3forsubsequentstudies

Nowthatmatchcharacteristicshavebeenidentified,aneedexiststoidentifyaperformancemeasuresthatwillbeabletoassessrugbyplayerfatigueinthedayspost-match.Asillustratedinthereviewofliterature,jumptestingisperhapsthemostrealisticperformancemeasureforuseintheappliedcontextwithinwhichthisseriesofinvestigationsoccur.Thefollowingexperimentalchapterthereforeaimstoassessthereliabilityofmultiplejumpmodalities,toascertainwhichisthemostapplicableforusewithinassessmentsofmatchfatigue.Additionally,thelikelyrestorationofperformanceexperimentalchaptersthatwillfollowthisjumpreliabilitystudy,needtoinvolveassessmentofmatchcharacteristicsdata,thereforefurthersupportingthecompletionofmatchcharacteristicassessmentwithinthisthesis.

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4 WithinandBetween-SessionReliabilityofJumpPerformanceinEliteRugbyUnionPlayers

4.1 Abstract

CMJtestingiscommonlyusedwithinelitefieldsportsettingstoassessNMF.Thisstudyassessedthewithinandbetween-sessionreliabilityofthreejump-tests,includingCMJ,SJ,singlelegdropjumpleftleg(SLDJ-L)andsinglelegdropjumprightleg(SLDJ-R),todeterminewhichjumpprotocolwasmostreliableandreportedontheirresultantmeasurementerror.Participantscompletedtwotrialsofeachjumpduringeachsession,onthreeoccasions.Within-sessionreliabilitywasdeterminedviaintraclasscorrelationcoefficients(ICC)andbetween-sessionreliabilitydeterminedusingbothICCandrepeatedmeasuresANOVA,withBonferronipost-hocanalysis,ornon-parametricequivalent,usedtocheckforlearningeffects.Reliabilitywithin-sessionforCMJ,SJandSLDJ-L(ICC0.938,ICC0.954and0.759respectively)jumpheight,demonstratedhighreliability,whileSLDJ-Rjumpheightshowedlowreliability(ICC0.445).Between-sessionsCMJandSJshowedhighreliability,includingtrivialtosmalleffectsizes(CMJICC=0.906;SJICC=0.866),withnosignificantdifferences(p>0.05)injumpheightobservedbetweendays.Between-sessionsreliabilityforSLDJjumpheightshowedhighreliabilityforleftleg(ICC=0.875)andmoderatereliabilityfortherightleg(ICC=0.759),withasmalleffectsizebetweensessionsfortheleftlegandtrivialeffectsizefortherightleg,yetbothwerenon-significant(p>0.05)betweendays.ThisstudyillustratesthatCMJjumpheightrepresentshighreliabilitybothwithinandbetween-sessionacrossallthreetestingdays,incontrasttotheSJ,SLDJ-LandSLDJ-R.FindingsalsoshowthatCMJdemonstratesthelowestSDD(1.7%)betweensessions.Whencomparingunilateraljumpstobilateraljumps,itwasclearthatCMJprovidesthemostsensitiveandreliabledata,thereforeitissuggestedthatunilateraljumpsshouldnotbeusedasaperformanceindicator,duetolowerreliability.Inaddition,practitionersshouldconsiderachangeinjumpheightof≥1.7%asmeaningful,whenassessingeliterugbyunionplayersperformingCMJ.

4.2 Introduction

Theverticaljumphaslongbeenusedasamethodofassessinglowerlimbpowerandhasbeenreportedtopossesssensitivityintrackingtraininginducedchangesforpeakpoweroutputandrateofforcedevelopment(Carlocketal.,2004;McLellanetal.,2011d).Jumpingingeneral,isoneofthemostprevalentactsperformedinsport(Markovicetal.,2004),withathletesinmanysportsoftenrequiredtojumpinordertoperformtheirroleinateamgameoranathletictask;includingjumpingtointerceptaballinfootballorjumpingtoavoidanobstacleinathletics.ResearchbyBoscoetal.(1987)notedperformancequalitiesofjumpingandrunningtobesimilarinnature,withverticaljump,therefore,highlyrelevantforassessingsportingperformance,wherealargerunningelementexists.Approximately500groundimpactshavebeenreportedtooccurinrugbymatchsituations,withmanyoftheselikelytobefromjumpingactions(Cadoreetal.,2013;Sheppard,Gabbett,&Stanganelli,2009).Manyofthejumpingaspectsofgamemovementinteamsportsappearatimportantmomentsinthegame,ofteninordertocontestpossessionandlikelytobecriticalmomentsingameoutcome.Activitiesthatdonotinvolvejumping,suchastacklinginrugby,alsoutilisepowerelements,uponwhichaneffectivemeasurementofpowerisrequiredwhenmonitoringtheathlete’sdevelopment(Klavora,2000).

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Anindividual’sabilitytogenerateforcequicklyisakeyperformancemeasurementforathletescompetinginmanyteamsports,hencejumptestshavebeenutilisedtomonitorpowerandtheeffectsoftrainingandfortalentselectionpurposes(Markovicetal.,2004).Whenmeasuringjumpperformance,thegoalofmanypractitionersistomeasurejumpheight,withtheroleofpowerwithinthismeasurebeinginterrelated.However,asreportedbyWinteretal.(2016),theuseoftheterm“power”isoftenmisplaced.Poweristheproductofforceandvelocity,withpowerdescribedastherateofworkortheforcemultipliedbythevelocityofmovement(Kawamori&Haff,2004).Withinthecontextofjumpperformancetesting,itisessentialthatpractitionersunderstandtherelationshipbetweenjumpheightandpower,asoneisnotadirectmeasureoftheother.Inessence,jumpheightiscommonlyusedasaproxyforpower,yettheunderstandingofthedifferencebetweenthesetwomeasuresiskey.Intheirreviewofmechanicaltermscommonlyusedinsportandexerciseresearch,Winteretal.(2016)recommendedtheuseoftheterm“intensity”alongsidetheappropriateunitmeasurementwhendiscussingpowerelements,tobestdescribethespecifickindofexerciseperformed.

Withthegoalofassessinglowerlimbjumpingability,manyjumptests,includingverticaljump,havebeendeveloped.Verticaljumpisperhapsthemostcommonlyreportedjumpmodality,yetmanysimilarjumptestscommonlyusedintheappliedsettingincludeCMJandSJ.Theverticaljumphasbeenalsobeenreportedtorepresentaninaccuratemeasureofexplosivelowerlimbpower,whenarmswingispermitted,duetothemorecomplexnatureoflegandarmcoordination(Leardetal.,2007;Markovicetal.,2004;Youngetal.,1997).Leesetal.(2006)concludedthatarmswingcontributestojumpperformancebyaidingthestoringandreleaseofenergyfrommusclesandtendonsaroundtheankle,kneeandhipandbyinitiatingapullforceattheshoulderjointtherebyincreasingjumpheightby10%ormore(Leesetal.,2004).Harman(1990)reportedthatthisincreaseinjumpheightisnotduetoupwardaccelerationofthearmsseenduringthejump,butbytheforcevelocityrelationshipofthemusclecontraction.Simultaneouslytheupwardaccelerationofthearmscreatesadownwardforceontherestofthebody,slowingthecontractionofthequadricepsandglutealmuscles,sothatmoreforcecanbeexerted.Duetotheaboveeffectsregardingvariabilityofverticaljumps(usingarmaction),thistypeofjumpassessmenthasgenerallybeenexcludedfromrecentresearch(Aceroetal.,2012),withbilateraljumpperformancescommonlybeingconductedwithhandsonhipsorholdingabarontheshoulderstominimisevariability.

ResearchbyHarmanetal.(1990)reportedthatunilateraljumpperformancehadastrongerrelationshipwithsprintperformancethanabilateraljump.DespiterecentjumptestinginvestigationsfocusingsolelyontheSJandCMJandnotunilateralderivatives(Gallardo-Fuentesetal.,2016;Gathercole,Sporer,&Stellingwerff,2015;McMahon,Murphy,Rej,&Comfort,2016;Till,Jones,Darrall-Jones,Emmonds,&Cooke,2015;Westetal.,2014),theuseofunilateralderivativesshouldnotbediscounted,asmanymovementsassociatedwithteamsportplayareconductedononelegandthereforethevalidityofunilateraltestingiswarranted.Whenconsideringthatunilateraljumpingisatypicalplyometricexercise,widelyusedasaneffectivetrainingmethod(Young,MacDonald,&Flowers,2001)andconsideredtobeafasterstretchshorteningcyclemovementthantheCMJ,itsneedforfutureinvestigationisfurtheremphasised.

Inadditiontousingjumpteststomeasurelowerlimbjumpingability,recentresearch(Cormacketal.,2013;Cormacketal.,2014;Hamilton,2009;McLellan&Lovell,2012;McLellanetal.,2011a,2011b;Taylor,2012)hasfocusedonutilisingverticaljumpswithastandardised

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protocoltoassessNMF,asdiscussedinChapter2.3.3.Arecentstudyineliterugbyleague,foundthatCMJperformancewasimpairedforupto24hourspost-match,reportinga26%reductioninPRFD24hourspost-match(McLellanetal.,2011a,2011b,2011c,2011d;Twistetal.,2012).AsseeninthestudybyMcLellanetal.(2011a),PRFDonaveragewas12653N.s-1acrossrugbyleagueplayers24hoursbeforethegameandonaverage9379N.s-124hourspost-match.Additionally,anotherstudyonrugbyleagueplayers(McLeanetal.,2010)reportedthatCMJflighttimeandrelativepowerweresignificantlyreducedinthe48hoursfollowingthematch.Moreover,McLeanetal.(2010)reportedthatCMJvariablesreturnedtonearbaselinevaluesfourdaysaftermatches.TheabilitytoassessNMFwillprovideabetterunderstandingofathletes’readinesstotrainandthepossibleforesighttoaltertheirtrainingloadbasedupondata.Itis,however,importantforpractitionerstonotethataninstantmeasureofNMFisoftenrequiredineliteteamsportsettings,meaningthatheinvestigationofkineticmeasuresmaybediscountedinfavourofamoreinstantaneousmeasure,suchasjumpheight.

Whenusingforceplates,theinabilitytotestonasportspecificsurfacesisconsideredadisadvantage,yetthemanyadvantagesofforceplatesoutweighthedisadvantagesandtheyarethereforeconsideredtobethe“goldstandard”instrumentforjumpassessment(Casartellietal.,2010).Opticalmeasuringsystems(infraredmats)havealsobeencriticallyanalysed(Glatthornetal.,2011).TheOptoJumpsystem(Microgate,Bolzano,Italy),whichconsistsofonereceiverandonetransmitterbarwasshowntohaveexcellentreliability(Glatthornetal.,2011)withrecommendationstouseOptoJumpandforceplate(QuattroJump,Kistler,Winterthur,Switzerland)interchangeably(Bosquetetal.,2009).Glatthorn(2011)reportedintraclasscorrelationcoefficients(ICCs)forreliabilityof0.997–0.998,despiteasystematicdifferenceinjumpheightbetweenforceplateandOptojump(2.5%;p=0.001).ThemainbenefitoftheOptoJumpopticaltimingsystemisthatitallowssubjectstobeassessedforjumptestsonthesamesurfaceuponwhichtheywouldperformduringtheirsportingactivity.Cautionwas,however,advisedwhenusingopticaldevices’suchasOptoJumpasmisalignmentofphotoelectriccellscancausediscrepanciesinresults.AmorerecentstudybyCastagnaetal.(2013)reportedasignificantdifferenceintwoportabledevices(OptoJumpandMyoTest),assessingCMJflighttimes,comparedtothatcollectedviaaforceplate.Oneoftheseportabledevices(OptoJump)showedasignificantlylowerflighttimethanthatrecordedonaforceplate,furtheremphasisingtheneedforfuturestudyintothevalidityandreliabilityofjumptestinginstruments.InastudybyCastagnaetal.(2013),assessingvalidityofverticaljumpperformanceassessmentsystems,itwasstatedthattheOptoJumpwasconsideredtobemoreaccurateandreliablethattheMyoTest(Sion,Switzerland),whichutilisedabodyaccelerometerattachedtoparticipantswaist.Inconclusion,Castagnaetal.(2013,p.766)agreedwiththeworkofBosquetetal.(2009),statingthatthe“OptoJumpwasavalidandaccuratemethodofassessingflighttimewhenaforceplateisnotavailable”.AlongsidethereportedhighreliabilityofOptoJumpandperhapsofmostimportanceinsupportingitsfutureinvestigation,isthenotionthatthisinstrumentismorecosteffectivethanaforceplate.Thismeansthatthelikelihoodofcontinueduseinmanysportingsettingsisimproved.

Thisstudyaimedtoassessthereproducibility,oftheperformanceofthreejump-testingprotocols(CMJ,SJ,SLDJ-LandSLDJ-R)assessingjumpheightonanOptoJump,bothwithinandbetweensessions.Theassessmentofjumpheightwasconsideredtobeofimportance;astimerestrictionsinmanyeliteteamsportsettingsdiscounttheassessmentofmorelabourintensivekineticmeasures.Similarly,theassessmentofanOptoJumpwasrequired,asthecostimplicationsofforceplateuseoutweighitsadvantagesformanysportsettings.Lastly,the

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assessmentofbothbilateralandunilateraljumpwasconsiderednecessary,whenconsideringthatmanyrugbyunionmatchplayactivitiesarenotalwaysperformedfromtwofeet.Resultsfromthisstudywillinformpractitionersaboutwhichjumpprotocolismostreliableandtheresultantmeasurementerrorofeachmethod,whileassessinganindividual’sabilitytoreplicateperformance.ItwashypothesisedthattheCMJwouldbethemostreliablejumpmodalityforwithinandbetween-sessionsperformances,as,firstly,itisthejumpmethodthatwasmostcommonlyperformedbythetestsubjects,andsecondly,CMJisthejumpmethodthatisleastlikelytocarryavariabilityoftechniqueadopted,whencomparedtoSJandSLDJ,whichperhapsrequiremorecoachinstructionandfamiliarisation.

4.3 Materialsandmethods

4.3.1 ParticipantsEighteliterugbyunionplayers(age21.0±4.4years,height185.0±8.0cm,mass90.0±8.2kg)fromthesameprofessionalrugbyclubvolunteeredforthestudy.Participantswereallhealthyandactiveindividualswhohadnocurrentinjuryissues.AllsubjectsprovidedwritteninformedconsenttoparticipateandSalfordUniversityResearchandEthicsCommitteeapprovedthestudy.

4.3.2 JumpsThreetypesofjumpweretestedwithinthisstudy,withtworepetitionsofeachjumpperformedonthreeseparatedays.Participantswereaskedtostandardiseactivitylevelsanddietaryintakeforthe24hourspriortotesting.ThejumpsperformedincludedaCMJ,aSJandaSLDJ.Priortotesting,participantsengagedintwofamiliarisationsessionstoensurethattechniqueswereappropriateandstandardised.Participantsplacedtheirhandsonthehips,foralljumps,toeliminatecontributionofarmmovement(Taylor,2012).Thiswasalsothemethodtowhichallparticipantswereaccustomedduringregulartestingintheirsportingenvironment.Inlinewithpreviousstudies,assessingCMJandSJperformance,protocolssuchashandsonthehipsthroughoutthejumpandextendedlegsthroughoutflighttopreventtuckingoftheknees,(whichhadbeenreportedtocauseinaccuracies)wereimplemented(Flanagan,Ebben,&Jensen,2008;Taylor,2012).Priortoperformingthejumps,subjectswereaskedtoperformfiveminutesofstationarycyclingandtwominutesofprescribeddynamicstretching.

4.3.2.1 CountermovementJump(CMJ)techniqueTheCMJwasperformedfromastandingposition,withthewholeplantarpartofthefoottouchingthejumpingsurfaceandthehandsrestingonthehips.Acountermovementwasconductedbytheparticipantsuntilthekneeanglereachedapproximately90°,thenimmediatelytheparticipantsjumpedashighastheycould,withtheirlegsremainingstraightuponflight,thereforepreventinganytuckedlegswhichwouldleadtoinaccuratemeasurement.Uponlandingtheparticipantsmadecontactwiththetestingsurfacewithkneesextended,onlyflexingtoabsorbtheimpactoncecontacthadbeenmadewiththefloor.Participantswereencouragedtojumpashighaspossible,priortoeachjump,withallparticipantsreceivingverbalfeedbackabouttheirperformanceaftereachjump.

4.3.2.2 SquatJump(SJ)techniqueTheparticipantshadhandsontheirhipsthroughouttheSJ,andwhencuedtheparticipantsmovedfromatallstandingstartingpositionintoasemisquatposition,whichtheyheldforthreesecondsbeforecommencingtheirjump.Afterthejumpparticipantsreceivedverbalfeedbackabouttheirperformanceandwhereencouragedtojumpashighaspossible,withno

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countermovementjumpmadeatthestartofthejump,asidentifiedfromvisualinspectionoftheforce-timedata.Ifcountermovementoccurred,participantsrestedforafurther60secondsandthenrepeatedtheattempt.PreviousresearchbyLaTorreetal.(2010)assessingtheeffectofstartingkneeangleduringSJshowedthatanincreaseheight,peakforce,andmaximalvelocitymayoccurasaresultofangleamplitude.Thenotionofkneeanglewasthereforeconsideredwithinthistestingprotocol,withanangleofgreaterthan90°recommendedinaccordancewiththeresearchbyLaTorreetal.(2010).

4.3.2.3 SingleLegDropJumps(SLDJ)techniqueParticipantswereinstructedtoplacehandsonthehipsthroughouttheSLDJandinstructedto“jumpforheight”whenlandingintheareadirectlybelowtheraisedstartingboxposition.TheboxthatthesubjectsstartedonfortheSLDJwas30cmhighandtheboxthesubjectsfinishedonwas14cmabovethefloorwherethelaserslay,enablingthemtoperformcorrectlythisunilateralmovement.

4.3.3 ProcedureDespitethetestingbeingconductedpost-match,thetime-pointsofassessmentwereconsistentthroughoutthisstudyandthetrainingandmatchprotocolpriortotestingcommencingoneachoccasionwasstandardised.Inaddition,theplayerstestedwithinthisstudywereaccustomedtogames,asthistestingwasconductedduringthecompetitivephaseoftheplayers’season,meaningnodifferingeffectsofgamefatiguecouldhavealteredresultsbetweenweeks.Theorderofthejumpswasstandardised,tominimisetheeffectoffatigueororderduringsubsequenttestingsessions,withone-minuterestintervalsbetweenjumpsallowingrestorationofthephosphagensystemtoensuremaximaleffort.Astheunilateraljumpinvolvedthemosteccentricforces,SLDJ’swereperformedlast.SJandCMJwereperformedfirstandsecondrespectively,astheyweredeemedlessfatiguingandarebilateralinnature,providinganaturalprogressiontowardsunilateraljumps.TheCMJwasseenasagoodprogressionfromtheSJ,henceitwasthesecondjumptobeperformed.Additionally,inaccordancewithpreviousresearch,itwasthoughtthattheorderdetailedaboveforthesejumpscouldpotentiateeachjump(Harmanetal.,1990),givingmaximalresults.Possiblepotentiationwithinthisstudy,however,wasnotconsideredtobeofparticularconcern,asthejumpsusedwerecommonlyperformedbytheeliteathletesparticipatinganddespitetheorderbeingstandardised,aprotocolofjumptechniqueandtheactivitiesperformedinthedayspriortotestingwasreplicatedthroughout.

4.3.3.1 InstrumentTheinstrumentusedwithinthisresearchtoassessjumpheightwastheOptoJump(Microgate,Bolzano,Italy),whichwasshowntohaveexcellentreliability(Glatthornetal.,2011),withrecommendationsfortheuseofflighttimepreviouslyreported(Cormack,Newton,McGuigan,&Doyle,2008)andusedinpreviousresearch(Buchheitetal.,2008).AnOptoJumpisdescribedasanopticalmeasuringsystemconsistingoftransmittingandreceivingbarscontaininglightEmittingDiodes(LED),whichcommunicatewitheachother.OptoJumpsystemsarepresentlyusedbymanyelitesportsteams,makingitpossibletomeasureflightandcontacttimeswithanaccuracyof1/1000ofasecond.TheOptoJumpwasplacedonthegymfloor,withoneboxeitherendoftheOptoJumptoenableperformanceoftheSLDJ.Thesamplingfrequencywas1000Hzandthesensorswerelocated3mmfromthetestingsurfaceuponwhichtheOptoJumpbarswereplaced.TheOptoJumpwas1minlengthwithspacingbetweensensorsbeing1.041cmapart,meaningthattherewere96sensorspermetreofOptoJump.

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4.3.3.2 JumpHeightandFlighttimeJumpheightwascalculatedviaflighttimeusingthefollowingequationutilisedbyMcMahonetal.(2015)andadaptedfromthatproposedbyBoscoetal.(1983).

JumpHeight=(9.81m.s-2xflighttime2)/8

Toensureaccuracyandreliability,participantsusedaconsistentlandingtechniqueonCMJandSJ,wherethelegsandhipsareextendeduntilcontactwasmadewiththefloor.Flexingofthekneesorthehipsdelayscontactwiththematandthereforedistortsflighttime.

4.3.4 StatisticalAnalysesAllstatisticalanalysiswasconductedonSPSSforwindows,withanapriorialphalevelsetatp<0.05.Within-sessionreliabilitywastestedviaintraclasscorrelationcoefficients(ICC)(Model3,1).Between-sessionreliabilitywasdeterminedusingbothICCandRMANOVAwithBonferronipost-hocanalysis,ornon-parametricequivalent,assessinglearningeffects.PartialetasquaredwasreportedasrecommendedbyCohen(1988)andcalculatedtoseeiftherewereanymeaningfuldifferencesbetweentestingdays.Despitethesamplepopulationbeingeliteandthereforedifficulttorecruitfor,thelowsamplesize(n=8)involvedinthisstudymeantthateffectsizeswerecalculated.InaccordancewiththeviewsofBuchheit(2016),thesoleuseofpvaluesshouldbediscountedagainstastheyaresamplesizedependant.Effectsizes(ES)werealsodeterminedusingtheCohensdmethod,andinterpretedbaseduponthecriteriasuggestedbyRhea(2004)andinterpretedasfollows;trivial=<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.Post-hocstatisticalpowerwascalculatedusingGPower3.1(Fauletal.,2009),foralargeeffectsizeof0.5,atotaln=8wassufficienttodeliveranactualpowerof0.76.ThereliabilitywasconsideredacceptableiftheICCr≥0.8(Cortina,1993).SEMandsmallestdetectabledifferences(SDD)werecalculatedtoprovideinformationuponwhetherachangeinanindividual’sperformanceissignificant,withSEMcalculatedusingthe

formula:SD pooled ∗ 1 − ICC andSDDcalculatedfromtheformula:( 1.96 ∗ 2 ∗SEM).LimitsofagreementwererepresentedusingBland-Altmanplotswithinsessionsfordayoneoftesting.

4.4 Results

4.4.1 Within-sessionvariabilityandreliabilityTable4.1:Descriptive(mean±standarddeviations)andreliabilitystatistics,withintestingdaysforjumpheightforCMJ,SJandSLDJ

Leg Trial1(cm) Trial2(cm) ICC SEM(cm) SDD(cm)

CMJ 39.40±3.40 39.32±2.94 0.938* 0.17 0.49(1.3%)

SJ 35.10±3.81 34.75±3.79 0.954* 0.23 0.65(1.9%)

SLDJ Left 22.70±3.05 23.56±3.07 0.759 0.36 1.01(4.4%)

Right 23.96±2.89 22.73±3.25 0.445 0.42 1.17(5.0%)*Reliabilitysignificant(p<0.001)

Within-sessionreliabilityforCMJheightdemonstratedhighreliability(Table4.1),whichisalsoillustratedwithinFigure4.1,withsimilarreliabilityforSJperformance(Table4.1,Figure4.2).

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Figure4.1:Bland-AltmanplotforCMJwithinsessionone

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Figure4.2:Bland-AltmanplotforSJwithinsessionone

Within-sessionSLDJperformancedemonstratedmoderatereliability(Table4.1),whichisalsoillustratedwithinFigure4.3.Rightlegperformancesshowedlowreliability(Table4.1),whichisalsoillustratedwithinFigure4.4.

Figure4.3:Bland-AltmanplotforSLDJLwithinsessionone

Figure4.4:Bland-AltmanplotforSLDJRwithinsessionone

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4.4.2 Between-sessionBetween-sessionreliabilitywashighfortheCMJ,yetsignificantdifferenceswerenotedbetweentestingdaysoneandtwo(Table4.2).Between-sessionreliabilityintheSJshowedhighreliability,withtrivialandnon-significantdifferencebetweendays(Table4.2).SLDJalsoshowedmoderatereliabilityforbothleftlegandtherightleg,withsmalltotrivialeffectsizesthatwerenon-significantbetweendays(Table4.2).

Table4.2:Descriptive(mean±standarddeviations)andreliabilitystatistics,betweentestingdaysforCMJ,SJandSLDJ

Jump Day1(cm)

Day2(cm)

Day3(cm)

ICCr Partialetasquared

SEM(cm)

SDD(cm)

CMJ 39.96±3.04

37.91*±2.90

38.73±3.69

0.906 0.329 0.23 0.65(1.7%)

SJ 35.49±4.21

37.21±3.73

35.80±3.56

0.866 0.171 0.39 1.08(3.0%)

SLDJ Left 24.26±2.95

23.51±4.62

21.58±4.01

0.875 0.321 0.39 1.09(4.8%)

Right 24.53±2.44

23.63±5.25

19.42±4.36

0.759 0.199 0.65 1.80(7.9%)

*Statisticalsignificancebetweentestingdaysoneandtwo

TheSLDJ-RshowedthelargestSDD(7.9%),withthelowestSDDbeingobservedintheCMJ(1.7%).

4.5 Discussion

Theresultsofthisstudyareinlinewiththehypothesis,showingthattheCMJdemonstratesthehighestreliabilitywithinandbetweensessions,whencomparedtoSJandSLDJ.CMJalsoresultedinthelowestSDDwithin(1.3%)andbetweensessions(1.7%),withsignificantdifferencesnotedbetweensessiononeandsessiontwo,althoughnostatisticallysignificantdifferenceswereobservedbetweensessiontwoandsessionthree.DespiteSLDJ-L,SLDJ-RandtheSJshowingmoderatereliability,theSDDsforthesetaskswerehigherthantheCMJ,rangingfrom3.0-7.9%betweensessions,thereforefurthersupportingthehypothesisthatbilateraljumpsaremorereliablethanunilateraljumps.

4.5.1 Within-sessionBilateraljumpsresultedinthemostreliableperformanceswithinsessions(Table4.1).ReliabilityofSLDJwithin-sessionwasconsideredunacceptable(ICCr<0.8),forbothleftandrightleg(Table4.1).Thehighestwithin-sessionreliabilitywasobservedduringtheSJ(r=0.954),withtheCMJprovidingthesecondmostreliablemeasure(r=0.938).Thehigherreliabilitywithin-sessionforbilateraljumps,whencomparedtounilateraljumps,islikelyduetobilateraljumprequiringlessvariationintechniqueadoptedandbythesejumpsbeingeasiertoperform.Theseresultsareconsistentwithotherresearch(Bosquetetal.,2009;Glatthornetal.,2011),whichshowedthatbilateraljumpsusinganopticalmeasuringsystemsarereliableanddemonstratesthattheathletescanreliablyreplicateCMJandSJperformances.

4.5.2 Between-sessionBetween-sessionreliabilityfollowedasimilarpatterntothewithin-sessiondata,yetCMJappearedasthemostreliable(r=0.906),withsignificantdifferencesnotedbetweensessiononeandsessiontwo,althoughnostatisticallysignificantdifferenceswereobservedbetweensessiontwoandsessionthree.Betweensessions,theSLDJ-Rwasconsideredunreliable(r=

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0.759),yetSLDJ-Lwasconsideredreliable(r=0.875)(Table4.2),withnosignificantdifferencesobservedbetweendays.DespiteasignificantdifferenceexistingbetweentestingdayoneandtestingdaytwoforperformanceofCMJ,onecouldconcludethatalearningeffectdoesnotexist,asthevaluesdecreasebetweendayoneandtestingdaytwo.Inaddition,whenconsideringtheeffectsizepresentedforCMJistrivial(Partialetasquared=0.329),thesignificantdifferencesnotedbetweensessiononeandsessiontwocouldbequestioned.ThereasonsforthisdifferencecouldperhapsbeexplainedbytheCMJstrategyemployedbytheplayers.Thedepththatplayersmovedtoontestingdayoneandtestingdaytwomayhavediffereddespiteattemptsmadetostandardisetheprotocol,yetthisisnotconsideredaconcernasthisstudywantedtoidentifyvariationacrosstestingdays.

AsreportedinsimilarresearchassessingjumpperformancesusingtheOptoJump,Glatthornetal.(2011)consideredOptoJumptobereliablefordetectingchangesinlongitudinalassessmentsverifyingtheeffectivenessoftrainingprograms,whenassessingCMJandSJ.Glatthornetal.(2011)notedhighICCvalues(mean0.985)andrandomerrorsaveraged2.81cm(2.7%).Withinthisstudy,SDDwasnotedas0.65cm(1.7%)forCMJand1.08cm(3.0%)forSJ.WhentryingtoidentifyNMFusingCMJ,jumpheight,assessedfromflighttimeusingtheforceplate,hasbeenconsideredtobethemostpreciseandreliableinstrument.However,inmanyteam-basedscenariosaforceplateisnotreadilyavailable,thereforetheOptoJumpwouldbethenextbestalternative,withadifferenceofgreaterthan0.49cm(1.3%)signifyingameaningfulchangewithin-sessionandadifferenceofgreaterthan0.65cm(1.7%)signifyingameaningfulchangebetweensession.Despitedifferencesexistingbetweensessiononeandsessiontwo,thesensitivityidentifiedforCMJ(0.65cm;1.7%)isapositivefindingofthisresearchandonethatshouldbeconsideredbypractitioners.

4.5.3 LimitationsofthisstudyThesmallsamplesizewithinthisstudycouldbeconsideredalimitation,yettheimplementationofeffectsizecalculationalongsideRMANOVAinaccordancewithrecommendationsbyBuchheit(2016)toassessmagnitudedisputethis.Thetrivialeffectsizefindingsinthisstudythereforefurthersupportstheuseofthissmallsamplesizeutilisingeliterugbyunionplayers.Anotherpossiblelimitationofthisstudysurroundstheself-selectedjumpprotocolforalljumpsbytheplayers.Playerswerenotedtoadoptdifferingjumptechniques,mainlywhereby;depthofbothSJandCMJonthedownwardphasevariedandwidthofstancewasindividuallyselectedwhichcouldhavealteredresults.Inaddition,thetechniqueadoptedduringtheSLDJ-LandSLDJ-Rdifferedmostlyonthestartofthejumpweresomeplayerswerenotedto“dropoff”theboxandsomewerenotedto“jumpoff”theboxontothelandingsurfacebelow.It,however,couldbearguedthatthisvariabilityinjumptechniqueimprovedtheecologicalvalidityofthisstudy,asnotallplayerswouldmoveinthesamemannerpossiblyduetoinnatelocomotionskillsdevelopedfromanearlyage.


DespiteunilateraljumpsbeinglikelytoidentifyNMFmoreeasily,resultsfromthisresearchquestiontheirreliability.Thelargediscrepanciesinresultsforunilateraljumps,mainlyassociatedwithparticipanttechniqueadopted,meanthatbilateraljumpsshouldbeusedforperformanceassessmentinsteadofunilateral,withCMJbeingthejumpmodalitythatwouldproducethemostreliablemeasureofperformance.Achangeof0.65cm(1.7%)canbeconsideredmeaningfulwhenassessingeliterugbyunionplayersperformingCMJandthereforethisvaluecanbeimplementedtoassessperformancemeasuresandreadinessonadailybasis.

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TheidentificationofCMJasmorereliablethanSJandSLDJmeansthataneednowexiststoassessifCMJassessmentconductedonanOptoJumpisasvalidasthatofthe“goldstandard”forceplate.AssessmentofOptoJumpvalidityisofimportance,astheapplied“realworld”settingwithinwhichfuturetime-courseofrestorationofperformanceinvestigationsaretobeconductedisnotsuitableforregularforceplateuse.Inaddition,jumpheightneedstobecomparedagainstkineticmeasurestowarrantitsuseinfollowingexperimentalchapters.

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5 CountermovementJumpinEliteRugbyPlayers–Acomparisonbetweendevices

5.1 Abstract

Methodsofassessingpoweroutputviaopticalmeasuringsystemshavebeenquestioned,despiteforceplatesusedinmanyenvironmentsduetotheiraccuratemeasurementofjumpheight.Forceplatesare,moreover,expensiveandimpracticalforuseinmanyteamsportsettings.ThisstudydeterminedthevalidityoftheOptoJump,whichcalculatesjumpheightfromflighttime,bycomparingCMJheightmeasuredbythesamemethodonaforceplate.ThisstudyalsocomparedCMJperformance,usinganOptoJumpmeasuringflighttime,tothatofaforceplateusingthetake-offvelocitymeasure,toexaminejumpheightasaneffectivemeasureofneuromuscularperformance,whilealsoprovidinga“sensecheck”forOptoJumpvalidity.Lastly,jumpheightmeasuredonaforceplateusingvelocityofcentreofmassattake-offwascomparedtothatofaforceplateusingtheflighttimemeasure,withtheassessmentofeccentricRFDalsoconsideredwithinthisanalysis.ResultsfromthisstudyindicatethatasignificantcorrelationexistsbetweenCMJheightmeasuredonanOptoJumpandCMJheightmeasuredonaforceplatealsocalculatedviaflighttime(ρ=0.907;p<0.05;r=0.924),thereforesupportingOptoJumpuse.Weakercorrelationswere,however,notedbetweenOptoJumpCMJheightandCMJheightmeasuredonaforceplateviavelocityattake-off(ρ=0.202;p>0.05;0.449)andbetweenCMJheightmeasuredonaforceplateviaflighttimeandCMJheightmeasuredonaforceplateviavelocityattake-off(ρ=0.210;p>0.05;0.410),whichcouldpossiblybeexplainedbysubjectsnotstandingstillontheforceplatepriortojumpcommencing,therebyaffectingthedeterminationofbodyweight.Additionally,resultssupporttheuseofOptoJumpjumpheight(CV<10%)whencomparedagainsteccentricRFD,whichwhenassessedonaforceplateexhibitlowerreliabilitybetweensessions(CV>10%).JumpheightfromCMJonanOptoJumpisthereforerecommendedasareliablemeasureofneuromuscularperformanceandprovidessupportfortheuseofCMJasameansforassessmentwithinrealworldsettingswhereuseofforceplatesisunrealistic.

5.2 Introduction

Jumptestingprotocolshavebeenscrutinised,withspecificjumpandpowertestingtoolscomingundercriticism,mainlyduetoincorrectdataanalysismethodsand/orthetestingofsubjectswhoareincapableofperformingthejumpscorrectly.Numerousinstrumentsmeasuringjumpheightandcontacttime(usingdifferenttechnologiesandcalculations)haveprovidedvaryingresults(Markovicetal.,2004).Forceplateshavebeenconsideredthe“goldstandard”forthemeasurementofjumptestsandhavebeenreportedtoprovideexcellentmeasurementaccuracyforestimationofpowerviaforwarddynamics,calculatedbytheforceappliedtothejumpingsurface(Owen,Watkins,Kilduff,Bevan,&Bennett,2014;Walshetal.,2006).Jumpinstruments,suchasopticalmeasuringsystemsthatsolelyassessflighttimeanddonotdeterminejumpheightfromtheimpulsemomentumrelationship,asusedbyDomireandChallis(2007),areopentoquestion,assubjectscanalterjumptechnique,suchasaflexedfootonlandingtoincreaseflighttime.Bycontrast,forceplateassessment,whichusesverticalvelocityofthecentreofmassattake-off,providesamoreaccuratemeasureofjumpheight,usingaforwarddynamicsapproach.Theoptimalmethodofdeterminingtake-offvelocityduringjumpsisproposedbyOwenetal.(2014)toinvolveanalysisofthecorresponding

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verticalcomponentofthegroundreactionforce(VGRF).TheVGRFiscalculatedfromthetimebefore(30ms)thestartofthejumpuntiltake-off,withtheimpulsemomentumrelationshipappliedtodeterminevelocityofthecentreofmass.Itsreliabilitywassupportedinpriorresearch(variability<±1%)(Street,McMillan,Board,Rasmussen,&Heneghan,2001).Owenetal.(2014)recommendedtheimplementationofa1000Hzsamplingfrequency,withthemeangroundreactionforcemeasuredforonesecondwhilestationarypriortojump,inordertoenablevalidmeasurementofbodyweight,whichisintegraltoforwarddynamicscalculations.

Themaindisadvantagesassociatedwithforceplatesarethattheyareexpensivetouseandoftenimpracticalinfield-testingscenarios(Casamichanaetal.,2013).Methodsofassessingneuromuscularfunctionviakineticmethods,suchastheforceplate,havebeencriticisedregardingdatacollectionandanalysisprocedures,duetotheirinfluencesonpoweroutputcalculations(Cormieetal.,2007).Significantdifferenceshavebeennotedbetweenjumpheightmeasuredviachangeincentreofmassdisplacementandjumpheightcalculatedusingflighttimeortake-offvelocity(Aragon-Vargas,2000).Muchofthecriticismregardingtheuseofkineticmeasuresconcernsthedifficultyinquantifyingsuchmeasuresandwiththeresultthatthefrequencyoftheiruseislimited.Forwarddynamicshasbeenusedtoassessjumpperformanceinpreviousresearch(Frenchetal.,2004;Owenetal.,2014),withgoodreliabilitynoted(Aragon-Vargas,2000).Aragon-Vargas(2000)assessedfourdifferentmethodsofcalculatingverticaljumpheight,showinggoodreliabilitywithin-sessionforall(r=0.97),withthechangeincentreofmassdisplacementmeasureusedasthecriterionagainstwhichtocomparetheothermethods.Theresultsdemonstratedthatflighttimeyieldsavalidandreliablemeasureofverticaljumpperformance,withtheotherthreejumpmeasures(twomethodsbasedofforceplateverticaltake-offvelocityandonebasedonflighttime)showingexcellentvalidity(r=0.97)comparedtothechangeincentreofmassdisplacementmeasure.

CMJuseforassessingchangeinperformancewithinrugbyunioniscommonplace(Argus,Gill,Keogh,etal.,2012;Darrall-Jones,Jones,&Till,2015;Gathercole,Sporer,&Stellingwerff,2015;Roeetal.,2015),yettheanalysisofCMJhasgenerallybeenlimitedtojumpheightassessmentandonlyrelatestotheconcentricphaseofverticaljumps(Cormie,McBride,&McCaulley,2009).Recentresearch(Gathercole,Sporer,&Stellingwerff,2015;Kennedy&Drake,2017a)hasthereforelookedateachofthephasesofthejumpandthewayinwhichthesubjectmovesthroughoutthistripleflexionandtripleextensionmovement.ThethreecommonlyreportedphasesofCMJincludetheunweightingphase,thebrakingphaseandthepropulsivephase,yetthesephasesareoftenmisunderstoodwhenassessingforce-timecurvesalone.Theun-weightingphaseinvolvestheonsetofdownwardmovementofthetrunktothepeaknegativevelocity;whilethebrakingphaseinvolvesthedecelerationofthedownwardmovementfrompeaknegativevelocitytowhenthemovementbecomesstationary.Lastly,thepropulsivephaseinvolvesmovementstartingfromthelowestpositionofthecentreofmasstotheinstantoftake-offwhenperformingaCMJ.

SupportforthereliabilityofOptoJumphaspreviouslybeenreportedbyGlatthornetal.(2011),whonotedveryhighICCsforCMJheightderivedfromflighttimeonbothanOptoJumpandCMJheightmeasuredonaforceplateviaflighttime,despitesystematicdifferencesoccurringbetweeninstruments(-1.06cm;p<0.001).Glatthornetal.(2011)notedexcellenttest-retestreliabilityoftheOptoJumpCMJheightmeasurement(ICC0.989;CV2.2%),althoughthejumpprotocolimplementedinthisstudyandthesubjectsusedwerenotconsideredeliteandthereforecomparisonsshouldbemadecautiously.Additionalpreviousresearch(Cormack,Newton,McGuigan,&Doyle,2008)hascalculatedthereliabilityofCMJvariablesinelite

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Australianrulesfootballplayers,reportinghighreliabilitywithin(1.1–1.7%)andbetweensessions(1.0–5.7%)formultiplekineticmeasures.However,findingsbyNibali,Tombleson,Brady,andWagner(2015)notedaverageeccentricRFDnottobereliable(CV21.3%),withconcernthereforeadvised,asaverageeccentricRFDmaynotbesensitivetotraininginducedchanges.Whenassessingkineticdata,Nibalietal.(2015)alsonotedthatverticaljumpstaskscanbeperformedwithouttheneedforfamiliarisation,withaverageconcentricforceandconcentricimpulsebeinghighlyreliable(CV2.7%),althoughjumpheightwasnotedastheonlyvariabletodisplaya%CVsmallerthantheSWC.WhenconsideringthesefindingsbyNibalietal.(2015),theneedforvalidityofthismeasurefortestingbothwithinandbetweensessionsisneeded.

OtherresearchofinterestregardingkineticmeasuresincludesthatbyMarquesetal.(2014),whoassessedverticaljumpsandreportedjumpheight,RFDandpeakforcealltobehighlyreliable(jumpheightCV7.0%,ICC0.89;RFDCV11.6%,ICC0.91;peakforceCV6.1%,ICC0.92).However,researchshowingrelationshipsbetweeneccentricRFDandCMJperformanceareconflictingwithMcLellanetal.(2011d)assessingtheRFDonverticaljumpperformanceandnotingpoorretestreliability(CV16.3%)withintwentythreephysicallyactivemen.McLellanetal.(2011d)did,ontheotherhand,notethatsignificantcorrelationsbetweenmaximumRFDandjumpheightcouldonlyexplain46%ofthevariancenotedinjumpheightandthattheothervarianceislikelytobeduebothtotheinexperienceofthesubjectsperformingthisexplosivemovementandthetestingprotocolimplemented.Additionally,researchbyEbbenetal.(2007)notednocorrelationbetweenaverageRFDandCMJ(r=0.19,p=0.22)andthereforequestionedtheusefulnessofRFDforassessingCMJperformance.

TheaimofthisstudywastocompareCMJperformanceusingdifferentdevices;oneusingjumpheightmeasuredviaflighttimeonanOptoJumpandtwomethodsofassessmentfromaforceplate,usingfirstlyvelocityofcentreofmassattake-offandsecondlyflighttime.Theresultsofthisresearchwillalsodeterminetestre-testreliabilityofajumpheightmeasurement;therebyprovidinga“sensecheck”forfuturechapterswithinthisthesisandinformingonwhetherornotjumpheightalonecandemonstratesensitivityofneuromuscularperformancewhenassessedviaCMJ.Baseduponpriorfindings(Glatthornetal.,2011;Jensen,Furlong,Graham,&Harrison,2011),itwashypothesisedthatjumpheightfromCMJonanOptoJumpwouldbejustasvalidameasureofneuromuscularperformancecomparedtojumpheightcalculatedonaforceplate.Additionally,baseduponpriorfindings(McLellanetal.,2011d;Moiretal.,2009;Nibalietal.,2015)itwasalsohypothesisedthatRFDforassessingjumpperformanceisnotasreliableameasureofassessingneuromuscularperformancecomparedtojumpheight.ThisnotionthereforesupportstheuseofCMJusingtheOptoJumpasameansforassessmentwithinrealworldsettings,wherethetimeconsuminganalysisassociatedwithforceplatesmeanstheiruseisoftenunrealistic.

5.3 Method

5.3.1 ParticipantsSeveneliterugbyunionplayers(age21.0±4.7years,height185.0±8.6cm,mass89.0±8.2kg)fromthesameprofessionalrugbyclubvolunteeredfortheassessmentoftheCMJheightagainstkineticmeasures(jumpheight,andmeaneccentricRFD).Participantswereallhealthyandactiveindividualswhohadnocurrentinjuryissues.AllsubjectsprovidedwritteninformedconsenttoparticipateandSalfordUniversityResearchandEthicsCommittee

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approvedthestudy.ThesamplesizesusedwithinbothresearchgroupswereconsideredsatisfactoryinaccordancewithguidelinesprovidedbyHopkins(2000).

5.3.2 ProcedureTheassessmentoftwoCMJtrialsacrossthreetestingdayswasconducted,withnogreaterthansevendaysbetweeneachassessment.TheCMJprotocolwasstandardisedthroughoutthethreetestingdays,withappropriatewarmupgivenpriortotestingandadequaterestadministeredbetweeneachtrial.Inaccordancewithpreviousresearch(Cunninghametal.,2013;McLellan&Lovell,2012;McLellanetal.,2011b;Westetal.,2014)thatusedkineticmeasures(RFD)toassessneuromuscularfunctionpreandpostrugbyunionmatchplay,thisresearchusedRFDtocompareagainstCMJperformance.JumpHeight(JH)measuredincm,andmeaneccentricRateofForceDevelopment(RFD)measuredin(N.s-1),providedmoredetailaboutCMJperformanceandassessedthereliabilityofCMJvalueswhenmeasuredviaOptoJump.AcustomMicrosoftExceldatacollectionsheetwasusedwithinthisresearchtocomparethevalidityofjumpheightbetweeninstrumentsandtocalculateperformancesfromforce-timedataagainstkineticmeasures(JHandmeaneccentricRFD),withthestatisticalanalysisperformedinSPSS.

Supportfortheuseofusinga0%loadforassessingjumpperformanceinordertomaximisepoweroutputwasnotedbyCormie,McBride,andMcCaulley(2008),withMcBrideetal.(2002)alsonotingthataccelerationofthesystemmassduringasquatjumpdecreasesastheexternalloadisincreased.Thismethodologicalrationaleisalsomorepracticallyrelevantforusewithinelitesettings,asitisoftennotviabletoimplementloadedjumpsincompetitionandtrainingsettings.Playersworeappropriatefootwearforeachjumpandweregiventhesameverbalinstructionspreeachattempt.Despitethetestingbeingconductedpost-match,theinfluenceofgameswasconsideredtobeunlikelytohaveaninfluenceuponresults,asthetime-pointsofassessmentwereconsistentthroughoutthisstudyandthetrainingandmatchprotocolpriortotestingcommencingoneachoccasionwasstandardised.Inaddition,astheplayerstestedwithinthisstudywereaccustomedtogamesandasthistestingwasconductedduringthenormalcompetitivephaseoftheplayers’season,possibleeffectsofmatchfatiguewereunlikelytohaveanadverseimpactuponresults.

5.3.2.1 CountermovementJump(CMJ)techniqueTheCMJwasperformedfromastandingpositionwiththewholeplantarpartofthefoottouchingthejumpingsurfacewiththehandsrestingonthehips.Arapidcountermovementwasconductedbytheparticipantuntilthekneeanglereachedapproximately90°,thenimmediately,theparticipantjumpedashighastheycould,withtheirlegsremainingstraightuponflight,thereforepreventinganytuckedlegswhichwouldleadtoinaccuratemeasurementofjumpheightderivedfromflighttime.Uponlandingtheparticipantsmadecontactwiththetestingsurfacewithlegsextended,onlyflexingthekneesenoughtoabsorbtheimpactoncecontacthadbeenmadewiththefloor.Priortoeachjumptheparticipantwasencouragedtojumpashighaspossible.Post-jump,participantsreceivedverbalfeedbackabouttheirperformance.

5.3.2.2 Instruments

5.3.2.2.1 ForceplateTheforceplateusedinthisstudywasa400sPerformanceForcePlate(Innervations,Adelaide,Australia)operatedbysoftware(BallisticMeasurementSystem,FitnessTechnology).Theforce

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platewassettorecordforfiveseconds,samplingat600Hz,initiatedusinganexternaltrigger.ThissamplingfrequencywaswellwithintheguidelinespresentedbyHorietal.(2009),whorecommendedthatpractitionersconsidersamplingaslowas200HzforCMJassessment.Theforceplatewaszeroedbeforetestingcommenced,sothattheweightoftheparticipantwouldnotinfluencethemeasurement.Thethresholdfordeterminingtake-offandtouchdownwassetat5Nforallparticipants,inlinewithotherrecentresearch(Castagnaetal.,2013).

5.3.2.2.2 OptoJumpTheOptoJump(Microgate,Bolzano,Italy)wasusedtoassessflighttimeandtocompareagainstthecriterionmethodoftake-offvelocityontheforceplate,whichhadpreviouslybeenshowntohaveexcellentreliability(Glatthornetal.,2011).Similarlytothisstudy,TwistandSykes(2011)usedanOptoJumpintheirstudyofexerciseinducedmuscledamagefromsimulatedrugbyleaguematchplay.TheOptoJump(previouslyreportedinmoredetailwithinchapter4.3.3.1)wasplacedontopoftheforceplateonthegymfloor,withplayersstandingbetweentheOptoJumpbarswhenjumping.

Figure5.1:Anillustrationofthetestset-up,showingtheOptoJumpsittingalongsidetheforceplate

5.3.2.3 Dataanalysis

5.3.2.3.1 JumpHeightandFlightTimeFlighttimewasusedtocalculateOptoJumpjumpheight,withbothflightandtake-offvelocityusedtocalculatejumpheightfromforceplateforce-timedata.Jumpheightwascalculatedviaflighttime,usingthefollowingequationutilisedbyMcMahonetal.(2015),adaptedfromthatproposedbyBoscoetal.(1983).

JumpHeight=(9.81m.s-2xflighttime2)/8

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5.3.2.3.2 Force-timeanalysisForce-timeanalysisusestheimpulse-momentumrelationshiptodeterminevelocity,whichcalculatespowerthroughtheforwarddynamicsapproach(Cormieetal.,2007).KineticvariableswereassessedforboththeeccentricandconcentricphasesoftheCMJ.EccentricRFDconcernstheaverageforceexertedduringtheeccentricphaseoftheCMJandismeasuredinN.s-1,withtheabilitytohandlethemaximaleccentricforceintheminimaltimepossiblebeingatypicalindicatorofexplosivestrength.RFDrelatestoshortdurationcomponentsoftheSSCandarecharacterisedbytime-displacement(100to250ms)oftheankle,kneeandhipjointsduringCMJ.Theeccentricphaseconsistsofthepointinthedownwardmovementwheretheforcebeingexertedintotheforceplateexceedsbodyweight,untilthepointofzerovelocityatthelowestpointofthecountermovement.Inrecenttimes,theuseofRFDhasbeenemployedasamorespecificpredictorofexplosivestrength,incontrasttotheterm“power”thatisusedtoindicatemaximalexerciseperformance.Similarly,asreportedbyGathercole,Sporer,Stellingwerff,etal.(2015a)andbasedupontheresearchbyOwenetal.(2014),jumpstartthresholdinthisstudywassetatfivetimesthestandarddeviationofthenoise,inordertocalculatethestartofthemovementandtoimproveaccuratedatacollection.

Previousresearchhasutilisedtheflighttimecalculationviatheheightofriseofcentreofmass(Frenchetal.,2004;McBrideetal.,1999,2002).Theverticaltake-offvelocityofthecentreofmassiscalculated,wherebyacceleration(a)isdeterminedbydividingverticalgroundreactionforces(F)bythemassofthesystem(SM)ateachtimepoint.Asaccelerationandvelocityaretwodifferentmeasurements,accelerationismultipliedbytimetoprovidevelocity:

! = !/!"

Jumpheight(JH)fromvelocityofcentreofmasswascalculatedviathefollowingequation:

!" = (!^2)/(2 ! 9.81)

v=displacement/time

5.3.3 StatisticalAnalysesAllstatisticalanalysiswasconductedonSPSSforwindows,withanapriorialphalevelsetatp<0.05.ReliabilitywasdeterminedusingRMANOVAwithBonferronipost-hocanalysis,ornon-parametricequivalent.Effectsizes(ES)werealsodeterminedusingtheCohen’sdmethodandinterpretedbasedonthecriteriasuggestedbyRhea(2004);trivial=<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.Post-hocstatisticalpowerwascalculatedusingGPower3.1(Fauletal.,2009),foralargeeffectsizeof0.5,atotaln=7wassufficienttodeliveranactualpowerof0.69.Inaddition,partialetasquaredwasassessedtoseeiftherewereanymeaningfuldifferencesbetweentestingdays,asreportedandrecommendedbyCohen(1988).Within-sessionreliabilitywastestedviaintraclasscorrelationcoefficients(ICC)(Model3,1).ThereliabilitywasconsideredacceptableiftheICC≥0.8(Cortina,1993).SEMandsmallestdetectabledifferences(SDD)werecalculatedinordertoprovideinformationforonwhetherornotachangeinanindividual’sperformancewassignificant,withSEMcalculatedusingthe

formula:SD pooled ∗ 1 − ICC andSDDcalculatedfromtheformula:( 1.96 ∗ 2 ∗SEM).Inlinewithpreviousresearch(Cormack,Newton,McGuigan,&Doyle,2008;Marquesetal.,2014;McMahonetal.,2016),assessingjumpperformancemeasuresinbothteamandindividualsports,ameasuremustdemonstrateaCV<10%tobeconsideredreliable,withpractitionersthereforeneedingtoassess,ifthischangeisofpracticalsignificance.

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5.4 Results

5.4.1 JumpheightmeasuresfromOptoJumpandforceplateShapiroWilkstestsofnormalityrevealedthatOptoJumpjumpheight;forceplatejumpheight(flighttimeandtakeofvelocity)andeccentricRFDwerenotnormallydistributed(p<0.05).ReliabilitystatisticsdemonstratedthatOptoJumpjumpheightdisplayedahigherCVwithin-sessionthaneccentricRFD.Within-sessionCMJheightassessedonaforceplate,was,however,lowerthanthatpresentedforOptoJumpjumpheight(Table5.1).

Between-sessionreliabilitywasconsideredtobeacceptableforOptoJumpjumpheight,forceplatejumpheightfromflighttimeeccentricandRFDmeasuresofCMJ(ICC>0.8),althoughnotforjumpheightfromvelocityattake-offonaforceplate.OptoJumpjumpheight,forceplatevelocityattake-offandforceplateflighttimeillustratedlowerSDDthaneccentricRFD(Table5.2).AstrongpositiveSpearman’scorrelationwasnotedwhencomparingOptoJumpjumpheightandforceplatejumpheightwithflighttime(ρ=0.907;p<0.05;r=0.924)(Figure5.2),yetpoorcorrelationswerenotedbetweenforceplatevelocityattake-offandforceplateflighttime(ρ=0.210;p>0.05;r=0.449)(Figure5.3)andbetweenjumpheightfromvelocityattake-offonaforceplateandjumpheightderivedfromflighttimeonanOptoJump(ρ=0.202;p>0.05;r=0.410)(Figure5.4).

Table5.1:Descriptive(mean±standarddeviations)andreliabilitystatistics,withintestingdaysforCMJheightandRFD(N.s-1)

CMJ Day1average

Day1%CV

Day2average

Day2%CV

Day3average

Day3%CV

Allsessionsaverage

Average%CV

CMJHeightOptoJump(cm)

39.1±0.03 8.31% 37.6±0.02 7.23% 37.8±0.04 10.70% 38.2±0.03 8.74%

CMJHeightForcePlate(Flighttime)(cm)

40.6±0.01 1.69% 39.7±0.01 1.82% 39.8±0.01 2.92% 40.0±0.01 2.14%

CMJHeightForcePlate(VelocityatTake-off)(cm)

39.6±0.05 1.50% 36.8±0.08 2.21% 35.6±0.02 0.56% 37.3±0.05 1.42%

CMJEccentricRFD(N.s-1)

5242±443 8.9% 4841±466 10.50% 5286±330 6.56% 5123±413 8.67%

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Figure5.2:RelationshipbetweenOptoJumpjumpheight(fromflighttime)andforceplateflighttimeduringthesamejump,usingpooleddata

Figure5.3:Relationshipbetweenjumpheightfromflighttimeonaforceplateandjumpheightderivedfromvelocityattake-offonaforceplate,usingpooleddata

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)

ForcePlateFlightTime(cm)

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Figure5.4:Relationshipbetweenjumpheightfromvelocityattake-offonaforceplateandjumpheightderivedfromflighttimeonanOptoJump,usingpooleddata

Table5.2:Descriptive(mean±standarddeviations)andreliabilitystatistics,betweentestingdaysforCMJheight(cm)andRFD(N.s-1)

Jump Day1(cm)

Day2(cm)

Day3(cm)


SEM(m)

SDD(m)

OptoJumpCMJHeight(cm)

39.1±0.03

37.6±0.02

37.8±0.04

0.895 0.192 0.01 0.03(7.9%)

ForcePlateCMJHeight(Flighttime)(cm)

40.6±0.01

39.7±0.01

39.8±0.01

0.923 0.103 0.00 0.02(6.7%)

CMJHeightForcePlate(VelocityatTake-off)(cm)

39.6±0.03

36.8±0.02

35.6±0.04

0.728 0.528 0.00 0.02(6.2%)

CMJEccentricRFDForcePlate(N.s-1)

5242±1264

4841±1721

5286±1741

0.921 0.111 450.0 1247.5(24.3%)

5.5 Discussion

TheresultspresentedindicatethatasignificantcorrelationexistsbetweenOptoJumpCMJheightmeasuredviaflighttimeandCMJheightmeasuredviaflighttimeonaforceplate.ResultsfromthisstudywouldindicatethatOptoJumpjumpheightisajumpperformancemetricthatcanbeusedinelitesportsettingswhereaccessibilitytoforceplateswithindifferenttrainingenvironmentsaredifficult,thereforesupportingOptoJumpuse.

5.5.1 JumpheightmeasuresfromOptoJumpincomparisontoforceplateTheR2valueofρ=0.907presentedinfigure5.2aboveillustratesthatalinearrelationshipexistsbetweenOptoJumpjumpheightandforceplatejumpheight,withthecorrelationcoefficientofr=0.924furthersupportingthisnotion.Thisstudyandthatofpreviousresearch(Cormack,Newton,McGuigan,&Doyle,2008)notethatjumpheightisthemostreliableofthevariablesmeasured,thereforedisagreeingwiththeclaimbyGathercole,Sporer,andStellingwerff(2015)thatjumpheightreflectsagrossperformancemeasure.Gathercole,Sporer,andStellingwerff(2015)arguedthatdespiteplayersbeingaskedtojumpashighaspossible,itseemsthattheoutcomeandsubsequentvaluespresentedaremorelikelytomanifestthemselvesinmeasuresdirectlyrelatedtotheforceplateratherthantheresultantjumpheightperformed,withfutureassessmentofjumpperformancerecommendedtoinclude

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(cm)

OptoJumpJumpHeight(cm)

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kineticmeasuresinstead.Theresultsofthisstudydonotdisputethisnotionofalteredjumpmechanics,butdoshowthatjumpheightisasimpleandreliablemeasuretobeusedwhenkineticmeasurementtoolsareperhapsnotavailable.

Itisalsoimportantforpractitionerstonotethatthemeanjumpheightvaluesreportedwithinpreviousresearch(Jensenetal.,2011;Marquesetal.,2014)werelower(26cm)thanthosenotedwithinthisstudy.Thisfinding,alongwiththelowerCVvaluesidentified,couldperhapsbeexplainedbythelowerathleticlevelofthesubjectsinvolved.Alongsidetheincorporationofsub-elitelevelrugbyplayersintheresearchbyJensenetal.(2011),itisofnotethattheuseofarmswingwasallowedduringjumpcompletion,whereasnoarmswingwasallowedwithinthetestingprotocolimplementedwithinthisexperimentalstudy,meaningthatcautionregardingcomparisonwouldbeadvised.Previousresearch(Klavora,2000;McLellanetal.,2011d)hasshownthattheuseofarmswingwillresultinanincreaseintake-offvelocitywhencomparedtousingnoarmswing.WhencombiningknowledgeoftheuseofarmswingwiththefindingsinresearchbyMcLellanetal.(2011d),whousedaVertectoassessjumpheight,anyresultantcomparisonofjumpheightvaluesbetweenstudiesshouldbequestioned.Morecrucially,astheVertechasbeenshowntooverestimatejumpheightincontrasttothecalculationfromaforceplate,comparisonbetweensomestudiesisbetterdiscountedaltogether(Ferreira,Schilling,Weiss,Fry,&Chiu,2010).Differencesinabilityoftheparticipantsandthetoolsusedtoassessjumpperformancecould,perhaps,explainthedifferencesseenintheCV’sreported.Theresultsfromthisstudywould,however,supporttheviewsofJensenetal.(2011)forusingOptoJump,whenaforceplateisnotavailable.Althoughanycomparisonbetweenjumpheightvalueswouldbediscouraged,whereparticipantsandmethodologiesdiffer.

Inastudyassessingthevalidityofusingawearableaccelerometricsystem(MyoTest)forassessingverticaljumpheight(Casartellietal.,2010),itwasnotedthatjumpheightmeasuredviaflighttimeonaMyoTestoverestimatedjumpheightcomparedtoOptoJump(p<0.001),withasystematicbiasof7cmnoted,despiteahighreliabilityshown(>0.98).Thissystematicerrorshownforjumpheightassessedviaflighttimecouldpartlyexplainthedifferencesnotedinjumpheightvaluesreportedbetweeninstrumentsinthisexperimentalstudy,whileperhapsprovidingfurtherrationaleforthelowerreliabilitynotedwithin-sessionforOptoJumpcomparedtoRFD.WithintheresearchbyCasartellietal.(2010)itis,however,importanttonotethattwocalculationmethods(flighttimeandverticaltake-offvelocity)wereusedtoestimatejumpheightmeasuredontheMyoTest.Thepeakvelocitycalculatedduringthejumpingmovement,thereforeshouldbequestioned,asitdoesnotrelatespecificallytotake-offvelocity.Additionally,peaknegativevelocityisactuallyameasureofimpactwhichcanconsequentlyleadtooverestimationwithincalculations.Theresultsofthisstudyillustratea2cmdifferenceinjumpheightcalculatedfromforceplatecomparedtothosetakenfromOptoJump.However,whenconsideringthattheforceplatemeasurementstakenwithinthisstudyalsoincorporatedjumpheightfromflighttimeandjumpheightfromvelocityofcentreofmassattake-off,relevantcomparisoncanthereforebemadewiththeresearchofCasartellietal.(2010).

Thecomparisonoftheresultsofthisstudywithpriorresearchisilladvised,asthetestingprotocolimplementedwithindifferentstudiesislikelytovary.Thecomplexityofanytestingprotocolassociatedwithforceplates,meansthatdiscrepanciesindatacollectionareprobable.Oneareaofconcernistheneedtomakesubjectsremainstillonaforceplatepriortojumping.Practitionerscannotassumethatsubjectsaremadetoremainstillonaforceplatepriortojumping,aswasimplementedinpriorresearch(Owenetal.,2014;Streetetal.,2001)andthis

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notioncanperhapsexplainmuchoftheerroneousdataproduced.Protocolinthisexperimentalstudydidnotenforceaperiodofstandingstillanditcouldthereforebeassumedthatthisimpactednegativelyuponthevelocitymeasurementsproduced.Thistestingprotocolandresultantdataproducedcould,however,beconsidereda“realworld”consequenceofforceplatetesting,andwherethealternativeexpectationofplayersbeingenforcedtostandstillpriortojumpmovementisperhapsunrealistic.Asaconsequence,asobservedinthisstudy,manypractitionersdonotimplementastandingstillelementpriortojumptesting.Additionally,thecomplexityofobtainingaccurateforce-timedatacouldperhapsexplainswhymanypractitionerswhouseaforceplateonlyreportjumpheightfromflighttimecalculationsinsteadofviaforwarddynamics.Whenconsideringthatthevastamountofresearchinrugbyhasusedverticaljumpassessment(Darrall-Jones,Jones,&Till,2015;McMahonetal.,2016;Tilletal.,2015;Tilletal.,2014;Twist&Highton,2013;Twistetal.,2012),yettheyreportjumpheightinsteadofkineticmeasures,itcouldbeconcludedthatjumpheightalonecaptureswhatisneededbypractitionersinappliedsettings.Itcouldalsobearguedthatmanypractitionersdonotknowhowtodetermineforwarddynamics,asitscalculationiscomplicated,meaningthatfutureresearchislikelytosteerawayfromtheimplementationofforce-timedata,thusfurtheraddingtotheconfusionsurroundingthisperformancetestingmeasure.

5.5.2 ReliabilityofOptoJumpandforceplateTheresultsofthisstudydemonstratethatjumpheight,measuredviaflighttimecollectedduringasingleCMJonbothaforceplateandanOptoJump,exhibitshighreliability(CV<10%;SDD<10%).TheaveragecoefficientofvariationpresentedforOptoJumpjumpheightmeasuredviaflighttime(CV7.9%)islargerthanthejumpheightmeasuredviaflighttimeonaforceplate(CV6.7%),yetbothmeasuresofjumpperformanceexhibitedhighreliabilitywithinandbetweensessions(Table5.1and5.2).Itis,however,importantforpractitionerstonotethattheconsiderationofthebetween-sessionsvaluesisofmoreimportancethanthewithin-session,asthewithin-sessionvaluesarenotasimportantforassessingchangesinfatiguerequiredfromthisstudy,whilethebetween-sessionsvaluesarelikelytobemoresensitivetothismeasure.Research,ofinterestforpractitionersandthatspecificallyrelatestothisexperimentalstudy,isofferedbyJensenetal.(2011).Whenassessingreliabilityofjumpmeasuresinrugbyunionplayers,Jensenetal.(2011)presentedhighreliability(ICC0.966;CV5.1%)forOptoJumpusingtheflighttimecalculationreportedearlier(Chapter5.3.2.3).Thereforecomparisonsbetweentheseresultsarewarrantedconsideringthatsimilarmethodologiesused.TheresultscollectedwithinthisexperimentalstudyillustratethatthereliabilityofOptoJumpCMJheightissimilartothatreportedbyGlatthornetal.(2011),whonotedveryhighICCs(0.995–0.999)forbothOptoJumpCMJheightandCMJheightmeasuredonaforceplate.WhenconsideringthatjumpheightmeasuredonOptoJumpisnotmeasuredbydisplacementandinsteadcalculatedbymathematicalassumption,thevaryingreliabilitymeasurespresentedareperhapsofnosurprise,withthisfindingsupportedbythesystematicdifferencesidentifiedbyGlatthornetal.(2011)betweenOptoJumpCMJheightandCMJheightmeasuredonaforceplate(-1.06cm;p<0.001).

Inametaanalyticalreviewofthereliabilityofpowermeasurementsinphysicalperformancetests(Hopkinsetal.,2012),itwasnotedthatthelowestCVexpectedfortheassessmentofjumpheightwaslikelytobe2.0%,withCormack,Newton,McGuigan,andDoyle(2008)reportingthereliabilityofjumpheightassessmenttakenfromasingleCMJdemonstratingineliteAustralianrulesplayers(CV<5%).Morerecentresearch,specificallyrelatingtorugby(Roeetal.,2015),showedacceptablereliability(CV2.14%)forCMJpeakforce,yetdidnot

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reportjumpheightreliabilitymeasures.Roeetal.(2015)did,however,reportthatsuchreliabilitytestingshouldbebothpopulationandsportspecific,whichmayexplainthedifferingvalues,reportedbetweenstudies.Previousresearch(Cormack,Newton,McGuigan,&Doyle,2008;Tayloretal.,2010)assessingjumpperformancehasadoptedarbitrarythresholdvaluesof10%CVasshowing“goodreliability”.Withinthisexperimentalstudy,bothmeasuresofjumpheight(OptoJumpandforceplate)thereforeexhibitacceptablereliabilitybetweensessions(CV<10%),assimilarlyclassifiedwithinotherjumpperformanceresearch(Cormack,Newton,&McGuigan,2008;Cormack,Newton,McGuigan,&Doyle,2008;Tayloretal.,2010).DespiteAragon-Vargas(2000)notingexcellentreliability(CV13.4%to18.3%)forverticaljumponaforceplate,thisstudycouldarguethatthesevaluesdonotrepresentexcellentreliabilityas,thevaluesreportedwithinTable5.1arelower,despitesimilarmethodsofassessmentbeingused.

Fromtheresultsassessingreliabilitybetweensessions,itisclearthatjumpheightmeasuredontheOptoJumpofferslessreliability(CV7.9%),whencomparedagainsttheforceplatejumpheight.Thebetween-sessionvaluesnotedforOptoJumpCMJheightappearlessreliable(ICC0.775–0.895),thanthoseofGlatthornetal.(2011)(ICC0.998).However,asthejumpprotocolsimplementedwithinthetwostudiesdiffer,carefulconsiderationiswarrantedpriortoanycomparisonsbeingmade.Notonly,didtheset-upoftheOptoJumpontheforceplatedifferbetweenthestudies,butalsotheforceplateusedandthesamplingfrequencyset.ThisstudywouldthereforesupporttheviewsofGlatthornetal.(2011),whonotedthatthediscrepancynotedbetweenOptoJumpCMJheightandCMJheightmeasuredonaforceplatemaybemostlikelyexplainedbytestset-up.ThemisalignmentofthephotoelectricalcellsassociatedwiththeOptoJumpcouldhaveexplainedsomeofthedifferencesseen,alongsidethenotionthatasubject’sfootmayhavebrokentheelectricalcellbutnotyetlandedontheforceplate.Inaddition,itmustbeconsideredbypractitionersthatanypotentialdifferenceinsensitivityofelectricalcells(OptoJump),incomparisontothatofverticalreactionforces(forceplate),mayalsoaccountforthedifferencesnoted.

Previouswork,utilisingatimingmat,hasshowndisplacementofthecentreofgravityinCMJperformedonatimingmattobeareliablemeasurewithCVof6.3%(Arteaga,Dorado,Chavarren,&Calbet,2000).Similarly,Markovicetal.(2004)alsousedacontactmattodetermineCMJreliabilityandreportedanICCofr=0.98andTEvaluesof2.8%.TheresearchbyGlatthornetal.(2011)isperhapsthemostusefulforcomparisontothisexperimentalstudy,astheOptoJumpwasalsousedindeterminingreliability.AdditionalresearchofnoteforpractitionersisthatbyCasartellietal.(2010),whichillustratedhighreliability(ICC0.92-0.96)forMyoTest(flighttime),butpoorreliability(ICC0.56-0.89)forMyoTest(verticaltake-off),thereforedemonstratingtheunsuitabilityofusingflighttimemeasurementsandtheimportanceofcomparingsimilarcalculationswhenassessingkineticdata.

Lastly,supportforthereliabilityofCMJheightwasnotedbyCormack,Newton,McGuigan,andDoyle(2008)(CV2.4%;ICC0.93)whenassessingeliteAustralianrulesfootballplayers.AlthoughtheaverageCMJheightvaluesreportedbyCormack,Newton,McGuigan,andDoyle(2008)arehigher(48.8cm)thanthosereportedwithinthisresearchandthereliabilityreportedislower,(CV5.2%),comparisonscanstillbemade.Thedifferencesinreliabilityvaluesbetweenthesestudiescouldbeexplainedbythemethodology.Firstly,thestudybyCormack,Newton,McGuigan,andDoyle(2008)involvedathletesfromAustralianrulesfootballandthereforetheirphysicalperformanceabilitiesofaCMJarelikelytodiffer.Secondly,itisalsoimportanttonotethatalargersamplesizewasincorporatedwithinthisstudycompared

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tothatofCormack,Newton,McGuigan,andDoyle(2008).This,alongwiththesamplingfrequenciesusedalsodifferingbetweenprotocols;perhapsexplainthedifferencesreportedinreliability.

5.5.3 JumpheightincomparisontoRFDDatainresearchsettingsthatshowarelationshipbetweenRFDandCMJheightislimited,althoughfindingsfromthisexperimentalstudyshowthateccentricRFDmeasuredontheforceplatepresentssimilarreliabilityvalueswithin-session(CV8.6%)tothatofjumpheightmeasuredontheOptoJump(8.8%).Bothwithinandbetween-session,jumpheightmeasuredonaforceplateillustratedthemostreliablemeasureofCMJassessment,thereforesupportingitsnotionasthe“goldstandard”toolofmeasurement.Thefindingfromthisexperimentalchapter,reportingthatjumpheightassessedviaOptoJumpillustrateslowerreliabilityvalues(CV8.8%)comparedtoRFD(CV8.6%)within-session,issurprising.Kineticmeasuresarenormallyamoreinformativemeasurethanjumpheight,butthecontrastingfindingsfromthisstudyareperhapsduetothelackofaproperpre-jump“silentperiod”implemented.Onecannotthereforedismisstheuseofkineticmeasuresforjumpperformanceassessmentinfuturepractice,butcanincludepriorknowledgeofaforementionedRFDinaccuracieswhenmakingjudgements.

Despitetheabilitytodevelopforcerapidlybeingaprerequisiteforexplosivestrength,ascarcityofknowledgeregardingRFDcorrelationstoverticaljumpexist.TheavailabilityofreliabilitystatisticsforeccentricRFDislimited,withMoiretal.(2009)reportinglowerRFDvalues(CV17-21%)thanseenwithinthisstudy,yetitmustbenotedthatthevaluespresentedbyMoiretal.(2009)arefromnon-elitemenandwomenandthereforecannotbecompareddirectlywiththeeccentricRFDvaluespresentedwithinthisstudy(ICC0.921,CV24.3%).McLellanetal.(2011d)assessedRFDonverticaljumpperformanceusingaforceplate,notingpoorre-testreliability(CV16.3%)withintwenty-threephysicallyactivemen.Inrelationtotheresultsfromthisstudy,eccentricRFDalsodisplayedlowreliability.However,animportantpointforconsiderationwhencomparingtheresultsfromthisstudywiththeresearchofMcLellanetal.(2011d)isthatthisstudyusedadifferingsamplingfrequency(600Hz)tothatofMcLellanetal.(2011d)(1000Hz).AdditionalfindingsbyNibalietal.(2015)notedeccentricRFDnottobereliable(CV21.3%),withcautionadvised,aseccentricRFDmaybesensitivetotraininginducedchanges.ItisalsoimportanttonotethatNibalietal.(2015)didobservethateccentricRFDwassensitivetofatigue,thereforesupportingitsusewithinfatigueassessmentusingjumpingmovements,asisproposedinlaterchaptersofthisstudy.AswasrecommendedbyNibalietal.(2015)furtherinvestigationiswarrantedregardingthesensitivityofeccentricRFDtofatigue.

TheresultsofresearchbyMarquesetal.(2014),assessingthereliabilityoftime-forcevariablesusingalinearpowertransducer,arealsoofinteresttothisexperimentalstudy.Similartothisstudy,Marquesetal.(2014)concludedthatusingjumpheightcalculatedduringaCMJconstitutesavalidlower-bodymeasureofperformance.Marquesetal.(2014)alsoassessedverticaljumpsandreportedjumpheight,RFDandpeakforcealltobehighlyreliable(jumpheightCV7.0%,ICC0.89;RFDCV11.6%,ICC0.91;peakforceCV6.1%,ICC0.92).WithintheresearchbyMarquesetal.(2014),RFDwasdemonstratedtohavethelargestcorrelationwithjumpheight,withgreaterRFDbeingassociatedwithgreaterjumpheightandRFDreportedaslikelytoexplain69%ofthevarianceinjumpheightreported.TheuseofalinearpowertransducerwasnotedasreliablebyMarquesetal.(2014)forassessingforce-timedataduringCMJandwasrecommendedforusewhenthemoreexpensiveoptionofaforceplatewasnot

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available.Similarlytoasnotedwithinthisstudy,Marquesetal.(2014)concludedthatusingCMJjumpheightconstitutesavalidlower-bodymeasureofperformance.WithintheresearchbyMarquesetal.(2014)RFDdemonstratedthelargestcorrelationswithjumpheight,withgreaterRFDbeingassociatedwithgreaterjumpheightandRFDlikelytoexplain69%ofthevarianceinjumpheightreported.TheresearchbyMcLellanetal.(2011d)alsonotedasignificantrelationshipexistedbetweenverticaljumpdisplacement(VJD)andPRFDfortheCMJ(r=0.68;p=0.001),yettheresultsfromthisstudywouldcontradicttheseviews,as,despiteeccentricRFDwithinthisstudyshowinghighICCvalues,nocorrelationexistedbetweenOptoJumpjumpheightandRFD,whiletheSDDreported,illustratesthevariabilityassociatedwiththiskineticmeasure.

PerhapsmostimportantlyforfutureconsiderationwithintheassessmentofRFDvalues,istheunderstandingofhowthiskineticmeasureiscalculated.PriorresearchsuchasMcLellanetal.(2011d)reportspoorreliabilityforRFD,butdoesnotdeterminefromwherethismeasurewastaken.ThisexperimentalchapterassessedeccentricRFD,yetotherstudiessuchasMcLellanetal.(2011d)couldhavetakenaconcentricmeasureofRFD,oracombinationofbotheccentricandconcentricRFD,resultingintwopeaksontheforcetrace.ThisnotionofpoorclassificationandunderstandingofRFDassessmentwouldthereforefurthersupporttheuseofOptoJumpjumpheight.FurthersupportforthereliabilityofjumpheightassessedviaOptoJumpisillustratedinthisexperimentalstudy,whereOptoJump(CV7.9%)demonstratedbetterreliabilityvaluescomparedtoRFD(CV24.3%),whenassessingCVvaluesalone.Figures5.3and5.4showedthatpoorvariabilityinassessmentoccurredwithinkineticmeasures,aswasillustratedbythecorrelationvaluespresented.Theweakcorrelationsexistingbetween,firstly,jumpheightmeasuredonanOptoJumpandjumpheightcollectedonaforceplatefromvelocityattake-offandsecondlyjumpheightcollectedonaforceplatefromvelocityattake-offandjumpheightcollectedonaforceplateviaflighttime,aremostlikelytobeexplainedbythelackofaproperpre-jumpsilentperiod.

5.5.4 LimitationsofthisstudyWhenconsideringthatsomeparticipantsmayhavecarriedoveraleveloffatigueormusclesorenessintothesetestingdays,theresultantinfluencethismayhavehadupontheCMJperformanceneedstobenoted.Despitethetestingbeingconductedduringthecompetitivephaseofaplayingseasonandtestingstandardisedposteachgame,theinfluenceoftrainingandorlifestylechoicesmayhaveinfluencedtheCMJperformance.Theselimitationsareconsideredtobe“realworld”factorsintestingeliteplayers,wheredaysbetweengamesvary,trainingloadisoftenhighandthenotionofpractitionersbeingabletoinfluencetrainingschedulesbasedupontheneedforensuringreliabilityoftestresultsisunlikely.Additionally,afurtherpotentiallimitationofthisresearchsurroundstherelativelysmallsamplesize(n=7)usedwithinthisexperimentalstudy.AnincreasedsamplesizewouldhaveaddedgreaterdepthandbreadthtotheknowledgebaseofaCMJheightonanOptoJumpincomparisontothattakenfromaforceplate.

Anotherpotentiallimitationofthisstudyistheprotocolimplemented.ItcouldbearguedadditionalanalysisofallphasesandrelatedcharacteristicsofaCMJwouldbenefitpractitionerswhenassessingchangesinperformance.PhasesofaCMJsuchtheun-weightingphaseandthebrakingphasewouldprovidemoreinformationontheneuromuscularstrategyofthejump.However,aspreviouslydiscusseditisimportanttonotethataprotocolofkineticmeasurementusingaforceplateisunrealisticforthissettingandisinsteadbetterforresearchpurposes.Assessmentusingforceplatewouldnotbetime-efficientforasquadofupto50rugbyplayers,

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wheretherearelikelytobetimepressuresfromcoachestocompletetrainingsessionsandpost-matchdebriefs,priortothenextgamecommencing.Lastly,withinthisstudytheincorporationoftheOptoJump3mmabovetheforceplatewasnotconsideredaconcern,asthisanalysiswasconductedwiththeaimofassessingthereliabilityofthesameinstrumentandwasstandardisedthroughouttesting.However,theresultsfromthestudybyHealy,Kenny,andHarrison(2016),showinganunderestimationinflighttimewhenassessingdropjumps(RSI),areworthconsideration.Healyetal.(2016)notedthatthisunderestimationcouldperhapsbeexplainedbydifferencesinthecalculationofFT:CT,withregressionequationsthereforeadvisedforthefuture,inordertoensurevalidinterpretationofstudydata.


TheaimofthisstudywastocomparejumpheightfromOptoJumpandforceplate,investigatingthenotionthatjumpheightalone“overlooks”fatiguerelatedneuromuscularchangesandthattheimplementationofkineticCMJperformanceevaluationwouldaddmorerelevantinformation.DespiterecentresearchbyGathercole,Sporer,Stellingwerff,etal.(2015a)assessingfatiguesensitivityofCMJandreportingthatjumpheightshouldbeconsideredrepresentativeofthe“outcome”ofjumpperformanceandnotreflecttheneuromuscularstrategyofthejump,theresultsfromthisstudysomewhatcontradictthisnotion.Gathercole,Sporer,Stellingwerff,etal.(2015a)claimthatjumpheightmeasuresalonemisinterpretthephasesassociatedwithverticaljumpingandthereforeignoreimportantdata.Resultsfromthisstudy,wouldnotdisputetheirview,yetthefindingthatjumpheighttakenfromflighttimemeasuredonaforceplate,presentedonlyslightlybetterreliabilitythanjumpheightmeasuresonanOptoJumpareofimportance.ConsiderationofthenotionsofGathercole,Sporer,andStellingwerff(2015)regardingthephasesassociatedwithverticaljumpingis,however,worthwhile.WhenconsideringthatOptoJumpmeasuresaremoreeasilyobtainedandincurfewercostimplications,thejustificationfortheinclusionofkineticmeasurescanbequestioned.TheresultsofthisstudysupporttheuseofOptoJumpjumpheighttoassessperformancechangeasaresultoftheinfluenceofrugbytrainingandmatches.Lastly,itisperhapsadvisableforpractitionerstonotethatCormieetal.(2009)recommendedtheexaminationofchangestothepower,forcevelocityand/ordisplacementtime-curvesasbeingausefultoolforlongitudinalassessment.Incomparisontousinganalysisofperformancevariablesalonetheseshouldthereforebeconsideredforinclusioninfutureinvestigations.

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TheconfirmationoftheuseofCMJheightmeasuredonanOptoJumpleadsthenextinvestigationofthisthesistowardstheassessmentofCMJheightbetweenrugbymatches.Aswasillustratedinthereviewofliterature,fatigueispresentinthedayspost-match,yetthereliabilityofCMJheighttestingbetweenmatchesneedstobeexamined.ImprovedclarityuponthereliabilityofCMJheighttestinginthedaysbetweenmatcheswillbetterenablemoreaccurateassessmentoftime-courseofrestorationinfutureexperimentalchapters.

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6 Between-SessionReliabilityofaCountermovementJumpinEliteRugbyPlayersPreGame

6.1 Abstract

Jumptestsareconsideredtobeexcellentindicatorsofneuromuscularfunctionforteamsportathletes,duetothestretch-reflexactionsseeninjumping.Inmanyeliteteamsportsettings,jumptestingisusedtoassesssmallbutimportantchangesinperformance,althoughthereliabilityofCMJbetweengamesisyettobeidentifiedinelitelevelrugbyunion.Decrementinjumpperformancepost-matchrugbymatchhasbeenreportedtoexhibitdecreasedvaluesforupto24hours,withCMJpreviouslyreportedtomeasurefatigueaccurately.Dailyapplicationofmultiplejumpmodalitiesisunrealistic,withmanypractitionersusingCMJassessmentinpreferencetootherjumps,duetoitsrelevanceandfamiliaritywithineliteteamsportsettings.AspecifictestingprotocolthatmeasuresCMJperformancebetweengamesandenablesinstantinterpretationofmeaningfulchangeis,however,required.ThisstudyaimedtoassessthereproducibilityofoneCMJbetweensessions,usinganOptoJump,whichmeasuresflighttimeandpermitsthecalculationofjumpheight.ResultsfromthisstudyindicatethatbetweensessionsasingleCMJshowshighreliability(CMJICC=0.986,SDD2.4%),withnosignificantdifferences(p>0.05)injumpheightobservedbetweendays.PerformanceofasingleCMJ(measuringjumpheight)onanOptoJumpisthereforeconsideredtobeareliablemeasureforassessingpost-matchlevelsofreadinesswhenaforceplateisnotreadilyavailable,withadviceforpractitionersthatchangesof>2.4%shouldbeconsideredmeaningful.

6.2 Introduction

Jumptestshavecommonlybeenusedforassessingchangesinperformance,asjumpsareaconvenientexercisetoimplementintoahighperformancesportsettingsandprovidinggreatecologicalvalidity.Jumptestinghas,however,comeunderscrutinybecauseofthetechniquethatmanysubjectsuseandtheinconsistenttestingprotocoladministered(Markovicetal.,2004).Anindividual’sabilitytogenerateforcequicklyisakeyperformancemeasureforathletescompetinginmanyteamsports;hencejumptestshavebeencommonlyused.Testingirregularitiessuchasthesubject’sabilitytoswingtheirarmsforgreaterheightmeanthatrecentjumptestinghasfocusedsolelyontheSJandCMJ.CMJinvolvestheuseofthestretchshorteningcycle(SSC),wherebysubjectsperformadownwardmovementfromanerectstandingpositionuntiltheyfeelcomfortableandthenjumpforheightinanupwardmotion.Theassessmentofthemechanicsinvolvedwithinthismovement,providevaluabledetailforfuturetrainingprescription(Argus,Gill,Keogh,etal.,2012;Argusetal.,2009;Baker,2001c).

Inadditiontousingjumpteststhatmeasurepower,velocity,force,contacttimeandrateofforcedevelopment;recentresearchhasfocusedonutilisingverticaljumpstoassessNMF(Hamilton,2009;Mooneyetal.,2013;Roeetal.,2015;Rowell,Aughey,Hopkins,Stewart,&Cormack,2016;Taylor,2012),witheffectivenessofCMJconfirmedbyGathercole,Sporer,Stellingwerff,etal.(2015a).ThisSSCassessment,whenutilisingCMJ,canhelpguidepractitionersuponplayerrestorationandrecoveryinthedayspost-match.EvidenceshowinglackofrestorationpostrugbyunionmatchplaywaspresentedbyMcLean(2010),whoreportedthatCMJvariablesdidnotreturntobaselinevaluesuntilfourdaysaftermatches,whileWestetal.(2014)notedthatpeakpower,measuredviaCMJ,recoverednosoonerthan

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60hourspostrugbyunionmatchplay.FurthersupportforjumptestingtomeasurefatiguewaspresentedbyTwistetal.(2012)withinelitelevelrugbyleague,whoreportedthatCMJprovidedthemostappropriateindirectmarkerofbothtissuedamageandreductioninmuscleforcegeneratingcapacity.Reductionsinjumpperformanceareoftencausedbyachangeincalciumreleaseperactionpotential,whichleadstoimpairmentofexcitation-contractioncouplingandtheassociatedLFF.ThisresultantLFFhasanimpactuponplayers’jumpperformancepotential,postmuscledamagingexercisesuchasrugbyunion(Skurvydas,Jascaninas,&Zachovajevas,2000),andthereforesupportsCMJassessmentpost-matchtomeasurefatigue.

CMJisajumpmethodthatislesslikelytocarrythevariabilityoftechniqueobservedinotherjumpmethods,asreportedinChapter4.4.FurtherinvestigationintoassessingthevariabilityofasingleCMJperformance,postrugbyunionmatch,isthereforerequired.Resultsfromthepreviouschapter(Chapter5)wouldsupportthisview,whereitwasnotedthatCMJexhibitedhighreliabilitybetween-sessionwhencomparedtoSJandSLDJ.TheresultsfromChapter5involvedtwojumpspertrial,yetduetotimeconstraintswithineliteteamsportsettings,thelikelihoodofbeingabletoperformmultiplejumpswithinadailyassessmentofreadinessisunrealistic.Duetothese“realworld”limitations,asinglemeasureofCMJperformancethatmeasuresjumpheightaloneisperhapsamorerealistictoolforperformanceassessment.CMJdisplaysrelevancetorugbyspecificmovements,which,whencombinedwithitseaseofadministrationwithinregulargymbasedsessions,makeitacommonlypreferredassessmenttoolforNMF.SupportfortheuseofasoleCMJwasnotedbyCormack,Newton,McGuigan,andCormie(2008),whoshowedthatsingularCMJflighttimepresentedmoresubstantialreductionsinperformancecomparedtofiverepeatedCMJs,suggestingthatrepeatedjumpsmakeitlessabletodistinguishbetweenlevelsofneuromuscularfunctiondespitetheirreactivenatureandSSCinvolvement.

Asaresultofmanypractitioners’inabilitytoconductmultiplejumptestspre-trainingandtheunreliablenatureofbetween-sessiontestingnotedforSJandSLDJasnotedintheChapter4,thisstudyaimedtoassessthereproducibilitybetweensessionsoftheperformanceofoneCMJ.ThisstudywillalsodetermineiftheuseofoneCMJ(jumpheight)issufficientforuseinfutureresearchandidentifySWCbetweensessions.Theidentificationofthemostreliablemeasuresoftestingforuseinfieldsettings,ratherthanincontrolledlaboratoryconditions,wasnotedbyHopkinsetal.(2012).Aspreviouslyresearched(Hopkinsetal.,2012),measuresthatprovidethesmallesttypicalerrorandarealsopracticalforusewithineliteteamsportfieldsettingsarekey.AjumptestsuchasasingleCMJneedssufficientlyhighreliabilityforuseinresearch,whichassessessmallbutimportantchangesinperformance,althoughitspracticalityforuseinthefieldisalsoofimportance.ItwashypothesisedthatasingleCMJwouldbeareliablejumpmodalityforassessingbetween-sessionsperformances.ResultsfromthisstudywillinformpractitionersaboutthereliabilityofasingleCMJandtheresultantmeasurementerrorandinadditionwillassessanindividual’sabilitytoreplicateperformance.

6.3 Method

6.3.1 ParticipantsTwelveeliterugbyunionplayers(age28.0±5.2years,trainingage9.0±4.9,height183.6±5.1cm,mass97.9±12.3kg),fromthesameprofessionalrugbyclub,volunteeredforthestudy.Participantswereallhealthyandactiveindividualswhohadnocurrentinjuryissues.AllsubjectsprovidedwritteninformedconsenttoparticipateandSalfordUniversityResearchand

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EthicsCommitteeapprovedthestudy.ThesamplesizeusedwithinthisstudywasconsideredsatisfactoryinaccordancewithguidelinesprovidedbyHopkins(2000).

6.3.2 ProcedureThisstudyassessedbetween-sessionsreliabilityofasingleCMJacrosstwotestingsessions.Testingsessionswereseparatedbynolongerthanfourteendaysforallplayersandthetrainingweeksthroughoutthetestingperiodwerestandardised.Playersworeappropriatefootwearforeachjumpandweregiventhesameverbalinstructionspriortoeachattempt.Despitethetestingbeingconductedpost-match,theinfluenceofgameswasconsideredtobeunlikelytohaveaninfluenceuponresults,asthetime-pointsofassessmentwereconsistentthroughoutthisstudyandthetrainingandmatchprotocolpriortotestingcommencingoneachoccasionwasstandardised.

6.3.2.1 InstrumentTheinstrumentusedtoassessjumpheightwithinthisresearchwastheOptoJump(Microgate,Bolzano,Italy),previouslyreportedinmoredetailwithinchapter4.3.3.1.PlayersstoodbetweentheOptoJumpbarswhenjumping,withjumpheightassessedviaflighttime.

6.3.2.2 CountermovementJump(CMJ)techniqueTheCMJwasperformedfromastandingposition,withthewholeplantarpartofthefoottouchingthejumpingsurfacewiththehandsrestingonthehips.Acountermovementwasconductedbytheparticipant,untilthekneeanglereachedapproximately90°,thenimmediatelytheparticipantjumpedashighastheycould,withtheirlegsremainingstraightuponflight,thereforepreventinganytuckedlegswhichwouldleadtoinaccuratemeasurement.Uponlanding,theparticipantsmadecontactwiththetestingsurface,withkneesextendedandonlyflexingtoabsorbtheimpactoncecontacthadbeenmadewiththefloor.Flexingofthekneesorthehipsdelayscontactwiththematandthereforedistortsflighttime.Priortoeachjumptheparticipantwasencouragedtojumpashighaspossible.Post-jump,participantsreceivedverbalfeedbackabouttheirperformance.

6.3.2.3 JumpHeightandFlightTimeJumpheightwascalculatedviaflighttimeusingthefollowingequationutilisedbyByrneandEston(2002),adaptedfromthatproposedbyBoscoetal.(1983).

JumpHeight=(9.81xflighttime2)/8

6.3.3 StatisticalAnalysesAllstatisticalanalysiswasconductedonSPSSforwindows,withanapriorialphalevelsetatp<0.05.Between-sessionreliabilitywasdeterminedusingbothICC(Model3,1)andPairedsamplesTtests.InaccordancewithRhea(2004),Cohen’sdeffectsizes(ES)wereinterpretedasfollows;trivial=<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.Post-hocstatisticalpowerwascalculatedusingGPower3.1(Fauletal.,2009),foralargeeffectsizeof0.5,atotaln=7wassufficienttodeliveranactualpowerof0.49.ThereliabilitywasconsideredacceptableiftheICCr≥0.8(Cortina,1993).SEMandsmallestdetectabledifferences(SDD)werecalculatedtoprovideinformationforuponwhetherornotachangeinanindividual’sperformancewassignificant,withSEMcalculatedusingtheformula:

SD pooled ∗ 1 − ICC andSDDcalculatedfromtheformula: 1.96 ∗ 2 ∗ SEM).

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6.4 Results

6.4.1 Between-sessionreliabilityofasingleCMJpertestingdayBetween-sessionreliabilitywashighfortheCMJ(ICC=0.986;d=0.153;SEM0.003;SDD=0.01,2.4%)(Figure6.1),withtrivialandnon-significantdifferences(p>0.05)notedbetweendays.

Figure6.1:CMJheightfortestingdaysoneandtwo

6.5 Discussion

Aswashypothesised,asingleCMJcanbeconsideredtobeareliablejumpmodalityforassessingbetween-sessionsperformances.ResultsfromthisstudyfollowedasimilarpatterntothatreportedinChapter4and5,withasingleCMJmeasuredviaOptoJumpappearingashighlyreliable(r=0.906)betweensessions.DespiteChapter4showingdifferencesexistedbetweensessiononeandsessiontwo,whenassessingCMJperformance,thisparticularinvestigationshowsacontraryview:thattheperformanceofasingleCMJ(measuringjumpheight)isareliablemeasureforassessingpost-matchlevelsofreadiness.

SupportforthereliabilityofOptoJumphaspreviouslybeenreportedbyGlatthornetal.(2011),whonotedveryhighICCsforbothOptoJumpCMJheightandCMJheightmeasuredonaforceplate,despitesystematicdifferencesoccurringbetweeninstruments(-1.06cm;p<0.001).Glatthornetal.(2011)notedexcellenttest-retestreliabilityoftheOptoJumpCMJheightmeasurement(ICC0.989;CV2.2%).However,thejumpprotocolimplementedbetweenthisexperimentalstudyandthatofGlatthornetal.(2011)differs,whereby,forexample,thesubjectsusedwerenotconsideredtobeelitewithintheresearchbyGlatthornetal.(2011),meaningthat,asaresult,clearcomparisonsshouldbenotbemade.ThemisalignmentofthephotoelectricalcellsassociatedwiththeOptoJumpcouldalsohaveexplainedsomeofthedifferencesobserved,suchastheconcernthatasubject’sfootmighthavebrokentheelectricalcell,butnotyetlandedontheforceplate.Similarly,whenassessingreliabilityofjumpmeasures,Jensenetal.(2011)presentedhighreliability(ICC0.966;CV5.1%)forOptoJumpusingtheflighttimecalculationreportedearlier(Chapter5.3.2.3).Whenconsideringthatthe

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researchbyJensenetal.(2011)involvedsimilarmethodologyandperhapsmostimportantly,rugbyunionplayers,comparisonsbetweentheseresultsarewarranted.

MorerecentresearchspecificallyassessingCMJperformancewithinrugbyplayersbyGathercole,Sporer,andStellingwerff(2015)isalsoofinterest.Gathercole,Sporer,andStellingwerff(2015)notedthatflighttimeandpeakdisplacementcorrespondedwithincreasedtrainingload.OnemightthereforeassumethattheresultsbyGathercole,Sporer,andStellingwerff(2015)indicatethatjumpheightdecreasedalongsideincreasesintrainingvolume,yettheoppositeistrue.Itisinterestingforpractitionerstonotethattherewasanabsenceofchangeinthejumpheightvariableitself.ResultsfromtheresearchbyGathercole,Sporer,andStellingwerff(2015),assessingtheresponseofCMJperformancetoincreasesintrainingloadinelitefemalerugbyplayers,cannotbecomparedtotheabsoluteCMJvaluespresentedinthisstudy,asboththegenderofthesubjectsandfatiguecreateddiffer.ReadersarealsoadvisedtonotethattheassessmentofjumpheightusedwithintheresearchbyGathercole,Sporer,andStellingwerff(2015)incorporatedadifferenttestingprotocolandthattheassesseddatawastakenfromwithintrainingperiodsandnotfromtestingpost-matchplay,aswasthecaseinthisstudy.

AsreportedinChapter5,whenassessingtwoCMJperformancesusingtheOptoJump,aSDDof1.7%wasnotedtobeofinteresttopractitionersworkingintheeliterugbyenvironment.Datafromthisstudyalsoaddstotheknowledgebase,with,forexample,thevalueof2.4%changeforasingleCMJbeingsmallerthanthevaluereportedbyGlatthornetal.(2011).Glatthornetal.(2011)notedhighICCvalues(mean0.986),lowcoefficientofvariation(2.5%)andlowrandomerrorsaveraged(2.87cm),thereforesupportingCMJasreliablefordetectingchangesinlongitudinalassessments.WhentryingtoidentifyNMFusingCMJ,jumpheight,assessedfromflighttimeusingtheforceplate,hasbeenconsideredthemostpreciseandreliable,yetaspreviouslyexplainedinChapter5,formostteam-basedscenariosaforceplateisnotreadilyavailable.Whenconsideringthefinancialoutlayassociatedwithforceplateuse,thelikelihoodofrugbyclubsbeingabletoimplementsuchtechnologyisunlikely;thereforetheOptoJumpwouldbethenextbestalternative.Thisstudyaddstotheknowledgebasebyidentifyingadifferenceofgreaterthan1cm(2.4%)injumpheightsignifyingmeaningfulchangebetweensessions,whilerecommendingtheassessmentofasingleCMJperformance.

6.5.1 LimitationsofthisstudyOnepotentiallimitationofthisresearchsurroundstherelativelysmallsamplesize(n=12).DespitethesamplesizebeinglargerthanthoseusedintheinvestigationsreportedinChapters4and5,anevenlargersamplesizewouldperhapshavepresentedgreaterdepthandbreadthtotheknowledgebaseofasoleCMJ.Alongsidesamplesize,anotherpotentiallimitationofthisstudysurroundstheself-selectedCMJprotocoloftheplayers.PlayerswerenotedpotentiallytohaveadopteddifferingCMJtechniques,mainlywherebydepthofCMJonthedownwardphasevariedandwidthofstancewasindividuallyselected.Theseindividuallyselectedjumptechniquescould,therefore,havealteredresults.Itcould,however,bearguedthatthevariabilityinCMJtechniqueimprovedtheecologicalvalidityofthisstudy,asnotallplayerswouldnormallymoveinthesamemannerespeciallyduringthecompetitionphaseofaneliterugbyunionplayingseason.Fatigueandphysicalmobilityissuesduetothephysicalnatureofthegamesandthetrainingthattheplayersundertake,arefactorsthatcancommonlyinfluencemovementandtechnique.

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Fromthisresearch,onecouldconcludethatalearningeffectdoesnotexistbetweentestingdaysforperformanceofasingleCMJ.Asaconsequence,contrarytotheviewsofpastresearchasingleCMJmeasuredviaOptoJumpappearstobeahighlyreliablemeasureofassessingbetween-sessionsperformances.Futurepracticerecommendsameaningfulchangeof2.4%(1cm)asbeingofnoteforpractitionersworkingintheeliterugbyenvironments,whenassessingCMJperformancebetweensessions.Thisstudythereforeaddstotheknowledgebaseexistingforbetween-sessionassessmentsofCMJperformanceineliterugbyunionplayers,supportingtheOptoJumpasthenextbestalternativeforassessingasingleCMJperformancewhenforceplatesarenotavailable.

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DespitethischapterfirstlyconfirmingthereliabilityofconductingoneCMJinthedaysbetweenmatchesandsecondlyidentifyingameaningfulchangeof2.4%(1cm),agreaterunderstandingofthetime-courseofrestorationofCMJinthedayspostrugbymatchisneeded.Theabilityforappliedpractitionerstobeabletoquantifybothmagnitudeanddurationofperformancedecrementwouldbeofmajorbenefitfortrainingprescriptioninthedayspostmatch.InadditiontotheassessmentofCMJheightasameasureofperformance,aneedalsoexiststoassessanothermeasureofpost-matchrecovery,toprovidefurtherconfidencetofutureCMJheightinvestigations.

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7 ChangeinCountermovementJumpPerformanceandWell-beingScoresofProfessionalRugbyUnionPlayersPost-match

7.1 Abstract

Plannedperiodisationwithoutconsiderationforrestorationofperformanceandtestingoftime-courseofrecoveryislikelytoputplayersatriskofsub-optimalperformanceorinjuryrisk.Stressonrugbyplayers’bodiesisoftenmorefrequentlyaccumulatedbygamesituations,whereplayersareaskedtocompeteonaweeklybasis.CMJandself-reportwell-being(WB)testingprotocoliscommonlyusedwithinelitefieldsportsettingsinordertoassessNMFandperceivedfatigue,whenperformanceisimpairedintheimmediatedayspost-match.ThisstudyaimedtocompareCMJperformanceandWBscoresatpre-matchandthreetime-pointspost-match(60hours,90hoursand170hours),inordertodevelopabetterunderstandingoftime-courseofrecoveryinelitelevelrugbyunionacrosspositionalgroups.RelationshipsbetweenchangesinCMJperformance,WBscoresandmatchcharacteristics(totaldistancecovered,distancecoveredinZone5,distancecoveredinZone6,accelerations,decelerationsandimpactsencounteredinZones4,5and6)werealsoinvestigatedacrosspositionalgroups.DifferencesinCMJandWBacrosstime-pointsweredeterminedusingrepeatedmeasuresANOVAwithBonferronipost-hocanalysis,ornon-parametricequivalent,illustratingthatbothCMJperformanceandWBscorewerereducedat60hourspost-match,90hourspost-matchand170hourspost-match,withWBscorereducedtoagreatervalueandforalongertime-coursethanCMJ.Ameaningfulchangeof2.6cm(-6%)changeinCMJperformancewasnotedalongsidea-9%changeinWBscoreat60hourspost-match.Inaddition,correlationswerestrongandsignificantbetweentotaldistancescovered(p=0.002;r=0.396),decelerations(p<0.001;r=0.532),D5(p<0.001;r=0.488)andD6(p<0.001;r=0.489)at60hourspost-matchwithchangesinCMJperformance.Furthercorrelationswerenotedbetweenaccelerations(p=0.001;r=0.558)at60hourspost-matchwithchangesinCMJperformancefortheforwardsonly.ThedatafromthisstudyaddstotheknowledgerelatingtochangesinCMJperformanceandself-reportedWBpost-matchinrugbyunion,althoughtheevidencefromthisstudywoulddisputetheviewsofprevioustime-courseresearch,whenconsideringthelongertime-courseofrecoveryassociatedwithbackscomparedtoforwards.

7.2 Introduction

Rugbyunionhasbeenreportedtoinvolvebothintenseanaerobicexerciseinterspersedwithlowerintensityboutsofaerobicexercise,withmatchdistancesaveragedacrossaseasonbeing5850±1101mforforwardsand6545±1055mforbackspergame(Cahilletal.,2013).Thehighlevelofimpacts(>795pergame)andthemetaboliccost(worktorestratiosofgreaterthan1:4)involvedinasportsuchasrugbyunionarecontributingfactorstowardsthephysiologicalandmechanicalstressassociatedwithEIMD(Austinetal.,2011a;Robertsetal.,2008).EIMD.Additionally,theassociatedtime-courseofrecoveryhasbeenextensivelyresearched(Hausswirthetal.,2011;McLellan&Lovell,2012;Twist&Eston,2009;Twist&Sykes,2011),withcorrelationsnotedbetweenthetotalnumberofimpactsexperiencedwithineliterugbyleaguematchplayandcompromisedneuromuscularfunction,whenassessingjumpperformanceinthe48hourspost-match(McLellan&Lovell,2012).

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Atypicalprofessionalrugbyseasoninthenorthernhemispherecontainsover30gamesandinvolvesbluntforcetraumaandhighrunningvolumesintrainingandmatches(Alaphilippeetal.,2012).Thevolumeandintensityofwork,includingassociatedtraumafromcontactcompletedinarugbyunionmatch,resultinfatigueandextendedrecoverytimepost-match,withWestetal.(2014)notingthatpeakpower,measuredviaCMJ,recoverednosoonerthan60hourspost-match.Duetobluntforcetraumaandhighrunningvolumesfrombothtrainingandgamesoverthecourseofaplayingseason,rugbyplayersbecomefatigued(Argus,Gill,Keogh,etal.,2012;Cresswell&Eklund,2006;Fulleretal.,2007).AsreportedbyGilletal.(2006),thepresenceofresidualfatigue,carriedoverfromthepreviousgamesandtraining,isrepresentedbyincreasedcreatinekinase(CK)levels,withreductionsinperformancemeasuresalsobeingreported(Crewtheretal.,2009).Itis,however,importantforpractitionerstonotethatrestorationofperformancemeasuresisofutmostimportanceforathletesandthatthismustbeachievedpriortosubsequentcompetition,irrespectiveofbiochemicalmarkers.Inessence,restorationofperformanceisperhapsmoreimportantthananyresidualbiochemicaldisruptions,astheabilityofrugbyplayerstobeabletoperformtheirrolewithinmatchplayisparamount.Biochemicaldisruptionmaybeevidentuponassessmentofrugbyplayersinthedayspost-match(Crewtheretal.,2009;Lindsay,Lewis,Scarrott,Gill,etal.,2015;Smartetal.,2008;Takarada,2003;Westetal.,2014),althoughifthisbiochemicalimbalanceisnotaffectingaplayer’sabilitytoperformoptimally,thensurelythisisoflessofaconcernthanalackofrestorationofperformancemeasures,whichpotentiallysignifyaninabilitytoexecuteoptimalperformance,despitefatiguebeingpresentinbothcases.

Intenseexercise,suchasrugbyunionmatchplay,hasbeenshowntocausetemporalimpairmentsinimmunefunction,withdisturbancesinimmunitylastingupto38hourspost-match(Cunniffeetal.,2010).Frequently,thegreatestphysicalstimuliofarugbyplayer’sweekisthematch,yethightrainingloadscombinedwithmatchexertionsandinsufficientrecoveryhavebeenreportedinrugby,oftenpushingplayersintostatesofoverreachingwithresultantreducedneuromuscularfunction(Coutts,Reaburn,Piva,&Murphy,2007).Recentresearchfromrugbyunion(Jonesetal.,2014)supportstheviewthatmuscledamageisposition-specific,withthenumberofimpactsencounteredduringamatchrelatingdirectlytothelevelsofmuscledamage,indicatedbyincreasedlevelsof(CK).Mashikoetal.(2004b)notedthattheblunttraumaassociatedwithmatchdemandsperformedbyforwardsmayproducelongerlastingmuscledamagethanthatexperiencedfromeccentricactions,whichbackswouldbemorelikelytoencounter.Aswasillustratedinpreviousresearch(Reardon,Tobin,Tierney,&Delahunt,2016),forwardsaremorelikelytoincurcontactsduringmatch-play,withrecentresearchbyRoeetal.(2017),notingincreasedlikelihoodofupperbodyNMF,reducedwellbeingandgreaterelevationsinCKposttrainingsessionsinvolvingcontactthansessionswithoutcontact.

FurtherevidenceofmatchcontactsandresultantfatiguewasnotedbyTwistetal.(2012),wheretotalcontactsforforwardswasreportedtocorrelatewithallmarkersofpost-matchfatigue(musclesorenessr=0.62;perceivedfatiguer=0.69;CKr=0.74;jumpflighttimer=-0.55),yetonlyflighttimewascorrelatedwithoffensivecontactsinbacks(r=0.54).ThisresearchbyTwistetal.(2012)usedtime-motionanalysistoassesscontactsencounteredbyprofessionalrugbyleagueplayers,reportingthatbackspresentedgreaterdecrementinperformancethanforwards,whenassessingchangesinCK,perceptualandneuromuscularfatigue48hourspost-match.Theinfluenceofconcentricandeccentricforcesduringmatchplay,uponresultantmuscledamage,wasalsopresentedbyJonesetal.(2014),whoreported

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thathighspeedrunningwasapredictorofmuscledamageforbacks.Thesehigh-speedrunninginvolvementsarelikelytoincludedecelerationandaccelerations,which,whenconsideredalongsidethefindingsfromChapter3(thatbacksencounteragreaterfrequencyofthesematchdemandscomparedtoforwards)isanimportantconsiderationforfuturetime-courseofrestorationresearch.Theresearchpresentedabove,therefore,highlightstheimportanceoflookingattherelationshipsbetweenmatchcharacteristicsthatassesspositionaldifferencesandthemuscledamageresponsecreated,withhighlevelimpactsandhighspeedrunningbeingthemainareasoffocus.

Priorresearchhasillustratedthenegativeinfluenceofhighintensityrugbyspecificactivities,suchassprintingandcollisionsalongwiththeresultantmuscledamageresponse(Jonesetal.,2014;McLellan&Lovell,2012;Moreletal.,2015).Inaddition,fromtheevidencegatheredinChapter3itwasnotedthattotaldistancecovered,highintensityrunningzonesandimpactsinhigherzonesarelikelytohaveaninfluenceupondelayedrestorationofperformancepost-match.WhenconsideringtheresearchbyMcLellanetal.(2011a)showingimpactsinhigherzones(>8.1G)werepositivelycorrelatedwithsignificantmuscledamage,andtheresearchbyJonesetal.(2014)showingcorrelationsbetweenhighspeedrunning(>5m.s-1)andsprinting(>5.6m.s-1)andincreasedplasmaCK,theneedtofurtherinvestigatespecificGPSmetricsiswarranted.Theinfluenceofspecificmatchdemands(specificallythehighintensitymetrics)arethereforeofinteresttopractitioners,whenassessingrestorationlevelspostrugbyunionmatchplayacrosspositionalgroups.Highforcemusclecontractionssuchasthoseexperiencedinaccelerations,decelerationsandcollisionsituations(whicharelikelytobeassociatedwithimpactsinZones4,5and6)areassumedtoresultingreaterdecreasesinperformance,andthereforealsowarrantinvestigation.

Anaccumulationoftrainingstress,ifmanagedproperly,willhaveapositiveeffectupontheathlete,however,ifmanagedpoorlyandinsufficientrecoveryoccurs,FORcandevelopintothemoreseveretrainingresponsephenomenonofOT.Subjectivemeasures,specifically,havebeenusedtomonitorfatigueinpreviousresearch,includingself-reportwell-beingquestionnairesshowingreducedperceptionofrestorationacrossalongitudinalperiod(Cresswell&Eklund,2006),withcorrelationsbetweenOTscoresassessedviaquestionnaireandalteredCKvaluesapparentinthestudybyAlaphilippeetal.(2012),whichassessesbiochemicalmarkersoveralongitudinalperiodinrugbyunion.Neuromuscularfunctiontestsareperhapsthemostcommonlyusedformsofassessingplayerfatigueinteamsportsettings;andincludevaryingformsofjumptests,plyometricpush-ups,sprintperformances,sub-maximalandmaximalperformancetestsandisokineticdynamometry(Duffieldetal.,2012;Johnstonetal.,2013;Twist&Sykes,2011).Decreasedjumpperformancehasbeenreportedforupto24hours,withareported26%reductioninPRFD(McLellanetal.,2011b;Twistetal.,2012).

Despitetheuseofarugbyspecificactivitybeingthemostlikelyactivitytoindicatereadinessintheimmediatedayspost-match,itspracticalityforusewithinaweeklytrainingcycleisunrealistic.Manystudies(Gathercole,Sporer,&Stellingwerff,2015;Johnstonetal.,2015;McLellanetal.,2011d;Westetal.,2014)assessingrateofrecoverypostfatigueinrugbyhave,therefore,assessedrestorationofperformancethroughusingteststhatarereproducibleanddonotinduceaddedfatigue.Inanassessmentofmultipletests(CMJand20msprint),todetectNMFpostfatiguingexercisewithteamsportathletes,Gathercole,Sporer,Stellingwerff,andSleivert(2015b)notedmoderatereductionsinCMJat72hours,while20msprintperformanceshowednoreduction,thereforerecommendingtheiruse.Oneaimofthisresearchwasto

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compareCMJperformanceandWBscorespre-matchand60hours(post-match),90hours(post-match)and170hours(post-match),inordertodevelopabetterunderstandingoftime-courseofrecoverypost-matchinelitelevelrugbyunion.Secondly,thisresearchaimedtodeterminewhetherornotthereweredifferencesinCMJperformanceandWBscores;baseline,60hours(post-match),90hours(post-match)and170hours(post-match)andalsobetweenpositionalgroups(forwardsandbacks)asaresultofthematchdemandsspecifictothesegroups.Thirdly,thisresearchaimstoassesschangesinCMJperformanceandWBperformancebetweenpositionalgroups(forwardsandbacks),GPSvariablesusedtoassesstheinfluenceofspecificmatchdemandsuponrestorationofperformance.Inlinewiththepreviousresearch(McLellan&Lovell,2012;McLellanetal.,2011b;Twistetal.,2017;Twist&Sykes,2011;Twistetal.,2012;Westetal.,2014),itwashypothesisedthatdelayofrestorationofCMJperformanceandreducedWBscoreswouldbepresentintheimmediatedayspost-match,andthatforwardswouldtakelongertorecoverfrommatchdemandthanbacks.RelationshipsbetweenchangesinCMJperformance,WBscoresandmatchcharacteristics(Totaldistancecovered,distancecoveredinZone5and6,accelerations,decelerationsandimpactsencounteredinZones4,5and6)werealsoinvestigated.Onlythesematchvariableswereinvestigated,asthesemetricswereconsideredtobeimportantforfurtherinvestigation,inlightofresearchoutlinedabove(Lindsay,Lewis,Scarrott,Gill,etal.,2015;McLeanetal.,2010;McLellanetal.,2011a,2011b;Roeetal.,2017).

7.3 Method

Thisstudyfocusedupontwomeasures;neuromuscularfunction(CMJheight)andsubjectiveself-reportwell-being(WB).ThesetestmeasureswerethenrelatedtoGPSdata(Totaldistancecovered,accelerations,decelerationsandimpactsencounteredinZones4,5and6),inordertoassesstheeffectofgamedemandsuponsubsequentCMJperformanceandWBat60hours,90hoursand170hourspost-match.Comparisonsweremadebaselinetodetermineifthesevariableshadreturnedtonormalpriortothestartofthenextmatch.

7.3.1 ParticipantsTwenty-sevensubjects(Age27.7±4.6years,trainingage8.4±4.7years,bodyweight,98.1±11.2kgandheightbeing184.3±6.3cm)wereassessedacrossfivegamesresultinginfifty-ninedatasets,withsomeplayerspresentingdatafrommorethanonegame.Ofthe59datasamples,forwardsrepresented31instances,whilethebacksrepresented28instances.Allparticipantsweretakenfromwithintheprofessionaltrainingsquadattheparticipatingrugbyclub.

7.3.2 ExperimentalApproachThisstudywasconductedinaccordancewiththeDeclarationofHelsinkiandwasapprovedbySalfordUniversityInstitutionalReviewBoard.Theseven-weekassessmentperiodcoveredfivegamesandwastakenduringacompetitivephaseofarugbyunionplayingseason.Throughouttheseven-weekperiod,nocoach-ledrecoverystrategieswereadministeredupontheparticipants,suchasicebaths,toaidrestorationofperformance.Anyrecoverymethodsutilisedbytheparticipantswerenotedandtakenintoaccountforfurtheranalysis.Participantswereadvisedtomaintaintheirusualrecoveryprocesspost-matchthroughoutthetestingperiod,includingnutritionalinterventionsoractiveswimrecoverysessions.

Throughoutthetestingperiod,trainingvolumewasconsistentbetweengames;onaverage,eachweekconsistedoftworesistance-trainingsessionsandfiverugbysessions.Ascommonlyseenwithinteamsportsettings,wheregamesareweekly,trainingvolumetaperedasgameday

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approached.Fortheperformancetestinganalysis,onlyplayerswhocompletedover30minutesofmatcheswereincluded.Thirtyminuteswasconsideredtobeanappropriategame-timeexposureforplayerstoexperiencetraumaandfatiguethatmightaffecttheperformancemeasuresassessed.AsillustratedbyresearchoutlinedinChapter1ofthisthesisandfromtheresultsrecordedinChapter3,eliterugbyplayersarelikelytobesubstitutedatvaryingtimepoints,dependinguponpositionalgroup(Forwards50-65mins;Backs70-75mins),withthesevaryingtimes,therefore,beinglikelytoaffectrestorationofperformancelevelspost-match.

Duetothestructureofthetrainingweeksassociatedwiththisstudy,performancetestsweremeasuredatpre-match,60hourspost-match,90hourspost-matchandat170hourspost-match(priortothesubsequentmatch).Pre-matchtestswereconsideredthebaselineuponwhichtocomparethepost-matchvaluesagainst,withtestsconductedapproximatelythreehourspriortokickoff.Thesetime-pointswerechosenastheyweretheonlyavailabletime-slotsthatcouldbeconsistentlyassessedacrossthisstudyandinadditionwereconsideredtobeaconsequenceof“realworld”testingintheelitesportenvironment,wheretrainingschedulesoftenchangepost-match.

7.3.3 JumptestingTheCMJwasselectedinlinewithpreviousresearch(Johnstonetal.,2015;Johnston,Gabbett,etal.,2014;McLeanetal.,2010;McLellan&Lovell,2012;McLellanetal.,2011b;Twistetal.,2012;Westetal.,2014)inordertomeasureneuromuscularperformanceandwasperformedfromastandingposition,withthewholeplantarpartofthefoottouchingthejumpingsurfaceandthehandsrestingonthehipsthroughout.Acountermovementwasconductedbytheparticipantsuntilthekneeanglereachedapproximately90°,thenimmediatelytheparticipantsjumpedashighastheycould,withtheirlegsremainingstraightuponflight,thereforepreventinganytuckedlegswhichwouldleadtoinaccuratemeasurement.Uponlandingtheparticipantsmadecontactwiththetestingsurfacewithakneeangleextendedto180°andflexeduponcontactwiththesurface.Post-jump,eachparticipantreceivedverbalfeedbackabouthisperformance,withonlyonejumpbeingallowedforeachindividualduetotimeconstraints.ThiswasnotconsideredtobeanissueasallindividualswerefamiliarwithCMJprotocol.InlinewithpreviousstudiesassessingCMJperformance,protocolssuchashandsonthehipsthroughoutthejumpandextendedfeetthroughoutflighttopreventtuckingoftheknees,wereadministered,asthesealternativetechniqueshavebeenreportedtocauseinaccuracies(Flanaganetal.,2008;Taylor,2012).AllCMJswereperformedatadepthatwhichthesubjectswerecomfortableandtheywereinstructedto“jumpashighaspossible”.CMJwasperformedwithoutarmswing,asanincreaseinjumpingheightof10%hasbeenobservedwhencountermovementjumpingwitharmsisperformedcomparedtowithoutarms(Leesetal.,2004).AlljumpswereperformedonanOptoJumpopticalmeasuringsystem(Microgate,Bolzano,Italy),previouslyreportedinmoredetailwithinChapter4.3.3.1.PlayersstoodbetweentheOptoJumpbarswhenjumping,withjumpheightassessedviaflighttime.

7.3.4 Self-reportwell-beingquestionnairesAllplayerscompletedaWBquestionnaireuponwakingintheirownhomes,usinganonlineplayermanagementtool.ThisquestionnaireassessedWBviatheplayers’subjectiveresponsestoquestionsaroundtheirsleep,musclesoreness,moodandappetite.ThequestionnairestructurewasbasedupontherecommendationsofHooperandMackinnon(1995)andwascompletedoneverytrainingdaythroughoutthetestingperiod.TheWBquestionnaireusedwithinthisresearchwasonethatwasfamiliartotheparticipantsandwascompletedatthe

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sametime-pointstotryandensurereliability,consistencyandreproducibility.WBassessmentwasscoredoutoften,withzerobeingpoorandtenbeinggood.AsamplequestionnairecanbefoundwithinAppendixA.DespiteWBassessmentbeingregularlyimplementedinmanyrugbyspecificscientificstudiesandconsideredtobeeasytoimplement,thereliabilityofWBuseisyettobeassessed.ThemainreasonbehindthelackofacademicresearchtosupportWBusesurroundsthenotionthatself-reportsubjectiveWBisdifficulttoquantify.InordertomeasurethereliabilityofWBquestionnairessubjectswouldhavetocompleteastructuredWBassessmentonmorethanoneoccasionwithinashortspaceoftime.However,thiswouldperhapsbedeemeddifficulttocontrol,assubjectscouldpotentiallydeliberatelyrememberwhattheyhadcompletedinthepriorassessmentandreplicateit,thereforequestioningthereliabilityofthedatacollected.

7.3.5 MatchanalysisandGPSdataAnalysisofGPSdataandassociatedtrainingvolume(distances,speedsandimpactsforexample)hasbeenutilisedinmanystudiesofrugbyunion(Austinetal.,2011a;Cahilletal.,2013;Coughlanetal.,2011)andisconsideredanessentialtoolofmanyelitesportteampractitioners.

Measurementswereconductedonplayersfromoneclub,withGPSunits(StatSportsViper,NorthernIreland)beingusedthroughoutallgamestoassessmovementpatterns,samplingata10Hzfrequency.ReliabilityofGPSanalysisinteamsportsettingshasbeenconfirmedinmanypreviousstudies(Coutts&Duffield,2010;Cumminsetal.,2013;Johnston,Watsford,etal.,2014;Varleyetal.,2012),withit’sworthoutlinedingreaterdetailinChapter2.1.2.TheindicesassessedfromtheGPSdatawere;totaldistancecovered,distancecoveredinZone5,distancecoveredinZone6,accelerations,decelerationsandimpactsencounteredinZones4,5and6.Allparticipantstookpartinnormaltrainingweeks,prescribedbythestaff,withnotrainingbeingalteredforthepurposeofthisstudy.

Table7.1:Categorisationofdistancescoveredandimpacts

Zone1 Zone2 Zone3 Zone4 Zone5 Zone6Speed(m/s)Speed(km/h)

0–1.5 1.51–3.0 3.01–4.0 4.01–5.5 5.51.–7.0 7.01+0–5.40 5.41–10.80 10.81–14.40 14.41–19.80 19.81–25.20 25.21+

ImpactsinZones(G)

3–5 5–7 7-9 9–11 11-13 13–15

Forthepurposesofdiscussingthedistanceandimpactzones,shorthandabbreviationswereused.D5relatedtodistancecoveredinZone5,D6todistancecoveredinZone6.Similarly,impactzoneswereabbreviatedtoIm4forimpactsencounteredinZone4,Im5forimpactsencounteredinZone5andIm6forimpactsencounteredinZone6.

7.3.6 StatisticalAnalysesStatisticalanalysiswasperformedusingSPSSVersion20(IBM),withanapriorialphalevelsetatp<0.05.DistributionsofanalysedvariableswereassessedusingShapiroWilktest.TwoseparaterepeatedmeasuresANOVA’swithBonferonnipost-hocanalysiswereconductedtodeterminechangesinCMJperformanceandWBscoresat0,60,90and170hours(immediatelypriortonextgame).Effectsizes(ES)werealsodeterminedusingtheCohen’sdmethod,andinterpretedbaseduponthecriteriasuggestedbyRhea(2004)andinterpretedasfollows;trivial=<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.

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Relationshipswereassessedamongstthewholedatasetandseparatelyforforwardsandbacks;inordertodetermineassociationsbetweenGPSmatchperformancedataandchangeinCMJperformanceandWBscore(Pre-matchscore–post-matchscore).Correlationsweremadeusingbothparametricandnon-parametricequivalents,whereappropriate.Whenmultiplecorrelationsweremade,thepvaluewascalculatedviaBonferonnipost-hocanalysisinordertodeterminethetruesignificance.Associationswerealsoassessedseparatelyforforwardsandbacks,asaresultofthedatapresentedinTables3.4and3.5withinChapter3.4.2alongwiththosepresentedinpriorresearch(Cahilletal.,2013;Coughlanetal.,2011;Cunniffeetal.,2009;Jonesetal.,2015;Lindsay,Draper,etal.,2015;Robertsetal.,2008),thusillustratingdifferencesinmatchcharacteristicsbetweenforwardsandbacksacrossmanymetrics(distancecovered,accelerations,decelerations,distanceinZone6andImpactsinZone6).

7.4 Results

7.4.1 ChangesinCMJperformancepretopost-matchShapiro-WilktestsofnormalityrevealedthatCMJ(jumpheight)wasnormallydistributedattime-pointsbaseline,60and170hourspost-match(p>0.05),butnotat90hourspost-match(p=0.012).Alongsideabsolutevalues,relativevaluesalsodemonstratednormaldistributionviaShapiro-Wilktests,whenassessingthepercentagechangeinCMJ(jumpheight)attime-pointsbaseline,60,90and170hourspost-match(p>0.05).Asaresult,aFriedmantestwasconductedshowingasignificantdifferenceinjumpheightacrosstime-points(p=0.000),withmultipleWilcoxontestswithBonferonnicorrectiondemonstratingasmallyetsignificantdecreasebetweenCMJperformancepre-game(baseline=39.9±5.3cm)and60hours(37.3±4.8cm,p=0.000,d=0.51),90hours(37.1±5.3cm,p=0.000,d=0.52)and170hourspost-match(38.7±5.1cm,p=0.015,d=0.23)(Figure7.1).CMJperformanceat60hours(37.3±4.8cm)wassignificantlylowerthanat170hourspost-match(38.7±5.1cm,p=0.045,d=0.28),withasignificancedifferencealsonotedbetween90hourspost-match(37.1±5.3cm)and170hourspost-match(38.7±5.1cm,p=0.003,d=0.30).Nosignificant(p>0.05)ormeaningful(d=0.039)differencewasnotedbetween60hoursand90hourspost-match.

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Figure7.1:ComparisonofCMJperformancespreandpost-match(n=59)

7.4.2 ChangesinWBperformancepost-matchIncontrasttoCMJ,Shapiro-WilktestsofnormalityrevealedthatWB(totalscore)werenormallydistributedatalltime-points(p>0.05).Alongsideabsolutevalues,relativevaluesalsodemonstratednormaldistributionviaShapiro-Wilktests,whenassessingthepercentagechangeinWBscoreattime-pointsbaseline,60,90and170hourspost-match(p>0.05).Asaresult,RMANOVAtestsrevealedthatWBscoresweresignificantlydifferent(p<0.001),whencomparingbaseline(3.77±0.47)to60hours(3.43±0.54)(p<0.001,d=0.67),90hours(3.40±0.52)(p<0.001,d=0.74)and170hours(3.65±0.58)(p<0.001,d=0.22)post-match,yetnotbetween60and90hours(p<0.05,d=0.05).Inaddition,significantdifferenceswerenotedbetween60hoursand170hourspost-match(p<0.001,d=0.39)(Figure7.2).

0

5

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35

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Baseline 60 90 170

JumpHeight(cm

)

Hours*signiwicantly(p<0.05)lowerthanbaseline#signiwicantly(p<0.05)lowerthan170hours

*# *# *

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Figure7.2:Changesinwellbeingscorespretopost-match(n=59)

7.4.3 AcomparisonofchangesinCMJperformancepreandpost-matchbetweenforwardsandbacks

Friedmantestshowednosignificantdifferenceinjumpheightforforwardsacrosstime-points(p>0.05)(Baseline36.9±0.82cm;6035.7±0.97cm;90;35.4±1.06cm;170hours36.7±0.94cm).Incontrast,Friedmantestshowedasignificantdifferenceinjumpheightforbacksacrosstime-points,withmultipleWilcoxontestsandBonferonnicorrectiondemonstratingasignificantdecreaseinCMJperformancebetweenbaseline(43.2±3.9cm)and60hours(39.0±3.2cm,p<0.000,d=2.30),90hours(39.1±3.9cm,p<0.000,d=2.57)and170hours(41.0±3.9cm,p=0.005,d=1.57).Additionally,forthebacks,CMJperformancewassignificantly(p=0.010,d=0.53)lowerat90hourscomparedto170hourspost-match,althoughnosignificantdifferences(p>0.05)werenotedbetween60and90hourspost-matchand60and170hourspost-match(Figure7.3).

0

0.5

1

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4.5

Baseline 60 90 170

WellBeingScore(0-5)

Hours*signiwicantly(p=0.000)lowerthanbaseline#signiwicantly(p=0.000)lowerthan170hours

*# **

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Figure7.3:ChangesinCMJperformancepretopost-match(Forwardsn=31;Backsn=28)

7.4.4 AcomparisonofchangesinWBperformancepreandpost-matchbetweenforwardsandbacks

RMANOVArevealedthatWBscoresforforwardsweresignificantlydifferentbetweenbaseline(3.7±0.3)and60hours(3.4±0.3;p<0.001,d=1.00)post-matchandbetweenbaselineand90hours(3.4±0.4;p<0.001,d=0.84)post-match,yetnosignificantdifferenceswerenoted(p>0.05)betweenbaseline(3.7±0.3)and170hours(3.7±0.3)post-matchandbetween60hours(3.4±0.3)and90hours(3.4±0.4)post-match(Figure7.4).Additionally,forwardsshowedsignificantdifferencesbetween60hours(3.4±0.3)and170hours(3.7±0.3;p<0.001,d=-1.00)post-matchandbetween90hours(3.4±0.4)and170hours(3.7±0.3;p=0.005,d=-0.84)post-match.BacksalsoshowedsignificantlydifferentWBscoresbetweenbaseline(3.7±0.4)and60hours(3.3±0.4;p<0.001,d=1.00)post-match,baseline(3.7±0.4)and90hours(3.3±0.3;p<0.001,d=1.13)post-matchandbaseline(3.7±0.4)and170hours(3.5±0.5;p=0.023,d=0.44)post-match,yetnosignificantdifferenceswerenoted(p>0.05)between60hours(3.3±0.4)and90hours(3.3±0.3)post-matchandbetween60hours(3.3±0.4)and170hours(3.5±0.5)post-match(Figure7.4).

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Baseline 60 90 170

JumpHeight(cm

)

Hours

FORWARDS BACKS

*signiwicantly(<0.001)lowerthanzerohoursforbacks#signiwicantly(p=0.003)lowerthan170hoursforbacks

* *#*

170

Figure7.4:ChangesinWBscorepretopost-match(Forwardsn=31;Backsn=28)

7.4.5 RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscoresShapiro-WilktestsofnormalityrevealedthatwithintheGPSvariables,intensityandD5,werenormallydistributed(p>0.05),yettotaldistancecovered,D6,accelerations,decelerations,sprints,ImZ4,ImZ5andImZ6werenotnormallydistributed(p<0.05).Asaresult,Spearman’scorrelationswithBonferonnipost-hocanalysiswereconductedshowingnosignificantrelationshipbetweenCMJandWBandthematchdemandsvariablesselectedforanalysisat170hourspost-match.However,Spearman’scorrelationswerestrongandsignificantbetweentotaldistancescovered,decelerations,D5andD6at60hourspost-matchwithchangesinCMJperformance.Additionally,changesinCMJperformancedisplayedastrongandsignificantrelationshipbetweendecelerationsat90hourspost-match(Table7.2).

Table7.2:RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscores

Distancecovered(m)

D5(m) D6(m) Decelerations Im5 Im6

CMJChange60hours

r=0.396;p=0.016*

r=0.488;p<0.001*

r=0.489;p<0.001*

r=0.532;p<0.001*

r=0.145;p=2.716

r=0.073;p=4.656

CMJChange90hours

r=0.244;p=0.496

r=0.133;p=2.520

r=0.294;p=0.192

r=0.365;p=0.032*

r=-0.111;p=3.224

r=-0.025;p=6.800

WBChange60hours

r=0.305;p=0.152

r=0.322;p=0.104

r=0.186;p=1.264

r=0.072;p=4.712 r=0.144;p=2.216

r=0.056;p=5.400

WBChange90hours

r=0.188;p=1.232

r=0.185;p=1.288

r=0.158;p=1.832

r=-0.031;p=6.544

r=-0.114;p=3.128

r=-0.141;p=2.296

*statisticallysignificant(p<0.05)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Baseline 60 90 170

Well-beingScore(0-5)

Hours

FORWARDS BACKS

*signiwicantly(p=0.000)lowerthanzerohoursforforwards/backs€signiwicantly(p=0.001)lowerthan170hoursforforwards#signiwicantly(p=0.005)lowerthan170hoursforforwards

*€ *#* * *

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7.4.6 RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscoresacrosspositionalgroups

WhenassessingtherelationshipsbetweenmatchcharacteristicsandbothCMJandWB(forwardsn=31;andbacksn=28),similarlytothewholesamplegroup(n=59),nosignificantrelationshipswerenotedforselectedmatchdemandsvariablesat170hourspost-matchforbothpositionalgroups.However,Spearman’scorrelationswithBonferonnipost-hocanalysiswereconducted,showingastrongandsignificantrelationshipbetweenaccelerationsat60hourspost-matchwithchangesinCMJperformancefortheforwardsonly.Nosignificantrelationshipswerenotedforselectedmatchdemandsvariablesat90hourspost-matchforbothpositionalgroups(Table7.3).

Table7.3:RelationshipsbetweenmatchdataandchangesinCMJperformanceandWBscoresacrosspositionalgroups

D6(m) Accelerations Decelerations Im6

ForwardsCMJChange60hours

r=0.364;p=0.352 r=0.558;p=0.008*

r=-0.177;p=2.720 r=-0.023;p=7.208

ForwardsCMJChange90hours

r=-0.036;p=7.576

r=0.365;p=0.352 r=-0.373;p=0.312 r=-0.260;p=1.264

BacksCMJChange60hours

r=0.203;p=2.408 r=0.102;p=4.840 r=-0.028;p=7.104 r=0.243;p=1.696

BacksCMJChange90hours

r=0.209;p=2.280 r=-0.255;p=1.520

r=-0.130;p=4.072 r=0.026;p=7.160

ForwardsWBChange60hours

r=0.162;p=3.080 r=0.248;p=1.432 r=0.158;p=3.160 r=0.115;p=4.296

ForwardsWBChange90hours

r=0.045;p=6.488 r=0.206;p=2.136 r=-0.008;p=7.744 r=-0.119;p=4.200

BacksWBChange60hours

r=0.012;p=7.600 r=-0.035;p=6.872

r=0.358;p=0.496 r=0.012;p=7.608

BacksWBChange90hours

r=0.083;p=5.408 r=-0.238;p=1.792

r=0.196;p=2.536 r=-0.188;p=4.400

*statisticallysignificant(p<0.05)

7.5 Discussion

Themainfindingofthisstudysupportspreviousresearch(McLeanetal.,2010;McLellanetal.,2011b;Twistetal.,2017;Westetal.,2014)andthatwhichwashypothesisedpriortotesting,illustratingclearlythatadelayofrestorationofCMJperformanceandreducedWBscoresispresentintheimmediatedayspostrugbyunionmatchplay.Itis,however,importanttonotethatsomefindingsinthisstudyareincontrasttothosehypothesised.Forexample,itappearsthatbacksexperiencegreaterreductioninbothCMJandWBpost-matchandtakelongertorecoverpost-match,incomparisontoforwards.ItwasalsoofnotethatWBprovidedamoresensitivemeasureoftime-courseofrestorationcomparedtothatofCMJ.

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7.5.1 NormalCMJchangeAcrossthewholesamplegroup(forwardsandbacks),significantchangeswereobservedforCMJperformancebetweenbaselinepre-matchandallthreetime-pointsassessedpost-match(60hours,90hoursand170hourspost-match).Nosignificantchangeswere,however,observedforCMJperformancebetween60and90hourspost-match,yettheywerenotedbetween90hoursand170hourspost-match.ThechangeinCMJperformancecomparedtobaselinewasshowntobe-6.5%at60hourspost-match,-7.0%at90hourspost-matchand-3.0%at170hourspost-match,withindividualvariationsidentifieduponinspection.Time-courseofrecoveryassessedviaCMJperformancehaspreviouslybeenidentifiedinotherstudies,withatleasttwodaysmodifiedactivitypost-matchrecommendedtofacilitateoptimalrecoveryinrugbyleague(McLellan&Lovell,2012).Manysimilarstudies(Masoetal.,2004;Smartetal.,2008;Takarada,2003)haveusedothertestingindices(creatinekinase,testosteroneandcortisol)tomeasurereturntobaselinepost-matchesofrugbyunion,withrecommendationsalsobeingmadefortraininginthe48hourspost-match.

Incontrasttotheresultsofthisstudy,previousresearchassessingCMJpostfatiguingexercisehasreportednodecreasesinCMJoutput(jumpheight),althoughcomparisonwiththeseresultscouldbequestionedastheydidnotinvolverugbyplayers(Boullosa,Tuimil,Alegre,Iglesias,&Lusquiños,2011;Cormack,Newton,&McGuigan,2008).TheCMJperformancereduction,notedat60hourspost-matchwithinthisstudy(-6%),wasassumedtobearesultofmatchexertion,whichincludedblunttrauma(AverageIm5=45;Im6=57)andthetotaldistance(4692maveragedacrossthegames)coveredbytheplayersduringagame.Perhapsmostimportantforconsideration,isthenotionthatthesignificantdecrease(p<0.001;2.6cm,-6.5%)inCMJinperformanceat60hourspost-matchseenwithinthisstudy,isgreaterthanthemeasurementerrorpreviouslyreported1.0cm(-2.4%)inChapter6,whenassessingCMJreliabilitybetweensessions.Onecould,therefore,assumethatachangeof2.6cm(-6.5%)ismeaningfulandcannotbeaccountedforbymeasurementerror.Asaresult,futureresearchinvestigatingCMJperformancepost-matchwarrantsalteredtrainingprescriptionintheimmediatedayspost-match,inordertoensureagreaterlikelyhoodofimprovedrestorationofperformance.Furthersupportforthis-6%changebeingmeaningful,isevidencedbypreviousresearchers(Cormacketal.,2013;Cormack,Newton,&McGuigan,2008;Cormack,Newton,McGuigan,&Cormie,2008;Mooneyetal.,2013),whonotedthatan-8%decreaseinFT:CTwasindicativeofNMF.Ofnote,however,forpractitionerswhenassessingpriorresearch,isthat,firstly,manyofthesestudieswereconductedinAustralianrulesfootballandsecondly,thatthereliabilityofFT:CTandthecalculationusedtoequatethesevalueshasbeenquestioned(Gathercole,Sporer,&Stellingwerff,2015).

Twistetal.(2012)reportedaninverserelationshipbetweengamecontactsandimpairedflighttimeduringaCMJ,indicatingthatplayersthatareinvolvedinmorecontactsexperiencemoreloadingonthelowerlimbsmusculature.ItcouldbearguedthatthedecreasedCMJperformanceobservedinthisstudycouldbeattributedtoseveralfactors:muscledamageofthelowerlimb,possiblyresultingfromthenumberofcontactsencounteredduringgameplay;neurologicalfatigue;orthelargeproportionofaccelerationsanddecelerationsperformedpriortocontactsituations.McLellanetal.(2011b)foundsimilarresultswithreductionsinPRFDattributedtothetraumafromcontactsituationsandnotednottorestoreuntil48hourspost-match.Itis,however,importanttonotethatbiochemicalmarkersinthehourspost-matchwerenotedtotakelongertorecoverthanPRFD,withCKremainingelevatedupto120hourspost-match.TheeffectofcontactsexperiencedingamesuponPRFDwithinjumptesting,as

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reportedbyMcLellanandLovell(2012),shouldperhapsbecombinedwithfindingsfromotherperformancemeasurestoprovidemoredetailwithinfuturetime-courseofrecoveryinvestigations.

DespitetheresultsfromthisstudyillustratingtheabilityforCMJheighttodetectchangesinrestorationofperformancepost-match,theresultsoftheresearchbyGathercole,Sporer,Stellingwerff,etal.(2015a)are,however,importantforconsideration.Inananalysisofmalecollege-levelteam-sportathletes,Gathercole,Sporer,Stellingwerff,etal.(2015a)notedthatmostkineticvariablestakelongertoreturntowardsbaselinevaluesat72hourspost-exercise,whencomparedtoCMJoutput(typicallyconcentricfocusedvariables),withtheseviewsfurthersupportedineliterugbyunion(Kennedy&Drake,2017a;Kennedy&Drake,2017b).Gathercole,Sporer,Stellingwerff,etal.(2015a),therefore,recommendedthatpractitionersconsiderNMFbyassessingchangesinbothoutputand/ormovementeconomy.Themainreasoningfortheinclusionofkineticdata,whenassessingfatiguebymanyauthors,(Cormieetal.,2009;Ebbenetal.,2007;Gathercole,Sporer,&Stellingwerff,2015;Gathercole,Sporer,Stellingwerff,etal.,2015a;Gathercole,Stellingwerff,etal.,2015),isthatthebiphasicSSC-recoverypatternthatexistsfollowingteam-sportplay,needstobeconsideredtogainamorethoroughanalysisofNMFresponse.Biphasictrendscanbeexplainedbytheneuralandmechanicalresponsesresultingfrommuscledamageexperiencedduringexercise.Asmuscledamageiscommonplacewithinrugbyunionmatchplay(Johnston,Gabbett,etal.,2014;Jonesetal.,2014;McLellan&Lovell,2012;Takarada,2003;Westetal.,2014),theinfluenceofbiphasicSSC-recoverypatternisaconsiderationthatwarrantsattentionbyfutureresearchers.Suchviewsarefurtherendorsedwhenconsideringtherecentresearchineliterugby(Kennedy&Drake,2017a)showingkineticvaluesdecreasingbyagreateramountthanoutcomemeasurespostrugbyuniontraining.However,despitekineticvaluesdeemedmoresensitivetofatigue,theaforementioneddisadvantagesofkineticmethodsofassessmentmakethisformoftestinglessviablefordailyuseinappliedsettings.

7.5.1.1 CMJperformancebetweenpositionalgroupsOnesurprisingfindingofthisstudyisthelackofcontrastbetweentheCMJperformanceofbacksbetween60and170hourspost-match.Whenconsideringthat170hourspost-matchisimmediatelyprethefollowinggame,thiswouldintimatethatperformancehasnotrestoredtooptimallevelspriortocommencementofthenextgame.DespiteforwardsnotdisplayinganysignificantreductionsinCMJperformanceatthreetime-pointspost-match(-3.3%reductioninCMJperformanceat60hours;-1.5%reductioninCMJperformanceat90hours),thesevaluesaresmallerthanthosenotedforbacksat60hourspost-match(-9.6%60hourspost-match;-9.5%90hourspost-match).Onecouldassume,therefore,thatbacksexperiencedmoreadverseeffectsthanforwardsintheimmediatehourspost-match.AsmallermuscledamageresponseandtheresultanteffectuponpositionalCMJchangewasreportedinastudybyTwistetal.(2012)assessingNMF(CMJflighttime;24hoursBacks-2.9%,Forwards-3.9%;48hoursBacks-2.3%,Forwards-1.2%).However,asthisresearchbyTwistetal.(2012)wastakenfromrugbyleagueandassessedCMJviaadifferentmethodtothatundertakenwithinthisresearch,itshouldbeconsideredwithcaution.Moresignificantforthisexperimentalstudyisresearchfromprofessionalrugbyunion,specificallythefindingofTeeetal.(2016)thatforwardssufferprogressivelygreaterperformancedecrementsoverthecourseofmatchplaycomparedtobacks.Thisnotionwouldthereforeperhapsindicatethatforwardsarelikelytoexperiencelongertime-courseofrecoveryasaresultofthefatigue;yetthedatapresentedinthischaptercontradictsthis.

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Thegreaterdecrementinjumpperformanceobservedforbacks,comparedtoforwardswithinthisresearch,issupportedbythefindingthatthisdecrementalsolastedforlongeramongstbackscomparedtoforwards,asrepresentedbythelackofrestorationforbacksat170hourspost-match.Whenviewingtheseresultsspecifically,itcouldbeassumedthatagreaterandlongerdecrementinjumpperformanceisrepresentativeofahigherleveloffatigue,whichhasmanifesteditselfintoalongertime-courseofrecovery.Despitematchcharacteristicswithinthisstudybeingnormallydistributedandthisexperimentalstudynotbeingabletoidentifytheexactmechanismsthatcausedthisgreaterandlongerdecrementinbacks,thedifferencesobservedinmagnitudeandlengthofdecrementexperiencedbybacks,comparedtoforwards,couldperhapsbeexplainedbythematchdemandsencountered.ThisisalsoevidentwhenconsideringtheresultsfromChapter3.4.1,whichidentifiedthatbackscompletedsignificantlymoregameminutes,atgreaterintensityandwithsignificantlymoredistancecoveredinD1,D4andD6thanforwards.Thisidentificationofdifferencesinmatchdemandsbetweenpositionalgroups,whenconsideredalongsidethemagnitudeanddecrementofperformancerestorationreportedwithinthisstudy,isthereforeofinterestforfuturepractice.

AnotherpotentialreasonforthelackofrestorationofCMJperformanceamongstbacks,notedwithinthisstudy,isthatthetrainingsessionsundertakeninthedayspost-matchalsoinfluencedbacks’restorationofrecoveryrates,therebynotallowingthemtoreturntoexpectedpre-gamelevels.Forwards,incontrasttobacks,weredeemedtobemorecapableofreturningtooptimallevelsofperformancepost-match,with,surprisingly,nosignificantdifferenceinCMJperformanceat60hourspost-match,despitetrainingsessionsbetweengamesbeingcommon.TheresearchbyJohnstonetal.(2015),whichshowsmorehighlytrainedindividuals(intermsofrelativestrengthandaerobiccapacity)recoveringfaster,isalsoofconsiderationwhenassessingthedifferencesinratesofrestorationbetweenforwardsandbacks.BasedupontheresearchbyJohnstonetal.(2015),thismorerapidrestorationofperformanceforforwardscomparedtobacks,couldperhapsbeexplainedbyforwardstypicallydemonstratinghigherlevelsofstrength,althoughnoconclusionscanbemadeuponthisnotionasthesupportingevidencetoconfirmthesethoughtsislacking.

Despitematchcharacteristicswithinthisstudybeingnormallydistributed,thefindingthatbacksdidnotrestoreperformancepriortothenextgamecouldalsoperhapsbeexplainedbythecumulativefatigueexperiencedfromtraining.Trainingcompletedbybacksbetweengamesisdifferenttothatofforwards,withmoreemphasisbeingplaceduponhighspeedrunningandhighintensityeffortsuchasaccelerationsanddecelerations,andcould,therefore,explaintheinabilityofbackstorestoreperformancebetweenmatches.FurtherevidenceillustratingtheinfluenceoftrainingupondecreasedCMJoutput,waspresentedbyGathercole,Sporer,andStellingwerff(2015),withlongitudinalNMFtestingofrugbyplayersusingCMJheightrecommended.Theresultsfromthisstudyshowthatthedifferencesinrestorationratesforforwardsandbacksbetweengamesisonethatwarrantsattentionandisanareaoffutureinvestigationforpractitioners,whereassessmentofspecificmatchcharacteristicsisrequired.

7.5.2 NormalWBchangeAcrossthewholesamplegroup(forwardsandbacks),significantchangeswereobservedforWBbetweenbaselinepre-gameandallthreetime-pointsassessedpost-match(60hours,90hoursand170hourspost-match).Nosignificantchangeswere,however,observedforWBbetween60and90hourspost-match.ThechangeinWBscoreswasshowntobe-9.0%at60hourspost-match,-9.8%at90hourspost-matchand-3.1%at170hourspost-match,withindividualvariationsidentifieduponinspection.Similartoresultsreportedinresearchwithin

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professionalrugbyleaguebyMcLeanetal.(2010),thisstudyshowedthatoverallWBremainedsignificantlyreducedat60hourspost-match.ThemagnitudeofchangeinWBscoresnotedwithinthisstudywassimilartothatreportedbyHalsonetal.(2003),wheremoodstatealterationwasseenduringintensifiedtrainingperiodsinoverreachingcyclists(POMS-6590.4duringnormaltraining;116.4duringintensifiedtrainingperiod).Nichollsetal.(2009)notedthatrugbyunionplayersreportedmanyself-reportstressorsasbeing“worsethannormal”thedayafteramatch,incomparisontodaysprecedingandincludingmatchday.Additionally,inastudyinvolvingAustralianrulesfootballplayers,Gastin,Meyer,andRobinson(2013)notedthatsubjectiveratingsofwellnessappearedsensitivetochangesinload,whichsupportthefindingfromthisstudythatdespiteWBvaluesreducingintheimmediatehourspost-match,WBimprovespost-matchasthenextmatchdayapproaches.Itis,however,importantforpractitionerstonotethatcomparisonofreducedWBscorestootherresearchisdifficult,asoftenfiguresreportedaretakenfromarbitraryvaluesandthereforecannotbejudgedagainstvaluesfromotherresearch.Additionally,asWBquestionnaire-scoringprotocolvaries,theabilitytoquantifyameaningfulchangeisdifficult.Asaresultpractitionersare,therefore,advisedtouse%changevaluesinsteadofabsolutevalues.ThisnotionisevidencedbythelargeindividualvariationsinWBscoresidentifiedwithinthisstudyandissupportedinrecentresearchbyRoeetal.(2015),whichpresentedaCVof7.1%forWBquestionnaires,whichdespitebeinglowerthantherecommended<10%CVnotedbyBuchheitetal.(2011)isapointofconsiderationforfutureresearch.

Onecouldarguethattheuseofwell-beingquestionnairesinteamsportsettingsareespeciallyimportant,consideringthateachindividualmightrespondinadifferentmanner,asaresultofthetrainingdoseadministeredbythecoaches.ThisnotionofvariedindividualresponsestotrainingdoseissupportedbyevidencepresentedinthestudybyLovelletal.(2013),assessingfactorsaffectingrateofperceivedexertion(RPE)inrugbyleague.Thecategoricalnatureofquestionnairedatameansthatasmallchangeisdifficulttodetect,notonlybecauseWBscoreschangeinincrementsofonebutalsobecausethereliabilityofsuchmeasuresaredifficulttoquantify.Itcould,however,beconcludedfromthisstudythatperformancetestdataassessingneuromuscularfunction,combinedwithperceptualdatafromquestionnaires,wouldprovideamoreaccurateunderstandingofplayerfatigue,asthechangesinCMJperformanceandWBappeartorepresentasimilartrend.AsreportedbyTwistandHighton(2013),themultifacetedelementsoffatigueandthephysicalandmentalresponsesthatindividualathletesdemonstrate,meanthatsinglebiochemical,hormonalorperformancetestsdonotpresentaclearpictureofathletereadiness.Insteadathletesshouldbemonitoredwithinamulti-methodapproachthatwouldassessanychangebelowbaseline.RecentresearchbyGathercole,Sporer,andStellingwerff(2015),assessingtheinfluenceofincreasedtrainingloaduponelitefemalerugbyplayers,notedameaningfulcorrelation(r=0.34)betweenwellnessandCMJflighttime,thereforesupportingtheuseofWBdataforassessingrestorationofperformancepostrugbyunionmatchplay.

7.5.2.1 WBscoresbetweenpositionalgroupsSimilarly,asreportedforCMJperformance,backsdisplayedWBscoresinthehourspost-matchthatwouldsignifythatsub-optimalperceptionsofWBwerepresentimmediatelypriortosubsequentmatches,thereforeindicatingresidualfatigue.Forwardsdisplayeda-9.7%reductioninWBscoreat60hours,an-8.6%reductionat90hourspost-matchanda-1.4%reductionnotedat170hourspost-match.Thesevaluesaresmallerthanthe-12.9%reductionnotedat60hourspost-match,-11.8%reductionnotedat60hourspost-matchand-3.5%

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reductionnotedat170hourspost-matchforbacks.AswasnotedforCMJperformance,reductionsinWBscoresarelongerlastingamongstbacksthanforwards,whichcould,perhaps,alsobeexplainedbythematchdemandsencountered,orthetypical,accumulatedtrainingactivitiesperformedbetweenmatches.

7.5.3 Performancereductionacross170hoursassessingbothCMJandWBDespitepreviousresearchshowingthatrestorationofperformanceisrestoredat60hourspostrugbyunionmatchplay(Westetal.,2014),theresultsfromthisresearcharecontrastingasbothCMJperformanceandWBscoresareseennottoberestoredbacktopre-gamelevelsat170hourspost-match.Thecumulativefatigueapparentinthisresearch,aspresentedbyreducedWBandCMJvalues(throughoutmicrocycles),issimilartotheresearchofCresswellandEklund(2006),whoassessedburnoutacrossaplayingseasonusingquestionnaires.Adecrementinperformancemeasuresthroughoutacompetitiveplayingperiodisperhapsnosurprise,consideringboththemovementdemandsexecutedineachofthematchesandtheweeklycompetitivestructureofprofessionalrugby,whereplayersarerequiredtoperformeveryweekendforaperiodofninemonths.Similarlytothisresearch,Alaphilippeetal.(2012)supportedtheviewthatfatigue(assessedbybiochemicalparameters)increasedthroughoutaplayingseasoninrugbyunion.Alaphilippeetal.(2012)investigatedbiochemicalmarkersoverthecourseofaplayingseasonandnotedcorrelationsbetweenovertrainingscoresandbiochemicalmakers,whilealsonotingapositivecorrelationbetweenminutesplayedandincreasedCKlevels.Theevidencefromthisstudywouldalsoindicatethatcumulativefatigueacrossaplayingseasonhadaneffectuponrestorationofperformance.Itis,however,importanttonotethattrainingwithinthesedaysbetweenmatchesmayhavehadalargerinfluenceuponperformancemeasuresthanmatchesthemselves,andcouldthereforehavecontributedtoreducedCMJandWBvaluesat170hourspost-match.

Lastly,itisimportantforpractitionerstonotethatthepreviousresearchshowingadecrementinperformancelastingforlessthan170hourspost-exercise(McLeanetal.,2010;McLellanetal.,2011b)wasnottakenfromrugbyunion.Inaddition,itshouldbenotedthatthedatafrommuchofthepreviouslymentionedresearchassessingrecoverypostrugbyunionmatchplay,iscollectedfromthesouthernhemisphere(Coutts,Reaburn,Piva,&Murphy,2007;Johnstonetal.,2015;Johnston,Gabbett,etal.,2014;Lindsay,Lewis,Scarrott,Gill,etal.,2015;Masoetal.,2004;McLeanetal.,2010;McLellan&Lovell,2012;McLellanetal.,2011a,2011b;Takarada,2003).AsnotedbyGannon,Stokes,andTrewartha(2015),thestructureoftheplayingandtrainingseasoninthesouthernhemisphereisverydifferenttothatofthenorth,duetothereducednumberofmatchesplayedinthesouthernhemisphereandthesubsequentimpactthatthishasuponwindowsofopportunitytotrain.Inthesouthernhemisphere,thecumulativefatiguethroughoutaplayingseasoncouldbearguedtobelessthanthatseeninthenorthernhemisphere,whereplayersareoftenrequiredtoplaymorethanthirtygamesperseason(approximatelyoneeveryweek).Thisreducedmatchdemand,wouldthereforelikelymanifestitselfinanincreasedabilityofrugbyunionplayersinthesouthernhemispheretorestoreperformancepost-matchmorequickly.

7.5.4 RelevanceofGPSparametersuponCMJperformanceandWBscoresWithinthisstudy,significantrelationshipswerenotedbetweenselectedGPSparametersandCMJperformanceonly.Itwasnotedthatasdistancecoveredincreased,percentagechangeinCMJperformanceworsens(p<0.05),implyingthatthedistancecoveredbyplayersduringgameshadaneffectuponresultantCMJperformanceat60hourspost-match.TimespentinD5andD6alsopresentedasignificantrelationshipwithCMJperformance(p<0.05)at60hours

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post-match,meaningthatpractitionerscouldassumethatagreatertimespentinD6wouldleadtoagreaterreductioninrestorationofperformancepost-matchplay.Fromtheresultsofthischapter,itwasalsointerestingtonotethatdecelerations(manyofwhicharelikelytobecompletedpostD6movements)weresignificantlycorrelatedwithCMJperformanceat90hourspost-match(p<0.05).Thisviewthatagreaternumberofdecelerationsandtimespentinthehigherspeedzones(D5andD6)arecorrelatedwithreducedCMJperformance,wouldbeofsignificantinteresttopractitionerswhenassessingoutsidebacks’restorationofperformance.Whenconsideringthelargevolumeofthehighintensitymetrics(accelerations,decelerationsandsprints)thatbackscompletewithinmatchplay(asillustratedwithinChapter3),therolethatthismighthaveupontime-courseofrestorationofperformanceisfurtheremphasised.

Priorresearch(Quarrieetal.,2013)recommendsthatpractitionersprovideforwardswithmoretimetorecoverpost-matchthanbacks,giventhegreatercontactloadstheysustain,yetevidencefromthisstudywoulddisputetheseviews,whenconsideringitsresultsthatshowlongertime-courseofrecoveryassociatedwithbacks,comparedtoforwards.Despitestrongcorrelationsexistingbetweenforwards’accelerationstasksandreducedCMJperformance(Table7.3),nosignificantdifferenceexistedforCMJperformanceatanytime-pointpost-match.ThispointwouldthereforedisputetheviewthatcollisionandcontactsituationswereresponsibleforreducedCMJperformance,as,incontrasttobacks,nocorrelationswereobservedbetweenimpactsandCMJperformanceandnoreductioninCMJperformanceisnotedamongstforwardsatanytime-pointpost-match.ThelargernumberofImpacts>Zone3(notedwithinChapter3)attributedtoforwards,perhapssuggeststhatforwardsexperiencealargevolumeofblunttraumaduringmatchplay.Evidencefromthischapterwould,however,suggestthatthistraumaisnotafactorinCMJperformancescorespost-match.Instead,perhaps,thetraumathatforwardsexperienceismainlyupperbodytraumaassociatedwiththeirpositionaltasksandthereforetheresultantNMFthatexperiencedaffectstheupperandnotthelowerbody.Similarly,sinceCMJmeasureslowerbodypowerviamovementofthelowerlimbs,traumatothelowerbodywouldbemorelikelytoaffectitsperformancethanupperbody.Upperbodytraumaisjustaslikelytooccurduringmatchplay,yettheinfluencethishasuponCMJperformanceisquestionableandshould,therefore,beassessedviaamorespecifictestingprotocol.

7.5.4.1 RelevanceofGPSparametersuponCMJperformanceandWBscoresbetweenpositionalgroups

Onfurtheranalysisoftherelationshipsbetweenmatchvariablesacrossbothpositionalgroups,itwasinterestingtonotethatasignificantrelationship(p<0.05)wasnotedbetweenCMJandaccelerationsat60hourspost-match.Itcould,therefore,bearguedthattheexistencewithinforwards,ofthisrelationshipbetweengreaterfrequenciesofaccelerationsat60hourspost-matchandreducedCMJperformanceisperhapsduetoforwardshavingtoaccelerateanddecelerateintocontactsituationsduringgames.Thesegreaternumberofcontactsituationsexperiencedbyforwards,comparedtobacks,whichwasreportedinpreviousresearch(Jonesetal.,2015;Jonesetal.,2014)(Forwards31±14;Backs16±7),couldresultinthesignificantrelationshipshownbetweenforwards’accelerationsandCMJperformanceinthedayspost-match.DespitebackscompletingmoresprintsandtimespentinD6duringmatchplay(asrepresentedinChapter3),comparedtoforwards,theresultsfromthischaptershowthatforwardsperhapsexperienceagreaterleveloffatiguefromaccelerationtasks.Consideringthatmanyofforwards’accelerationsareperformedpriortocontact/collisionsituationsand

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thereforeresultinagreaterlevelofneuromuscularfatigue,asrepresentedbyreducedCMJperformance,therelationshipidentifiedisperhapsmoreclearlyunderstood.Additionally,whenconsideringthatforwardstypicallyplayforfewerminutesthanbacks(Table3.4;Chapter3),andthereforeundertakeamoreintensifiedperiodofwork,andthatthisstudyprovidesevidenceoftheeffectsoftheseonrestoration,thenthisshouldbeamajorareaofconsiderationforpractitioners.

Asaresultoftheaforementionedidentification,thatforwardsexperiencedmoreimpactsthanbacks(Chapter3),thiswasperhapsanareathatwouldhavebeenexpectedtoshowpositivecorrelationswithCMJperformanceandWBscores.However,whenassessingtheplayinggroupasawhole(n=59)nocorrelationsexistedamongstIm5andIm6.Furtheranalysisofbothpositionalgroups(forwardsn=31;backsn=28)alsoshowednosignificantrelationshipbetweenimpactsandCMJperformanceorWBscores.Theabsenceofacorrelationbetweenimpactsanddelayedrestorationofperformanceissomewhatsurprising,yetcouldperhapsbeexplainedbythesmallsamplesizewithinthisresearch,andthereforeonethatwarrantsfurtherinvestigation.ThisfindingcouldalsoperhapsbeexplainedbythenotionsproposedbybothLindsay,Lewis,Scarrott,Draper,andGieseg(2015)andReardonetal.(2016)thattheforce,angleandbodypartsinvolvedincollisionsarelikelytobeadeterminingfactorinfluencingmuscledamageandthereforerestorationofperformance.ConsideringthesignificantrelationshipdiscoveredregardingaccelerationsamongstforwardsandreducedCMJperformance,alongwiththepotentialinfluenceofaccelerationsintocontact/collisionsituations,theneedtoassesswherethehighlevelimpactactuallyoccurwithinpositionalgroups’matchdemands,isanareaofpotentialfutureresearch.Improvedabilityofpractitionerstoquantifywherehighlevelimpactsoccurwithinthematchandwhetherornottheyinvolvedaccelerations,decelerationsand/orcontactsituationswithinthesameinstanceofplay,willshedfurtherlightuponplayermatchdemandsandtheirprobableeffectuponrestorationofperformance.

7.5.5 LimitationsoftheresearchAlongwiththeaforementionedneedtoincreasethesamplesizewithinthisresearch,themainlimitationinvolvesthelackofmultipletime-pointspost-match,uponwhichtoassesschangeinCMJperformanceandWBscores.Additionaltime-points,priorandpostthe60hourspost-match,wouldhaveprovidedaddedvaluetotheresearch.Theinabilityoftheresearchertogainadditionaltestingtime-pointswasduetologisticalconstraintsoftheplayerstrainingscheduleinthedayspost-match,meaningthataccesstoplayersforassessmentwaslimited.Thislimitedaccesstoplayersinthedayspost-matchisconsidereda“realworld”scenariowithineliteteamsportsettings,wheredaysofffromtrainingareoftenemployedtoenhancerecoveryandimproveperformancerestoration.

Anotherpossiblelimitationwiththisstudyisthat,similarlytopreviousresearch(Cormack,Newton,McGuigan,&Cormie,2008;McLeanetal.,2010),analysisofCMJperformancewasfocuseduponoutcomerelatedvariables.Asdiscussedpreviously(Chapter5),theanalysisofkineticvariablesthatassesstheSSC(specificallyeccentriccomponentsofjumpingmovement)wouldprovidemoredetailonthereasonsforlackofrestorationofperformance.Despitethefocusofthisstudybeingtodetecttime-courseofrecoveryofCMJandWBmeasuresandnottodetectNMF,itisperhapsalsoalimitationofthestudy,thatnoinclusionofkineticvalueswasmadeafterconsideringtheevidencepresentedbyGathercole,Sporer,andStellingwerff(2015).AssessmentofNMFandassessmentoftime-courseofrecoveryaretwodistinctprocessesandshouldwarrantseparatetestingprotocols,althoughitshouldbenotedthatthelinkbetween

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thetwoareasoffocuscouldprovidefuturedirectionforresearchpractices.Lastly,despitebiochemicalanalysisbeinganexpensiveandinconclusiveperformancemeasure(asoutlinedinchapter2.4.4),itsuseinfutureinvestigationiswarrantedinordertogainabetterunderstandingofthephysiologicalcostofgamesandperhapshelpadvisepractitionersuponwhichactivitiestoundertakeinthedayspost-match.Thislackofinclusionofphysiologicalanalysisoftheperformancedecrementobservedcouldthereforealsobeconsideredtobealimitationofthisstudy.

7.6 Practicalimplications

ThefindingsofthisstudyindicatethatbothCMJperformanceandWBwerereducedat60hourspost-match,90hourspost-matchand170hourspost-match,withchangesreportedsimilartopreviousresearch(Cormack,Newton,McGuigan,&Cormie,2008;Cormack,Newton,McGuigan,&Doyle,2008;Gastin,Meyer,etal.,2013).Restorationofperformanceimprovedfrom60hoursto170hourspost-match,yetwasstillnotedtobebelowpre-gamelevelsatthislatertime-point.WhenconsideringresultsfromChapter4,showingmeaningfulchangeinCMJbetween-sessions[1.0cm(2.4%)],practitionersshould,perhaps,keepinmindthemagnitudeoftheCMJdecrementbeforeadjustingindividualplayertrainingprescription.Also,whenmakingdecisionsuponindividualplayertrainingprescription,practitionersareadvisedtoconsiderthepositionalgroup,asdatafromthisstudyshowsthatforwardstendtorestoreperformanceataquickerratethanbacks.

ThisresearchalsoshowsthatWBisreducedtoagreatervalueandforalongertime-coursethanCMJbetweenbaselineand60hourspost-match(CMJ-6.5%;WB-9.0%),baselineand90hourspost-match(CMJ-7.0%;WB-9.8%)andbaselineand170hourspost-match(CMJ-3.0%;WB-3.1%).Considerationforthesevaluesanddifferencesintime-courseofrecoverybetweenCMJperformanceandWBscoresshouldbenotedbypractitionerswhenimplementingtrainingschedulesinthedayspost-match.ThissupportfortheuseofWBquestionnairesisanimportantfindingfromthisstudy,asmanyrugbyclubswithlimitedresources,couldimplementitsuse,as,notonlyisitcosteffective,butresultsfromthisstudyshowthatitisalsoagoodindicatorofperformancechange.Despiteinsufficientrecovery,priortocommencinganothertrainingsessionorgame,beingcommoninmanyteamsportenvironments,aswellasbeinganimportantaspectthatshouldbeconsideredwhenpreparingathletes,thisinnotonethatshouldcausemuchconcern.Themoreimportantconcernshouldperhapsbethelevelofperformancedecrementalthoughnotsimplythatthereisadecrementinthefirstplace.Implementingperformancetestingintodailytrainingschedulesisperhapsthemostdifficultaspectformanypractitionersinthefield;yetthisresearchaddssupporttotheuseofCMJandWBtomeasurerestorationofperformance.Whenconsideringthatplayersarerequiredtoresumeresistancetrainingintheimmediatedaysfollowingamatch,gym-basedsessionscouldperhapsprovidetheopportunityforcoachestomonitorperformanceduringexercisessuchasCMJ,uponwhichtheycouldmakedecisionsonreadinesstotrain.Ifpractitionersareconfidentinmakinginformeddecisionsbaseduponreadinessoftheirathletestoperform,improvedperformanceandreducedincidenceofinjuryfromtrainingandcompetitionareseeminglytooccur.Inadditiontopractitionersbeingabletomakeinformeddecisionsuponwhetherathletesshouldtrain,perhapstheareathatelitepractitionersshouldbefocusinguponshouldbetheneedtoimprovereadinessifandwhenrequiredandhowtodoso.Specificrecoveryprotocolsandadjustabletrainingschedulesinthedaypost-matcharethereforeofgreatimportance.

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ResultsfromthischaptersupporttheuseofbothCMJandWBtoassesstime-courseofrestorationinthedayspostmatch.However,thefindingsshowingnosignificantcorrelationsbetweenCMJheightandhighmagnitudeGPSimpactsweresurprising.AneedthereforeexiststoassesstheoccurrenceofGPSimpactsduringmatchplay,viauseofvideorecordingsalongsideGPSdata.AstheinfluenceofhighmagnitudeGPSimpactswasnotedasnotbeingrelatedtodelayedtime-courseofrestorationinthedayspostmatch,futureresearchinthisthesisneedstoassesswhenandhowoftenhighmagnitudeimpactsoccurduringmatchplayandwhatactivitiesplayersarepreformingwhentheyaccruethem.

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8 QuantificationofGPSimpactsusingvideoanalysisinEliteLevelRugbyUnion

8.1 Abstract

Anunderstandingoftheimpactsexperiencedbyeliterugbyplayersduringmatchplay,isanimportantconsiderationforpractitionersinimprovingtheirabilitytoassesstheinfluencetheseimpactsmayhaveuponrestorationofperformancepostmatchplay.Thepurposeofthisstudywastoquantifythefrequencyandmagnitudeofimpactsexperiencedduringgame,withspecificattentionpaidtowardsthoseactivitieswhichresultedinimpactsduringgameplay,combiningbothGPSsoftwareandvideoanalysistools.ThiscombinationofmethodsenabledcomparisonbetweenimpactinstancesidentifiedbytheGPS,whichcouldthenbecross-referencedagainstvideofilestoascertainwhichmatchdemandsillicittheseimpacts.Usingvideoanalysis,datawascollecteduponnineparticipants(age27.7±5.5years,height186.1±10.3cm,mass97.4±13.2kg,trainingage9.4±5.7years),withresultsshowingnosignificantdifferenceinpercentagedistributionorabsolutevaluesofimpactsresultingfromdecelerations(p>0.05).RMANOVArevealednosignificantdifferenceinpercentagedistribution(p=0.028)andabsolutevalues(p=0.061)forcollisionsoccurringbetweenimpactzones.Friedmantestsrevealedasignificantdifference(p<0.001)inthepercentagedistributionandabsolutevaluesofimpactsasaresultofchangesofdirection,withthegreatestnumberofimpactsfromchangeofdirectionoccurringinZone4(90.7±18.8%;3.8±3.2),whichwassignificantlygreaterthanthenumberofimpactsfromchangesofdirectioninZone5(p=0.015,0.0±0.0;d=6.82;p=0.007,0.0±0.0%;d=1.67)andZone6(p=0.021,9.2±18.8%;Cohen’sd=4.33;p=0.011,0.2±0.4;d=1.57).Asignificantdifference(p=0.007)inthepercentagedistributionofimpactsasaresultofaccelerationswasnoted,however,resultsfromWilcoxontestswithBonferronicorrectionrevealedthatnodifferenceswereobservedbetweenimpactzonesfromaccelerations.Whenassessingabsolutevalues,Friedmantestsrevealedasignificantdifference(p<0.05)inthefrequencyofimpactsasaresultofaccelerations,withWilcoxonrevealingthatthegreatestnumberofimpactsfromaccelerationsoccurredinZone4(10.8±13.2),whichwassignificantlygreaterthanthenumberofimpactsfromaccelerationsinZone5(p=0.018,0.7±1.3;d=1.07)andZone6(p=0.049,1.5±2.2;d=0.98).Aswashypothesised,collisionsaccountedforhighermagnitudeimpactsthanothermovements.Asaresultofthisresearch,itcanbeconcludedthatplayermovementpatternsidentifiedfromGPSimpactsmayprovidemisleadinginformation.PractitionersworkingintheelitefieldarethereforerecommendedtocombinevideoandGPSdatatodevelopagreaterrepresentationofthematchinvolvementsassignedtoimpactsexperiencedduringmatchplay,asthevaluespresentedfromGPSoutputsalonecannotbetakenatfacevalue.

8.2 Introduction

Theabilitytoidentifyandunderstandthespecificmatchdemandsplaceduponrugbyplayers,haslongbeenrecognisedasanessentialcomponentfordevelopingappropriatetrainingandrecoveryprogrammes,withtheaimofimprovingsubsequentperformance(Robertsetal.,2008).ThedevelopmentofGPSandvideoanalysistechnology,providessportssciencepractitionerswithdetailedobjectivedatarelatingtospecificmovementdemandsofplayersinrugbyunion(Austin&Kelly,2013;Cumminsetal.,2013;McNamara,Gabbett,Naughton,Farhart,&Chapman,2013),withvariationsinmatchdemandsbetweenposition(Chapter3)

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(Cahilletal.,2013;Lindsay,Draper,etal.,2015;Reardonetal.,2017)andbetweenplayinglevels(Cahilletal.,2013;Coughlanetal.,2011;Cunninghametal.,2016;Venteretal.,2011)alsohavingbeenidentifiedasbeingimportant.Manystudieshaveattemptedtoassesstheinfluenceofmatchvariablesuponrestorationofperformance(Cunniffeetal.,2010;Duffieldetal.,2012;Johnstonetal.,2015;Johnston,Gabbett,etal.,2014;McLellan&Lovell,2012),yetfewstudieshaveincorporatedcollisionorimpactvariableswhenevaluatingmatchdemands.

ResearchbyMcLellanandLovell(2012)notedthatneuromuscularfatiguewashighlydependentuponthenumberofheavyimpacts(>7.1G)experiencedduringgameplay,withmanyauthorsnotingpositionaldifferencesinthenumberofimpactsexperiencedduringmatchplay(Coughlanetal.,2011;Cunniffeetal.,2009;Lindsay,Draper,etal.,2015;Venteretal.,2011).DespitetheresearchbyMcLellanandLovell(2012)involvingbothtime-motionanalysisandGPSinassessingtheinfluenceofneuromuscularimpactsandcollisionsduringeliterugbyleaguematchplay,theresultspresenteddidnotquantifywhichspecificmatchmovementsexhibitmuscletraumathatwoulddelaypost-matchrestorationofperformance.Theneedforamoredetailedanalysisofimpactsresultingfromaccelerations,decelerations,changesofdirectionandcollisionsisthereforerequired,withanimprovedunderstandingoftheimpactsresultingfromthesematchdemandslikelytobenefitpractitionersworkingintheelitefield.

BothGPSandvideoanalysisareregularlyusedinappliedsettings,yetbothmethodsofdatacollectionhavelimitationsandbenefitsintheiruse.Time-motionanalysisusingvideobasedanalysissystemshavebeenemployedforthelast30yearstoassessmatchdemands(Deutschetal.,2007;Duthieetal.,2003a)andcontinuetobeutilisedextensivelyinavarietyofteamsports(DiSalvo,Collins,McNeill,&Cardinale,2006;King,Jenkins,&Gabbett,2009;Spenceretal.,2004),withvideoanalysisappearingtoproducevaliddata(Duthie,Pyne,&Hooper,2003b).Limitationsofvideoanalysisforassessingmatchdemandsdo,however,exist,mainlyinthatitisalabourintensiveprocesswhere,unlikeGPS,onlyonesubjectcanbetrackedatatime,whenusingtime-motionmethodsviaoneoperator.Inaddition,theintensityofeachactivitycollectedviavideoanalysiscannotbequantified,makingmatchdemandsmoredifficulttoassess.Thereliabilityoftime-motionanalysiswithinrugbyunionhaspreviouslybeenresearchedbyDuthieetal.(2003b),whonotedthatthetotaltimespentbyindividualsperformingmovementsinvolvingstaticexertions(thatarelikelytoincurimpacts)presentsmoderatetopoorreliability(5.8-11.1%TEM).Lastly,perhapsthemostinfluentiallimitationofvideoanalysisforassessingmatchdemandsisusererrorandthesomewhatsubjectivemeasuresthatareinvolvedwithinthisdatacollectionprocess.Interandintra-reliabilityofdatacollectedinvideoanalysisisofnote,withwhatoneusermaycategoriseasaspecificmovementormatchdemand,potentiallybeingdifferenttothatofanotheruser,therebyproducingcontrastingresults.Variancesinthereliabilitydataforintra-coderanalysiswerepreviouslyinvestigatedbyDeutschetal.(2007),withatypicalerrorofmeasurementreportedof4.3-13.6%.

Supportfortime-motionanalysismethodswasnotedbyDogramaci,Watsford,andMurphy(2011),withrecommendationsfortheuseofsubjectivenotationalanalysisasbeingbothvalidandreliableintrackingplayermovements.Dogramacietal.(2011)alsorecommendedtheuseofnotationaltime-motionanalysisinplaceofGPS,whenassessingfieldsportswhereshortsprintsandchangesofdirectionarecommon,asapreferredandmoreeffectivemethodformovementanalysis.However,theinabilityofvideoanalysistoquantifymagnitudeofeffortorimpactwithintheeventsidentified,meansitsuseislimited.Whenconsideringthatrecent

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technologicaladvancesinGPSsolutionshaveprovidedpractitionerswiththeabilitytoanalysedatainrealtimewithregardstoplayers’movementintensityandresultantfatigue,time-motionanalysishasbecomesecondarywithinmanyteamsportsettings.Insteaditismainlyusedforpost-matchanalysisbysportspecificcoaches,wheredecision-makingandindividualplaywithinthecontextofthegamearebetterdisplayedbytime-motionmethods.ReliabilityofGPSanalysisinteamsportsettingshasbeenconfirmedinmanypreviousstudies(Coutts&Duffield,2010;Cumminsetal.,2013;Johnston,Watsford,etal.,2014;Varleyetal.,2012),withCouttsandDuffield(2010)reportingtotaldistancebeingstablebetweenmatchvariationsinrugbyleague(<5%CI),whileJohnston,Watsford,etal.(2014)showedalargerdegreeofbetweenmatchvariabilityforhigherspeedactivities(TEM=0.8-19.9%).Criticalmovementsforgoodperformanceinrugbyincludetheabilitytomaximallyaccelerate,decelerateandchangedirectionatspeedoverashortdistance,yetwhenassessingthereliabilityandvalidityofteamsportspecificrunningpatterns,Jennings,Cormack,Coutts,Boyd,andAughey(2010)havequestionedtheuseofGPSsystemsfortheassessmentofbriefhighspeedstraightlinerunning(CV=77.2%).

Itis,however,interestingtonote,thatcollisioneventsrecordedusingGPShavebeencomparedtovideoanalysisandwerenotedtostronglycorrelate(r=0.89,0.97and0.99)withmild,moderateandheavycollisionsrespectively,thereforesupportingGPSuse(Gabbett,Jenkins,&Abernethy,2010).Incontrast,recentresearchinelitelevelrugbyunion(Reardonetal.,2016)illustratedinaccuraciesincollisionassessment,wherethesmallestmeandifferencebetweenmicrotechnologyandvideocodingwasnotedatthe2.5Gcollisionthreshold,withstatisticaldifferencesnotedbetweensomepositionalgroups.Furtherinaccuracieshavebeennotedinelitelevelrugbyunion(Clarke,Anson,&Pyne,2017;Kelly,Coughlan,Green,&Caulfield,2012),wherecollisionrecallassessment(theabilitytodetectcollisionswithalownumberoffalsepositives)wasnotedasbothgender(Women’s=0.45;Men’s=0.69)andcodespecific,betweenthefifteens(0.93)andsevens(0.45-0.73)versionsofthegame.ThefindingbyReardonetal.(2016)thereforehasimplicationsforfuturecollisionassessment,withthemanipulationofG-forcethresholdshavingnoeffectuponaccuracyandtheimplementationofcollisioncountsbaseduponaposition-specificbasisbeingrecommended.

Impactswithoppositionplayersortheplayingsurfaceinrugbyunionarealsolikelytoinducemuscletraumaandresultantfatigue,yetthecommonlyreportedGPSandvideoanalysisdatacollectionlimitationsdiscussedabove,meanthatmanyofthemovementsthatillicitandquantifyimpactsmaybeexcludedfrompost-matchanalysis.AgreaterunderstandingofthehighlyspecificgamerelatedactivitiesinvolvedwithinrugbyunionmatchplayandthelikelyGPSimpactassociatedwitheachmovementisneededtobetterunderstandimpactsincurredduringspecificmatchdemands.Anillustrationoftheresponsewhichimpactsarelikelytohaveuponpost-matchfatigue,wasillustratedbyJohnston,Gabbett,etal.(2014)wheremarkersofmuscledamage(CKbloodanalysis)followingsmallsidedrugbyleaguegameswerereportedtostillberising24hoursfollowingthecontactgameincomparisontothenon-contactsmallsidedgame(ES0.86).ThisviewwasalsorecentlysupportedbyRoeetal.(2017),whonotedincreasedlikelihoodofupperbodyNMF,reducedwellbeingandgreaterelevationsinCKposttrainingsessionsinvolvingcontactthansessionswithoutcontact.Asreportedwithinrugbyuniontime-motionanalysisresearch(Deutschetal.,2007;Dochertyetal.,1988),themajorityofcollisioneventshappenduringtacklesituations,potentiallyemphasisingthatagreaternumberoftackleshasgreaterimpactuponNMF.However,whenconsideringthattime-motionanalysisonlyprovidesafrequencyofeventswithnomagnitudeofload,someofthedata

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producedbytime-motionanalysisresearchmaybeerroneousandthereforemisleading,meaningtheimplementationofGPSanalysistoassessmagnitudeofloadandsubsequentinfluenceuponrestorationofperformanceisparamountasitprovidesthedetailsurroundingtheimpacts.

Reardonetal.(2016)statedthatGPStechnologywas,however,notavalidtechnologyfordetectingrugbyunioncollisions.AprocessofcombineddatacollectionincludingbothGPSdataandvideorecordingswasrecommendedbyCunniffeetal.(2009)foruseineliterugbyunioninordertoproduceamorethoroughanalysisofmatchdemands.InastudyassessingplayingdemandsinrugbybyCunniffeetal.(2009),moreaccuratedatawascollatedviaatriangulationofanalysispractices.Cunniffeetal.(2009,p.1202)statedthata“combinationofGPSsoftwarewithgamerecordingsmayproducemoreinsightintocategorisationofforces/accelerationsreceived/exertedduringthemanycontactelementswithinthegame”.Despiterecentresearch(Reardonetal.,2016)assessingcollisioncountsinelitelevelrugbyunionexisting,thisexperimentalstudydiffersasitaimstomatchsinglecollisioneventscodedbyGPStotherelevantpassageofplaywithinthevideofile.Theresultsofthisstudythereforehaveimplications,notonlyfortheplayersinvolved,butalsoforpractitionersaimingtoimplementtrainingsessionsinthedayspost-match.Notonlywillthephysicaldemand(createdbyimpacts)placedupontheplayerwithinmatchsituationsbeavailable,butalsoavideostoryofmovementpatterns(involvingimpacts)willbeavailableforanalysis.Fromthedataproduced,practitionerswillbeabletoplaceaccuratetrainingexpectationsuponplayersinthedayspost-match,astheimpactsexperiencedandtheconsequencesofimpactsuponplayerreadinesscanbeanalysedmorefully.Theaimofthisstudywastoidentifywhichactivities,baseduponvideoanalysis,areresponsibleforimpactsatdifferentintensities,withtheintensitymeasuredviathe

accelerometerintheGPSunit.Baseduponresultsfrompreviouschapters,impactsinvolving≥�9Gwereidentifiedasthemostlikelytoimpairsubsequentperformanceandthesethereforewarrantedfurtherinvestigation.Itwashypothesised,thatastheimpactincreases,thepercentageofimpactsfromcollisionswouldalsoincreaseandthepercentageofimpactsfromaccelerations,decelerationsandchangesofdirectionwoulddecrease.Findingsfromthisstudywillprovidefurtherinformationupontheactivitieswhichresultinthehighestimpactsexperiencedduringmatchplay.Evidencepresentedwillthereforehelppractitionerstomakemoreinformeddecisionsuponfuturetrainingprescriptionpostrugbyunionmatchplay,inordertoincreasethelikelihoodofsubsequentoptimalperformance.

8.3 Method

8.3.1 ParticipantsTheassessmentperiodcoveredsevengamesduringacompetitiverugbyunionplayingseason,withdatacollectedupononeindividualfromeachoftheninepositionalgroupsincludingprops(n=1),hookers(n=1),locks(n=1),backrows(n=1),scrumhalf(n=1),outhalf(n=1),centres(n=1),wings(n=1)andfullbacks(n=1);meaningninesetsofgamedatawereassessed(age27.7±5.5years,height186.1±10.3cm,mass97.4±13.2kg,trainingage9.4±5.7years).ThisstudywasconductedinaccordancewiththeDeclarationofHelsinkiandwasapprovedbySalfordUniversityInstitutionalReviewBoard.Allparticipantsprovidedwritteninformedconsenttoparticipateinthisstudy.

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8.3.2 ExperimentalapproachBothGPSandvideoanalysisdataprovideinformationupontheimpactsexperiencedduringgameplay.Datawascollectedfromthesamerugbyclubforallninepositionalgroups,andiftheplayerwhostartedthegameinonepositionwassubstituted,thedataproducedbythesubstituteplayerwascombinedwiththatoftheoriginalplayer,thereforeprovidingafullgamedurationofthepositionbeinganalysed.TheGPSfileusedforanalysiswasarawnumericaldatafile,detailingwhereimpactsoccurredwithinthematchdaytimeline.ThisGPSfilewasexporteddirectlyfromthe10HzGPSunits(StatSportsViper,NorthernIreland)detailedbelowinChapter8.3.3andwassubsequentlyimportedintothevideofootagetoascertainwhereaboutswithinthegametheseimpactsoccurred.VideofootagewasviewedthroughoutthedurationofeachgameandasensecheckwasmadewiththeStatSportsdataexporttoassessexactlywhattheimpactsrelatedtowithinthevideofileandwhetherthisinvolvedcollisions,changeofdirection,accelerationsordecelerations.

Collisions(includingorexcludingsetpieceelementsofrugbyunionmatchplay)acrossallpositionalgroupswasnotconsideredaconcernasthedatacomparisonbetweenallninepositionalgroupswasnormalisedviapercentagecalculationsofeachcollisionoccurring,meaningthispotentialdisparitybetweenpositionswasaccountedfor.Inordertoascertainthematchinvolvementsandtheimpactassociatedwiththesemovements,theGPSdataprovidedthemagnitudeoftheimpactexperiencedbytheplayers(illustratedbyGPSimpacts),whilethevideofootageactedasareferencefileagainstwhichtocomparetheGPSimpacts.ItisimportantforreaderstonotethatthisresearchusedvideoanalysistoviewmatchinvolvementsalongsidetheGPSdataanddidnotemploytypicaltime-motionanalysispracticestoassessmovementpatterns,thusprovidingspeeds,distancesandspeedsoflocomotivetasksasoutlinedbyDobsonandKeogh(2007).Asexplainedabove,GPSuseforlocomotivetasksisconsideredsuperiortotime-motionmethods,thereforethisresearchonlyusedvideoanalysistoclarifymatchinvolvementsandnottoquantifyandcomparelocomotionagainsttheGPSdata.

8.3.3 Matchanalysis

8.3.3.1 GPSanalysisThematchcharacteristicsexportedfromGPSunitsincluded:accelerations,decelerations,collisions,sprints,impactsinZone4(9-11G),impactsinZone5(11-13G)andimpactsinZone6(>13G).Measurementsweretakenwith10HzGPSunits(StatSportsViper,NorthernIreland)throughoutallgamesinordertoassessmovementpatterns.Playerpositionsweredefinedas:(1)backsorforwards;(2)props,hookers,locks,backrows,scrumhalf,outhalf,centres,wingsandfullbacks.ThemainfocusoftheGPSanalysiswastheassessmentofimpacts,usingStatSportsViperGPSunits,withthe100HztriaxialaccelerometerbeingusedtocollateimpactsandnotGPSdata.TheGPSdevicemeasuresGPSimpactswhenvaluesareabove2Gina0.1secondperiod.ImpactsareinstantaneousmomentsthroughoutamatchsituationmeasuredinG-forcesandareexpressedasaquantity,withanumberofimpactsateachofthe6zonescategorisedintheVipersystem.ItisimportanttonotethatGPSimpactsareacombinationofcollisionsandimpactscreatedfrommovement(stepping,jumping,anddecelerations).Forthepurposesofdiscussingtheimpactzones,shorthandabbreviationswereused.ImpactzoneswereabbreviatedtoIm1relatingtoimpactsinZone1,Im2forimpactsencounteredinZone2,Im3forimpactsencounteredinZone3,Im4forimpactsencounteredinZone4,Im5forimpactsencounteredinZone5andIm6forimpactsencounteredinZone6(Table8.1).AccelerationsanddecelerationswerealsocollatedbytheStatSportsViperGPS

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unit,withthisdatacollectedpurelybytheaccelerometer.Accelerationisachangeinvelocity/time(usingGPSdata),withindividualaccelerationthresholdssimilaracrosspositionalgroups,baseduponlongitudinalanalysisofplayersperformingmaximalaccelerations.PrescribedzoneswerethencategorisedfromthesemaximalvaluesandmanuallyinputtedintotheStatSportsVipersoftware.

Table8.1:Categorisationofimpactzones

Zone1 Zone2 Zone3 Zone4 Zone5 Zone6ImpactsinZones(G) 3–5 5–7 7-9 9–11 11-13 13-15

8.3.3.2 VideoanalysisNineindividualplayervideoswerecollectedwithallvideorecordingsfilmedonadigitalcamera(SonyAX14K)mountedonatripodandcapturedviafirewireontoanAppleMacBookProusingSportsCode(version10.3)analysissoftware.SportsCodesoftwareallowedtheimportingoftheGPSdatacollectedforfurtheranalysisviaanxmleditlist.Thesoleuseoftypicalgamefootage(sideonandcoveringmultipleplayers)wasconsideredtoobroadforusewithinthisstudyasdetailedanalysisofanindividualwasthegoal,thereforecloseup“sideon”individualplayercameraswerealsoadministeredalongside.Regularrugbyfootageasseenonpublictelevisionwouldshowtheindividualplayingwithintheteampattern,butwouldnotprovidespecificdetailsurroundingtheparticipantbeinganalysed.Asaresult,themaintelevisionrecordingcoveringtypicalmatchfootagewassynchronisedwiththeindividualplayervideowithinSportsCode,toshowthebroaderaspectofthegametheindividualisplayingwithin,whilealsocoveringthedetailoftheindividualrequired.Forexample,thiscombinationofvideoswouldsupplygreaterdetailtoactivitiesincontactsituations,wheretypicaltelevisionfootageoftheplayermaybeobscuredbyotherplayersonthefield,orbyreplaysofpreviouslycompletedmatchevents(scrum,ruckandtacklesituations).Duetothenatureofthisstudy,parametersmeasuredwithinbothmethodsofassessmentcouldbecross-referencedandvalidatedagainsteachother,asthetimingswereidenticalforboththeGPSanalysisandthevideofootage.Asaresult,fromthevideofootage,practitionerswouldbeabletodetermineiftheimpactdataelicitedbytheGPSdataatthemomentinquestionisactuallywhatisexpectedfortheseactions.

8.3.4 StatisticalanalysesStatisticalanalysiswasperformedusingSPSSVersion20(IBM),withanapriorialphalevelsetatp<0.05.Normalitytestingwasconductedonboththepercentagesdistributionofmatchcharacteristicsandtheabsolutevaluesthataccountforimpactsoccurring(changesofdirection,acceleration,decelerationandcollisions).NormalitytestingonpercentagesdistributionandabsolutevaluesofmatchcharacteristicswasconductedacrossimpactZones4,5and6andcomparisonsbetweenzonesandpositionsweremade.Asplayingpositionsaredifferentinthematchdemandsrequired(asillustratedinChapter3),analysisofthepercentagesdistributionofmatchcharacteristicswasconsideredimportantalongsideanalysisofabsolutevalues.RepeatedmeasuresANOVAswithBonferronipost-hocanalysis,ornon-parametricequivalent(Freidmantest,withmultipleWilcoxontestsforpairwisecomparisonandsubsequentBonferonnicorrectionapplied)wereconductedtocomparethedifferencebetweenpercentagedistributionofimpactsincurredbycollisionsandthosethatresultedfromchangesofdirection,accelerationordeceleration,acrossimpactzones.SubsequentrepeatedmeasuresANOVAswithBonferronipost-hocanalysis,ornon-parametricequivalent(Freidman

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test,withmultipleWilcoxontestsforpairwisecomparisonandsubsequentBonferonnicorrectionapplied)wereperformedtodetermineiftherewasasignificancedifferenceinthepercentageofactivitiesresultinginimpactswithineachzone.Furthermore,Cohen’sdeffectsizes(ES)werecalculatedtodetermineifanymeaningfuldifferencesoccurred,interpretedbaseduponthecriteriasuggestedbyRhea(2004)andwereinterpretedasfollows;trivial<0.25,small=0.25-0.5,moderate=0.50-1.0andlarge>1.0.

8.4 Results

Shapiro-Wilkstestsshowedthatdatawasnormallydistributed(p>0.05)forthepercentagedistributionofZone4collisionsanddecelerations,yetwasnotnormallydistributedforchangeofdirectionandaccelerations.Additionally,theShapiro-Wilkstestsshowedthatdatawasnormallydistributed(p>0.05)forthepercentagedistributionofZone5collisionsanddecelerations,yetchangesofdirectionandaccelerationswerenotnormallydistributed(p<0.05).Lastly,Shapiro-Wilkstestshowedthatdatawasonlynormallydistributed(p>0.05)forthepercentagedistributionofZone6collisions,whilechangesofdirection,decelerationsandaccelerationswerenotnormallydistributed(p<0.05).Whenassessingabsolutevalues,theShapiro-Wilkstestshowedthatdatawasnormallydistributed(p>0.05)forZone4decelerations,yetnotforchangeofdirection,accelerationsandcollisions.Additionally,theShapiro-Wilkstestshowedthatdatawasnormallydistributed(p>0.05)fortheabsolutevaluesofZone5decelerations,yetchangesofdirection,accelerationsandcollisionswerenotnormallydistributed(p<0.05).Lastly,theShapiro-Wilkstestshowedthatdatawasnormallydistributed(p>0.05)onlyforthepercentagedistributionofZone6collisions,whilechangesofdirection,decelerationsandaccelerationswerenotnormallydistributed(p<0.05).

Figure8.1showsthefrequencyofimpactsinZones4,5and6foreachactivity.Whenassessingtheseabsolutevalues,RMANOVArevealednosignificantdifference(p=0.061;Zone4=15±0.7;Zone5=11±0.6;Zone6=13±0.6)incollisionsbetweenimpactzones(Figure8.1).Friedmantestsrevealedthatasignificantdifference(p<0.001)occurredinthefrequencyofimpactsasaresultofchangesofdirection,withWilcoxonrevealingthatthegreatestnumberofimpactsfromchangeofdirectionoccurredinZone4(3.8±3.2),whichwassignificantlygreaterthanthenumberofimpactfromchangesofdirectioninZone5(p=0.007,0.0±0.0;d=1.67)andZone6(p=0.011,0.2±0.4;d=1.57).NodifferenceswereobservedbetweenabsolutevaluesforimpactsfromchangesofdirectionbetweenZones5and6(p>0.05).Friedmantestsrevealedthatasignificantdifference(p<0.05)occurredinthefrequencyofimpactsasaresultofaccelerations,withWilcoxonrevealingthatthegreatestnumberofimpactsfromaccelerationsoccurredinZone4(10.8±13.2),whichwassignificantlygreaterthanthenumberofimpactfromaccelerationsinZone5(p=0.018,0.7±1.3;d=1.07)andZone6(p=0.049,1.5±2.2;d=0.98).NodifferenceswereobservedbetweenimpactsfromaccelerationsbetweenZones5and6(p>0.05).Friedmantestsalsorevealedthatnosignificantdifference(p>0.05)occurredintheabsolutevaluesofimpactsincurredasaresultofdecelerations(Zone4=12.6±7.6;Zone5=4.6±2.6;Zone6=1.1±0.4).

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Figure8.1:FrequencyofimpactsinZones4,5and6foreachactivity

Figure8.2showsthepercentageofimpactsinZones4,5and6foreachactivity.RMANOVArevealednosignificantdifferenceinpercentagedistribution(p>0.05;Zone4=38.0±40.0%;Zone5=28.0±8.4%;Zone6=34.0±32.1%)betweenimpactzonesfromcollisions(Figure8.2).Friedmantestsdid,however,revealthatasignificantdifference(p<0.001)occurredinthepercentagedistributionofimpactsasaresultofchangesofdirection,withWilcoxon’stestshighlightingthatthegreatestnumberofimpactsfromchangeofdirectionoccurredinZone4(90.7±18.8%),whichwassignificantlygreaterthanthenumberofimpactsfromchangesofdirectioninZone5(p=0.015,0.0±0.0%;d=6.82)andZone6(p=0.021,9.3±18.8%;d=4.33).NodifferenceswereobservedbetweenpercentagedistributionofimpactsfromchangesofdirectionbetweenZones5and6(p>0.05).

Friedmantestsalsorevealedasignificantdifference(p=0.007)inthepercentagedistributionofimpactsasaresultofaccelerations,however,Wilcoxon’stestswithBonferonnicorrectionrevealedthatnodifferenceswereobservedbetweenimpactsfromaccelerations,betweenanyoftheimpactzones(Zone4=69.6±34.3%;Zone5=8.6±12.3%;Zone6=21.8±31.7%).Incontrasttoaccelerationsandchangesofdirection,Friedmantestsrevealedthatnosignificantdifference(p>0.05)occurredinthepercentagedistributionofimpactsasaresultofdecelerations(Zone4=50.1±33.2%;Zone5=19.2±16.9%;Zone6=30.7±40.9%).

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Figure8.2:PercentageofimpactsinZones4,5and6foreachactivity

Figure8.3showsthepercentagedistributionwithinandbetweenzonesforeachactivity,displayingthatthelargestfrequencymatchdemandinallzoneswascollisions(Zone4=32.7±40.0%;Zone5=61.9±8.4%;Zone6=76.3±32.1%)andthatthefrequencyofcollisionsincreasedincomparisontootherzonesasthemagnitudeoftheimpactalsoincreased.Decelerations(Zone4=27.9±33.2%;Zone5=25.3±16.9%;Zone6=6.6±40.9%)werenotedtodecreaseasthemagnitudeoftheimpactincreased,whileaccelerations(Zone4=30.8±34.3%;Zone5=12.8±12.3%;Zone6=15.8±31.7%)andchangesofdirection(Zone4=8.6±18.8%;Zone5=0.0±0.0%;Zone6=1.3±0.0%)werelowestinZone5.RMANOVArevealedthatthereweresignificantdifferences(p<0.05)inthepercentagedistributionofimpactswithinZone4,Zone5andZone6.Friedmantestsrevealedthatasignificantdifference(p<0.005)occurredinthepercentagedistributionofimpactswithinZone4,withWilcoxon’stestshighlightingthatthegreatestnumberofimpactsinZone4occurredasaresultofcollisions(32.7±18.8%),thisbeingsignificantlygreaterthanthenumberofimpactsinZone4fromdecelerations(p=0.012,27.9±33.2%)andchangesofdirection(p=0.008,8.6±18.8%;d=0.71).Nodifferences(p>0.05)wereobservedbetweencollisionsandaccelerationswithinZone4.Friedmantestsalsorevealedasignificantdifference(p<0.005)occurredinthepercentagedistributionofimpactswithinZone5,withWilcoxon’stestshighlightingthatthegreatestnumberofimpactsinZone5occurredasaresultofcollisions(61.9±8.4%),thisbeingsignificantlygreaterthanthenumberofimpactsinZone5fromchangesofdirection(p=0.012,0.0±0.0%)andaccelerations(p=0.025,12.8±12.3%;d=1.47).Lastly,Friedmantestsalsorevealedasignificantdifference(p<0.005)occurredinthepercentagedistributionofimpactswithinZone6,withWilcoxon’stestshighlightingthatthegreatestnumberofimpactsinZone6occurredasaresultofcollisions(76.3±32.1),thisbeingsignificantlygreaterthanthenumberofimpactsinZone6fromchangesofdirection(p=0.008,1.3±0.0%;d=3.30).

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Figure8.3:PercentagedistributionofimpactsacrossZones4,5and6foreachactivity

Table8.2:KeyofsignificantdifferencesinpercentagedistributionofimpactsacrossZones4,5and6foreachactivityrelatingtoFigure8.3

Keyofsignificantdifferences

£significantdifference(p=0.012)betweencollisionanddecelerationswithinZone4

*significantdifference(p=0.008)betweencollisionandchangesofdirectionwithinZone4

#significantdifference(p=0.012)betweencollisionandchangesofdirectionwithinZone5

$significantdifference(p=0.025)betweencollisionandaccelerationswithinZone5

€significantdifference(p=0.008)betweencollisionandchangesofdirectionwithinZone6

8.5 Discussion

Thefindingsofthisstudyindicatethatthemajorityoftheimpactsregisteredduringcollisionsareofahighermagnitudethanaccelerations,decelerationsandchangesofdirection.Inlinewiththehypothesis,theresultsconfirmthatasthemagnitudeofimpactsincreasethe

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percentageofimpactsfromcollisionsalsoincreaseandthepercentageofimpactsfromaccelerations,decelerationsandchangesofdirectiondecrease.

8.5.1 ImpactsresultingfromcollisionsWhenconsideringrecentliteratureassessingtheimpactsencounteredduringrugbymatchplay(Lindsay,Lewis,Scarrott,Draper,etal.,2015;McLellan&Lovell,2012;McLellanetal.,2011a;Suarez-Arronesetal.,2014),onewouldassumethatanimpactofgreaterthan9G(≥Zone4)wouldbeacollisionandtheresultsfromthisexperimentalstudyfurthersupportthisview.ThenotionthatwithinZone6themostimpactsaccruedwerefromcollisions(Frequency=13;Distribution=76.3%)wasexpectedwithinthisstudy,yettheresultsfromthisstudywhichshowedalargecontributionofimpactsfromcollisionsinZone4(Frequency=15;Distribution=32.7%)wasunexpected(Figure8.1and8.3).ThecausesofthecollisionimpactsoccurringinZone6arelikelytobeduetoboththematchdemandsoccurringinopenfieldplayandthoseencounteredwithinsetpieceelementsofmatchplay.Openfieldplaycollisionsinvolveaggressiveandforcefulmatchmovementsinanattempttoavoidanattackingplayergainingmomentum,orinrucksituationswheretheoppositionareattemptingtoregainpossessionoftheball.Similarly,setpieceelementsofmatchplayinvolveclosecontactcollision,wherebyplayersaredeliberatelyattackingweaknessesintheopposition’spre-plannedsetups,withaggressiveactionsconductedtospoilpossessionanddisruptteammomentum.Whenviewedduringgameplay,collisionactionsareclearlyveryphysicalinnatureandthereforeunsurprisinglycreatethehighestimpactforceswhencomparedtoothermatchmovementssuchaschangesofdirection,accelerationsanddecelerations.Playersarerequiredtoexertmaximalforceontotheoppositionduringcollisionmomentsinanattempttohaltorcontinuemomentum;meaningcollisionimpactsoccurringinZone6arelikely.

Muchofthepreviousresearchineliterugbyunionthathasassessedimpactsencounteredduringmatchplay,hasclassifiedimpactsas“heavy”,“veryheavy”or“severe”,withimpactsofthesehighmagnitudesexperiencedduringmatchplayassumedtocausesignificantchangesinmarkersofmuscledamage(Coughlanetal.,2011;Cunniffeetal.,2009;Lindsay,Lewis,Scarrott,Draper,etal.,2015;McLellan&Lovell,2012;McLellanetal.,2011a;Venteretal.,2011).Specifically,whenassessingneuromuscularresponsestoimpactspostrugbyleaguematchplay,McLellanandLovell(2012)noted“veryheavy”and“severe”impactsweresignificantlycorrelatedtochangeinPRFDandPP24hourspost-match,withcollisionsthatinvolvedimpacts>8.1Gnotedtoresultinprolongedneuromuscularfatigue.AdditionalresearchbyMcLellanetal.(2011a)ineliterugbyleague,notedthatthenumberofimpactsrecordedinZone5(8.1–10.0G)andZone6(>10.1G)duringmatchplaywassignificantlycorrelated(p<0.05)toCKforupto72hourspost-matchandthatthefrequencyof“heavy”to“severe”impactsexperiencedbyplayersduringmatchplayalsocorrelatedwithincreasedmuscledamageforatleast72hourspost-match.Morerecentresearch(Lindsay,Lewis,Scarrott,Draper,etal.,2015)hasnotedpositivecorrelationsbetweentotalneopterin/specificgravityandtotalimpacts(p<0.05)followingrugbyunionmatchplay,furthersupportingtheinfluenceimpactshaveuponrestorationofperformance.Post-matchmuscledamageandtheassociatedmusclecatabolismarethereforeofimportanceforconsiderationinthehourspost-match,asperformancedecrementsanddelayedrestorationofperformancearelikely.

8.5.2 Impactsresultingfromchangesofdirection,accelerationsanddecelerationsAswouldbeexpectedwithinthisstudy,thelargestnumberofchangesofdirection,accelerationsanddecelerationswereaccruedinZone4,yetsurprisingly,onlychangesofdirectionrevealedasignificantdifferenceinboththepercentagedistributionofimpactsand

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absolutevaluesbetweenzones(p<0.0001)(Figures8.1,8.2and8.3).Absolutevaluesdid,however,showsignificantdifferencebetweenzonesforchangesofdirection(Zone5,p=0.007,0.0±0.0,d=1.67;Zone6(p=0.011,0.2±0.4;d=1.57)andaccelerations(Zone5,p=0.018,0.7±1.3,d=1.07;Zone6,p=0.049,1.5±2.2,d=0.98).Despitenosignificantdifferencebeingnotedforaccelerationsanddecelerationsbetweenzonesforpercentagedistribution,decelerationsdidfollowthepatternofadecreasingfrequencyofimpactsasthemagnitudeincreased,yetaccelerationsrevealedagreaterdistributionofimpactsinZone6(Frequency=2.2;Distribution=15.8%)comparedtoZone5(Frequency=0.7;Distribution=12.8%)(Figures8.1and8.3).Uponfurtherassessmentofimpactsoccurringfromchangesofdirection,accelerationsanddecelerations,separatelyfromthoseincurredfromcollision,itwasfoundthatdecelerationsaccountedforthegreatestproportionoftheseexplosivemovementsinZone4.Duetothelikelihoodofchangeofdirection,accelerationanddecelerationmovementsappearinginZone4,onecouldperhapsquestiontherelevanceofthesematchdemandsforcreatingfatigue,whencomparedtoimpactsaccruedbycollisions.Despitethehighfrequencyofchangesofdirection,accelerationsanddecelerationswithinarugbyplayer’smatchdemands,theneedforpractitionerstofocusuponthemorelikelyfatigueinducingcollisionelementsofthegameareparamount,asthesearethematchdemandsthataremostlikelytolimitfutureoptimaltrainingability.

Researchuponwhichtocomparetheresultsfromthisstudyissparse.ThewelldocumentedresearchbyMcLellanandLovell(2012)hasbeenreferencedinmanyrecentinvestigationsofimpactsfromteamsportsettings(Cunninghametal.,2016;Jonesetal.,2015;Wellman,Coad,Goulet,Coffey,&McLellan,2016;Westetal.,2014),however,itisimportantforpractitionerstonotethattheirresearchonlyinvolvedcollisionimpacts.Aspriorresearchdidnotincludeimpactsincurredfromaccelerations,decelerationsandchangesofdirection,andsolelythosethatinvolvedcollisions,thecomparisonofimpactfrequenciesbetweenthestudieswouldbeilladvised.InadditiontotheresearchbyMcLellanandLovell(2012)notinvolvingaccelerations,decelerationsandchangesofdirection,theimpactzonesclassifications(measuredinG)weredifferenttothisstudy.Thedifferingimpactzoneclassificationsbetweenstudies,combinedwithadifferenceinGPSunitspecification,meanthatthefrequencyandmagnitudeofimpactsassignedtoeachstudyarelikelytobemisaligned.FutureresearchshouldthereforeperhapsconsiderthealignmentofGPSimpactzonesbetweenstudiestoenablebettercomparisonofdata.

WhenconsideringtheresultsfromChapter3,detailingthematchdemandsrequiredforpositionalgroups,thedistancescoveredareperhapsnotsurprisingandcannotbeconsideredabnormalwhenviewedalongsideotherresearch(Cahilletal.,2013;Lindsay,Draper,etal.,2015;Quarrieetal.,2013).However,incontrastwhenassessingthelargecontributionofimpactsfromcollisionsinZone4(Frequency=15;Distribution=32.7%)notedwithinthisexperimentalstudy,itcouldbearguedthatthehighintensitycollisioneffortsareextremeinfrequency(Figures8.1and8.3).Thisunexpectedfindinghasimplicationsfortheassessmentoflikelyfatiguewhich,whenconsideredalongsidethefindingsfromSuarez-Arronesetal.(2014),whichindicatethatcontactsinducegreaterinternalloads(measuredviaheartrateresponse)tothataccumulatedfromrunning,theinfluenceofcollisionsonrestorationofperformanceandtherolethatanalysisofimpactdatacanhaveuponthisinterpretationisfurtheremphasised.Inaddition,therecommendationsbyReardonetal.(2016)areofimportanceforfutureconsiderations,asassessmentofcollisioncountsinrugbyunionshouldperhapsinvestigatesmallerG-forceincrements.TheseassessmentsofsmallerG-forceincrementswoulddevelopa

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betterunderstandingofmicro-technologycollisionclassificationandthereforepotentiallyavoidthefalsepositivesseenwithinthisexperimentalstudy,whenassessingimpacts.Lastly,apotentialpointforconsiderationisthatresultsfromthisexperimentalstudy,inparticularthatofChapter3,wouldindicatethatelitelevelrugbyplayers(andspecificallythebacklineplayers),needtobeconditionedtoabletoperformahighfrequencyofchangesofdirection,accelerationsanddecelerationswithintrainingandmatchplay.Ifelitebacklineplayersarenotconditionedtoperformthesedemands,itcouldbearguedthatavoidanceofinjuryandachievementofoptimalperformancewillbesub-optimal.

8.5.3 ImpactcategorisationBasedupontheresultsofthisstudy,thenotionthatGPScalculatesimpactsaccuratelycanbequestioned.Futurepracticeshouldperhapsincludetheanalysisofacollisionloadmetric,assoleimpactvaluesdonotillustratethefullmagnitudeofthematchdemandexperienced.Itcouldbearguedthatacollisionloadmetricwouldprovidemoredetailuponmatchdemands’likelyinfluenceuponrestorationofperformance,asthismetricwouldinvolvethesumofthespeedanddurationofthecollisionandthemagnitudeoftheimpactinvolvedwithinthecollision.Similarlytothefindingsofthisexperimentalstudy,previousresearch(Suarez-Arronesetal.,2014)hasshowndisparitiesbetweencollisionsrecordedviatheGPSunitsandthosecodedfromvideorecordings,withnon-significantcorrelationsreported(r<0.42,ES>1.4).Thenotionthathighmagnitudeimpactsencounteredduringrugbymatchplayinvolveonlycollisions,isdisputedwithinthisexperimentalstudy.SupportforthisisalsopresentedbyGabbett,Jenkins,andAbernethy(2011),whonotedthattheaveragenumberofimpactsperformedbyindividualplayerswereconsiderablygreaterthanthetotalnumberofcollisionstypicallyperformedduringmatchplay,furthersuggestingthatimpactdatatoassesscollisionsspecificallydatashouldbeinterpretedwithadegreeofcaution.Additionally,whenconsideringthatReardonetal.(2016)notedinunpublishedfindingsthataccelerationsarelikelytobemistakenforcollisions,duetotheG-forceexperiencedandthetiltinbodyorientationassociatedwithaccelerationactions,thequestionableaccuracyofimpactdataisfurtheremphasised.Thisnotionofaccelerationslikelytobemistakenforcollisionscouldbeexplainedbyanover-codingofimpactsatthe2Gthreshold,asrepresentedbythelargefrequencyofimpactsassociatedwithaccelerationswithinthisstudy.

AplayerloadvariablehasbeenresearchedbyCormacketal.(2014),withthismethodologyregularlygeneratedandupdatedbyGPSprovidersandusedbymanyteamsportpractitionerstomonitorplayers.Playerloadvaluesmeasurethecombinedloadacrossthreemovementplanesmeasuringaccelerationsanddecelerations,yettheexactalgorithmsandthereliabilityofsuchmetricsisunknownandthereforewarrantscautionpriortoimplementation.These“load”valuesarecalculatedbytherateofchangeofdirectionsintheupward,downwardandlateraldirections,allowingthreedimensionalmeasurementofactivities,suchasjumpingandimpactsinteamsportsettingstobemeasured,providingameasureoftotalloadappliedtoaplayerinmatchesortraining.Itis,however,importanttonotethatacollisionloadmetricneedsfurtherinvestigationtoassessitsapplicabilityforuseintheanalysisofrugbyunionmatchdemands.

8.5.4 LimitationsoftheresearchItisimportantforpractitionerstonotethatthenatureofthisstudyissubjectiveandthattheresultsareonlyarepresentationoftheindividualplayersinquestion.Theuseofonlyoneplayerperassessmentofimpactfrequencyandmagnitudesforeachpositionwasalimitationofthisstudy,yetthetimeconsumingnatureofthisanalysisandthe“realworld”natureofthe

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elitesettingfromwhichtheimpactdatawastakenweremajordeterminingfactorsinthetestingprotocolimplemented.Itiscommonlyseeninprofessionalrugby,thatsomeplayersplayingthesamepositionperformtheirrolewithinateamindifferentways,baseduponteamtacticsandtheirownindividualstrengthsandweaknesses.Asaresultoftheseindividualplayingstyles,itisunlikelythatthematchdemandsfortwogamesaregoingtobethesameandtheindividualnatureofthedatacollectedwouldthereforehaveimplications,meaningcomparisonbetweendifferingdatasetsisdiscouraged.Similarly,thecomparisonofforwardsandbackscouldnotbeconductedwithinthisexperimentalstudy,duetothereonlybeingninedatasets(oneperpositiongroup).However,itcouldbearguedthatthelikelydifferenceinimpactdatabetweengroupswasaccountedforvianormalisedpercentagecalculationsofeachcollision.Thisnotionofdifferencesoccurringacrosspositionalgroupsandtheuseofnormalisedpercentagecalculationsisthereforeanadditionalconsiderationforfutureresearch.Despitesamplesizesbeinglowinchapters4,5and6,theassociatedeffectsizessupportthefindingsfromtheseexperimentalchapters,whichwhenconsideredalongsidethenotionsofBuchheit(2016)disputingthesoleuseofpvaluesfurtherreinforcerecommendations.Inadditiontothelowsamplesizebeingalimitationofthisstudy,thenotionthattheresultspresentedbeingonlyareflectionoftheassessors’interpretationofthemovementsperformedwhileincurringimpacts,isalsoalimitation.Despitetheassessors’definitionofmovementsbeingconsistentthroughouttheanalysis,itwouldberecommendedinfuturepracticethatmultipleresearchersshouldbeusedtoassessthedataandimproveinterreliabilityaswasrecommendedbyAustin,GabbettandJenkins(2011).Similarly,despiteallplayerswearingtheGPSunitinthesamepositionbetweentheirshoulderblades,thediscrepancynotedbetweensomeplayerswearingtighterfittingplayingshirtsthanothers,andsomeplayerswearingtheirGPSunitsina“GPSvest”wasalsoconsideredalimitationofthisstudy.AssessmentoftheGPSfilescreatedalongsidethevideoenabledthecoachtousethenakedeyetoviewmovementinstanceswhereimpactsoccurredanditistheassessor’sbeliefthatsomeplayers’GPSunitswereperhapsmoresensitivethanothers.ThissensitivitywasperhapsnotduetotheinterreliabilityofGPSunitsused,butwasmostlikelyexplainedbythewayinwhichtheGPSunitwassittingbetweentheshoulderblades.OnassessmentoftheGPSfilealongsidethevideoitwasevidentthatmanyimpactsaboveZone4wereaccountedforbyfootstrikesontheplayingsurfaceforsomeplayersbutnotforothers,thereforesupportingtheviewthatthefitoftheGPSunitbetweentheshoulderbladeswasadeterminingfactorinthesensitivityofthefrequencyanddistributionofimpactsgenerated.Thisnotionwassupportedinrecentresearch(Barrettetal.,2016)whichillustratedtheinfluenceofwearingaGPSuniteitheratthescapulaareaorclosertotheplayer’scentreofmass.ResultsfromBarrettetal.(2016)insimulatedsoccermatchplayindicatedthatlowerlimbmovementstrategiestakenfromGPSunitspositionedatthescapulashouldbetakenwithcaution,asgreatercontributionstoverticalforceswerenotedindatatakenfromthescapulacomparedtothosetakenfromthecentreofmass.

8.5.5 FutureresearchdirectionsAswasconductedwithinthisresearch,absolutevaluesofimpactfrequencyandmagnitudeshouldperhapsbeusedalongsidethosedetailingpercentagedistributioninordertobetterguidepractitionersinfuturetrainingprescription.When“eye-balling”theresults,percentagedistributionvaluesforcollisionswerenotedtobevastlydifferentbetweenZones4,5and6,yetnosignificantdifferencewasnotedintheanalysisoftheresults.Incontrast,whenassessingpercentagedistributionvaluesforchangesofdirectionsignificantdifferenceswerenoted,despitenotbeingindicatedbyinitialviewingoftherelevantrawdata.However,when

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assessingtheabsolutevaluesforallfourmetrics(changesofdirection,accelerations,decelerationandcollisions)itisapparentthatmoredifferencesintheirfrequencydoexist.Practitionersarethereforeadvisedtouseabsolutevaluesalongsidepercentagedistribution,asitcouldbearguedthatthepercentagedistributionsofwhereimpactsoccurismisguiding.Inaddition,itcouldbearguedthatthefrequencyofimpactsfromcollisionisofmoreconcernforpost-matchanalysisthanthepercentagedistribution.Ahighfrequencyofimpactsfromcollisionwouldmostlikelyindicatealongertime-courseofrestorationofperformance,yetpercentagedistributioncouldmisleadpractitionersinthisassumption.

Manyoftheimpactsrecordedduringfootstrikesarelikelytobeverticalaccelerationsanddecelerationsandnothorizontalimpacts,despitethisbeingthedirectioninwhichtheplayerismoving.Theseverticalimpactsduringlowintensitymovementinmatchplayarethereforepresentingproblemsforpractitionerswhenassessingthefrequencyofimpactsgenerated≥Zone4.Aplayercoulddisplayalargevolumeofimpacts,butifmanyoftheseimpactsareverticalinnature(andperhapsaresultoffootstrikes),thelikelyfatiguecreatedisgoingtobelessthaniftheywereattributedtocollisions.ThenotionofverticalimpactsbeingofrelevancewhenassessinglikelyimpactloadwasalsonotedbyHausler,Halaki,andOrr(2016)anditcouldthereforebearguedthattheanalysisofimpactsattributedtoeitherlocomotionorcollisionisrequired.Inaddition,thisanalysisofimpactsattributabletospecificmatchdemandswouldbenefitfromtheassessmentofabsolutevalues,alongsidethosefrompercentagedistributions.Lastly,whenconsideringthelikelihoodofdifferingmatchdemandsbetweenplayersplayingthesamepositions,impactprofilesshouldperhapsbedifferentbothwithinandbetweenplayingpositions.Thiswouldmeanthattheanalysisofindividualimpactdatawouldbemoreaccuratelyclassifiedandacceptedforcontinueduseacrosseliterugbysettings.

8.6 Practicalapplications

Resultsfromthisstudyareinnovativeandaddtotheknowledgeofimpactsencounteredduringgameplay.However,fromthisresearchitcouldbearguedthatthevaluespresentedfromGPSoutputsalonecannotbetakenatfacevalue,aserroneousinterpretationofimpactsofhighmagnitudemaybeincorrectlyidentifiedascollisions.Duetothedatacollectionissueshighlightedaboveregardingimpacts,itisimportantforpractitionerstonotonlyviewthevaluesexportedfromGPSsoftware,buttoinsteadsyncthevalueswithvideofootage.Varyingrelationshipsinfatiguecreatedbetweenimpactsoccurringwithandwithoutcollisionsarelikely,meaningarecommendationforfuturepracticeintheassessmentofhowtheimpactoccurred.Itiscorrectforpractitionerstonotethatallimpactsexperiencedduringmatchplayarelikelytobefatiguing,butthenotionthatimpactsneedtobeclassifiediswarranted,assomeimpactswillimposemorefatiguethanothersdependinguponthematchdemandsandmovementsinvolved.Whenconsideringthatalmost25%ofhighmagnitudeimpactsconsistedofaccelerations,decelerationandchangesofdirection,therelevanceoftheimpactstotime-courseofrestorationofperformanceneedsinvestigatedfurther.DespitetheabovelimitationsexistingfortheuseofGPSdata,theabilitytoassessintensityandprescriberestorationpracticesfromthetechnologycurrentlyavailableisessentialforpractitionersintheelitefield.ThisassessmentofmatchdemandsincorporatingGPSimpactswithineliterugbyunionisthereforelikelytocontinue.Asaresultoftheevidencepresentedinthisexperimentalstudy,theaccuracywithwhichpractitionerscouldplanfuturetrainingpostrugbyunionmatchplayisquestioned.BaseduponGPSdataalone,theinformationprovidedmightnotpresentaclear

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pictureofthematchdemandsexperiencedandthereforeapractitioner’sabilitytomakeinformeddecisionsuponresultantfatigueisblurred.TheuseofbothvideoandGPSdatawillprovideagreaterrepresentationofmatchinvolvementsandtheirlikelyinfluenceuponfatiguepost-match,withpercentagedistributionandabsolutevaluesbeingkeytothisinterpretation.

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9 Thesisdiscussion

9.1 Introductionandrecapofexistingresearch

Theliteraturereviewconductedprovidesdetailsurroundingthephysiologicalcostofrugbyuniongameplayandtheteststhatarecommonlyusedtoassessmeasuresoffatiguepost-match.However,thisreviewofcurrentresearchshowedthatnocommonlyusedmonitoringtoolorprotocolexistswithregardstotheassessmentofrecoveryandrestorationofperformanceinthedayspostrugbyuniongame.Currentresearchproposesthatdifferencesinmovementpatternsandactivitiesundertakenbypositionalgroupsdooccur,withrecommendationsthatforwardsshouldbeprovidedwithmoretimetorecoverpost-matchthanbacks,giventhegreatercontactloadstheysustainandsubsequentlongertime-courserestorationofperformance(Quarrieetal.,2013).Priorresearchintimatedthatmechanismsoffatiguearewideranging(chronicandacute)(Alaphilippeetal.,2012;Jonesetal.,2014;Lindsay,Lewis,Scarrott,Gill,etal.,2015;Westetal.,2014)andthatmeaningfullevelsoffatigueneedtobedetectedviabothsubjectiveandobjectiveperformancetesting,suchasCMJandWB,inordertobetteradvisepractitioners.

Asidentifiedwithinthisliteraturereview,methodsofmeasuringperformancearevastinquantityandapplicabilitytothesportsettinginquestion,withmeasuresofneuromuscularfunction,hormonalmarkers,heartratederivedmeasuresandsub-maximaltestingoftenbeingutilised.ThisliteraturereviewenabledtheidentificationofCMJtestingandself-reportedwell-beingmeasuresastoolsformonitoringrestorationlevelspostrugbyunionmatchplay.Thischoiceofmonitoringtoolwasmostlydictatedbymethodologicalandlogisticalconsiderations,andtheseriesofinvestigationsthatfollowedmeasuredtheirreliabilityandrelevancetoeliterugbysettings.Theknowledgegainedregardingmatchdemandsandthelikelyfatigueresponsecreatedwillenablecoachesineliterugbytomakemoreinformeddecisionsupontiming,frequencyandintensityoftraininginthedayspost-match.Priorresearchhasnotincludedmatchcharacteristicsforplayersthathaveplayedlessthantheentiregame(<80minutes),yettheinclusionofmatchcharacteristicsforplayersthathaveplayedreducedminuteswouldbetterguideeliteenvironmentsuponresultantphysiologicalcost.Lastly,aprocessofcombineddatacollectionincludingbothGPSdataandvideorecordingswasimplementedwithinthisthesis,toprovidemoredetailsurroundingtheindividualposition-specificmovementpatternsandthelikelyresultantaffectthesematchinstanceshaveuponfatiguelevels.Recentresearchinrugbyleagueidentifiedimpacts>7Gasimportantforconsiderationoftiming,frequencyandintensityoftraininginthedayspost-match(McLellan&Lovell,2012).Thefinalexperimentalchapterofthisthesisthereforeinvestigatedthistheorywithineliterugbyunion,inanattempttoidentifywhichmatchdemandsaremostlikelytoinducethesehighmagnitudeimpacts.

9.2 Majorfindingsoftheresearch

Despitemanyoftheexperimentalchapterswithinthisthesisinvestigatingtopicsthathavebeendetailedpreviously,thecombinationofGPSandvideoanalysistechniquesandthetestingprotocolimplementedprovidednewfindingsinthematchdemandsexperiencedbyeliteplayersandarethereforeofimportanceforfuturepractice.Thematchcharacteristicsrevealedwithintheinitialexperimentalchapterareperhapsnotsurprisingwhenconsideredalongsideearlierresearchinthearea(Cahilletal.,2013;Coughlanetal.,2011;Jonesetal.,2015;Lindsay,

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Draper,etal.,2015;Venteretal.,2011),yettheevidencepresentedshowsmanypreviouslyunreporteddifferencesbetweenforwardsandbacks,potentiallybasedupontheincorporationofdatafromplayersthatplayedlessthan80minutes.Thisbroaderassessmentofgameminutesprovidesrugbyunioncoacheswithamoretruerepresentationofmatchdemands,acrossvaryingmatchdurations,whichcanthenbeappliedtofutureprescriptionoftrainingandmonitoringmethodologies.

Whenassessingabsolutevalues,nosignificantdifferenceswereobservedinthefrequencyofimpacts>Zone3betweenforwardsandbacks.Thisnon-significantdifferenceinthefrequencyofimpacts>Zone3isperhapssurprising,whenconsideringforwards’typicalmatchinvolvements.However,whentakingintoaccountthereducedmatchminutesperformedbyforwards(Chapter3)andthehighermagnitudeimpactsassociatedwithcollisionactivitiesduringmatchplay(Chapter8),theresultsareofaddedvalue.Backswereobservedtoperformatahigherintensityduringmatchplay(70.9±7.4m/min)thanforwards(64.0±6.3m/min;p<0.001,d=1.00),withbacksalsocompletingagreaternumberofaccelerations(32.2±10.6)comparedtoforwards(22.0±11.9;p<0.001,d=0.88)andagreaternumberofdecelerations(41.9±12.3)comparedtotheforwards(30.8±14.4;p<0.001,d=0.82).Incontrasttothehypothesis,resultsfromthisstudyalsoshowthatbacksexperiencedagreatertotalnumberofimpactsthanforwards(Forwards3176;Backs5501),howeverthisstudydoessupporttheviewthatforwardsareinvolvedinmore“heavy”impacts(>Zone3)(Forwards229±160;Backs226±151).Itwasalsoofnotewithinthisresearch,thatforwardsexperiencedasignificantlygreaternumberofIm6whencomparedtobacks,whichwhenconsideringtheseIm6instancesrepresenta13-15Ginvolvement,theresultantphysicaleffectthismusthaveupontheplayersinvolvedisapparent.

Despitemanyofthematchdemandsassessedinthisresearchbeinglowerthanthosepreviouslyreported(Cahilletal.,2013;Coughlanetal.,2011;Lindsay,Draper,etal.,2015;Reardonetal.,2015),theinfluenceofrelativeassessmentislikelytoexplainthis.Forexample,forwardsinthisresearchwerenotedtocompetefor66minutesonaverage,whichislowerthanthewholematchdurationfiguresreportedinothersimilarstudies.Theincorporationofrelativemeasureswas,however,consideredmoreapplicableformatchdemandsassessment,asitcouldbearguedthatthisstudyisperhapsmorerepresentativeofmodernrugbyunionwhereplayersareoftenaskedtoplaylessthanthefullmatchduration.AsreportedinChapter3.5,considerationofbothabsoluteandrelativemeasureisofimportance.TherelativevaluesforforwardsareperhapsofmoreinterestthanthebackswhenassessingthedatadisplayedaboveinTables3.4-3.9,wheresomevariablesmaypresentmoreinformationfromarelativeviewratherthananabsolute.Thisnotionofrelativeposition-specificassessmentmayhelpbetterguidepractitionersinfuturematchdemandanalysis.

Ofspecificinterestfromthisresearch,werethefindingsthatshowedthatdifferencesinmatchdemandsoccurbetweentheninepositionalgroups.Specifically,propstypicallyexperiencedthelowestnumberofimpactsinthelowerimpactzones(Im1,Im2andIm3),yetalsoexperiencedalargenumberofIm6values.Similarly,fullbacksshowedalargenumberofimpactsinthehighimpactzones(Im4,Im5andIm6),yettheyalsoexperiencedalargenumberoflow-levelimpacts.ThepositionsofhookerandbackrowalsoillustratedalargenumberofIm6valueswhencomparedtothevaluestheyexperiencedatthelowerimpactzones.Thismaynotbesurprisingconsideringtheirtypicalmatchinvolvements,yetitaddsweighttothenotionthatforwardsexperiencemorehighmagnitudeimpactsthanbacksandthatimpactdemandsalsodifferbetweenforwards’positionalgroups.Theseresultsthereforeprovideagreater

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understandinginrespecttothelikelyblunttraumaresultingfrommatchdemandsandshouldhelpguidepractitionersinplanningstrengthandconditioningprogrammesforpositionalgroups.

Chapters4,5and6assessedjumpmodalities,regardingtheirreliabilityandpracticalityforusewithineliterugbyunionsettings.Similarlytowhathasbeenreportedinpriorresearch(Markovicetal.,2004),resultsfromChapter4identifyCMJasthejumpmodalitythatillustratedthehighestreliabilitybothwithin(ICC0.938)andbetween-session(ICC0.906)acrosstestingdays,incomparisontotheSJ,SLDJ-LandSLDJ-R.AlongsideCMJbeingapreviouslyidentifiedjumpmodalityforuseinrestorationofperformancetesting(Gathercole,Sporer,Stellingwerff,etal.,2015b),theresultsofthisthesissupportthenotionthatCMJprovidesthemostsensitiveandreliabledataforjumpperformancemonitoringineliterugbyunionsettings.EvidencecollatedwithinChapter4showedthatCMJdemonstratesthelowestSDD(1.7%)betweensessionswhencomparedtoSJ,SLDJ-LandSLDJ-Randthereforeaddstotheknowledgebase.However,perhapsmostrelevantfromthisexperimentalchapterwasthefindingthatachangeinjumpheightof≥1.7%wasmeaningfulforCMJperformanceandthatthisvalueshouldbeusedforfuturepracticeinthesubjectarea.

AsaresultofCMJbeingidentifiedasthejumpmodalitythatexhibitsthehighestreliabilitywithinandbetweensessions,thesubsequentexperimentalchapteraimedtoassesstheuseofCMJmeasurementonanOptoJumpcomparedtothatonaforceplate.Theforceplateisconsideredthe“goldstandard”toolforjumpmeasurement,yetresultsfromthisexperimentalchapterindicatethattheuseofOptoJumpisalsoreliable(CV<10%).WithinChapter5,asignificantcorrelation(r=0.906)wasnotedbetweenOptoJumpCMJheightandCMJheightmeasuredonaforceplate,thereforesupportingthereliabilityoffutureOptoJumpuse.ResultsfromChapter6examiningasingleCMJshowedhighreliability(CMJICC=0.986,SDD2.4%),withnosignificantdifferences(p>0.05)injumpheightobservedbetweendays.DespiteChapter4showingdifferencesexistingbetweensessiononeandsessiontwo,whenassessingCMJperformance,Chapter6showsthattheperformanceofasingleCMJ(measuringjumpheight)isareliablemeasure.Therefore,aswasalsonotedinChapter5,thefindingsfromChapter6supporttheperformanceofasingleCMJ(measuringjumpheight)onanOptoJumpasareliablemeasureforassessingpost-matchlevelsofreadiness,whenaforceplateisnotreadilyavailable.Thisfindingisthereforeofimportanceforguidingfuturejumpassessmentineliterugbysettings.

ThefinalexperimentalchapterutilisingjumpassessmentwasChapter7,whichaimedtoidentifymeaningfulchangeinCMJandself-reportedwell-beingscores.Duetothefindingsofthepreviousexperimentalchapters,CMJheighthadbeennotedasreliableandapplicableforuseineliterugbyunionsettingsandthereforewarrantedfurtherinvestigationregardingexpectedchangepost-matchplay.ResultsfromChapter7showedthatbothCMJperformanceandWBscorewerereducedat60hourspost-match,90hourspost-matchand170hourspost-match,withinterestinglyWBscoresreducedtoagreatervalueandforalongertime-coursethanCMJ.Ameaningfulchangeof2.6cm(-6%)inCMJperformancewasnotedalongsidea-9%changeintheWBscoreat60hourspost-match,thereforeaddingtotheknowledgebaseofexistingresearchsurroundingthetime-courseofrecoverypostmatchplay.DespitecorrelationsnotedbetweenD6(p=0.044;r=0.950)andaccelerations(p=0.001;r=0.953)at60hourspost-matchwithchangesinCMJperformancefortheforwards,evidencefromthisstudywoulddisputetheviewsofprevioustime-courseresearch(Quarrieetal.,2013),whichreportedthatalongerrecoverytime-coursewouldlikelybeassociatedwithforwards

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comparedtobacks.Asaresultofthisexperimentalchapter,practitionersarethereforeadvisedtoconsiderbacksashavingalongertime-courseofrecovery.Inconjunctionwiththis,thematchdemandsofpositionalgroupsmayalsoguidethelengthofrecoverypost-matchandthereforetheuseofGPSdatawarrantsconsideration,alongsideperformancechangemeasures,whenassessingplayers’readinesspost-match.

Lastly,withinChapter8,aswashypothesised,collisionsaccountedforhighermagnitudeimpactsthanothermovementmatchdemands.However,newfindingsfromthisresearch,combiningvideoandGPSdata,doshowthatthereliabilityoftheclassificationofimpactsidentifiedwithinthisstudyareaconcern,asindividualplayermovementpatternsandtheresultantoutputprovidedfromtheGPSwerenotedtoprovidemisleadinginformation.Additionally,thefrequencyofimpactsexperiencedasaresultofaccelerationanddecelerationwereshowntobeanimportantconsiderationforfuturetrainingprescriptionandanalysisoflikelyrestorationofperformanceinthedayspostmatchplaywasnotedasanewfindingandonewarrantingfurtherinvestigation.Asaresultofthisexperimentalchapter,practitionersworkingintheelitefieldarethereforerecommendedtocombinevideoandGPSdata,whilstalsoincorporatingbothabsoluteandrelativevalues.Thismethodologyshouldhelptodevelopagreaterrepresentationofthematchinvolvementsassignedtoimpactsexperiencedduringmatchplay,asthevaluespresentedfromGPSoutputsalonecannotbetakenatfacevalue.

9.3 Limitationsoftheresearchconducted

9.3.1 “Realworld”limitationsThemainlimitationofthisresearchinvolvesthelackofmultipletime-pointspost-matchuponwhichchangeinCMJperformanceandWBscoreswereassessed.Sixtyhourspost-matchwasthemostcomparabletimepointbetweenthatofpreviousresearchandthisthesis,yetitisclearthatincludingtimepointspriortoandpostthe60hourspost-matchwouldhaveprovidedaddedvalue.Theinabilityoftheauthortogainadditionaltime-pointspriorandposttothe60hourspost-matchwasduetologisticalconstraintsoftheplayers’trainingschedule,meaningaccesstoplayersforassessmentwaslimited.Afurther“realworld”limitationsthatpreventedthecollectionofadditionaldata,thatwouldhavebenefittedtheresults,wasthatthedatawascollectedfromonlyoneteam.Despitethedatacollectedaddingtotheknowledgeofmatchdemandswithinrugbyunioninthenorthernhemisphere,thelimitationofthedatabeingfromonlyoneteamisapointforpractitionerstoconsiderwhentheyareexaminingtheresults.However,aspreviouslydiscussed,thedirectcompetitionthatexistsbetweenmanyteamswithinEurope,meansthatsharingofinter-teamdatamaybeunlikelyandthatthislimitationisthereforeunlikelytoberesolvedinfutureresearch.

Additionally,apointforconsiderationandpotentiallyanother“realworld”limitationofthisthesiswasthatdespiteallthegamesandweeklytrainingstructureswithinthisresearchbeingconsistent,somegamesinvolvedmoretravelthanothers,meaningtheeffecttravelcouldhavehaduponsubsequentCMJperformanceandwell-beingneedsfurtherinvestigation.Thisnotionoftraveluponperformancedecrementwasnotedinrecentresearchfromthesouthernhemisphere(Georgeetal.,2015),wheretravelresultedinmoremissedtacklesand(1.7±1.3),lessgainlinesuccessinthefirsthalfofgames(-3.0±1.9)andlesspointsscoredinthesecondhalfofgamesbyawayteams.Similarly,inyouthsoccerplayers,largepositivecorrelations(r=0.70-0.87)werenotedbetweenwell-beinganddistancetravelledtoawaygamelocation.Travelorlackoftravelbetweenhomeandawaygamescouldthereforehavebeenalimitationofthisthesis,yetsimilarlytothelimitationregardinglimitedtimepointsforperformance

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assessment,logisticalconstraintssurroundingtheplayers’seasonalschedulewerethemaindeterminingfactorinthechoiceofgamestobeassessed.

Theaboveissuesdetailinglimitationsassociatedwiththelogisticsofthe“realworld”settingwithinwhichthisresearchwasconducted,areanimportantconsideration.However,readersneedtoconsiderthatthisthesisandanyfutureinvestigationsneedtobeecologicallyvalidtobeapplicableintheappliedsetting.Therefore,theconcernssurroundingthelackofadditionaltime-pointsforassessmentofrestoration,thepotentialissuessurroundingtravelandthenotionthatthedatafromthisthesisisonlyrepresentativeofoneteamareperhapsaccountedfor.Theideathatanyfuturestudiescanbeimplementedintoanappliedsettingandthatthetestingprotocolcouldguidethetrainingschedulewithinwhichassessmentsaretakingplaceisnaïve.Itisunlikelythatrugbycoachesworkingintheelitefieldwillallowforalterationoftrainingschedulespurelyforinorderfortestingtobeconductedandthepotentialconflictthisinterventioncouldcauseasaresultoftryingtoimplementsuchplans,meansthatthisisasituationthatshouldbeavoided.

Asaresultofsuch“realworld”issues,theinformedselectionofCMJandWBastoolstoassessrestorationinthiselitesettingwasmostlyguidedbylogisticalinfluences.Oncereliabilitywasnotedforthesemeasures,therationalefortheirusewaswarranted.ItcouldbearguedthatotherperformancetestscouldhaveprovidedmoreinformationuponrestorativestatethanCMJandWB,yetthelogisticalissuessurroundingsuchtestswouldhaveoutweighedthebenefitoftheirinclusion.Forexample,thisthesiscouldhaveconductedtwitchpotentiationonanisokineticdynamometerasthiswouldhavebeenamoreaccuratemeasureoffatigue,yetlogisticallyitisunlikelythatthisformoftestingwouldhaveworkedwithintheappliedsettinginwhichthisthesisstood.Theunstructurednatureoftrainingweeksthroughoutarugbyunionplayingseasonandthelogisticsthatsurroundmanagementofasquadoffifty-plusplayers,maketheseformsofintricatetestingimpractical.Elitesportisanever-evolvingsettingandalogisticallydifficultscenariowithinwhichtoconductresearch,withpractitionersadvisedtobeawarethatasoundstudydesignisoftenmorerealisticthanaperfectone.

9.3.2 LimitationsofCMJprotocolimplementedAsdiscussedabove(Chapter9.3.1),amajorlimitationofthisthesiswastheinabilitytotesttheplayersatadditionaltime-pointspost-match,withthisthereforehavinganinfluenceupontheCMJtestingprotocolimplemented.However,asnoted,the“realworld”limitationsassociatedwithdailyaccesstoeliteplayersdictatedthetime-pointsselected.AnotherpossiblelimitationwiththisstudywhenconsideringtheevidencepresentedbyGathercole,Sporer,andStellingwerff(2015),isthattheanalysisofCMJperformancewasonlyfocuseduponoutcome-relatedvariables.Asdiscussedpreviously,Gathercole,Sporer,Stellingwerff,etal.(2015a)arguedthatoutcomedrivenCMJanalysisdoesnotassessthelaterelementoftheSSC-recoverypatternandthereforeoverlookssomekeyinformation.BaseduponthisresearchbyGathercole,Sporer,Stellingwerff,etal.(2015a)itcouldbeassumedthatrugbyplayersadapttheirCMJstrategytoavoidanydecreasedjumpheightvaluebeingpresented,despiteNMFexisting.Forexample,aplayermayadjusttheireccentricdepthandresultantconcentricforceduringCMJexecution,dependentupontheircurrentneuromuscularfunction.Withinthisthesis,itcouldthereforebearguedthatthelackofdecrementshowninjumpheightforforwardscomparedtobackscouldbeexplainedbythemovementstrategiesofsubjectsnothavingbeenassessed.TheresultsofGathercole,Sporer,Stellingwerff,etal.(2015a)donotdisputethenotionthatCMJtestingisasuitabletesttodetectfatigue-inducedchangesinNMfunction,yetitdoesrecommendanalysisofbothtypicalCMJvariables(jumpheight)and

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kineticvariables(RFD)toprovideamoredetailedanalysisreflectingbothCMJoutputandmovementstrategyemployed.Itis,however,theauthor’sviewthattheaforementionedlogisticalandfinancialimplicationsofassessingCMJperformanceusingkineticmeasuresdonotwarranttheuseofaforceplate.

Theimplementationofrecentresearchregardingtheinclusionofkineticvariables(Claudinoetal.,2016;Gathercole,Sporer,Stellingwerff,etal.,2015a;Kennedy&Drake,2017a;Kennedy&Drake,2017b;Roeetal.,2015)withinfuturepracticeiswarrantedanditsomissioncouldthereforebeincludedasapotentiallimitationofthisthesis.However,whenconsideringthatultimatelythisthesisaimedtoassesswhetherplayershadrestoredperformancepriortothenextgame(asmeasuredbypreandpost-matchjumpheight),thestrategyforhowtheyachievedthisjumpheightisperhapsirrelevant.Itcouldbearguedthatplayersmayachievethisjumpheightviaadifferentstrategyandinadifferentmovementpattern,whichalthoughinformativeisimmaterialtothisthesis.TheimpulseplayerscreateduringCMJperformancewilldeterminetheirvelocityattake-offandthereforethenotionthatyoucanadopttwodifferentstrategiesofCMJtocreatethesameimpulse(byproducinglowerforceoveragreaterperiodoftimeorahigherforceoverashorterperiodoftime),shouldbeconsidered.Thisimpulse(calculatedbymultiplyingforcebytime)willresultinthesameacceleration,thesamevelocityoftake-off,andwillthereforeyieldthesamejumpheight,makingthestrategyofmovementunimportant.Despitethestrategyemployed,ifplayersarenotedtohaverestoredCMJheightbacktopriorperformancelevels,itcouldthenbeassumedthatthisjumpheightcouldbetransferredtothefieldandthereforeutilisedtoachieveapositiveoutcome(winningalineoutforexample).Atpresent,thedisadvantagesofusingaforceplatestilloutweightheadvantagesanditisunlikelythatallteamsportpractitionerswillinvestinsuchtechnologydespitetheevidencepresentedabove.Theimplementationofsuchjumpassessmentprotocoldependsconsiderablyupontheleveloffinancialandscientificsupportavailabletothepractitioners.ThiscombinedNMFassessmentapproachtypicallyrequiresaforceplateforassessmentandthereforelimitsthemajorityofrugbyteams,duetobothfinancialandpracticalimplicationsofitsuseintheelitefieldonadailybasis.

ConsideringtherestorationofperformanceassessmentsconductedwithinthisthesissurroundingtheuseofmeansquadCMJvalues,highlightsanotherpotentiallimitation.EvidencetosupporttheuseofindividualassessmentofCMJperformance,insteadofmeansquadCMJvalues,waspresentedbyGathercole,Sporer,Stellingwerff,etal.(2015a),whonotedthatdifferentindividualsexhibitmarkeddifferencesinrecoveryprofilepostfatiguingexerciseandthattheNMFresponseelicitedduringCMJperformancemustthereforealsobeindividualised.AdditionalsupportforindividualisedjumptestingwaspresentedbyHamilton(2009),whonotedlimitedworthinassessingmeansquadjumpvaluesandinsteadrecommendedthatpractitionersfocusuponindividualscorestoaccuratelymeasurefatiguepreandpostsoccermatch.Itcouldbearguedthatimplementationofindividualisedjumptesting,alongsidetherecommendationsofRoeetal.(2015)tousemeanvaluesoftwoorthreejumps,wouldperhapsprovideimprovedreliabilityandsensitivityincomparisontoanindividualjumpmeasuringamaximaljumpheightvalue.

Lastly,afuturedirectionofjumptestingprotocoltoassessNMFandthereforeapotentiallimitationofthisresearchsurroundstheuseofaDJ.DespiteaunilateralSLDJbeingexaminedinChapter4andconsideredtobeunreliable(SLDJ;ICC0.759-0.875)andthereforeimpracticalforuseinappliedsettings,thepotentialuseofaDJthatisbilateralshouldperhapsbeconsideredinfutureinvestigations.ItcouldbearguedthataDJthatencompassesbilateral

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landingandtake-off,enablesincreasedsensitivityinpartduetoaDJusingbothcontactandflighttimemeasures.TheresultsfromChapter4andtheviewsofHamilton(2009),whonotedincorporationofDJ-RSIbeingaperformancetestcapableofassessingNMF,wereconsideredwhendecidinguponwhichjumpperformanceteststoinclude,yettherationaleforaSLDJcannowbequestioned.ThereasoningbehindtheincorporationofSLDJatthecommencementofthisthesis,wasthatHarmanetal.(1990)reportedthatunilateraljumpperformancehadastrongerrelationshipwithsprintperformancethanbilateraljumps.InhindsightitcouldnowbeassumedthattheassessmentofimpairedneuromuscularfunctionmayhavebeenbetterassessedviautilisationofabilateralDJ.TheresultsfromChapter4andtheunpublishedviewsoftheauthor,notedthatthetechniqueadoptedduringtheSLDJdifferedmostlyonthestartofthejumpwheresomeplayerswerenotedto“dropoffthebox”andsomewerenotedto“jumpoffthebox”ontothelandingsurfacebelow,meaningadiscrepancyinresultswaslikely.UtilisationofabilateralDJwouldhavestillassessedtherelativelyshortcontractiontimesinvolvedinsuchamovement,yetwouldhaveprovidedlessopportunityforalteredtechniqueasassociatedwiththeSLDJandthereforemayhaveledtomoresensitivemeasures.

9.3.3 GPSlimitationsDespiteGPSbeingacommonlyusedtooltomanagetrainingloadinmanyeliterugbysettings,evidencefromthisresearchillustratesthatlimitationstoitsusedoexist.Firstly,itappearsthatmuchofthedatacollectedandsubsequentlyproducedbyGPSunitssurroundstheuseofaccelerometerdata.ManyGPSprovidershaverecentlyaddedmetricsutilisinggyroscopesalongsideaccelerometerdata,yetasisillustratedbythisresearchthereliabilityandpracticalityoftheirusecanbequestioned.ResultsfromthisstudywouldsupporttheviewsofChambers,Gabbett,Cole,andBeard(2015),thatGPSiscapableofassessingsportspecificmovements,buttheabilityofGPStoquantifycollisionelementsofrugbyunionmatchisstillunwarranted.WithinStatSportsVipersoftware,arugbyspecificcollisionmetrichasbeendevelopedtoquantifywhenacollisionhasoccurred,byusingthegyroscopeandtheaccelerometerdata.Essentially,thismetricisderivedfromthegyroscopeexperiencingatiltinitsaxis(asiscommonlyseenduringcollisionmovementsbyplayersinrugby)andanimpactregisteringintheaccelerometerwithinasimilartimeframe,withthemagnitudeofthecollisiondeterminedviathespeedanddurationofthecollision.Thecollisionsarethereforecategorisedviaaweightingsystemwithinthesoftware,yetthespecificsoftheseweightingsarenotdisclosedtoend-users.Resultsfromthisstudywould,however,disputethismetric,asitwasnotedforoneoftheplayersassessedthatmultiplecollisionswereincorrectlyassignedtohim,whenhesimultaneouslydeceleratedasheapproachedaruck(thereforeaccruinganimpact)andbentovertopickuptheball.

TheuseofasolemetriccanthereforebeclassifiedasalimitationofGPSuse,withthealgorithmsthatquantifycollisionmetricsusinggyroscopes,forexample,requiringfurtherinvestigation.Researchwithinotherteamsports(Gabbettetal.,2010;Gastin,McLean,Spittle,&Breed,2013)usedonlythegyroscopetoassessplayercollisionmovementsanddidnotusethesumofrotationalforcesfromthegyroscopeincombinationwiththesumofperpendicularforcesfromtheaccelerometeralsohousedwithintheGPSunits.Despiteresearchexisting(Kellyetal.,2012)toconfirmthereliabilityofcorrectlyidentifyingcollisionsinelitelevelrugbyunion(recallandprecisionrating0.933and0.958respectively),noevidencehascurrentlybeenreportedtosupportStatSportsVipersoftwareintheanalysisofcollisioninstances.Inaddition,whenconsideringtheperceivedreluctanceofmanysoftwaresupplierstoprovidedetailinthequantificationofimpactandloadcollatedbyGPSunits,theneedforamore

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thoroughexaminationofimpacts,theiroccurrencewithingameplayandtheincorporationofthisdatawithinGPSdataanalysisisemphasised.Futuredevelopmentofcollisionsdetectionwithinthesoftwareandthevalidationofimpactforceswillimprovetheapplicabilityforuseineliterugbysettings.

Despiteitnotbeingthefocusofthisthesis,thelackofvalidityoftheassessmentofcollisionsasareliablemetricofuseinrugbyunion,isaconcernandisconsistentwiththefindingsofHausleretal.(2016).Similarlytoasseeninthisthesis,Hausleretal.(2016)conductedameta-analysisofGPStechnologyandrevealedthatinconsistenciesareevidentbetweencollisionidentificationandcategorisationbetweenmagnitudes.However,inareviewcomparingamicro-technologyunit(minimaxX;CatapultSports)withvideo-basedcodingoftheactualcollisionsineliterugbyleague(Gabbettetal.,2010),nosignificantdifferencesweredetected.Despitecorrelationsnotprovingvalidity,Gabbettetal.(2010)observedstrongcorrelations(r=0.96,p<0.01)betweencollisionsrecordedviatheminimaxXunitsandthosecodedfromvideorecordings,thereforedemonstratethattheminimaxXmicro-technologyunitsofferasoundmethodofquantifyingthecontactloadofcollisionsportathletes.Yet,morerecently,disparitiesbetweencollisionsrecordedviatheGPSunitsandthosecodedfromvideorecordings,werenotedwithinrugbysevensmatchplay(Suarez-Arronesetal.,2014)withnon-significantcorrelationsreported(r<0.42,ES>1.4).Thedifferencesinfindingsbetweenthesestudiescould,however,beexplainedbythetechnologyused,thestudypopulationsinvolvedandtheexperimentalconditions,asnotonlydidthesportdiffer,butsodidthecontext(trainingormatch).

Uponviewingthematchesusedforassessmentwithinthisstudy,itwasnotedthatthewayinwhichtheimpactfromacollisionexperienceiscategorised(Zone4toZone6)oftendependsupontheorientationofthewaythecollisionismadewiththegroundortheopposition.Whenviewingindividualcollisioninstancesthataccruedhighmagnitudeimpacts,itcouldbearguedthatiftheopponentismovinginthesamedirectionastheattackerordefender,thisislikelytohaveaninfluenceuponlesseningthemagnitudeofimpactassignedtothem.Withintheindividualanalysisofplayerfiles,someplayerswereseentomakeatackle,yetthetacklecompletedregisteredas<9Gandthereforewasnotincludedwithinthefinalanalysisofwhereimpactsoccurred.However,whenassessingsomeaccelerationsconductedbyplayers,itwasnotedthatonmultipleoccasionssomeoftheseaccelerationinstancesregisteredas>9G.Theseresultsmaybecorrect,butonviewingthevideoinstancesforthesemovementstheresearcherwouldquestionthis,whencomparingthesematchinstancestocollisioninstancesthatdidnotregisterashighimpactvalues.Whenconsideringthatcollisionmetricsdevelopedwithinthesoftwareofteninvolvehighmagnitudeimpacts,theapplicabilityofimpactmagnitudeanditsuseforassessmentofmatchdemandsandfuturetrainingprescriptioncanbequestioned.Collisionprofilesshouldperhapsbedifferentacrossplayingpositionsandtheidentificationofcollisionzonesmoreaccuratelyclassifiedandacceptedforuseacrosseliterugbysettings.AnotherareaofinvestigationwithinGPSclassificationthatwarrantsinvestigationistheweightingofmovementtasks.AswasevidentwhenviewingthevideofilesencompassedinChapter8,itcouldbearguedthatmovementdemandsthatelicitimpactsintheGPSunitshouldnotbegloballyweighted.AlandingfromajumpingmovementfromaplayerthatelicitsaZone6impact,forexample,willbeunlikelytohavethesamefatigueeffectasaZone6impactfromacollisionsituation.Thisnotionthereforewarrantsfurtherinvestigation,especiallywhen

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consideringtheindividualfrequencyofimpactsproducedviamovementdynamicsdiscussed.ThesefindingswouldthereforefurtherlendtowardstheviewthatabsolutevaluesneedtobeaccountedforinanalysisofGPSimpactsandnotsolelypercentagedistribution,asthelikelyfatigueresponsefromcollisionsisgoingtobelongerlastingthanthoseattributedtoothermovementtasks.Lastly,withinthisthesis,thediscrepancynotedbetweensomeplayerswearingtighterfittingplayingshirtsthanothers,andsomeplayerswearingtheirGPSunitsina“GPSvest”isconsideredalimitationofGPSresearch.

9.4 Practicalapplicationsandfutureresearchdirectionsasaresultoftheresearchconducted

9.4.1 FuturejumptestingprotocoltoassessrestorationofperformanceThisthesisidentifiedCMJasapplicableintheassessmentofrestorationofperformancetestinganditsuseinmanyelitesettingsislikelytocontinue.FindingsfromthisthesisfurthertherecommendedprotocolforCMJtestinginmeasuringfatigue,withachangeinjumpheightof≥1.7%beingnotedasmeaningful.ResultscollectedwithinthisthesisalsosupporttheperformanceofasingleCMJ(measuringjumpheight)onanOptoJumpasareliablemeasureforassessingpost-matchlevelsofreadiness,whenaforceplateisnotreadilyavailable.PerhapsmostimportantlyforfutureimplementationofCMJtesting,wasthefindingthatreducedCMJperformancewasnotedat60hourspost-match,90hourspost-matchand170hourspostrugbyuniongame.Thisfindingwouldthereforesupportthenotionofreducingtrainingvolumeinthedaysimmediatelypostrugbyunionmatchplay,yetwouldalsosupportpreviouslyunpublishedobservationsthateliterugbyplayersoftendonotrestoreperformancepriortothenextgamecommencingandthatplayersoftenplayinasub-optimalstate.Asaresultofthisthesis,recommendedtime-courseofrecoveryisthereforenotedtobelongerthanthatshownfrompreviousresearch(Westetal.,2014)andshouldbeamajorconsiderationforrugbyadministratorswhenschedulingfixtures.Inaddition,afindingfromthisresearchthatneedstobeconsideredwithinfutureCMJtestingprotocolisthediscoverythatbackshavealongertime-courseofrecoverycomparedtoforwards.Consideringthatthisfindingdisputestheviewsofprevioustime-courseresearch(Quarrieetal.,2013),whichreportedalikelylongertime-courseofrecoveryassociatedwithforwardscomparedtobacks,theneedforpositionalCMJtestingprotocolisperhapsrequired.Aswasincorporatedwithinthisresearch,themajorityofstudieshaveusedthehighestCMJperformancetoassessfatigue,withrecentresearchaddingsupporttotheuseofjumpheighttoassessneuromuscularstatus(Claudinoetal.,2016).Itisclearfromtheresultsintheexperimentalchaptersabove,thatutilisingCMJasafatiguetestprovidesaddedvaluetotheprotocolthatshouldbeimplementedinthedayspostrugbyunionmatchplay.DespitethisseriesofinvestigationsproposingtheuseofasoleCMJ(mainlyduetologisticalconstraints),recentevidencepresented,regardingthenumberofrepetitionsandaveragemeasures(incontrasttohighestvalues),arealsoimportantforconsiderationwithinfuturejumptestinginassessingfatigue.Perhapsmostinterestingbaseduponthemeta-analysisconductedbyClaudinoetal.(2016)isthataveragedjumpresults(ofrepetitionsconducted)werereportedtobemoresensitivethanthehighestsinglejump,indetectingfatigue.ResearchbyRoeetal.(2015),discussingCMJprotocolforNMFassessment,isalsoofnoteforfutureimplementationineliteappliedrugbysettings.Roeetal.(2015)reportedthatCMJmetricsarereliable(CV<5%),whenassessedwithtwoorthreerepetitionsofaCMJ.TheresultspresentedbyRoeetal.(2015)supporttheearlierfindings(Cormack,Newton,McGuigan,&Doyle,2008)thatmean

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forcewascapableofdetectingSWC,however,itisstillimportanttonotethatthefindingsofCormack,Newton,McGuigan,andDoyle(2008)aretakenfromasingleCMJprotocol,thereforeillustratingalackofcommonlyusedCMJprotocol.PerhapsthemostimportantconsiderationforpractitionerswhenimplementingCMJtoassessNMF,aretheviewsofGathercole,Sporer,Stellingwerff,etal.(2015a),whoquestionedtheuseofCMJheight.Gathercole,Sporer,Stellingwerff,etal.(2015a)insteadrecommendedusingvariablesthatassesschangesinjumpperformanceoutcome,butalsovariablesthatassesschangesinthemovementeconomyoftheathleteinquestion.CMJcouldbeconsideredaslowSSCactivityandthereforeitsusefordetectingthehigher-endmoreexplosiveandneuralfatiguingelementsofreadinesscouldbequestioned.TheinclusionofkineticvariablestomonitorNMFresponses,whichdifferinfocusbaseduponcircumstances(intensity,durationandtypeofactivity),ispotentiallythenextareaoffocusforresearchinrestorationofperformanceinelitelevelrugbyunion.TheresultsfromthisthesisdosupportjumpheightformeasuringNMFinthedayspostrugbygame,yetpractitionersshouldconsiderthatNMFmayalsopresentitselfasanalteredmovementstrategyonCMJperformance,ratherthanjumpheightassessmentalone.AlongsidetheinvestigationofspecifickineticvariablesinmonitoringNMFresponses,thenotionofstartthresholdsrelatedtoabsoluteandrelativeforcechangesneedsfurtherinvestigation.AsnotedbyGathercole,Sporer,Stellingwerff,etal.(2015a),itisimportantforpractitonerstoconsiderthatsomemethodsofassessmentareoftenpronetofalsestarts,withstandardisedjumpinitiationtimeperhapsbeingabetterstrategytoensurerelaibility.UponreviewingthefindingsofGathercole,Sporer,Stellingwerff,etal.(2015a)itcouldthereforebeconcludedthatacombinedapproach(outcomeandstrategy)toCMJassessment,wouldperhapsprovidemoresensitivityinNMFdetection,andthedataprovidedwouldpotentiallydisplaymoreinformationupontheathlete’spreparednessforsubsequenttraining.

Lastly,despitethefocusoftheexperimentalChapter7beingtodetecttime-courseofrecoveryofCMJandWBmeasuresandnottodetectNMF,itcouldbearguedthattheassessmentofNMFisalsowarrantedinfuturetime-courseofrecoveryresearch.Fromtheliteraturereviewconducted,itisclearthatassessmentoftime-courseofrecoveryandNMFaretwoindividuallydistinctprocessesandshouldthereforewarrantseparatetestingprotocols.Itis,however,importantforpractitionerstonotethattheuseofCMJisquestionedwhenassessingNMFinelitelevelrugbyunion,duetoitslackofspecificity.Thematchdemandspresentedfrompriorresearch(Cunniffeetal.,2009;Cunninghametal.,2016;Jonesetal.,2015;Quarrieetal.,2013)notelargefrequencyofsprints,accelerationsanddecelerations,whichitcouldbearguedaremorelikelytobeperformedduringmatchplaythanverticaljumpingmovements,thereforequestioningtheapplicabilityofCMJ.AdditionalresearchquestioningCMJapplicabilityispresentedbyMarrieretal.(2016),whoindicatedthatthechangesinCMJperformancewereunaffectedbyasimulatedrugbyunionsevenstrainingsession,whilethe30msprinttimeincreasedinresponsetotheprescribedtrainingsession.Marrieretal.(2016)thereforerecommendedtheuseofmaximalsprintsthatmeasureforceoverahorizontalplane,asamoresuitableassessmentofNMFinrugbyunion,wherethesemovementsaremorelikelytooccurincomparisontomovementsintheverticalplane.However,aspreviouslyexplained(Chapter2.4),therationaleandapplicabilityofimplementingmaximalsprintsinthedayspost-matchwhichmeasureforceoverahorizontalplane,isperhapsunrealistic.

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9.4.2 ApplicationofsubjectiveandobjectivemeasuresofrestorationAlongsideanalysisofCMJwithinthisthesis,theassessmentofWBscoresinthedayspost-matchalsorevealedresultsofinterestforfuturepractice.ThefindingthatWBscoresreducedtoagreatervalueandforalongertime-coursethanCMJisoneofimportanceforfutureapplicationsinelitesettings.Despiteevidencefromthisthesissupportingtheuseofbothobjectiveandsubjectivemeasuresofmonitoringathlete-trainingresponse,subjectivemeasureswereconsideredmoresensitiveinmeasuringfatigue.FurtherevidenceforsupportingtheuseofsubjectivemeasureswasnotedbySawetal.(2016),whofoundintheirsystematicreviewthatsubjectivemeasuresreflectedacuteandchronictrainingloadswithsuperiorsensitivityandmoreconsistencythanobjectivemeasures.Practitionersarethereforeadvisedtoimplementsubjectivemeasureswithintheirtestingbattery.ThereliabilityandsensitivityofWBscoresidentifiedwithinthisthesisandtheirusealongsideobjectivemeasures(specificallyCMJ),inamixedmethodsapproachtomonitoringrestorationofperformanceineliterugbyunionmatchplay,isrecommended.Additionally,whenconsideringthelargevariabilityandfinancialexpenseassociatedwithmanyobjectivemeasuresofperformanceandthelowfinancialexpenseassociatedwithmanysubjectivemeasures,theviewsofSawetal.(2016)thatsubjectivemeasuresareaviableoptionformonitoringacutefatigueinthedayspostrugbyunionmatchplay,isfurthersupported.Baseduponunpublishedobservationsthroughouttheauthor’scareerinelitesport,itcouldalsobearguedthatperhapssometimesthebestmetrictomonitoranathlete'sreadinesscomesfromaskingplayerssimpledailyquestionsregardingtheirgeneralwell-being.However,ineliterugbyenvironments,wheresquadsizesarelarge,thepracticalityofbeingabletospeaktoeveryplayerpretrainingsessionisunrealisticandthereforesupportsthecontinueduseofself-reportwell-beingquestionnairesthatplayerscancompleteintheirowntime,thereforelimitingunrealisticpractitionerresponsibilities.

Futureinvestigationsassessingreadinessonadailybasiswithinteamsportsettingswillperhapsfocusuponmeasuresofperformancederivedfrombothobjectiveandsubjectivetesting.RecentresearchbyThorpeetal.(2015),assessingfatigueduringacompetitivephaseofanelitesoccerplayingseason,notedthatperceivedratingsoffatiguealongsiderMSSDweresensitivetodailyfluctuationsinhighintensityrunning.DespitetheaforementionedlimitationsofusingHRderivedmeasures(Chapter2.4.5)forassessingfatigueandthesmallcorrelationidentifiedbyThorpeetal.(2015)betweenrMSSDandhighintensityrunning,theresultsdoshowthatvagalrelatedtimeindicesareapotentialareaofinvestigationforrestorationofperformanceassessmentineliterugbyunionplayers.Itisperhapslesssurprisingthatmoderatetostrongcorrelations(r=-0.51,p<0.001)wereobservedbetweentheplayersperceivedratingoffatigueandvariationsinhighintensityrunning,withThorpeetal.(2015)notinga400mincreaseinhighintensityrunningleadingtoa1AUdecreaseinperceivedfatigue.Resultsfromthisthesis,wouldthereforesupporttheviewsofThorpeetal.(2015),withWBscoresrecommendedasanappropriatetoolfornon-invasiveassessmentoffatiguestatusineliterugbyunionplayers.Itshould,however,benotedthatWBapplicationshouldbeadministeredinamixedmethodsapproachtomonitoringrestorationofperformanceineliterugbyunionmatchplay.

9.4.3 Position-specifictestsofperformancerestorationAsaresultofthisresearchitcouldbearguedthat,alongsideindividualdatabeingassessedincomparisontomeanvalues,theobjectiveperformancetestsconductedshouldalsobepositionalinfocus.Thecontentoftheseobjectiveperformancetestsshouldperhapsbeguided

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bythematchdemandsthatindividualpositionsarerequiredtoperform,witharestorationofperformancetestmeasuringthelikelyfatigueinducedbythesedemands.TheviewsofGathercole,Sporer,Stellingwerff,etal.(2015a)supportthisnotion,recommendingaprocessofidentificationofvariablesthataresubjecttochangeinspecificpositions.Itislikelythatsomestrategy-focusedvariablesaremoresensitivetoperformancechangethanothers,thereforepotentiallyexplainingtheexclusionofsometestingoptions.Fatigueinpositionssuchasfullbackandwing,whichhavebeennotedwithinthisthesistoexperiencemoreaccelerationsthanotherpositions(Chapter3),maybebetterassessedbyaperformancetestthatmeasuresalowerbodyexplosiveelement.Positionsthatcompletealargevolumeofaccelerationsanddecelerationsduringmatchplay,shouldperhapshavetheirNMFassessedbyforceatzerovelocity,asthismeasureislikelytooffergoodrepeatabilityandappearsusefulforinferringchangesinmovementstrategyduringtheeccentricphase.Likewise,apropandafullbackhavebeenshown(Chapter3)toexperiencedifferingdemandsduringgameplayandthereforetheperformancetestthatisconductedshouldperhapsreflectthis.Anadditionalconsiderationtosupportthisnotion,wasthefindingfromthisthesisthatforwardsexperiencealessreducedCMJperformanceintheimmediatedayspost-matchcomparedtobacks,despiteexperiencingalargervolumeofhighmagnitudeimpactsduringmatchplay.Onecouldthereforearguethatimplementingtheuseofa“plyometricpushup”toassessposition-specificupperbodyfatigueofforwardsinthedayspost-matchwouldbemoreappropriate.Theaboveevidence,combinedwithunpublishedobservationsfromexperimentalChapter8(showingforwardsexperiencingmoreballcarries,tacklesandsetpiececollisionsthroughoutgameplaythanbacks),meanitcouldbearguedthatthelikelyfatigueresponseofforwardsismorerelatedtoupperbodymusclesoreness.ItisthereforeperhapsunsurprisingwithinChapter7,thatCMJdidnotdetecthighermagnitudeoffatigueinforwardscomparedtobacks,asCMJisaimedatassessinglowerbodymechanicsandnotupperbodymechanics.Aspreviouslyexplained,highmagnitudeimpactsexperiencedviaballcarries,tacklesandsetpiececollisions,arethoughttohaveagreaterinfluenceuponrestorationofperformancepost-match.Assuch,theuseofa“plyometricpushup”inassessingupperbodyfatigueinfutureresearchmaybeamorereliablemeasureforusewithinassessmentofforwards’time-courseofrestoration.Whenconsideringthisnotionofa“plyometricpushup”beingusedtoassessupperbodyfatiguepost-match,theuseoftheOptoJumpshouldnotbediscounted,usingtheflighttimecalculationwithintheOptoJumpsoftware.Thisdataassessingupperbodyfatiguecouldprovidepractitionerswithascoreuponwhichtomakeinformeddecisionsuponforwards’fatiguepost-match.EvidencetosupportthisnotionwaspresentedbyRoeetal.(2015),whonotedgoodreliability(CV<5%)for“plyometricpushup”assessedacrossflighttime(2-3repetitions),peakforce(1andrepetitions)andmeanforce(1-3repetitions).Lowerreliabilitymeasures(CV>5%)havepreviouslybeenreportedfor“plyometricpushup”(Hogarth,Deakin,&Sinclair,2013)thereforesupportingitsuse,yetthesub-eliteleveloftherugbyleagueplayerswithinthestudymeanitsrelevancecanbequestioned.PerhapsmostinterestingfromtheresearchbyRoeetal.(2015)wasthefindingthatonlymeanforce(2and3repetitions)wascapableofdetectingSWCandthisissomethingthatwouldrequireconsiderationfrompractitionerslookingtoimplement“plyometricpushup”intotheirfatiguetestingprotocol.Flighttime(2and3repetitions),peakforce(1and3repetitions)andmeanforce(1-3repetitions)alldisplayedaCVof<5%,thereforepotentiallydiscountingtheiruse.

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Lastly,inadditiontotheprescriptionofperformancetestsalignedwithpositionaldemands,thenotionthatperformancetestsshouldbeprescribedbaseduponmechanicalormetabolicelementsisanotherareaoffutureinterestinthissubjectarea.Priorresearchhasidentifiedthelikelymetabolic(Cummins,Gray,Shorter,Halaki,&Orr,2016;Jonesetal.,2014;Kempton,Sirotic,Rampinini,&Coutts,2015;Lindsay,Lewis,Scarrott,Gill,etal.,2015;McLellanetal.,2011b;Twist&Highton,2013)andmechanicalfatigue(Coutts,Reaburn,Piva,&Murphy,2007;Johnstonetal.,2015;Johnston,Gabbett,etal.,2014;Johnstonetal.,2013)inducedbyrugbymatchplay,yetthemechanismsofeffectassociatedwiththeseresponsesarestillunclear.Itcouldbearguedthatpositionalgroupsexperienceeitherapredominatemechanicalormetabolicfatigueasaresultofmatchplayandthereforetheperformancetestsimplementedshouldaimtoinvestigatethisresponse.Similarly,apositionalgroupthatexperiencesmoreimpactsshouldperhapshaveaperformancetestimplementedthatassesseselementsofmusclesoreness,asthisisthelikelyresponsethatwouldbeassumed.Itis,however,importantforpractitionerstonotethatpriortosuchposition-specificperformancetestingbeingimplemented,developmentoftechnologythatwouldbeabletotestsuchmeasuresneedstobereviewed.

9.4.4 FutureGPSintegrationforrecoveryinterventionBasedupontheresultsofthisthesis,futureimplementationofGPSanalysisinmonitoringfatigueandtheimplementationoftraininginterventionsshouldencompassanalysisofmovementpatternsandmorespecificallythewayinwhichplayersencountertheimpactsoccurredduringmatchplayandtraining.Asexplainedpreviously(Chapter9.3.3),thewayinwhichaplayerexperiencesanimpact(collisionormovementtask)willhaveamajorinfluenceupontheresultantfatiguecreated,meaningthatGPSanalysisutilisingimpactmetricsshouldinvolvethecombinedmethodapproachdetailedinChapter8.TheevidencepresentedinChapter8showsthatGPSdoesnottellusersallthattheyneedtoknowregardingmatchdemands,andinsomecasescanperhapsbemisleading.Inadditiontoacombinedapproach(GPSandvideo)beingrecommended,theuseofrelativeGPSmeasuresisproposedforfutureimplementation.Totheauthor’sknowledge,noresearchhasattemptedtomeasurerelativeGPSmetricsandresultantfatigue,yettherecentresearchbyDelaneyetal.(2016),illustratingconsiderablyhigherrelativeintensities(150-180m/min-1)ofmatchplaycomparedtopreviousresearchinprofessionalrugbyunion(Cahilletal.,2013;Lindsay,Draper,etal.,2015),signifiestheneedforrelativemeasurement.EvidencesupportingtheuseofrelativemeasuresispresentedintherecentresearchbyDelaneyetal.(2016),whorecommendedtheuseofarollingaveragesapproachforintensityassessment,astheirresearchshowedtheintensityofmatchplaytobegreaterasthelengthofthemovingaveragedecreased(ES=0.05-2.96),therebyillustratingthatwholematchvaluesmaynotbereflectiveofthemostintenseperiodsofmatchplay.ThisevidencethereforehighlightsaninherentissuewhenconsideringintensitymetricsandonethatwarrantstheconsiderationofrelativeGPSmetricsforpractitioners,whencomparingplayersandassessingresultantfatigueinfutureresearch.Futureinvestigationneedstobeaimedtowardsthewayinwhichrelativeintensity(m/min)duringmatchplayisperformedforeachpositionandinadditiontheresultantfatigueresponsecreatedasaresultofrelativeintensity.Forexample,oneplayercouldspend40minutesat8km/hand40minutesat4km/handanothercouldspend40minutesat10km/hand40minutesat2km/h,thereforebothequatingtoatotaldistanceof8kmandarelativeintensityof100m/min.However,despiteboththeseplayersachievingthesamedistances,thewayinwhichtheyachievedthisdistanceisdifferentandthereforepotentiallydoesnotpresentaclearpictureoftheirmatchdemandsandlikelyfatiguecreated.

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Inadditiontothefutureuseofcollisionload(asdiscussedinChapter8.5),theuseofsoftwarederivedloadmetricssuchasDynamicStressLoad(DSL)andMetabolicPower(MP)usedtoassessthephysiologicalcostofrugbyunionmatchplayalsoneedinvestigatedfurther.DespiteDelaneyetal.(2016)notingMPvaluesof11-13.5w/kgacrossvaryingpositionsandrecommendingassessmentofthismetricusingarollingaveragesapproach,recentresearch(Hader,Mendez-Villanueva,Palazzi,Ahmaidi,&Buchheit,2016)inhighlytrainedsoccerplayersquestionedtheuseofMPasameasureofrunningload,whencomparingchangesofdirectionandstraightlinerunning.WhenconsideringthatrecenttrendsinGPSsolutionshaveseendevelopmentofusers’abilitytotrackindicessuchasheartrate,impactsandstressloadsinstantaneouslyandreportavalueof“load”experienced,thereliabilityofthemetricsandtheirassociatedalgorithmsneedstobecriticallyappraised.DSLisusedtoassesstheoverallloadofimpacts,assessingmagnitudeofimpactsandclassifyingtheeffectthishasuponfatigue.However,similarlytocollisionloadmetrics,theuseofDSLisyettobevalidatedandisafutureareaofinvestigationwithinmatchdemandsresearch.

Futureresearch,incorporatingimpactassessments,shouldalsoperhapsinvolveananalysisoftheexactpointsduringmatchplayatwhichcollisionsaremostlikelytooccur.Itcouldeitherbearguedthatthemajorityofimpactswilloccuratthestartofthematch,whenplayersarefreshandthereforeabletoexertmaximalintensitytoimpacts,oritcouldbearguedthatplayersaremorelikelytoperformhighermagnitudeimpactsinlaterpartsofthematchwhenfatigueismorecommonandopportunitiestoregainpossessionoftheballorhaltattackingmomentumaremoreprevalent.Informationprovidedfromananalysisofimpacttimingsduringmatchplay,wouldperhapshelpguidepractitionersuponfuturetrainingprescription,astheexpectedtimingandmagnitudeofimpactsduringgameplaywillbemorefullyunderstood.Secondly,analysisofrugbyplayersinalaboratorysetting,movingoverforceplateswhilewearingGPSunits,wouldprovidemoredetailaroundtheimpactsbeinggeneratedduringlocomotionandthereliabilityofGPSunitimpactclassificationsacrosszones.Thefindingsofsuchananalysisofimpactclassificationszones,usingthecommonlyreported“goldstandard”forceplateasareferencepointagainstwhichtocompareGPS,wouldbetterguidepractitionersupontherelevanceofGPSimpactdatawithineliteteamsportsettings.

BasedupontheresultsfromexperimentalChapter3and8,itcanbeassumedthataccelerationsanddecelerationscanbeconsideredtoaccountforalargeandcrucialelementofeliterugbyunionmatchplay.AnotherfutureGPSintegrationforassessingrecoveryinterventionshouldthenperhapsincludetheanalysisofenergeticcostsofaccelerationanddecelerationtasks.Giventhehighenergeticcostofacceleratingandthetissuedisruptionassociatedwithdecelerating,theneedformoreresearchintotheinfluenceofthesetasksuponresultantfatigueiswarranted.Researchassessingenergycostandmetabolicpowerinelitesoccer(Osgnach,Poser,Bernardini,Rinaldo,&DiPrampero,2009)notedthatinstantaneousmetabolicpowercanbecalculatedduringmatchplay,demonstratingthatrunningspeedscangeneratedifferentmetabolicdemandsdependingupontheaccelerationincorporated.TheresearchbyOsgnachetal.(2009),thereforeaddedtotheknowledgeoftheinfluenceofhighintensityrunning(includingaccelerationsanddecelerations)uponfatigue,astheresultsshowedthatplayerscovered18%oftheirtotaldistance>16km/h-1,yetthiscorrespondedto42%ofthetotalenergybeingathighpower(>20w/kg-1).Morerecently,however,thisexperimentalapproachwasquestionedbyBuchheit,Manouvrier,Cassirame,andMorin(2015),withtheapplicationofthismethodologyutilisingGPSnotedtounderestimatetheenergydemandsofsoccerspecificdrills,especiallyduringrecoveryphases.TheuseofGPSinthecalculationofenergeticcostsis

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thereforequestioned.Supportfortheuseofmetabolicpowerforthedevelopmentoftheunderstandingofthephysicaldemandsofteamsportplay,does,however,existandhasbeennotedbymanyauthors(Castagna,Varley,PóvoasAraújo,&D’Ottavio,2016;Couttsetal.,2015;Cumminsetal.,2016;Kemptonetal.,2015),yettotheauthor’sknowledgenospecificmetabolicpowerresearchhasbeenpresentedwithinrugbyunion.Whenconsideringtheaforementionedpoorreliabilityissuesassociatedwithshortdistancehigh-speedmovementssuchasaccelerationsanddecelerations,theuseofGPStoassessthesemetricsandresultantfatiguecanbequestioned.

Lastly,whenassessingimpacts,itcouldperhapsbearguedthatimpactzonesshouldbeindividualised,assomeplayersarelikelytobeabletotoleratelargerimpactforcesthanothers.Futureresearchshouldperhapsaimtoincorporatetheanalysisofimpactforcesbaseduponpriorresearch,showingwhatareconsidered“normal”forthesepositions.Asaresultofthisanalysis,comparingconcurrentdataagainstthatofpositionalnorms,abetterunderstandingofthelikelyresponseimpactsencounteredduringeachmatchmayhaveuponlikelyrestorationofperformancecanbeassumed.Additionally,futureimplementationoftrainingprogrammeprescriptioncouldbeadministeredbaseduponlongitudinalGPSdatathatassessespositionalmovementdemands.When“eyeballing”theresultsfromChapter8,itwasevidentthatnopositionalgroupappearedtodisplayapatterninthedistributionoftheirchangesofdirection,accelerationsordecelerationsacrossimpactzones.However,theimplementationoflongitudinaldatacollection,usingGPSandvideo,mayperhapsprovideaddeddetailuponthemagnitudeofchangesofdirection,accelerationsordecelerationspositionsexperiencedacrossimpactzones.Thisinformationwouldthereforehelpbetterguidepractitionersupontherequiredconditioningcomponentsofpositionalgroups.Itis,however,importantforpractitionerstonotethatperformancedata,suchasGPSordataderivedfromtesting,shouldonlybeusedasaguideandnotanaselementofperformancecoachingwhichisdictatordriven.Basedupontheresultspresentedintheexperimentalchaptersaboveanddatapreviouslyreported(Buchheit,2014;Buchheitetal.,2014),itcouldbearguedthattheimportantelementforcoachesistoassessathletereadinessinaholisticmannerandmakeeducatedandinformeddecisions,whichareguidedbybothdataand“coachingart”,whilstalsoensuringtheyarenon-emotionalinnature.

9.4.5 Athleticresilience,trainingloadsandhastenedrestorationofperformanceHighertrainingloadswerenotedbyVeugelers,Young,Fahrner,andHarvey(2015)toprovideaprotectiveeffectagainstbothinjuryandillnessineliteAustralianrulesfootball,withthisthesisalsonotingthatrecoveryratescanbeassumedasindividualinnature,andcanperhapsbeguidedbytrainingload.ArecentlyupdatedversionoftheaetiologymodelwasrecommendedbyWindtandGabbett(2016),examiningtheinfluenceoftrainingloadsuponinjury.Thisnotionoftrainingloadanalysisandsubsequentinterventionisparamountfordevelopingathleticresiliencethatcancontributetohastenedrestorationofperformance.SimilarresearchproposedbyHulin,Gabbett,Lawson,etal.(2016)investigatingacute:chronicworkload,alsosupportsthisview.Perhapsmostimportantlyforpractitionersworkingineliterugbysettings,werethefindingsbyHulin,Gabbett,Lawson,etal.(2016),thatshowedthatplayerswithahighchronicworkloadaremoreresilienttoinjury.Ahighchronicworkloadcombinedwithamoderate(0.85-1.35)acute:chronicworkloadratiowasrecommendedbyHulin,Gabbett,Lawson,etal.(2016)tobeappropriateforthedevelopmentofinjuryresiliency.

Highertrainingloadshavenotalwaysbeenrecommendedforimprovingrugbyplayerresilience,without-datedviewsbyGabbett&Jenkins(2011,p.209)originallyproposing“the

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harderrugbyleagueplayerstrain,themoreinjuriestheywillsustain”.However,asknowledgehasbeendevelopedinthistopicarea,thesameauthorsarenowinagreementthattrainingloadmayactuallyassistindevelopingplayerresilience(Hulin,Gabbett,Caputi,Lawson,&Sampson,2016;Hulin,Gabbett,Lawson,etal.,2016;Johnstonetal.,2015).SimilarlytotheresearchbyHulin,Gabbett,Lawson,etal.(2016),arecentinvestigationassessingacute:chronictrainingloadsineliteyouthfootballplayerswarrantsattention.Bowen,Gross,Gimpel,andLi(2016)notedthataccumulatedworkloadandinjuryriskarerelatedandthatprogressiveincreasesinchronicworkloadmaydevelopplayers’physicaltolerancetoacuteloads.Malone,Roe,Doran,Gabbett,andCollins(2016b)alsosupportedthenotionthatmoderateincreasesinworkloadinGaelicfootballappeartoprovideaprotectivemeasureagainstinjury.Thesestudiesthereforefurtheremphasisetheviewthatincreasedlevelsofconditioningandappropriateloadmanagementmayresultinquickerrecoveryratespostrugbyunionmatchplayandincreasedresiliencetoinjury.Trainingloadandreadinessassessmentareinextricablylinkedandwhenapplyingtheabovetrainingloadevidencetothefindingsfromthisthesis,performancetestingusingCMJandWBshouldbeimplementedtoregularlyassesstheeffecttrainingandplayingishavinguponeliterugbyplayers’dailyreadiness.

Thenotionoftrainingloadsinfluencingthelikelihoodofinjuryisnotanewphenomenon,yetaswaspresentedbyGabbett(2016),theimplementationofsmartertraininginplaceofhardertraining(usingmanyofthemethodscritiquedandexaminedfurtherinthisthesis)arekeyforfutureimprovementsinthistopicarea.Perhapsthenextlevelofinvestigationregardingthetrainingloadparadox,shouldinvolvetheassessmentofposition-specifictrainingloadratios.Basedupontheresultspresentedinthesisandtheevidencecritiquedpreviously,theseposition-specifictrainingloadratioswouldnotonlyhelppreventavoidableinjuries,butcouldalsoaidinthedevelopmentofappropriatetrainingloadstimulithatwouldlikelyhastenrestorationofperformancetime-course.EvidencetosupportthisnotionispresentedbyMurrayetal.(2014),whoshowedthatinjuryratesofspecificplayingpositionsareinfluencedbytheamountofrecoverybetweenmatches.ThenotionsbyMurrayetal.(2014)thereforesupporttheviewsofthisthesis,inthatmatchdemandsandspecificallyphysicalcollisionshaveimplicationsforfuturerecoveryprogramming.

Theeffectofplayers’physicalconditionandoverallfitnesslevelsontime-courseofrestorationalsoneedstobeinvestigated.Killenetal.(2010)notedthatmaximalaerobicpoweractedasaprotectivemeasureforinjuryandthiscouldperhapsmeanthatplayerswithbetteroverallfitnesslevelsnotonlyareprotectedfrominjurybutalsorecoveratquickerrates.TheseviewsweresupportedbyrecentresearchinGaelicfootballbyMaloneetal.(2016b),recommendingahighaerobiccapacitytoofferinjuryprotectionagainstrapidchangesinworkload.SimilarlyJohnstonetal.(2015)notedthatplayerswithwelldevelopedhighintensityrunningandlowerbodystrength,weredeemedasabletorestoreperformancepost-matchplaymorequicklythanplayersthatdidnotdisplaytheseattributes.Ifthisevidence,supportinghighfitnesslevelsbeingapotentialstrategytoimproverestorationofperformancepost-match,isbelievedtobeconsistentacrosseliterugbyunionsettings,itcouldperhapsbearguedthatathleticresilienceandimprovedfitnessisthefirstobstacleforpractitionerstoovercomeintheirdesiretoimproveplayerreadinessbetweengames.

Lastly,anadditionalpointforconsiderationwithintheanalysisoftheresultscollatedregardingchangesofdirection,accelerationanddeceleration,isthenotionthatinatypicaltrainingweekplayersareexposedtoalargerfrequencyofchangesofdirection,accelerationanddeceleration,thanimpacts.Thisexposuretochangesofdirection,accelerationanddecelerationonadaily

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basis,meansthatitcouldbearguedthatpractitionersshouldonlyassessimpactsfromcollisions,asthesearethelessregularlyexperienceddemandsandarelikelytohaveagreaterinfluenceuponrestoration.Adaptationandanabilitytohandleloadexperiencedfromchangesofdirection,accelerationanddecelerationispotentiallylikelytooccurnaturallywithintraining.Recently,thisnotionofappropriateexposuretomaximalvelocityeventsactingasaprotectivemeasureagainstinjurywaspresentedbyMalone,Roe,Doran,Gabbett,andCollins(2016a)ineliteGaelicfootballplayers,yetevidencetospecificallysupportthisfindinginelitelevelrugbyunionisstillunfound.ThefocusoffuturerecoveryandrestorationprotocolsusingGPSimpactsshouldthereforeperhapstakemoreofaspecificapproach,toincludequantificationofimpactsfromcollisionsandnotallimpactinstances.Thisnotioncouldthereforeformthebasisoftherationaleforexcludingthoseimpactsnotexperiencedfromcollision,andwouldenableeasieranalysisandquantificationofimpactsoccurredinrelationtotheirlikelyeffectuponrestoration.

9.4.6 PhysiologicalandpsychologicalrestorationpostrugbyunionmathplayItcouldbearguedthatallaspectsofmatchoutputneedtoberecoveredfrom,meaningrecoverymustthereforebeindividualisedandshouldencompassbothphysicalandmentalrestoration.Onerecentstudyofinterest,istheworkbyRattrayetal.(2015)whoproposedthatmodernpost-exerciserecoverystrategiesshouldfocusuponnotonlyperipheralmechanisms,butcentralmechanismsalso.Asdemonstratedinthisthesis,muchoftheattentionofrecoverystrategiesandtheireffectivenesshasfocuseduponperipheralmeasuresoffatigue,yettheviewsofRattrayetal.(2015)proposethenotionthattheassessmentofcentralfatigue,alongsideperipheralfatigue,isanimportantconsiderationforfuturepractice.Whenconsideringthehighcognitiveloadexperiencedbyrugbyunionplayers,bothinthebuilduptomatchplayandduringthematchitself,theneedtoassessthispsychologicalstressorandinfluenceahasteningofrestorationofperformancefromacentralfatigueviewpointisparamount.Morefocusedfutureresearchuponthebrainanditsroleinrecoverypostexerciseisneeded,withinvestigationintotherecoverymodalitiesthatmoreeffectivelyimpactthecentralfatigueassociatedwiththebrainbeingkey.

Theabilityofsportssciencepractitionerstotargetcentralfatigue,asaninterventiontoimproverestorationofperformancefollowingrugbyunionmatchplay,wouldbeamajoradvancementintheareaofrecovery.Furthersupportfortheimplementationofcentralfatigueassessmentandassociatedrecovery,isnotedwhenassessingtheaforementionedresearchbyNoakes(2012).WhencombiningtheviewsofNoakes(2012)(emphasisingtheroleofcentralfatigueinperformancedecrement)withthenotionsofRattrayetal.(2015)(illustratingtheimportanceofcentralfatiguewithintherecoveryprocess),onecouldarguethatcentralfatiguepredeterminesperipheralfatigue,soshouldperhapsbetargetedinitiallytohastentheperipheralfeelingsofperceivedfatigue.Futurerecoveryinterventionplanningshouldthereforetakeintoaccountelementsofarugbyplayer’sdailylife,including,forexample,peerpressureandpotentialpressurefromsponsors.Practitionersworkingintheelitefieldareadvisedtolookbeyondphysiologicaltime-courseofrecoveryassessment,andinsteadincludeacombinedapproachofphysiologicalandpsychosocialrecoveryintervention.

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9.5 Finalconclusion

Aneedforcontinuedresearchinrugbyunionmatchdemandsexists,astheresultspresentedregardingtheapplicabilityofGPSmetricsintheircurrentformatarequestionable.MoreaccurateGPSloadassessmentmetricsarerequired,withfuturetechnologicaldevelopmentsinmatchdemandassessmentbeingrecommendedtoincludeacombinationofdatatakenfromtheGPS,accelerometerandgyroscope.Suchsoftwareadvances,combinedwiththeuseoftheGPSandvideoanalysistechniquesappliedwithinthisthesis,couldprovidemoredetailintermsoftheactivitiesperformedbypositionalgroupsandthelikelyresultantfatigue.Asaresult,amoremeaningfulanalysisofmatchdemandswillbedevelopedthroughbetteridentificationofmovement.Relativemeasuresarealsorecommendedforinvolvementinfuturematchdemandsresearch,asitcouldbearguedthatthisthesisisperhapsmorerepresentativeofmodernrugbyunionthanthoseconductedpreviously.Observationsfromthisthesiswouldindicatethatrelativevaluesforforwardsareperhapsofmoreinterestthanthoseofthebackswhenassessingsomevariables,astheypresentmoreinformationfromarelativeratherthananabsoluteview.Thenotionofarelativeposition-specificassessmentwouldbetterguidepractitionersinfuturematchdemandsanalysis.

OtherimportantfindingsfromthisthesisidentifiedCMJandWBasbeingapplicableforuseinrestorationofperformancetesting,withachangeinCMJheightof≥1.7%beingmeaningfulandthereforewarrantingfurtherinvestigationbypractitioners.DespiteCMJheighttestingshowntobeofuseineliterugbysettingsforassessingrestorationofperformance,WBassessmentalsoindicateditsworth.Resultsfromthisthesiswouldindicatethateliterugbyplayersoftendonotrestoreperformancepriortothenextgamecommencingandthatplayersoftenplayinasub-optimalstate.ThereducedCMJperformanceandWBscoresnotedat60hours,90hoursand170hourspostrugbyunionmatch,betweenpositionalgroups,isofimportanceforfuturetrainingprescriptionintheimmediatedayspost-match.Finally,resultsfromthisthesiswouldindicatethatthedifferencesintime-courseofrestorationbetweenpositionalgroupsandreportedforCMJperformanceandWBscores,couldbeexplainedbyboththematchdemandsencounteredandthetypicallyaccumulatedtrainingactivitiesperformedbetweengames.Whenconsideringthenumberoffixturesinaseasonandthefactthatmatchdemandsexperiencedbyplayersareever-increasing,thefindingsfromthisthesisareofprominenceformanystakeholderswithintheelitegame.

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11 Appendix

11.1 AppendixA

Figure11.1:Examplewell-beingquestionnairerelatingtoChapter

WEEKLY WELL-BEING MONITORSCHEDULE: MON TUE WED THU FRI SAT SUN

SLEEP QUALITY(record figure from 1-10 that best relates to your sleep quality from last night)

10 = undisturbed987654321 = little/none

ENERGY LEVELS(record figure from 1-10 that best relates to your energy levels this morning)

10 = fresh987654321 = exhausted

MUSCLE SORENESS(record figure from 1-10 that best relates to your body condition)

10 = no pain987654321 = pain interupting training

MOOD(record figure from 1-10 that best relates to your mood)

10 = motivated987654321 = negative

APPETITE(record figure from 1-10 that best relates to your appetite)

10 = excellent987654321 = none

SUMMARYDAILY SCORES (TOTAL):

WEEKLY AVERAGE SCORE:

11.2 AppendixB

Table11.1:Descriptive(mean±standarddeviations)andreliabilitystatistics,withintestingdaysforImpulse(N.s)andconcentricpower(W)relatingtoChapter5

CMJ Day1average

Day1%CV

Day2average

Day2%CV

Day3average

Day3%CV

Allsessionsaverage

Average%CV

CMJImpulse(N.s)

229±4.1 1.7% 224±8.1 3.6% 222±7.3 3.2% 225±6.5 2.8%

CMJPeakConcentricPower(W)

4661±109 2.2% 4493±466 10.5% 4367±88 2.0% 4507±121 2.6%

Table11.2:Descriptive(mean±standarddeviations)andreliabilitystatistics,betweentestingdaysforImpulse(N.s)andconcentricpower(W)relatingtoChapter5

Jump Day1(cm)

Day2(cm)

Day3(cm)


SEM(cm)

SDD(cm)

CMJImpulseForcePlate(N.s)

228±18.6

223±22.7

221±22.5

0.847 0.090 8.5 23.7(10.60%)

CMJPeakConcentricPowerForcePlate(W)

4661±450

4493±547

4367±453

0.851 0.224 188.2 521.7(11.5%)

247

11.3 AppendixC

Table11.3:Descriptive(mean±StDv;CI=95%confidenceintervals)acrossselectedmatchdemandsdataforallpositionsrelatingtoChapter3

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackGameTime(mins)

61.2±14.2(CI57.7-64.8)

56.6±16.8(CI50.6-60.5)

70.6±10.8χû(CI67.7-73.4)

70.9±14.3∞(CI68.0-73.8)

63.7±11.8(CI59.5-67.8)

66.3±14.2(CI64.1-71.3)

76.0±9.4¥(CI73.5-78.4)

73.2±13.9§(CI69.7-76.7)

77.0±8.0*#(CI73.8-80.1)

Intensity(m/min)

59.6±5.4(CI58.2-60.9)

66.7±4.9μ(CI64.9-68.4)

66.5±6.7Ψ(CI64.7-68.2)

64.8±5.6Ψ(CI63.6-65.9)

74.4±6.5ζθ(CI72.1-76.6)

71.9±5.1ϕφϖ(CI70.1-73.7)

68.1±8.1Ψ(CI65.9-70.2)

69.0±6.4Ψξ(CI67.4-70.7)

76.2±6.1Ωα(CI73.8-78.6)

Accelerations 13.6±7.0(CI11.9-15.3)

21.5±9.9(CI18.0-25.0)

26.6±9.3Ψ(CI24.1-29.0)

24.7±13.6Ψ(CI21.9-27.4)

31.5±10.7Ψ✚(CI27.7-35.2)

37.5±10.3¥η(CI33.9-41.1)

29.2±8.9Ψ(CI26.9-31.5)

34.1±11.3¥νΑ(CI31.2-37.0)

32.6±7.5Ψχ(CI29.6-35.5)

Decelerations 20.3±7.7(CI18.4-22.2)

28.9±11.8(CI24.7-33.1)

34.5±10.8Ψ(CI31.6-37.3)

36.0±16.7Ψ(CI32.6-39.4)

35.1±9.4Ψ(CI31.8-38.4)

43.4±12.9Ψβ(CI38.8-47.9)

43.6±10.8ΨΔţ(CI40.8-46.5)

42.8±13.4¥★ŵ(CI39.4-46.2)

46.0±9.8¥(CI42.1-48.9)

Ψsignificantlygreater(p<0.001)comparedtoPropsΩsignificantlygreater(p=0.03)comparedtoOutHalvesandWingsηsignificantlygreater(p=0.006)comparedtoLocksνsignificantlygreater(p=0.002)comparedtoLocks*significantlygreater(p=0.01)comparedtoScrumHalfandHookers#significantlygreater(p=0.003)comparedtoProps¥significantlygreater(p<0.001)comparedtoPropsandHookers§significantlygreater(p=0.001)comparedtoPropsandHookers∞significantlygreater(p=0.01)comparedtoPropsandHookersχsignificantlygreater(p=0.03)comparedtoHookersφsignificantlygreater(p=0.004)comparedtoHookersμsignificantlygreater(p=0.001)comparedtoProps✚significantlygreater(p=0.01)comparedtoHookers★significantlygreater(p=0.03)comparedtoScrumHalves

ϕsignificantlygreater(p<0.001)comparedtoPropsandBackRowξsignificantlygreater(p=0.003)comparedtoBackRowαsignificantlygreater(p<0.001)comparedtoProps,Hookers,LocksandBackRowχsignificantlygreater(p=0.03)comparedtoHookersβsignificantlygreater(p=0.007)comparedtoHookersΔsignificantlygreater(p=0.008)comparedtoLocksθsignificantlygreater(p=0.005)comparedtoLocksûsignificantlygreater(p=0.03)comparedtoPropsζsignificantlygreater(p<0.001)comparedtoProps,HookersandBackRowϖsignificantlygreater(p=0.03)comparedtoLocksΑsignificantlygreater(p=0.01)comparedtoBackRowţsignificantlygreater(p=0.002)comparedtoHookersŵsignificantlygreater(p=0.01)comparedtoLocks

248

Table11.4:Descriptive(mean±StDv;CI=95%confidenceintervals)acrossdistancedataforallpositionsrelatingtoChapter3(symbolspresentedonTable11.5)

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackDistance(m)

4285±893(CI4065-4505)

4469±1238(CI4029-4908)

5517±979Ψ(CI5259-5774)

5411±1134⌘Ψ(CI5181-5641)

5408±978≠(CI5067-5750)

5583±1191≠(CI5167-5999)

6043±966¶Ψ(CI5791-6295)

5926±1295¥(CI5597-6255)

6904±740$£€(CI6617-7191)

DistanceZone1(m)

1799±487(CI1679-1919)

1474±429(CI1322-1627)

1963±479(CI1837-2089)

2043±482i(CI1945-2141)

1692±381(CI1559-1825)

2029±499(CI1855-2203)

2405±456ΒΚ⏏(CI2286-2524)

2337±562ΨΓΣΑ£(CI2194-2480)

2328±371¢₠≈(CI2184-2472)

DistanceZone2(m)

1043±319(CI965-1122)

1451±410#(CI1306-1597)

1748±383Ψ✪(CI1647-1849)

1663±382Ψ★(CI1586-1741)

1421±273≠(CI1325-1716)

1439±269≠(CI1345-1533)

1574±338Ψ(CI1485-1662)

1446±400Ψ(CI1344-1548)

2078±275¤πϖu(CI1971-2185)

DistanceZone3(m)

847±210(CI795-899)

926±296(CI821-1031)

1046±306≠x(CI965-1127)

863±244(CI814-913)

971±217(CI895-1047)

948±228(CI869-1028)

824±225(CI766-883)

861±263(CI794-928)

1042±199(CI965-1119)

DistanceZone4(m)

394±124(CI364-425)

536±223(CI457-615)

589±240Ψ(CI526-580)

568±254Ψ(CI517-620)

1009±214$⏏⌫®(CI934-1084)

848±227⌃ΨΓ(CI769-927)

748±191Ψ✚ϖ þ(CI698-798)

708±230Ψ(CI650-767)

922±177¥⌃(CI853-991)

DistanceZone5(m)

118±56⌘(CI104-131)

73±47(CI57-90)

142±54₠(CI127-156)

202±119✓₠(CI178-226)

281±76¥⌃♮(CI254-308)

273±88¥⌃(CI242-304)

322±107$(CI294-350)

346±113$(CI317-374)

429±118$♭♫(CI384-475)

DistanceZone6(m)

17±23β(CI11-23)

4±10(CI1-8)

6±9(CI3-8)

20±24✚ŵ(CI15-25)

33±21⌃₠(CI25-40)

43±35û⌃₠(CI31-55)

51±42$(CI40-62)

139±72$℗(CI120-157)

101±50$∧∨(CI82-121)

249

Table11.5:KeyfordescriptivedistancedatainTable11.6relatingtoChapter3

*significantlygreater(p=0.01)comparedtoScrumHalfandHookers#significantlygreater(p=0.003)comparedtoProps¥significantlygreater(p<0.001)comparedtoPropsandHookers§significantlygreater(p=0.001)comparedtoPropsandHookers∞significantlygreater(p=0.01)comparedtoPropsandHookers⌘significantlygreater(p=0.03)comparedtoHookers$significantlygreater(p<0.001)comparedtoProps,Hookers,LocksandBackRow£significantlygreater(p=0.001)comparedtoScrumHalf€significantlygreater(p=0.003)comparedtoOutHalf¶significantlygreater(p=0.002)comparedtoHookers≠significantlygreater(p=0.002)comparedtoPropsΨsignificantlygreater(p<0.001)comparedtoPropsΩsignificantlygreater(p=0.03)comparedtoOutHalvesandWingsαsignificantlygreater(p<0.001)comparedtoProps,Hookers,Locks,BackRowandWingsχsignificantlygreater(p=0.03)comparedtoHookersΓsignificantlygreater(p=0.001)comparedtoHookersΣsignificantlygreater(p=0.004)comparedtoLocks¢significantlygreater(p=0.005)comparedtoPropsandLocks₠significantlygreater(p<0.001)comparedtoHookers≈significantlygreater(p=0.004)comparedtoScrumHalves¤significantlygreater(p<0.001)comparedtoProps,ScrumHalfandOutHalfusignificantlygreater(p=0.001)comparedtoCentre✪significantlygreater(p=0.001)comparedtoWingers★significantlygreater(p=0.03)comparedtoScrumHalves⌫significantlygreater(p=0.002)comparedtoCentre⌃significantlygreater(p<0.001)comparedtoLocks♭ significantlygreater(p=0.002)comparedtoScrumHalves♫significantlygreater(p=0.001)comparedtoOutHalves℗significantlygreater(p<0.001)comparedtoScrumHalf,OutHalfandCentre∨ significantlygreater(p=0.01)comparedtoOutHalves

ζsignificantlygreater(p<0.001)comparedtoProps,HookersandBackRowϕsignificantlygreater(p<0.001)comparedtoPropsandBackRowϖsignificantlygreater(p=0.03)comparedtoLocksβsignificantlygreater(p=0.007)comparedtoHookersξsignificantlygreater(p=0.003)comparedtoBackRowπsignificantlygreater(p=0.003)comparedtoHookerandWingsΑsignificantlygreater(p=0.01)comparedtoBackRowΒsignificantlygreater(p<0.001)comparedtoProps,Hookers,LocksandScrumHalfΚsignificantlygreater(p=0.001)comparedtoBackRowisignificantlygreater(p=0.002)comparedtoHookersxsignificantlygreater(p=0.004)comparedtoCentresignificantlygreater(p=0.005)comparedtoBackRow®significantlygreater(p=0.01)comparedtoWingers⏏significantlygreater(p=0.03)comparedtoOutHalves✚significantlygreater(p=0.01)comparedtoHookersþsignificantlygreater(p=0.004)comparedtoBackRow♮significantlygreater(p=0.03)comparedtoBackRow✓significantlygreater(p=0.005)comparedtoProps∧ significantlygreater(p=0.003)comparedtoScrumHalvesûsignificantlygreater(p=0.03)comparedtoPropsŵsignificantlygreater(p=0.001)comparedtoLocks

250

Table11.6:Descriptive(mean±StDv;CI=95%confidenceintervals)acrossimpactsdataforallpositionsrelatingtoChapter3

Position Prop Hooker Lock BackRow ScrumHalf OutHalf Centre Wing FullBackImpacts>Zone3

259±250(CI198-321)

291±145εn(CI239-342)

157±40(CI146-167)

225±109(CI203-247)

274±145τ(CI223-324)

186±77(CI159-213)

229±186(CI180-278)

197±155(CI158-237)

296±99ΘΠΩ★(CI257-334)

ImpactsZone1

1178±313(CI1100-1255)

1820±549⌃(CI1625-2015)

2232±533¢(CI2092-2373)

2019±476¢(CI1922-2115)

1998±566¢(CI1800-2195)

2042±528¢(CI1857-2226)

2053±441¢(CI1938-2168)

1901±521¢(CI1768-2033)

2553±510¢¤ΚΩ✚(CI2355-2751)

ImpactsZone2

716±195(CI668-764)

900±326(CI785-1016)

845±201β(CI792-898)

815±259(CI762-868)

1107±234¢ε¶ix(CI1025-1188)

948±255∞(CI859-1038)

762±337(CI674-850)

748±252(CI684-812)

902±182α(CI832-973)

ImpactsZone3

323±128ε(CI292-355)

379±158η(CI323-435)

231±76(CI211-251)

294±135(CI267-322)

449±166εγζδ(CI391-507)

307±102ι(CI271-343)

274±177(CI228-320)

273±132(CI239-307)

341±92θ(CI306-377)

ImpactsZone4

130±114(CI102-158)

148±79εΨ(CI120-176)

75±25(CI69-82)

112±59(CI99-124)

162±82εΠΩ(CI133-191)

106±41π(CI91-120)

111±101(CI85-138)

100±73(CI82-119)

142±51η(CI122-162)

ImpactsZone5

57±67(CI40-73)

62±35εΠζσ(CI49-75)

30±9(CI28-33)

46±26(CI41-51)

58±37η(CI45-72)

37±20(CI29-44)

48±48(CI35-61)

41±37(CI31-50)

66±27ηρΩ★(CI55-76)

ImpactsZone6

70±74(CI51-88)

80±33φvχi(CI68-92)

49±15(CI45-53)

67±27ω®(CI61-72)

52±27(CI43-62)

42±19(CI36-49)

66±43Ω(CI54-77)

53±49(CI40-65)

87±27ςΠ⏏§✚(CI76-97)

Θsignificantlygreater(p=0.001)comparedtoLocksσsignificantlygreater(p=0.001)comparedtoWingersΠsignificantlygreater(p=0.03)comparedtoBackRowΩsignificantlygreater(p=0.03)comparedtoOutHalfεsignificantlygreater(p<0.001)comparedtoLocksυsignificantlygreater(p=0.03)comparedtoWingersτsignificantlygreater(p=0.002)comparedtoLocks¢significantlygreater(p<0.001)comparedtoProps¤significantlygreater(p=0.009)comparedtoHookersΚsignificantlygreater(p=0.03)comparedtoScrumHalf✚significantlygreater(p=0.01)comparedtoWingers⌃significantlygreater(p=0.001)comparedtoPropsΨsignificantlygreater(p=0.02)comparedtoWingerssignificantlygreater(p=0.009)comparedtoBackRowπsignificantlygreater(p=0.004)comparedtoLocks⏏ significantlygreater(p=0.005)comparedtoScrumHalfφsignificantlygreater(p=0.007)comparedtoLocks

xsignificantlygreater(p=0.03)comparedtoFullBacks∞significantlygreater(p=0.01)comparedtoPropsαsignificantlygreater(p=0.03)comparedtoPropsβsignificantlygreater(p=0.01)comparedtoPropsγsignificantlygreater(p=0.004)comparedtoBackRowδsignificantlygreater(p=0.008)comparedtoWingersζsignificantlygreater(p=0.009)comparedtoOutHalfηsignificantlygreater(p=0.001)comparedtoLocksθsignificantlygreater(p=0.003)comparedtoLocksιsignificantlygreater(p=0.005)comparedtoLocksωsignificantlygreater(p=0.03)comparedtoLocks

ρsignificantlygreater(p=0.003)comparedtoBackRowςsignificantlygreater(p=0.006)comparedtoLock§significantlygreater(p=0.001)comparedtoOutHalfχsignificantlygreater(p=0.003)comparedtoOutHalf®significantlygreater(p=0.007)comparedtoOutHalf¶significantlygreater(p=0.03)comparedtoCentreisignificantlygreater(p=0.002)comparedtoWingersnsignificantlygreater(p=0.009)comparedtoWingers★significantlygreater(p=0.03)comparedtoWingers

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