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GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS1
GRAVITYDEFYERFOOTWEAR
WHITEPAPEREVALUATIONOFSTATEDBENEFITS
August2011
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS2
Abstract
ThefocusofthispaperistoquantifyandqualifythebenefitsofGravityDefyershoesonthehuman
bodyduringthegaitcycleandinastaticposition.Thematerialsitedwillcorrelatetheseactionstothebenefitstheseshoesprovidetothepeoplewhowearthem.AnalysisofthecompositionoftheGravityDefyershoeiscrucialtounderstandingthecorrectivefunctiontheshoesprovideandtheresulting
benefits.Aspartofthisexaminationwewillobservethepiecemakeupoftheshoesachieveadirectunderstandingofeachpart’sroleinthereductionofpainandfatigue.
Herein,seriousconsiderationisgiventoheelstrike,forefootstrike,footconditionsandpathologies,posturalalignment,andfatigue.Datarelatingtoshoeconstruction,stability,andcontrolwillalsobethoroughlybrokendowntoexplaintheactualbenefitsandfunctionalityoftheseshoes.Asimple
comparisonofothershoebrandsfeaturingsimilartechnologies(coilsorspringsystems)tothatutilizedinGravityDefyershoesprovidesawealthofdataandfurtherjustifiestheclaimsmadebyGravityDefyer.Significantdataandresearchwasfoundtologicallysubstantiateclaimsofpainrelief,fatigue
reduction,appearingtaller,andanincreaseinadditionalenergy.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS3
Introduction
1.1 EstablishingtheNeedforBiomechanicallySoundFootwear
Fordecadesshoemanufactureshavediscussed,marketedandproducedshoestoaddressconditionsofthehumanfoot.Manyofthesemanufacturesmakeclaimsofcomfort,yetthereisnothingthatmakestheirshoessignificantlydifferentfromtherestoftheindustry.Shoesforcenturieshavefollowedthe
basicpremiseofasolidoutsolewithleatherupper.Theprimarydeviceusedtomakeonebrand’sfootweardistinctfromanotherwasthealterationofthedesignand/ormaterialoftheupperandtheinclusionofmoreandvariedmaterialsusedintheconstructionofthesoleandmidsoleduetoadvances
inchemicalengineeringandadvancedproductionmethods(Poly‐Urethane,EVA,other)Selectingacomfortshoeunderthesecircumstancesisabitlikethechoiceofapplesorapples.
Customshoeshavelongbeenmadeforpeoplewithseriousfootconditionsthroughouttheworld.Someoftheconceptsusedtoproduceamedicalbenefithavebeenincorporated,withvaryingsuccess,intoshoesproducedforthegeneralpublic.Typicallytheseareconsideredtobejustatrendshoeorafad
shoeinsteadofalong‐termsolutiontoanexistingproblem.Ofthoseshoesproducedwiththemedicalconceptbuiltintothem,mostareonthemarketforonlyashortperiodoftimebeforetheirefficacyhas
eitherbeendisprovenorthepubliclosesinterestinthem.GravityDefyerInc.hasproducedGravityDefyershoessince2005.Theyareunlikeanyothershoeonthe
markettoday.Theshoesprovideadirectbenefittotheconsumerandunlikefadproducts,havemaintainedanoverallacceptancebythegeneralpublic.IndesigningandproducingGravityDefyershoes,thecompanyhastakenanapproachuncommontoshoemanufacturers.Theyfocustheirefforts
on1)generalcomfort,2)applyingadvancesinmaterialsandtechnologytobestbenefitthehealthandwell‐beingoftheconsumer,and3)style.
GroundReactionForce
AccordingtotheCenterforDiseaseControl85%ofthegeneralpublicisexperiencingsometypeofbiomechanicaldisease,ofthose85%–thevastmajority–wouldgreatlybenefitfrombiomechanicallycorrectiveshoes:
shoesdesignedtochange,correctandalleviatethesymptomsthesepeopleexperience.TheprimaryobjectivesofbiomechanicallycorrectiveshoesarethereductionofGroundReactionForce(GRF:Theforceexertedbythe
groundonabodyincontactwithit.)andthecorrectionofbodyalignment.Theseconcernsarenotnew,butaddressingthemthroughashoeis.Whilethemajorityoffootwearbrandsfocusonthedispersionofforcethroughthe
useofEVAoranothershockabsorbingmaterial,GravityDefyerhasdevelopedashoethatisalsoamechanicaldevice.Ithasbeenengineeredtoperformtwoprimaryfunctionsfromwhichitsbenefitsarise.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS4
1. ToreducetheaccumulatedimpactdamageoftheGRF.2. Tobalanceandreturnthehumanfoottoaneutralposition,therebycorrectingaspectsofbody
misalignment.Throughtheapplicationofhumanbiomechanicstoshoeconstruction,GravityDefyershoes
demonstratetheabilitytoaddress,changeandmakeshoesatoolthatapersoncanactuallybenefitfromwearing.
1.2 Currentstateofshoemanufacturingindustry
Shoemanufacturinghasgonethroughvastchangesfromwhatwasconsideredagoodcomfortableshoe30yearsago.Cornersareoftencutforcostmanagement;functionandsupportaresacrificedforstyle,
weightandproductiontimehavereplaceddurability.GravityDefyershoesfortunatelydonotadheretothisphilosophy.Theirapproachinproducingashoeistoprovidecomfortandsupportwhilestillencompassingstyleandfunctionality.GravityDefyershoesareconstructedwiththefundamental
platformsharedbyotherqualitycomfortshoes.Whatseparatesthemfromtheircompetitorsistheirapplicationofbiomechanicalprinciplesthatareknowntobenefittheconsumer,yetarenotincorporatedinotherfootwear.
1.3 Contemporarystandardsusedinshoeproduction.
Intheshoeindustry,thecriteriaforagoodcomfortablepairofshoesisconsideredtobecomposedof5
mainpoints:(2,3,4,10,16,20,22,29).
Shank‐Thesolidstabilizingsupportrunningthroughthemiddleoftheshoe,
underthemidsoleand/orupperlayeroftheoutsoledesignedtoreinforcetheshoesstrength.TheShankis(steel,plastic,orcomposite)usedtoprovideadditionalstabilitytothearchaswellcontroltotheheel.(2,3,4,10,16,20,22,29)
HeelCounter‐Thereinforcedposteriorsegmentoftheshoe,whichisdesignedtowraparoundtheheelofthefootandcontrolmovementoftheheel.Thisadditional
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS5
materialcreatesanimprovedfit,feelandsupportofthefoot.Thisallowsforgreatcontrolandstabilizationduringthegaitcycle.(2,3,4,10,16,20,22,29)
RoundedToeBox‐Theshoesforefootmustbeshapedtoallowampleroomfor
thetoearea.Thisisaccomplishedbyprovidingadeeperandwidertoeboxthancommonlyusedinfashionfootwearwheresharpanglesandclosefitmaycausenumerouspathologiesincludedhammertoes,clawfoot,bunionsandotherskin
irritations.(2,3,4,10,16,20,22,29)
Genderandethnicvariationsinfootanatomy
RemovableInsole‐Aremovableinsoleisrecommendedforallfootweartoallowtheapplicationofcustomorthoticsandcorrectivedevices.Thisfeatureallowstherewearertomodify,oradjusttheinteriorfitoftheshoeandcorrectforknown
pathologies.(2,3,4,10,16,20,22,29) Breathability‐Theabilityofairtopassthroughthefootweariscalled
breathability.Itcombinestwodesirabletraits,Airpermeabilityandwatervaporpermeability.Breathabilityisadesirablefeatureforhealthandcomfort.Closedfootwearcompoundstheheatgeneratedbyyourbodycausingtemperatureshigher
thanthatoutsidethefootwear.Oncecombinedwithperspiration(moisture),thesepropertiesformanidealenvironmentformicrobialgrowth.Shoesthatfeature
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS6
breathabilityarebothmorecomfortableandadvanceproperfoothealth.(2,3,4,10,16,20,22,29)
2.1 GravityDefyerShoes:ASummaryofTheirCompositionandIntendedApplication
BreakingdownthefunctionalityofGravityDefyersshoesstartsbyunderstandingthemaincomponent
thatseparatesthisshoefromthatofothermanufacturers,theTrampolinesystem.
2.2 TheTrampolinesystem
TheTrampolinesystemisashockabsorbingmechanismintegratedwithintheposterior
heelregionofthesole.Itconsistsoffivecomponents:1)amidsolewithmoldedside‐wallsandacavitylocatedbeneaththeheel2)aprimaryshockabsorbingspringorcoil,3)twostabilizingshockabsorbingspringsorcoilsand4)aheelplatewithrubber‐
polymertrampolinesurface.5)thefoot‐bedwhichsupportsthefootandresiststheactionofthetrampolineprovidingadynamicfloatingsupportsystem.
2.2.1 Midsole,MoldedSide‐Walls,TrampolineCavityandShankThemidsoleisconsideredthebodyoftheshoe.Themidsoleofeachshoeismadeof
EVA(Ethylene‐VinylAcetate).Thismaterialisanindustrystandardforthedispersionofforce.InGravityDefyershoes,themidsoleprovidesshockprotectionfromthemid‐footregionthroughthemetatarsalsandtoes.Themidsolehousestheshank.Theshank
extendstothemetatarsalsofthefootallowingforforefootbendandprotectsthefootbylimitingflexationofthearchwhileprovidingadditionalstabilityandcontrolfromtheheelandarchofthewearer.Theheelregionistooledtoformahollowspaceor
trampolinecavitydirectlybeneaththeheel.Theresultantsemi‐rigidsidewallactsasthefoundationforthetrampolinestructure.Thesesidewallsactasasecondarystageinabsorbingshockandwillflexunderextremeforces,furtherreducingGRFandallowsfor
thetransferofforceandmassthroughthesoleoftheshoe,whilenotimpactingthewearerwiththewaveofforceradiatingthroughtheirbody.
2.2.1 PrimaryShockAbsorbersandTwinShockAbsorbingStabilizers
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS7
Thespring(orcoil)systemistheprimarydefenseagainstGRFandprovidesmoreenergyreturnthanEVAorothermaterialsusedincontemporaryfootwear.Theysetina
triangularconfigurationandintegratedintotheposteriorheeloftheouterlayerofthetrampolinesole.Asafurtherbenefit,theactionoftheshockabsorberscompensatesforunequalorunevendistributionofweightandpressure.Ifawearerispronetohavefat
padshift(VarusorValgum)(10,22,25)thespringsworkindependentofeachothertoaccommodatethewearer’spressurepattern.Thespringsvaryinresistancebasedontheshoesize(andpresumedweightincreaseofthewearer).Asanexample,asize10
man’sshoeusesabluespring,withacapacityof220psi.Thisspringactsastheprimaryshockabsorber.Tworedsprings,eachwithacapacityof60psiactasstabilizers.Thecombinedliftofthethreespringswithouttakingintoaccounttherubberpolymer’s
elasticpropertiesisapproximately600lbsandprovidesoptimulsupportforapersonofaveragesizeduringmostcommonactivities(standing,walkingandrunning).
2.2.1 TheHeelPlateTheheelplateisan8mmsectionofsolematerialsuspendedonaplateofrubberpolymer.Whendepressed,theheelplateretreatsintotheheelcavityofthemolded
midsole.Duringthisactiontherubberpolymerisstretchedaddingitselasticpotentialenergytotheshockabsorbingforceoftheothershockabsorbingelements.
2.3 TheOutsole
TheoutsoleoftheshoesaretooledandcomposedofEVAorPUtoprovidethebestcontrolonvarioussurfaces.Thecompositionoftheoutsoledictateshowtheshoeinteractswiththe
environmentthroughfriction(grip)andslipresistance.ThesolesofGravityDefyershoesreflectindustrystandardsandpracticesforshoesineachclass,whethertheybeforsportshoesoracasual/dressshoe.Theoutsoleshavenotyetbeenratedforslipresistance,oilorchemical
resistance.
2.4 HeelCounter
TheheelcountersoftheGravityDefyershoesarereinforced.Theyareintheposteriorupperpartoftheshoe.Mostmanufacturersneglectthisimportantfeatureinfootwear.TheheelcountercoversthecalcaneusorheelwhilesupportingtheAchilles.
2.5 ToeBox
ToeboxinGDshoesaredesignedandmanufacturedforcomfort.Generousroomandspaceisgiventotheforefoot.Theshoesaremadeinmedium,wide,andextrawidetoallowforproper
fit.Whilethespacinginthetoeboxallowsforvariationinfootanatomy.FreemovementofthetoesisreinforcedwhilestillholdingthefootinplacewiththevampandQuarter.(10,29)
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS8
2.6 RemovableInsoles
RemovableInsolesarefeaturedinallGravityDefyershoes.Thisisimportantbecauseitallowsthewearertochangeouttheinsoleforamedicallyprescribedorthotic,toadjusttheshoefit,ortoextendthelifeoftheshoeiftheinsoleisworndown.TheremovableinsoleinallGravity
DefyershoesismanufacturedfromPU.Theyhaveabuiltupregioninthearchtoprovideadditionalsupportandcontrol.Anaddedfeatureoftheinsoleisthedomepocketcreatedintheheeloftheinsole,directlyunderthecalcaneus.Thisfeaturegivesadditionalcomfortby
improvingheelplacement,centeringandcuppingtheheel.(2,10,16,22,29)*Imageofourinsole
2.6 FitandAdjustability
Duetoalackofeducationandchoice,themajorityofpeopletodaywearill‐fittingshoes.Thisisanimportantfactorrelativetocomfortandmaycontributetothedevelopmentoffoot
pathologies.
2.6.1 FixedSizesGravityDefyershoesaremanufacturedinbothfullandhalfsizesfromsize5‐11female
men7.5‐15andareavailableinarangeofwidthsfrommediumtoxtra‐xtrawide.2.6.2 WidthAdjustability
Twocomponentsacttoprovideaproperfitandfeelforyourfootwear.
2.6.2.1Choiceofclosures.
GravityDefyerscomeinawiderangeofclosuretypesincludingslipon,elasticandlace‐up,butthemostimportanttoindividualsrequiringaproperfitformedicalreasonsisthelace‐upvariety.Lace‐upshoesprovideadjustabilityat
severalpointsalongthearchandarerecommendedforpersonswithdiabetesandothercirculatoryconditions.
2.6.2.2WideandAdjustableWidths.SelectGravityDefyershoeshavebeendesignedwithadditionalwidth.Throughtheadditionofanadjustmentlayer(dubbedthePerfectFitinsole)beneaththe
standardinsole,onemayadjustthefitandfeeloftheshoetobestsuittheirneeds.Thisisagreatfeatureandbenefittowearerswithnarroworslimgirthfeet.
2.7 VentilatedUpperConstruction
GravityDefyershoesmadeofleatherprovideindustrystandardventingthroughpiercingandgrommetswhereapplicable.Athleticshoesusemeshedfabriclayers.Thismeshiscomposedof
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS9
crossedgridlayerstoallowpenetrationofairinandoutoftheshoesthroughpredeterminedmeshairholes.Thisfeaturecombineswiththesignificantamountofroominthetoeboxallows
fortheairtomovefreelyinandoutoftheshoes.Theairthatpenetratesintothechamberfromthemidsoleoftheshoeisreleasedthroughtheventopening.
2.7 AVS3VentilationSystem
BothleatherandathleticshoesfeaturetheAVS3VentilationSystem,asystemthatharnessestheexpansionandcontractionofGravityDefyer’suniquetrampolineheeltoformavacuum
pump.Thesystemconsistsofaheelcylinder,channelsthathavebeenmoldedintothemidsole,openventsthatallowairtopassfromtheshoetothesechannels,andaone‐wayvalvelocatedintheheelcylinder.Freshairisdirectlyintroducedfromtheoutsideoftheshoes,always
maintainingthesameconsistencewiththeairtemperatureofthesurroundingarea.Oncompressionoftheheelcylinder,heatedairfromtheshoe’sinteriorisexpelledthroughtheone‐wayvalveinthesidewallofthemidsole.Astheheelcylinderexpands,theone‐wayvalve
closesforcingthevacuumsystemtodrawairfromtheinterioroftheshoe.Thevacuumcreatesnegativepressuresuckinghotairfromtheinterioroftheshoebedandcarriesittowardtheheelcylinder.Thiscyclerepeatswitheverystep.Calculationsindicatethatone8ththeavailable
volumeoftheshoe’sinteriorisexpelledwitheachcycle.(AVS3TechnicalData)
3. BiomechanicalAdvantageOverOtherFootwear
GravityDefyersworkbasedonatrampolineconcept.ThistrampolineislocatedintheposteriorsoleoftheshoesabsorbingtheinitialcontactofGFRwhileallowingtheheelofthewearertocontinuedrivethroughtheheelwithoutfeelingtheimpact.Asecondarybenefitofthisshockabsorbingactionisthe
two‐stagenatureofitscompression.Astheheelplatformretreatsintothemidsoleitcompensates,allowingforbalancedcontactoftheheel.Asthemid‐footandforefootmakecontactthefrontalplainoftheforefootisthenincontactwiththegroundatanequalandflatplane.Thisactionwiththeaddition
oftheinsole,allowsforthewearertomakepropertransferofweightthroughthemetatarsals1st‐5th,loadingthe1stMPT(MetatarsalphalangealJoint)(2,11,25,26),Sesamoids(2,11,25,26),andHallux(2,11,25,26)andreleasingoutofthedistalendofthephalangewhichiswidelyconsideredtheideal
methodofweighttransferandreleaseinthehumanfoot.Asweightistransferredforward,theheelofthewearerispropelledupandforwardbythesprings.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS10
Figure. 3.30. Phases of step (Gage, 1990, p.298)
3.1 WalkingandStandingWalkingandStandingplayamajorpartdaytodayactivitiesthatmostofthepopulationwill
performwitheaseandexperiencelittle‐to‐nodiscomfort.Duringtheseactionswerarelytakeintoconsiderationthedurationandquantityofimpactforceonthehumanbody.Duringthewalkingphaseofthegaitcycle,thehumanbodyisexposedto1.5to3timesthebodyweightof
thewalker(1,10,12,20)Thissignificantpressureincreaseonjoints,tissues,andalignmentofthebodywillcausechangesandalterationinfunctionality.Thiscanandoftendoesleadtotheexperienceofpain,discomfort,andmedicalpathologiesinaprolongedperiodoftime.(6,10,
12)Walkingisanessentialfactorinmaintainingorachievinggoodoverallhealth.Thebenefitsofwalkinghaveshowntobeasbasicasmovementfunctionbutmaygreatlyincreaselifespan.*GraphorTablefromoneofthenotedsites
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS11
GravityDefyershoespromotewalkingandallthebenefitattainedbyit.ThesebenefitsareenhancedbyindividualswearingGravityDefyershoesindifferentareas.Asillustratedinthe
imageabove,thenaturalgaitcycleofthehumanbodyisverycomplex.Therearepointsinthegaitcyclewherethehumanbodyhasloadedtheentiremassofthebodyontoanareaassmallajusttheforefootortoes.Aswetakeastepourweightshiftsandourlegsandarmscounter
balanceeachotherandourbodytomaintainanuprightpositionandallowustocontinuetotransferandmoveourbodiesforward.
Whenwearetransferringourweightwewillinitiallyloadtheheelorcalcaneuswithourentireweight,GravityDefyershoesreducetheimpactofthisweightfromthegroundonthecalcaneus.AstheweightcompressesthespringsthesoleabsorbtheimpactofGRFand
dissipatesit.TheremainingimpactforcethatdoestransferupthebodyisagainreducedbythecushioningprovidedbyGravityDefyershoes’Polyurethaneinsoles.Bymaintainingthealignmentofthebodythroughoutthegaitcycleanindividualwillexperiencegreatercomfort,
andeaseofmovement.Thereisthebenefitofthespringreturnorreboundeffect.Thisistheamountofliftorbounda
personwillexperienceduringheelliftorcalcaneuspropulsion.Aftereachheelstrikethespringsystemcompresses,asthesidewallsalsomoveintotheheelandtheGRFisreducedthespringsloadandreleasewiththecalcaneus.Thissendstheforceup,assistingthefootandbodyby
minimizingtheamountofmuscleactivityandenergyneededtopropelthefootandlegforward.Thisreductioninmuscleuseallowsforlongwalksandincreaseddistances.Thebenefitsofthese
resultshaveagreateffectonthephysicalbodyaswellasthementalandemotionalstateofaperson.Thevalueoftheconfidenceandimprovedresultsishardtoquantifyforthepersonandtheiroverallhappiness.
3.2 StandingWheninastaticposturethehumanbodyisdesignedtoworkasaloadedstructure.(1,3,6,7,23)
Theentiremassofthebodyisloadedonthefeet.Thepositionorpostureofthehumanmusculoskeletalhasadirectrelationtothegait.Withoutproperpostureoralignmentthedurationofstaticpositioningwillcausephysicalstressorsthroughoutthebody.Postureand
positioningofthebodyisvitalwhenconsideringconditionsandpathologiesthataffectthestructure.(4,5,6)Variousconditionsbecomeapparentwheninthestaticorstandingpositionandareoftenexperiencedbytheindividual.Somecommonconditionsoftenexperiencedbythe
majorityofthegeneralpublicarecompressionofthejoints,poolingoffluids,swellingandaching,andattimesnumbnessortingling.Theseareallresultsofprolongedpressureonthebody,specificallyfromthelowerlumbar(back)downtothefeet.
InitiallyGravityDefyershoesweredesignedtoaddresstheGRFexperiencedwhenwalkingonhardsurfaces.Theresultofthetrampolineconceptwhenappliedtostandinghasprovento
providegreatbenefitstoanywearerintheshoes.Theamountofenergyexpendedbythebodytostandgreatlystrainsallthemusclesthatholdthebodyinthestandingposition.(4,27,28)
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS12
Consideringthatfactthefatiguethatsetsinwilleventuallystarttodiminishtheabilitytoholdthepositioninplaceandtheamountoftimetheindividualwillbeabletostanditsimportantto
alloworprovideanpersonwithanareawheretheycanstandwithminimalamountsofcontactforce.Wecaneasilydeducethisbyapplyingbasicideasandprincipalsofalignment.(4)Ifapersonconsidersthatanindividualstandingonwhatiscommonlyknownasanti‐fatiguemat
reducesandprolongsthedurationoftimethatindividualcanremaininastandingposition.(13,14,21,23,24)Thesematsusepolymersthatcushionthecontactforce(Contactforceistheforceexertedbythegroundonaperson’sbodywhileinastaticorstandingwhichisequalto
theindividual’sweightbeingexertedontotheground)andallowthestandingbodytoincreasetheamountoftimestanding.Itisreasonabletoconsiderthatthebenefitsreceivedwillgreatlydecreasethediscomfortandreducepainwhereconditionsthatcausepainexist.
ApersonwearingGravityDefyershoeswillexperiencetheabilitytoloadfullyonthecalcaneuswithproperalignmentofthebody.Thisisaccomplishedbythewaythespringsysteminteracts
withthebody.Firsttheycompresswiththemassofthebodyloadingdirectlyabovethesprings.Thisgivesthepersonthebenefitofreducingtheloadimpactonthebody,joints,andthemusculoskeletalstructure.Becausetheimpactiscompressedinthespringsandnotthebody,
thebodywillnothavetoexpendenergy,muscleactivityorcompensateforpositionallowingthepersontoremainstandingforlongerperiodsoftime.Personshavingpreviousconditionsaffectingthebodyincluding,pathologies,andnon‐standardhumandevelopmentperhapshave
themosttogain.(4,7,11,19)GravityDefyershoesaddressalignmentbyfirstcompensatingforweightshiftorimbalance.Forexample,ifanindividualhasanoverlypronatedalignmentofthe
calcaneusorinversionofthecalcaneus,(19)thespringwillcompensatefortheimproperdistributionofweight.(4)Thiscorrectionwillallowforamorebalancedstanceallowingtheloadingoftheentirestructuretoholdaneutralpostureforalongerperiodoftime.Theheel
counteroftheshoesandPUinsoleassistbykeepingtheentirefootinplace.Itredistributestheweightfromsolelyontheheeltothearchandmid‐footarea.(16)Thisagainallowsforlessstrainonjoints,improvedcirculationandreducedmusclefatigue.
3.3 ImpactForceContactforceistheforceexertedbythegroundonaperson’sbodywhileinastaticorstanding
whichisequaltotheindividual’sweightbeingexertedontotheground.(14,15,18)ContactForceisparalleledtoGroundForceReaction.(1,9,21)GFRisitselfdefinedasthereturnofenergyorforcefromcontactwiththegroundsurfaceonthebodymorelikelyappliedwhen
walking.(7,)Theeffectsoftheseforceshaveadirecteffectonthesoft‐tissueandskeletalcomponentsofthehumanbody.Theimpactforcescauseoscillationsinthewobblingstructuresofthebody,leadingtoinstability,overcompensation,andvariationofthenaturalfrequenciesin
themusculoskeletalgaitcycle.Studiesshowthefirmnessorrigidityofthesolesofshoesdirectlyfactorintochangesinthetimeofpeakimpactforce.Changesoradaptationsinthemusclestoreducetheresonanceoftheimpactwavehaven’tconclusivelyruledoutsofttissuevibration
withinthemuscle.(9,12,14,15)
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS13
Illustrations•A.PeakImpactforcesduringtheGaitcycle.
•B.Theduration(shockwave)ofimpactforceduringGaitcycle.•C.GroundReactionforcerelativetoGaitcycle.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS14
4. GeneralizedPain,FatigueandOtherPathologies
4.1 Fatigue
Fatigueisalackofenergyorexhaustionofthebodyormentalstatecausedbystress.Fatiguecanbeconsideredanaccumulationofmultiplefactorshavingtodowithspecificsourceswhich
canleadtoaneventualbreakdownoftheindividualwhetherphysical,mentalorboth.Intheareaofprolongedstanding,shoescanbeanimportantandintricatepartofreducingorenablingthesestressors.(11,19,23)Ofteninthestandingpositionthealignmentofthebodyisthe
principalcauseofmusclefatigue.Themisalignmentofthestructureorbonesplaceaddedstresstothemusclestoholdthestructureinplace.Priortothemusclesystemexhaustingallenergytherewillbeindicatorssuchassoreness,aching,andsimpleadjustmentstopositioning.Thisis
toallowabreakinthestressonthemuscle.(11,19)GravityDefyershoesaddressfatiguebyactingasaloadmoderatorandallowsthemusculo‐
skeletalsystemtoremainrelaxedforalongerperiodthanotherfootwear.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS15
4.2 Pathologies
Thehumanbodyandfeetaresusceptibletocertainspecificmedicalconditionsfromprolongedwalkingorstanding.Notallpathologiesorconditionsarecausedbythisactionbuttheexistenceofthemwillgreatlyreduceorimpedeonesabilitytoperformbasicnecessaryactionswithgreat
discomfortifatall.
4.2.1HeelPain
HeelPainisorcanoftenbeattributedto3mainsources.
4.2.1.1OverUse
Overuseofthegeneralareaafflictingtheimmediateandsurroundingtissuesandnerves.Constantuseleadstoinflammationofthetissueswhileapplyingpressureonthenervesleadingtotheuncomfortablefeelingofpain.The
constantinflammationofthesetissuescanleadtodamage,sometimespermanent.
4.2.1.2PlantarFasiitis
PlantarFasciitisisthetighteningofinflamedthicktissuesonthe
plantarareaofthehumanfootandtissue.Thiscanbeaverydebilitatingconditionwhich
requirestimetoheal.Commoncorrectionsincludestretching,icing,orthotics,andpropershoes.
Oftenpeopleinextremecasewillbegivencortisonetonumbandreducethepainontheinflamed
tissuesandnerves.(9,10,24,25)
GravityDefyershoeshelpalleviatePFin3basicways.Firstisbyreducingthe
pressurebeingappliedtotheinflamedarea.Thisisaccomplishedbytheabsorptionofpressuretothespecificarea.ThetrampolinesystemwillcompressintothesoleoftheshoediminishingtheGRFonthewearer.The
secondbenefitisthatthewearerwillexperiencesomestretchingofthePlantarFisciatissue.Thestretchingwillgivesomereliefbecausethetissueisexpandingandcontracting.Theactionsofthesetypesofmovementpromotehealingof
theinflamedtissues.ThethirdbenefitfromwearingGravityDefyershoestoanindividualwithPlantarFasciitisisthesupportofthearch.ThisisabenefitbecauseattimesthecauseofthePFisthattheanteriorandposteriortibial
tendonsarenotsupportingthearchandallowingformovement.GravityDefyer
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS16
PUinsolessupportthisstructureandreducetheamountofmovementinthearchandpressureonthecalcaneus.Thissupportofthearchwillalsostretchthe
PlantarFasica,againpromotinghealingoftheinflamedtissue.
4.2.1.3HeelorBoneSpurs
He
el
He
elSpursorbonespursareconditionsthatcanbehelpedbyGravityDefyershoes.
Whenapersonwiththisconditiontakesastep,theheelistheinitialpointofcontact.(9,10,24,25)Unfortunatelyfortheindividualthisisareaofthefootbeingeffect.InGravityDefyershoesthisimpactisreducedanddistributed
through‐outtheshoesasthetrampolinesystemabsorbsthepressureandimpactwhilenottransferringittothecalcaneusorheel.Thisalsoallowsthe
individualtowalkwithoutanalteredgate.ThisconditionishelpedbythePUinsolesoftheshoe.ThesoftPUoffersadditionalcushioningnotfoundinothershoesaswellasanarchsupport.Thearchsupportintheinsolepartiallyfillsin
thearchandhelpssupportthestructure.Thesupportgiventothearchreducestheamountofpressurethatwillbeloadedontheheel.Theheelorcalcaneuswillnolongerbeloadedfully.Thisisadirectanddistinctbenefitandfeature
othershoescouldnotofferapersondealingwithspurs.
4.2.4LowerBackPain
Lowerbackpainisoneoftheareasofthebodywherevariousfactorscomeintoplay.Whenanindividualisexperiencingbackpaintheoriginofthepaincancomefromacombinationoffunctioningpartsorfromoneofthecomponentsoftheback.
Understandingthiscanhelpnarrowdownthechoicesofthecause.Thelowerbackiscomposedofthevertebra,disc,nerves,sacrumandsofttissues.Eachindividualareamaybethecauseofdiscomfortorareasmayworkinconjunction
withtheforementionedassociatedpart.
SpursHeelspursareboneygrowthsthatcanbeintheshapeofhooksorspursgrowingontheheelor
calcaneus.Itisaverypainfulconditionthatcanbeconfirmedbyx‐rayandfromsymptom
identificationtheindividualisormaybeexperiencing.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS17
CommonPathologiesofthebackareconsideredtobelumbarstrain,traumaorinjury,discherniation,nervecompressionorpitching,andorarthritis.Theconditionsarealladdressedwithconsiderationofeachindividualpart..(9,10,24,25)Mostcanandare
reducedinpainseveritybythesimpleactofreductionofpressureoftheentirearea.GravityDefyershoeshaveassistedinprovidingaidtosufferersofbackpain.Theability
toalignthebodyintoaneutralcorrectedandloadbearingpositionallowsthebacktoreducestrainonthearea.GravityDefyershoesdothisbyfirstloadingallpressureandweightonthetrampolinesystemwherethecalcaneusrest.Theadjustmentand
correctionofthespringsforweightdisplacementorunbalancehelpstabilizethebodyandallowforproperlowerbodyalignment.Oncethecalcaneusisinaneutralpositionthetalus,tibia,fibula,andfemurallalignabovethem.Byproperlyhavingthelower
limbsalignedthepelvisregionwillalsoloadandalignwiththelowerlimbs.Thiscorrectionofposturewillleadthesacrumandlumbervertebraes1‐5toaligndirectlyabove.Withthischangethepressureandstrainontissues,nervesandmusclesis
reduced. 4.2.3HipPain
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS18
Hippainistypicallyconsideredtobeanadvancedagecondition.(9,10,
24,25)Todaywearefindingthathippainisnotalwaysaresultofagingbutmayalsobecausedbywearand
tearonthehipjointandthesurroundingtissues.Themorecommonissuesaremusclestrain,
tendonitis,arthritispain,andsnappinghip.
Ingeneraltheseconditionsarecreatedbyconstantuseofthespecifictissue,muscleorareaduetomisalignmentoroveruse.(9,10,24,25)Inallaspectsoftheseconditionsthediscomfortfromthepaincanleadtomoreseriousissuesifnotaddressed.Gravity
Defyerprovidesthereductionsofthesymptomsbyallowingforbettermovementwithoutpain,improvedalignmentoftheareaandbody,andcondensingthepressureandstrainbeingappliedbyuseinthemisalignedposition.
Thisagainisachievedbytheuseofthetrampolinesystembalancingthefootintotheneutralposition.Oncethealignmentofthepositioniscorrected,thepressureandstrainarerelievedonthetissuesandallowstensiononthemusclestoberelieved.
ByabsorbingtheimpactofGRFonthebodyandjointsthehipisallowedtoloadandflexwithgreatereasyandminimalcompensation.Theaddedbenefitofimproved
muscleefficacyandreducedactivityfreestheareaofoveruse.4.2.3Sciatica
Sciaticaoccurswhenthereispressureordamagetothesciaticnerve.(9,10,24,25)This
nervestartsinthelowerspineandrunsdownthebackofeachleg.Itcontrolsthemusclesat
thebackofthekneeandlowerlegandprovidessensationtothebackofthethigh,partof
thelowerleg,andthesoleofthefoot.Sciaticapaincanvarywidely.
Itmayfeellikeamildtingling,dullache,oraburningsensation.Insomecases,thepain
issevereenoughtomakeapersonunabletomove.Thispainmostoftenoccursononeside.Somepeoplehavesharppaininonepartofthelegorhipandnumbnessinotherparts.Thepainornumbnessmayalsobefeltonthebackofthecalforonthesoleofthe
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS19
foot.Theaffectedlegmayfeelweak.Sciaticpainoftenstartsslowlyandmaygetworse,commonlyafterstandingorsitting,atnightatrest,whensneezing,coughing,or
laughing,andwhenbendingorwalkingmorethanafewsteps.GravityDefyershoestakethepressureoffthelowbackareawherethesciaticnerveisoftenaffected.Byadjustingthepostureofanindividualwiththeself‐adjustmentofthe
trampolinesinGravityDefyershoes,apersoncanreducethestrainonthesciaticregion,thelumbarregionoralterpelvicmissalignment.Theimprovementofbody,lumbar,andlimbpositioningaccompaniedbythereliefoftensionofthemuscles
surroundingthesciaticnerverelievesthecompressednerve.Asaresult,painreliefallowstheindividualtoresumeday‐todayactivitieswithminimaldiscomfortandgreatmobility.
4.2.3PainAssociatedwithAgingThehumanbodygrowsandages.Jointsformtheconnectionsbetweenbones.They
providesupportandhelpyoumove.Anydamagetothejointsfromdiseaseorinjurycaninterferewithyourmovementandcausealotofpain.Manydifferentconditionscanleadtopainfuljoints,includingosteoarthritis,rheumatoidarthritis,bursitis,gout,
strains,sprains,andotherinjuries.Jointpainisextremelycommon.Inonenationalsurvey,aboutone‐thirdofadultsreportedhavingjointpainwithinthepast30days.Kneepainwasthemostcommoncomplaint,followedbyshoulderandhippain,but
jointpaincanaffectanypartofyourbody,fromyouranklestoyourshoulders.Asyougetolder,painfuljointsbecomeincreasinglymorecommon.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS20
AstudyperformedbytheUniversityofMalaya,(18)showedthattheolderapersonis,thegreatertheimpactorcontactforceisonthebody.Overaperiodof12monthsit
wasfoundthatsubjectsolderthan40yearsofageexperiencedagreatnumberofareasofdiscomfortorpainascomparedtothesubjectsthatwereunder40yearsofageduringthesimpleactofstanding.Thepercentagesofactualpainseverityalsovaried,
theoldersubjectsexperiencedanywherefrom25to75%morepainthandidtheyoungersubjects. Thisisleadsustospeculatethatanaveragepersonwithminimaltonopersistingconditionswouldlikelyfeelpainanddiscomfortintheareasofmostuse
duringwalkingorstanding.Thecausesmayvary,butconstantandprolongedactivitygenerallyactsastheprimarycatalyst.
TheuseofGravityDefyershoesfortheolderagedemographiccanbeasourceforfreedomandacontinuanceofalifestylethatismoreactive.Withthepropulsionandreductionofimpactforcestheelderuserwouldfeellessdiscomfortandhavemoreenergytobeabletowalkandstand.WiththepopulationoftheUSandtheworldasawholelivinglongerGravityDefyershoesareavitaltooltofreedomandmovement.Thebenefitsanindividualcanreceivearelimitless,includinganadditionofmoreyearsofactivelifestyleswithoutpain.
IfGravityDefyersshoesassistinthealignmentofthepostureandpositionofthebodytoreducepressureandfatigue,onecanconcludethatapersonwouldbenefitby
wearingtheseshoesfornon‐specificjointpainaswell.WhenwearingGravityDefyershoes,thecorrectionofpositioningintheskeletalstructurewillreducethewearonjoints.Thisisaccomplishedbythebody’snaturaldesignedtousethejointsintheir
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS21
intendpositionandnotoutofmisalignment.Thetrampolinesystemanditscorrectivecapabilitiescreatethecorrectiveactionnecessarytopretendandaltertheoveruseof
thejoints.
5. ProductComparisons
Therehavebeenpreviousattemptsatcreatingandusingaspringorcoilsysteminashoethatwillprovideabenefittotheweareroftheshoes.ThemorecommonorknownbrandsareSpira,Z‐coil,andtheNovelSpringBoot.Asaspringshoe,theirengineeringdataandcustomertestimonialsprovide
supporttotheclaimsbothmechanicalandanecdotal.Themechanicalpropertiesoftheseindicatesthatthecategoryofbiomechanicalspringshoesoffersa
reductionofGRFatheelstrikeofupto19%withanenergyreturnofupto87%addingtoforwardmotion.
5.1 NovelSpringBoot
NovelSpringBootsweretestedandcomparedtoanaverageshoeonthemarket.Aftertestingonmaleandfemalesubjectsitwasfoundthattherewasareductionoftheimpactwhenrunningonthewearer.TherewasfoundtobeanadjustmenttotheimpactcostofthelowerextremitieswhenwearingtheNovelSpringBootproducts.(27).ThisNovelSpringBootallowedthebodytoreducetheGRF,concludingthatthereisadirectbenefitinwearingashoeconstructedtoabsorbordiminishtheforceofimpact.Theactualbenefittothebodywouldpotentiallyincludefewerinjuriestothecalcaneus(fractures,spurs)(21,23),tissuedamage(plantarfasciitis,Achillestendinitis)(21,23,24),andstructuralimpact(posture,alignment)(4,10,17).Withthisasabaseline,wecanseethattheconceptofthespringshoecanhaveadirectbenefittothewearer.
5.2 ZcoilZ‐coilshoesaretheshoesmostoftenassociatedwithaspringsystem.ThedesignofaZ‐coilisashoeinthePlantarFlexedpositionwitha3‐5inhighspringintheheeloftheshoe.Thisshoeisdesignedtoreducetheimpactofforceonthebodywhilealsoequalizingthepressureonthetotalfootarea.(28)Whentheseshoesweretesteditwasfoundthattheshoesdoreducetheamountofpressurefromprimaryimpact.Theeffectwasnotconclusiveforfastwalking.Thepercentagesdemonstratethattherewas20%lessloadingoftherunnersduringtheirgaitcycle.Thisalsoresultedinabenefittoexcessivepronationorsupination.(10,24,28,29)Studiesprovidepositiveresults.CSULBfoundthatmaximummeanpressurewaslowerby18%inastandardgaitvelocity.Themaximumforcewasreducedbyarangeof13‐19%inafastvelocitygaitcycle.Theactualbenefitthatcouldbeappliedtothehumanbodyfromthisreportisthat,GRFis
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS22
notcausingtheusualamountofdamageandimpactwavethroughoutthebodyasitdoeswhenwearingastandardbrandofshoes.
5.3 SpiraSpiradesignedashoethatplacedaluminumspringsintotheheelandtheforefootareasofthemidsole.ThiswasaccomplishedbytoolingintotheEVAbasemidsole.Oncetheareawasclearedout,aplasticbottomcoverwasplacedintothesole.Thisplasticwasmoldedtoholdthespringsinplacewithdeterminedspringmolds.Withthespringsinplace,anadditionaltopplasticwasplacedonthemidsole,whichisthencoveredwiththeinnersoleoftheshoe.Thedesignwastoabsorbtheimpactontheheelaswellasontheforefoot,whichwasnamedWaveSpringTechnology.SpirashoesandtheirWaveSpringtechnologystudieswereperformedbyMichiganStateUniversity,CollegeofEngineeringandLaboratory.ThepurposeofthestudywastoidentifyiftherewasanactualimpactreductionofGRFonthehumanfootwhenwalkingandorjumping.Inthereportitwasfoundthat20%ofthebodyweightimpactofanindividualwasreduced.Thespringsystemalsoreturned87‐96%oftheenergytothewearer.5.4 MBTMBTshoesorRockerbottomshoesareshoesdesignedwitharollingorroundedsole.Thissoleisdesignedtoextendfromtheheelorcalcaneusthroughtothedistalendofthephalangesortoes.ThedifferencewithMBTproducedshoesisthatintheheelofthesole,thereisacushionpadorcelonpadthatabsorbstheimpactforceandtransfersitthroughthesole.ThisallowstheweartoexperienceareductioninjointpainandGRFissues.InacasestudyitwasfoundthatMBTshoeshelpreducetheimpactforceandpainonwearswithkneejointarthritis.Therewasareductionof16.6%inthefirst3weeks(30,TheeffectivenessofMBTshoes…)andatotalof25.6%bytheendofthe12weekstudy(30).Therewasalsotheadditionalbenefitofstrengthincreaseinthelowerlegmuscles,improvedbalanceandperformance,anddurationofworkoutperiods.Theonlygroupthatdidnotseethesameresultswasthegroupthatwasobeseoroverweight.Forthisgroupthereductionwasminimal,resultinginthecontinuedeffectsofOsteoarthritisoftheknee.
Thoughthesethreeshoes(NovelSpringBoot,Z‐Coil,SpiraandMBT)differinconstructionandapplication,itisclearthattheresultswouldbequitesimilarandvalidatetheirpotentialmedicalapplication.Byreducingtheforcethatcausepain,activatinganddeactivatingmusclegroups,andmaintainingbodyalignmentthroughbalanceandposturepeoplecangreatlybenefitbywearingGravityDefyershoes.ShoessuchasGravityDefyerofferamechanicaladvantageoverstandardshoes.Theyarebiomechanicallyengineeredforthereductionofpressure,controlofthefoot,andmaintenanceofproperalignmentofthelowerbodybenefitscanbeeasilyachievedbythewearingoftheshoesalone.
GRAVITYDEFYERFOOTWEAR–EVALUATIONOFSTATEDBENEFITS23
6.Conclusion
Resultsfromindividualarethebestgageforunderstandingifaproductisworkingornot.GravityDefyershoespasstheeyetestoncomparisontotheaverageshoeanddirectcompetitorfeatureshoesonthe
markettoday.Theconceptofdesigningashoewithbiomechanicsofwalkingandtheeffectsofstaticpositioningonthebodygreatlychangewhatandhowshoesshouldbemade.GravityDefyersshoeshavejumpedaheadofthetypicalshoeplatformandarechangingthewayweseefunctionalshoes
today.Changingwhatapersonfeelsandhowtheirfoot,legandbodymoveduringthegaitcycleisanundertakingthatcanonlybeachievedbycreatingaproductthatactuallyworksandisbeneficial.
GravityDefyershoesaddressamajorityofconditionsthattheaveragepersonexperiencesandwillfacewhenstandingorwalking.Ifthisshoesandcompanycontinuetoprovidetheresultsthattheycurrentlyofferthewearer,theshoeindustrywillhavetochangehowshoesaredesignedanddeveloped.
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