human movement 17 (1) 2016

vol. 17, number 1 (March), 2016

University School of Physical Education in Wrocław University School of Physical Education in Kraków

University School of Physical Education in Wrocław (Akademia Wychowania Fizycznego we Wrocławiu) University School of Physical Education in Kraków (Akademia Wychowania Fizycznego im. Bronisława Czecha w Krakowie)

Human movement quarterlyvol. 17, number 1 (March), 2016, pp. 1– 60

editor-in-Chief alicja Rutkowska-Kucharska University School of Physical Education, Wrocław, Poland

associate editor edward mleczko University School of Physical Education, Kraków, Poland

editorial BoardPhysical activity, fitness and healthWiesław Osiński University School of Physical Education, Poznań, PolandApplied sport sciencesZbigniew Trzaskoma Józef Piłsudski University of Physical Education, Warszawa, PolandBiomechanics and motor controlTadeusz Bober University School of Physical Education, Wrocław, Poland Kornelia Kulig University of Southern California, Los Angeles, USAPhysiological aspects of sportsAndrzej Suchanowski Józef Rusiecki Olsztyn University College, Olsztyn, PolandPsychological diagnostics of sport and exerciseAndrzej Szmajke Opole University, Opole, Poland

advisory BoardWojtek J. Chodzko-Zajko University of Illinois, Urbana, Illinois, USAGudrun Doll-Tepper Free University, Berlin, GermanyJózef Drabik University School of Physical Education and Sport, Gdańsk, PolandKenneth Hardman University of Worcester, Worcester, United KingdomAndrew Hills Queensland University of Technology, Queensland, AustraliaZofia Ignasiak University School of Physical Education, Wrocław, Poland Slobodan Jaric University of Delaware, Newark, Delaware, USAHan C.G. Kemper Vrije University, Amsterdam, The NetherlandsWojciech Lipoński University School of Physical Education, Poznań, PolandGabriel Łasiński University School of Physical Education, Wrocław, Poland Robert M. Malina University of Texas, Austin, Texas, USAMelinda M. Manore Oregon State University, Corvallis, Oregon, USAPhilip E. Martin Iowa State University, Ames, Iowa, USAJoachim Mester German Sport University, Cologne, GermanyToshio Moritani Kyoto University, Kyoto, JapanAndrzej Pawłucki University School of Physical Education, Wrocław, PolandJohn S. Raglin Indiana University, Bloomington, Indiana, USARoland Renson Catholic University, Leuven, BelgiumTadeusz Rychlewski University School of Physical Education, Poznań, PolandJames F. Sallis San Diego State University, San Diego, California, USAJames S. Skinner Indiana University, Bloomington, Indiana, USAJerry R. Thomas University of North Texas, Denton, Texas, USAKarl Weber German Sport University, Cologne, GermanyPeter Weinberg Hamburg, GermanyMarek Woźniewski University School of Physical Education, Wrocław, PolandGuang Yue Cleveland Clinic Foundation, Cleveland, Ohio, USAWladimir M. Zatsiorsky Pennsylvania State University, State College, Pennsylvania, USAJerzy Żołądź University School of Physical Education, Kraków, Poland

Translation: Agnieszka PiaseckaDesign: Agnieszka Nyklasz

Copy editor: Beata Irzykowska Statistical editor: Małgorzata Kołodziej

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Circulation: 100

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cONTENTs

p h y s i c a l a c t i v i t y , f i t n e s s a n d h e a l t h

Ben D. Dickinson, Michael J. Duncan, Emma L.J. Eyre Exercise and academic achievement in children: effects of acute class-based circuit training .......................... 4

Jerzy Eksterowicz, Marek Napierała, Walery Żukow How the Kenyan runner’s body structure affects sports results .......................................................................... 8

a p p l i e d s p o r t s c i e n c e

Jennifer Wilson, John Kiely The multi-functional foot in athletic movement: extraordinary feats by our extraordinary feet ...................15

Janusz Jaworski, Michał Żak Identification of determinants of sports skill level in badminton players using the multiple regression model .....................................................................................................................21

Alicja Rutkowska-Kucharska, Karolina Wuchowicz Body stability and support scull kinematic in synchronized swimming .......................................................... 29

b i o m e c h a n i c s a n d m o t o r c o n t r o l

Rodrigo Rico Bini, Patria Hume A comparison of static and dynamic measures of lower limb joint angles in cycling: application to bicycle fitting ................................................................................................................................ 36

Matthew R. Rhea, Joseph G. Kenn, Mark D. Peterson, Drew Massey, Roberto simão, Pedro J. Marin, Mike Favero, Diogo cardozo, Darren Krein Joint-angle specific strength adaptations influence improvements in power in highly trained athletes .........43

Marcelo de Lima sant’Anna, Gustavo casimiro-Lopes, Gabriel Boaventura, sergio Tadeu Farinha Marques, Martha Meriwether sorenson, Roberto simão, Verônica salerno Pinto Anaerobic exercise affects the saliva antioxidant/oxidant balance in high-performance pentathlon athletes ................................................................................................................................................50

Publishing guidelines – Regulamin publikowania prac ......................................................................................... 56

2016, vol. 17 (1)

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ExErcIsE And AcAdEmIc AcHIEvEmEnT In cHIldrEn: EffEcTs of AcuTE clAss-BAsEd cIrcuIT TrAInIng

BEn d. dIcKInson 1 *, mIcHAEl J. duncAn 2, EmmA l.J. EyrE 21 University of central Lancashire, Preston, United Kingdom2 centre for Applied Biological and Exercise science, coventry University, coventry, United Kingdom

ABsTRAcTPurpose. For schools, the increasingly imposed requirement to achieve well in academic tests puts increasing emphasis on im-proving academic achievement. While treadmill exercise has been shown to have beneficial effects on cognitive function and cycling ergometers produce stronger effect sizes than treadmill running, it is impractical for schools to use these on a whole-class basis. There is a need to examine if more ecologically valid modes of exercise might have a similar impact on academic achievement. circuit training is one such modality shown to benefit cognitive function and recall ability and is easily operationalised within schools. Methods. In a repeated measures design, twenty-six children (17 boys, 8 girls) aged 10–11 years (mean age 10.3; SD ± 0.46 years) completed the Wide Range Achievement Test (WRAT 4) at rest and following 30 minutes of exercise. Results. stand-ardised scores for word reading were significantly higher post exercise (F(1,18) = 49.9, p = 0.0001) compared to rest. In contrast, standardised scores for sentence comprehension (F(1,18) = 0.078, p = 0.783), spelling (F(1,18) = 4.07, p = 0.06) mathematics (F(1,18) = 1.257, p = 0.277), and reading (F(1,18) = 2.09, p = 0.165) were not significantly different between rest and exercise conditions. Conclusions. The results of the current study suggest acute bouts of circuit based exercise enhances word reading but not other areas of academic ability in 10–11 year old children. These findings support prior research that indicates acute bouts of exercise can selectively improve cognition in children.

Key words: acute exercise, academic achievement, children

doi: 10.1515/humo-2016-0007

2016, vol. 17 (1), 4– 7

* corresponding author.

Introduction

Physical activity and physical education within schools is comprehensively researched and the health benefits of exercise for cardiovascular fitness and general health is widely acknowledged. Research has shown acute exer-cise to have beneficial effects on cognition and subse-quently academic achievement. It has been suggested that children gain cognitive benefits from physical activity [1, 2] with greatest improvements seen in complex mental processing [3]. standardised achievement in maths and reading [4] as well as increased performance in core aca-demic classes has been reported for children who partici-pate in vigorous physical activity outside of school [5].

For schools the increasingly imposed requirement to achieve well in academic tests puts more emphasis on methods of improving academic achievement. These increased demands place an importance on academic testing and as a result, many schools have responded with a decrease in time dedicated to non-academic subjects [4]. From this perspective, participation in moderate activity of boys and girls aged 2 to 14 has since fallen between 2008 and 2014 [6]. Minutes spent taking part in PE has also fallen [7].

Within schools, children generally engage with whole-class physical education and so it is important to review the exercise modality used in studies of this nature. Treadmill exercise has been shown to have beneficial

effects on cognitive function [8], while cycling ergom-eter use produced stronger effect sizes than treadmill running [9]. This study argued that cycling uses less metabolic energy compared with running and that run-ning resulted in greater ‘neural interference’ and more cognitive demands for movement. Duncan and John-son [10] also used cycle ergometer training at differing intensities and found that spelling and reading were improved, arithmetic impaired and sentence compre-hension unaffected. While the potential for acute ex-ercise to enhance academic achievement is attractive for educational practitioners/teachers, it is impractical for schools to use cycle ergometers or treadmills on a whole class basis. Thus, there is a need to examine whether different, more ecologically valid modes of exer-cise might have a similar impact on academic achieve-ment. Immediate recall scores were higher following submaximal intensity lessons involving both team games and aerobic training. This can be attributed to exercise-induced increases in physiological arousal and the cog-nitive activation induced by the exercise demands. cir-cuit training is one such modality which has shown benefit cognitive function and recall ability [11] and is easily operationalised in the school setting. No studies appear to have examined whether the changes seen in the aforementioned laboratory studies [8–10] can trans-late to the school setting in a practical way.

The current study sought to address this gap by exam-ining the effects of class-based exercise on preadolescent academic performance.

B.D. Dickinson, M.J. Duncan, E.L.J. Eyre, Exercise and academic achievement in children

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Material and methods

Participants

Twenty-six children (17 boys, 8 girls) aged 10–11 years (mean age 10.3; SD ± 0.46 years) from the town of War-rington, UK, participated in the study following institu-tional ethics approval and informed parent and child and school consent. A pre-exercise Physical Activity Readi-ness Questionnaire was also used to confirm that the children did not have any pre-existing condition that would be exacerbated by physical exercise. None of the children included in the study had a recognised special educational need (e.g. dyslexia) or behavioural problem and nor were they classified as ‘gifted and talented’ according to school records. children were all drawn from one school representing an area in the mid-range of socio-economic status within the town. children were not given any inducement to participate and were re-cruited voluntarily following a presentation given by the researchers to children and parents attending the school concerned.

Procedures

This study employed repeated measures design where-by participants completed an academic test, comprising measures of reading, spelling, arithmetic and sentence comprehension, as a control result. This was followed 1 week later by a 30-minute circuit style class exercise session followed by a re-sit of the academic test. Both sessions occurred on the same weekday and time of day one week apart.

Firstly, to establish baseline academic performance, the Wide Ranging Achievement Task [12] was adminis-tered. WRAT 4 is the updated version of the academic achievement test employed by Hillman et al. [8] and in addition to measures of word reading, spelling and arith-metic, now includes an assessment of sentence com-prehension. Word reading is a measure of the number of words correctly pronounced aloud and spelling is a measure of the number of words correctly spelt. The reading test comprised 55 words ranging from three-letter words such as ‘see’ and ‘red’, to more complex words such as ‘ubiquitous’ and ‘regicidal’ with children asked to read these aloud to the tester. In the spelling test, children read a series of 42 words in isolation and then in context (e.g. ‘go. The children want to go home’) and asked to spell these words in written form. The words range from two-letter (e.g. ‘go’) to nine-letter (e.g. ‘assidu-ous’) words. The arithmetic score is a measure of the number of mathematical problems correctly solved. In the assessment of sentence comprehension children were asked to provide the missing word in a given sentence e.g. ‘Dee is having a birthday party for her brother. He will be seven ___ old’ to measure the ability to compre-hend information contained in a sentence. This paper and

pencil assessment was administrated in silence in the children’s normal classroom and lasted approximately 20 minutes. The WRAT was also administered in the order prescribed by the test guidelines, i.e. (1) word and letter reading, (2) sentence comprehension, (3) spelling and (4) math computation.

A within-subjects repeated measures design was em-ployed whereby, one week after the initial WRAT4 test, the children participated in 30 minutes of class-based circuit training. Participants’ heights (cm) and body masses (kg) were assessed using a seca stadiometre and weighing scales (seca Instruments, Frankfurt, Germany). Heart rate monitors were used to measure the intensity of the session for 6 students selected at random and are accepted as a valid measure of assessment of intensity and have demonstrated reliability in test-retest studies [13]. The Polar Rs400 (Polar Electro, Kuopio, Finland) were used in the instance. Resting heart rate was re-corded for all participants after a 5-minute rest period in a supine position.

A 30-minute circuit-based exercise session was con-ducted with a full school class and consisted of exercise stations of requiring 30 seconds exercising followed by 30 seconds rest. The children were instructed to complete as many repetitions of the selected body-weight based exercises as they could during the 30 seconds. The ex-ercises selected were body weight focused, compound, whole body exercises, chosen as the children were fa-miliar with the exercises from previous PE lessons and designed to use large muscle groups. The circuit stations were star Jumps, squat Thrusts, Burpees, speed Bounces, Modified press ups, Tuck jumps, 5 m shuttle runs, ‘Moun-tain climbers’, press ups, sit ups, body weight squats, Bean Bag raises and stork balance. In order to establish exercise intensity post testing, heart rate was recorded every 5 minutes immediately after an exercise interval on a station.

On completion of the exercise session, the children repeated the full WRAT test procedure. The blue and green WRAT4 forms, considered to be equivalent versions, were administered as part of the experimental design to eliminate the potential for practice effects [12].

statistical analysis

For the purpose of analysis, standardised scores on WRAT 4 were employed. Data was screened for nor-mality (shapiro–Wilk, p > 0.05) and met the assumption. A repeated measures MANOVA was then employed to examine any differences in components of the WRAT, post control and post exercise conditions, wherein the independent variable was time (control vs. exercise) and the dependent variables were standardised WRAT scores for mathematics, reading, spelling, and sen-tence comprehension. Gender was used as a between subjects factor. Partial eta squared (P 2) was also used as a measure of effect size. The statistical Package for so-


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cial sciences (sPss, Version 20, chicago, Il, UsA) was used for all analyses.

Results

There was a significant multivariate effect for the intervention condition, F(4,15) = 5.54, p = 0.006, Wilks’ Lambda = 0.403, p

2 = 0.597. Gender was not significant (p > 0.05) in any of the analyses and is therefore not dis-cussed further. Analysis of each individual dependent variable, with Bonferroni correction, indicated that stan-dardised scores for word reading were significantly higher post exercise (F(1,18) = 49.9, p = 0.0001, p

2 = 0.735) com-pared to control. In contrast, standardised scores for sen-tence comprehension (F(1,18) = 0.078, p = 0.783, p

2 = 0.004), spelling (F(1,18) = 4.07, p = 0.06, p

2 = 0.185), mathematics (F(1,18) = 1.257, p = 0.277, p

2 = 0.065), and reading (F(1,18) = 2.09, p = 0.165, p

2 = 0.104) were not significantly different in control and exercise condi-tions. Mean ± SD of standardised WRAT scores in con-trol and exercise conditions are shown in Figure 1.

Discussion

The present study investigated the effect of an acute bout of exercise (30 minutes of circuit based exercise) com-pared to rest on academic performance (WRAT 4). The findings of the present study, that only word reading scores were significantly different between rest and exer-cise, matches similar studies using the WRAT test ex-ercise that found improved reading comprehension but not spelling or arithmetic [8] or improved spelling and reading scores [10]. These positive benefits could be attributed to the cognitive benefits resulting from physical activity [1, 2] particularly immediate and delayed recall [11]. The results also support those of [8, 10] in that acute bouts of class based exercise have an adverse effect on arithmetic.

The findings of the current study could also be inter-preted in another way. The Word reading test is the first

in the WRAT schedule and will occur within 20 minutes of the cessation of the exercise bout. The significance of results in only this test may be attributed to acute exer-cise-induced increases in memory storage and physiologi-cal arousal leading to temporary cognitive activation that are possibly time limited. This would be supported by higher immediate recall scores following submaximal intensity lessons involving both team games and aerobic training. If this were the case, however, increased scores should be realistically expected for all the tests. It is cer-tainly important to acknowledge that the order of test-ing required in the WRAT battery may indirectly affect the findings of studies with prolonged testing batteries post exercise and would be an area for further clarifica-tion in studies of this nature. Future alterations to the order of administration of the WRAT are limited by the test procedure itself. The order of administration of the tests in the present study followed guidance on use of the WRAT [12] and the way prior studies using this test have employed it [8, 10]. Firstly, Word Reading was administered, then sentence comprehension, spelling and lastly Math computation. There is the option for the four subtests to be given separately or in combination of two or more at one sitting; however, they emphasize the Word Reading subtest should be given before the sentence completion subtest. Thus, in the context of the current procedure, it may be that the temporal effects of the bout of exercise employed only lasted for around 20–25 minutes, to coincide with the post exercise period and the first part of the WRAT. This point is however speculative and further research would be needed to better understand any temporal effects of exercise on cognitive performance in children.

Exercise intensity was determined from the measure-ment taken from the heart rate monitors. Mean HR was 142 bpm which, when age adjusted, equates to 68% MHR, indicating moderate intensity (categorised as 65–74% of MHR). This intensity has been found to elicit improvements in reading [10], reading comprehension [8] and general improvement in cognitive processing speed [14]. However, in future work more stringent con-trol of exercise intensity may be a factor for considera-tion. Despite this, the method of exercise employed in the present study is arguably more ecologically valid and practical for class based interventions as compared to either Duncan and Johnson [10] who used a cycle er-gometer, or Hillman et al. [8] who employed treadmill based exercise.

Physiologically, the acute bout of exercise could have induced increased cerebral blood flow to the brain, with vigorous leg, arm and hand movements evoking marked focal increases in cortical blood flow of the contralateral hemisphere [15], stimulating areas of memory function and brain-derived neurotrophic factor [16]. These changes in cortical blood flow are similar to those in-duced by memory tasks and visual stimulation [15] and this may be the mechanism whereby cognitive perfor-

Figure 1. Mean ± SD of standardised WRAT scores in control and exercise conditions (*p = 0.001)


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mance is increased. Endurance exercise, such as circuit style exercise and running, has been proposed to pro-duce a deregulation of the highest level of consciousness associated with the prefrontal cortex and an adverse effect on executive control during exercise [17]. This hy-pothesis also proposes that all motor cortex activation will cease, and functioning restored, immediately as soon as the altered state, such as that produced by ex-ercise, has ended. standardised scores achieved could, therefore, possibly be affected not only by timing, and order of the WRAT protocol, but also by efficiency of physical recovery of the individual children. If this is the case, and with reference to the ‘neural interfer-ence’ and more cognitive demands for movement re-ported by Lambourne and Tomporowski [9] it would be advantageous in future research to ascertain the fitness of the children prior to the session. The reporting of posi-tive relations between fitness and standardised achieve-ment test performance [4] and increased performance in core academic classes in children who were able to engage in more vigorous physical activity [5] may imply that fitter children can cope with more neural interfer-ence before it affects cognitive function after exercise.

In summary, the present study provides no strong evi-dence that exercise intensity moderates the improve-ment in pre-adolescent post-exercise academic ability. Exercise was found to improve word reading independ-ent of intensity. Exercise did not improve sentence com-prehension, arithmetic, spelling or reading, with the relationship with exercise intensity requiring further investigation.

References1. sibley B.A., Etnier J.L., The relationship between physical

activity and cognition in children: a meta-analysis. Pediatr Exerc Sci, 2003, 15 (3), 243–256. Available from: https://www.researchgate.net/publication/235913924_sibley_BA_Etnier_JL_The_relationship_between_physical_activity_and_cognition_in_children_a_meta-analysis_Pediatr_Exerc_sci_15_243-256.

2. Tomporowski P., cognitive and behavioural responses to acute exercise in youth: a review. Pediatr Exerc Sci, 2003, 15 (4), 348–359. Available from: http://journals.humank-inetics.com/Acucustom/sitename/Documents/Docu-mentItem/2575.pdf.

3. Donnelly J.E., Lambourne K., classroom-based physical activity, cognition and academic achievement. Prev Med, 2011, 52 (suppl. 1), 36–42, doi: 10.1016/j.ypmed.2011.01.021.

4. castelli D.M., Hillman c.H., Buck s.M., Erwin H.E., Phys-ical fitness and academic achievement in third- and fifth-grade students. J Sport Exerc Psychol, 2007, 29 (2), 239–252. Available from: http://www.humankinetics.com/acucus-tom/sitename/Documents/DocumentItem/7336.pdf.

5. coe D.P., Pivarnik J.M., Womack c.J., Reeves M.J., Mali na R.M., Effect of physical education and activity levels on academic achievement in children. Med Sci Sports Exerc, 2006, 38 (8), 1515–1519, doi: 10.1249/01.mss.0000227537.13175.1b.

6. Health and social care Information centre, statistics on Obesity, Physical Activity and Diet, 2016. Available

from: http://www.hscic.gov.uk/searchcatalogue?productid=20797&q=title%3a%22statistics+on+Obesity%2c+Physical+Activity+and+Diet%2c+England%22&sort=Relevance&size=10&page=1#top.

7. Youth sport Trust, YsT National PE, school sport and Physical Activity survey Report, 2015. Available from: https://www.youthsporttrust.org/sites/yst/files/resources/pdf/national_pe__school_sport_and_physical_activity_survey_report.pdf.

8. Hillman c.H., Pontifex M.B., Raine L.B., castelli D.M., Hall E.E., Kramer A.F., The effect of acute treadmill walk-ing on cognitive control and academic achievement in pre-adolescent children. Neuroscience, 2009, 159 (3), 1044–1054, doi: 10.1016/j.neuroscience.2009.01.057.

9. Lambourne K., Tomporowski P., The effect of exercise-induced arousal on cognitive task performance: a meta-regression analysis. Brain Res, 2010, 1341, 12–24, doi: 10.1016/j.brainres.2010.03.091.

10. Duncan M., Johnson A., The effect of differing intensi-ties of acute cycling on preadolescent academic achieve-ment. Eur J Sport Sci, 2014, 14 (3), 279–286, doi: 10.1080/17461391.2013.802372.

11. Pesce c., crova c., cereatti L., casella R., Bellucci M., Phys-ical activity and mental performance in preadolescents: effects of acute exercise on free-recall memory. Mental Health Physical Activity, 2009, 2, 16–22, doi: 10.1016/j.mhpa.2009.02.001.

12. Wilkinson G.s., Robertson G.J., Wide range achievement test – fourth edition. Psychological Assessment Resources, Lutz, FL, 2008, Rehabil Couns Bull, 52 (1), 57–60, doi: 10.1177/0034355208320076.

13. Kohl H.W., Fulton J.E., caspersen c.J., Assessment of physical activity among children and adolescents: a re-view and synthesis. Prev Med, 2000, 31 (2), 54–76, doi: 10.1006/pmed.1999.0542.

14. McMorris T., Hale B.J., Differential effects of differing intensities of acute exercise on speed and accuracy of cognition: a meta-analytical investigation. Brain Cogn, 2012, 80 (3), 338–351, doi: 10.1016/j.bandc.2012.09.001.

15. Delp M.D., Armstrong R.B., Godfrey D.A., Laughlin M.H., Ross c.D., Wilkerson M.K., Exercise increases blood flow to locomotor, vestibular, cardiorespiratory and visual regions of the brain in miniature swine. J Physiol, 2001, 533 (3), 849–859, doi: 10.1111/j.1469-7793.2001.t01-1-00849.x.

16. Ratey J.J., Hagerman E., spark. The revolutionary new sci-ence of exercise and the brain. Little Brown and com-pany, New York 2008.

17. Dietrich, A. Functional neuroanatomy of altered states of consciousness: The transient hypofrontality hypothesis. Consciousness and Cognition, 2003, 12 (2), 231–256, doi: 10.1016/ s1053-8100(02)00046-6

Paper received by the Editor: November 4, 2015Paper accepted for publication: March 25, 2016

Correspondence addressBen D. DickinsonUniversity of central LancashirePreston, United Kingdome-mail: [email protected]

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How THE KEnyAn runnEr’s Body sTrucTurE AffEcTs sporTs rEsulTs

doi: 10.1515/humo-2016-0002

2016, vol. 17 (1), 8 – 14

JErzy EKsTErowIcz *, mArEK nApIErAłA, wAlEry ŻuKowFaculty of Physical Education, Health and Tourism, Kazimierz Wielki University, Bydgoszcz, Poland

ABsTRAcTPurpose. The aim of this study was to determine the dependency between somatic parameters of selected Kenyan marathon runners and results achieved in long-distance runs (marathon, half-marathon, 10,000 meters). Methods. The research study was conducted on a sample of 9 top-level long-distance Kenyan runners whose results in Poland correspond to International Masterclass. All runners’ (mean ± SD) age: 23.67 ± 4.41 years, weight: 55.98 ± 4.84 kg, height: 169.18 cm ± 4.15cm. All participants had their anthropometric measurements taken: length, width, size and sum of three skin-folds. Having taken those anthropo-metric measurements, Body Mass Index (BMI), Arm Muscle circumference (AMc), Waist to Hip Ratio (WHR), body mass and body fat (FM) (%), fat free mass (FFM) were calculated using the Durnin-Womersley method. Results and conclusions. significant relations (significant correlation, important dependency) were observed in dependency between 10,000 meters results and the foot breadth (r = 0.765) and torso length (r = 0.755). similar relationships occurred between marathon results and the arm length (r = 0.73), forearm length (r = 0.75) and hip width (r = 0.77).

Key words: somatic characteristics, body composition indices, Kenyan runners


Introduction

Many sport disciplines show correlation between se-lection of candidates for a particular sport discipline and somatic features. For instance, the taller the basket-ball player is, the more rebounds he makes during the game. It comes as no surprise that a basketball player’s height influences the efficiency in basketball. Predispo-sition for physical competition was a subject of many reports [1–3]. It became clear that not only physical traits (height, width and circumference measurements) play an important role in sport but also body composition: adipose tissue and its location throughout the body, fat free mass or water content in the body etc. [4–5]. Thanks to constant selections of candidates for sport disciplines, it is possible to identify athletes of such a body structure that enables them to score top results and at the same time eliminate athletes with poor results. The athletes’ strong will to beat their personal bests make sport activ-ists and coaches alter their selection criteria and choose the ones that promise masterful results. Particularly in-teresting with regard to what has been said is the phe-nomenon of extreme endurance abilities of Kenyan run-ners who have been ranked among top athletes in middle- and long-distance runs for the last 25 years. Their dominance is reflected in a series of world records set in the majority of endurance events. The laboratory tests revealed that black runners consume more oxygen (at maximum ontogenetic absorption ability) than white

runners at the same running speed [6–8]. It may lead to an increased utilization of fats while saving glycogen during physical activity as fats need oxygen to be oxi-dized. The consequence of extremely intensive training and selection of athletes, as not all Kenyans are predes-tinate for endurance events, is a specific body type that tends to be extremely thin, low in body mass, low in adi-pose tissue and with not very developed muscle tissue. Is it correct to state that this subpopulation is close to a somatic ideal in selected sport disciplines? Giving an answer to the above question may enrich the knowledge on building an endurance ability with the use of par-ticular body parts.

The aim of this study was to determine the depend-ency between some somatic parameters of selected Ken-yan runners and their results in long-distance runs (marathon, half-marathon, 10,000 meters).


The research sample consisted of nine professional, long-distance Kenyan runners (all black) who for several years took part in a series of running competitions in Poland (street runs, marathons, half-marathons). They ran once a week, every weekend for 5–6 weeks and then they went back to their country. All tested competitors hold leading times for top running events, which in Po-land are equivalent to Masterclass. All runners come from the same geographic region, that is the Great Rift Valley in Kenya and train in st Patrick International sport club in Iten town. Profile of the runners – (values are given in mean ± SD) age: 23.67 ± years, height: 169.18 ± 4.15 cm, weight: 55.98 ± 4.84 kg. Measure-

J. Eksterowicz, M. Napierała, W. Żukow, How the Kenyan runner’s body structure affects sports results

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ments and calculations were done in July 2013 during the athletes’ presence in Poland, in the civilian-mili-tary sports club “Zawisza” in Bydgoszcz. The following anthropometric measurements were taken: length meas-urements (cm): body height (V–B), arm length (a–r), fore-arm length (r–sty), upper limb length (a–da III), lower limb length (tro–B), foot length (ap–pte); width meas-urements: shoulder breadth (a–a), hip width (ic–ic), pelvic width (is–is), hand width (mm–mu), palm width (mr–mu), foot breadth (mtt–mtf); and the circumfer-ences of: fully expanded/deflated chest, waistline, hip-line, fully flexed and extended arm muscle, thigh and calf. Measurements of the thickness of three skinfolds were taken in the following body parts: triceps skinfold (TsF), vertical fold, subscapular skinfold (scsF), hori-zontal fold, suprailiac skinfold (sIsF), diagonal fold. On the basis of those measurements Body Mass Index (BMI) kg/m2, Arm Muscle circumference (AMc), Waist to Hip Ratio (WHR), Fat Mass (FM) (kg), Fat Mass (FM)(%), Fat Free Mass (FFM) (kg), Fat Free Mass (FFM) (%) were calculated using the Durnin and Womersley formula [9].

Body Mass was measured on a commercial scale (TANITA BF 662M Japan). The length and width meas-urements were taken using an anthropometric appa-ratus. The circumference measurements were taken with the use of an anthropometric tape, the thickness of skinfolds was measured with skinfold calipers. All the measuring instruments were part of an anthropometric apparatus set made by siber Hegner & co., Ltd (switzer-land). All measurements were taken by the same inves-tigator, applying standard anthropometric methods ac-cording to the procedure of the International Biological Programme [10]. The study was performed according to the Declaration of Helsinki. Written informed con-sents were obtained from all participants.

In order to find some association between the results of long-distance events and results of anthropological measurements spearman’s correlation coefficient was calculated. correlation dependency between two charac-teristics X and Y is distinguished by the fact that merit of one feature is equivalent to median merit of the other feature. The interpretation proposed by the correlation coefficient Guilford is an assessment of the strength (power) of the correlation, to verify the statistical sig-nificance of the student t-test can be used for correla-tion coefficient. As a result of this test for the sample n = 9 correlation coefficients with a value greater than 0.58 are statistically significant at = 0.05 significance level (below 0.20 – weak correlation, slight dependency; 0.20–0.40 – low correlation, evident dependency but slightly important; 0.40–0.70 – moderate correlation, important dependency; 0.70–0.90 – high correlation, significant dependency; 0.90–1.00 – very high corre-lation, strong dependency).

subjects of the study were examined taking into consideration two variables: characteristic X (somatic parameters) and characteristic Y (run results). statistical

information crucial for estimating correlation between features X and Y was prepared on the basis of correla-tion table.

Results

Table 1 reports the results of anthropological mea-surements and the results of long-distance events. In Table 2 the results of measurements of tested circumfer-ences and some anthropological features of Kenyan run-ners are presented. Table 3 shows correlation coefficients between results of the following events: 10,000 meters, half marathon, marathon and selected anthropometric measurements. Important relationships were observed between the following results: important correlation (statistically significant dependency at the level of mate-riality 0.05) – between results obtained in 10,000 me-ters run and foot breadth ( = 0.76), and torso length ( = 0.75). similarly, an important correlation (significant dependency) was observed between marathon results and the following parameters: arm length (r = 0.73), forearm length (r = 0.75), hip width ( = 0.77). A mod-erate correlation (statistically significant dependency at the level of materiality 0.05) was found between 10,000 meters results and the following parameters: body mass (r = 0.49), BMI (r = 0.43), arm length (r = 0.54), shoulder breadth (r = 0.53), thigh circumference (nega-tive correlation, r = –0.46). The same moderate correla-tion (important statistically significant dependency at the level of materiality 0.05) was shown in relation-ship between half marathon results and the following parameters: arm length (r = 0.50), upper limb length (r =0.45), foot length (r = 0.51), hips breadth (r = 0.43), foot breadth (r = 0.54), torso length (r = 0.40), calf circum-ference (negative correlation, r = –0.43). Moderate corre-lation (statistically significant dependency at the level of materiality 0.05) was found between marathon results and the following parameters: BMI (r = 0.40), upper limb length (r = 0.58), torso length (r = 0.46), WHR in-dex (r = 0.41). No relationship was observed between re-sults of the examined runs and other somatic parameters.

Discussion

Black Kenyan and Ethiopian runners have dominated endurance events in recent years. Those athletes mostly come from a high-altitude region of the Great Rift Valley (2300 m above sea level). That region is a homeland of champions who are ranked as the best middle- and long-distance runners in the world. Kenyan runners’ supe-riority in long-distance runs is often linked to the ad-vantage of living in thinner air (hypoxia), which is the likeliest reason of their increased endurance ability.

Presently, Kenyan runners from this region hold most of the world records in the following events: men’s 800 meters, 3,000 meters steeplechase, 5,000 meters, 10,000 meters and marathon; women’s 5,000 meters.


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Table 1. Number profile of selected anthropological measurements of Kenyan marathon runners and their results achieved in selected events

Tested feature SD Min Max

10,000 meters (s) 1730.43 33.24 1791.0 1698.47Half-marathon (s) 3753.61 67.84 3840.16 3600.15Marathon (s) 8080.30 158.59 7800.57 8280.25Body height (cm) (B–V) 169.18 4.15 161.0 177.0Body mass (kg) 55.98 4.84 48.0 63.1Fat mass FM (%) 5.41 1.75 4.56 9.28Fat free mass FFM (%) 94.59 1.75 90.72 96.83

sum of skinfolds (mm): 13.97 1.96 11.7 18.5– subscap 5.46 1.70 3.5 9.6– triceps 4.09 0.81 3.0 5.0– suprial 4.42 1.10 3.0 5.0

Length measurements (cm):– arm (a–r) 33.04 1.93 30.50 35.80– forearm (r–sty) 26.38 2.99 23.40 27.20– upper limb (a–da III) 80.51 3.80 76.40 87.10– lower limb (tro–B) 90.02 2.77 85.60 97.70– foot (ap–pte) 25.72 0.88 24.00 26.60– torso (tro–a) 50.96 3.20 46.00 54.30

Width measurements (cm):– shoulder (a–a) 38.66 2.72 33.40 41.50– hip (ic–ic) 28.73 1.47 26.20 31.00– pelvis (is–is) 23.02 1.21 20.80 24.60– hand (mm–mu) 10.04 0.56 9.50 10.50– palm (mr–mu) 8.00 0.56 7.00 9.00– foot (mtt–mtf) 9.77 0.68 9.00 11.20

Numerous scientists, e.g. Temfemo et al. [11], seeking for a reason of such an exceptional endurance ability indicate the difference in quadriceps of white runners and black Kenyan ones. Kenyans have a lot more capil-lary around microfibers and much more mitochondria. smaller fibers of African athletes enable mitochondria to approach capillary vessels that encompass fibers, which allow easier oxygen diffusion from capillaries to mito-chondria and efficient oxidation.

Weston et al. [12] reported that black athletes tend to have increased muscle enzyme levels that burn fat and store glycogen when compared to their white counter-parts. This enables them to improve their endurance es-pecially when finishing middle- and long-distance runs. It is worth mentioning that a great density of capillaries and increased number of mitochondria in the muscular system were observed in the inhabitants of other high-altitude regions such as Peru, Mexico and Tibet.

some researchers pay closer attention to Kenyans’ diet [13–14]. The diet is very simple: small portions of fried meat, boiled and raw vegetables, fruit, eggs, milk and their favorite ugali groats. Additionally, they use veg-etable sauces, bean, corn, fruit or parts of plant sprouts and sometimes meat. such a diet contains a lot of car-bohydrates, mineral components, vitamins and fibre

but lacks fats, especially animal ones. It is worth men-tioning that traditionally Kenyans eat 2 meals a day.

Most researchers accentuate existence of dependency between consumption of drinks rich in simple sugars and building running endurance and physical capacity in comparison with sportsmen who consume pure water.

Burke [15] notices that Kenyans and Ethiopians quite often undertake commonly known eating habits that aim at mobilization of muscle glycogen. It is mostly about periodic reduction of carbohydrates, especially simple ones (glucose, fructose) in the marathon runner’s diet followed by a radical increase in simple sugar supply. It may enhance adaptation to endurance effort and thus improve sports results. According to Beis et al. [16], the improvement in physical capacity and endurance is also related to higher oxidation of simple carbohydrates (aqueous solution of glucose + fructose 60g/h) that leads to better effects than doses of 30g/h or 15g/h. Big portions of simple sugars (> 90g/h) may cause higher produc-tion of energy, up to 20–50%. Jeukendrup [17] notices that high physical effort that leads to intensive carbohy-drates oxidization, even its high contents, works against harmful consequences of glycemic index (GI).

comparing morphological structures of black and white athletes, we noticed the following somatic charac-


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teristics of black runners: lower body mass, significantly lower adipose tissue that results in much lower BMI, long-er lower limbs, smaller calf circumference and shorter torso [18]. They certainly increase endurance abilities, especially in endurance events. In our study all the Ken-yan runners were distinguished by low BMI (19.55 ± 1.51), low body fat (5.41 ± 1.75%) and slim calves (37.84 ± 6.43 cm). similar results were published by Knechtle et al. [19] and Kong et al. [20]. In the chosen elite Kenyan runners they noticed low BMI (20.1 ± 1.8), low body fat (5.1 ± 1.6%) and slim legs (34.5 ± 2.3 cm), however in our study a negative correlation between the calf circum-

ference and run time was found. The aforementioned authors tested duration of ground contact time during an endurance run and observed the difference between both limbs. They noted that the ground contact time of dominant leg was 170–212 ms, while that of the other leg was longer, about 177–220 ms. The short ground contact time, according to the authors, may be related to the running economy as there is less time needed to stop the front of the body. The differences in ground contact time between both limbs are most likely related to their slightly different functions.

According to a biomechanical model for running,

Table 2. Number profile of selected measurements (circumferences) and indicators (anthropologic) of examined Kenyan marathon runners

Tested feature SD Min Max

circumference measurements (cm): – chest measurement – aspiration (cm) 87.28 3.88 83.00 94.50– chest measurement – expiration (cm) 82.53 4.63 78.00 90.00– waist measurement (cm) 70.33 4.52 64.50 76.00– hip measurement (cm) 85.33 3.25 81.00 91.00– arm measurement – tensed (cm) 26.06 2.81 22.00 32.50– arm measurement – relaxed (cm) 23.56 2.16 21.50 29.00– thigh measurement (cm) 47.66 6.29 46.00 47.00– calf measurement (cm) 37.84 6.43 33.00 54.10

IndexesBMI 19.55 1.51 17.50 22.90AMc Index 22.27 2.10 20.24 27.56WHR Index 0.82 0.05 0.78 0.92

Examined runners were thin and had low body mass with low anthropological indicators.

Table 3. The correlation of selected parameters and results of long-distance runs

10,000 meters Half-marathon Marathon

Height 0.26 –0.13 –0.03Body mass 0.49* 0.17 0.34BMI 0.43* 0.25 0.40*sum of fat-skin folds –0.36 –0.06 0.16Adipose tissue % –0.36 –0.06 0.16Fat free mass % 0.36 0.06 –0.16Arm length 0.54* 0.50* 0.73**Forearm length –0.04 0.08 0.75**Upper limb length 0.14 0.45* 0.58*Lower limb length –0.34 –0.37 –0.13Foot length 0.36 0.51* 0.57shoulder breadth 0.53* –0.15 0.25Hip width 0.30 0.43* 0.77**Foot breadth 0.76** 0.54* 0.29Torso length 0.75** 0.40* 0.46*WHR –0.38 –0.15 0.41*AMc 0.13 –0.05 –0.08Thigh circumference –0.46* –0.26 0.01calf circumference –0.19 –0.43* –0.23

* moderate correlation (statistically significant dependency at the level of materiality 0.05) ** significant correlation, important dependency (statistically significant dependency at the level of materiality 0.05)


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speed depends on a) the step length b) the frequency of gait (v = l × f, where: v – speed, l – length, f – frequency of gait). On the other hand, the step length depends on the length of the lower limbs, flexion angle (to the front side) as well as the extension (to the back side). The step length is also related to the body morphology, however the aforementioned angles depend on movement tech-nique Erdman [21]. If a runner of a certain height of the body has a too long torso, his limbs are relatively short-er. Thus, his step length is going to be shorter as well. Hence, the positive correlation between the run time and the torso length is observed. Whereas, a runner of the same body height but longer lower limbs will make longer steps. This in turn results in negative correlation between the run time and the length of a lower limbs. The step frequency is related to the muscle preparation as well as muscle-nerve stimulation at a certain frequency, especially as far as endurance is concerned. The discussed frequency depends also on overcoming resistances such as: a) limbs inertia and, to less extent, b) the soft tissue extensibility. The limb with a broad expanded foot has a higher moment of inertia. The moment of inertia, among others, is the sum of the foot mass and its squared distance from the rotation axis of the hip-joint. The higher moment of inertia is, the bigger effort must be done by the muscles to move the limbs. Therefore, it is not recommended to have too expanded feet (hence, the positive correlation between the foot size and run time), but it is also not good to have too long lower limbs, because of the too long distance between the foot and the hip-joint, which results in more difficult lower limbs movements.

According to the above, too long upper limbs also do not favor a fast and long-term rotary motion around the axis of the shoulder-joint. Hence, the positive cor-relation between its length and run time.

The negative correlation between the thigh circum-ferences and shinbone is the results of the need for lower limb strength during the run, especially for the 10 km distance. There is no need to have too much basic strength; principally, the muscular endurance is important.

Another issue to discuss is the racing tactic, which, among others, consists of speed distribution during the whole distance. Erdmann and Lipińska [22] found that when the best runners were braking the world records for the long-distance runs, their speed distribution was horizontal (the speed was closed to constant) or slightly rising. Whereas, many other runners start the race at excessive speed and then slow down, which results in a worse run time. For runners who have better physio-logical and morphological predispositions, it is easier to keep the pace steady, close to constant running speed, and have better running times.

It is remarkable that three fourth of the best Kenyan runners belong to the Kalenjin tribe [23]. Kalenjin people make up only 12% of Kenya’s population while the Kalenjin tribe makes up around 1/2000 of the world’s

population. In recent years Kenyan athletes have domi-nated the majority of the most important athletic events such as the IAAF World Indoor championships, World cross country championships, Olympic Games and most famous marathon races. It was estimated that they had won three eighth of all the trophies in middle- and long-distance races. Their achievements were described by specialists as “The highest geographic density of sport achievements ever recorded”. seeking for reasons of the remarkable endurance abilities of the Kalenjin tribe mem-bers, researchers point out that the fundamental factor is living in a high-altitude region (over 2000 m a. s. l.). It seems that people living in thin air for generations have developed acclimatization to hypoxia. Weston et al. [24] points out that living in high-altitude areas always is linked with lowered oxygen concentration. To compen-sate lack of oxygen, the body has to increase the number of erythrocytes that transport oxygen, which at lower altitudes creates advantageous conditions to increase compound aerobic capacity. Although some reports do not confirm the above findings. The study by saltin et al. [25] showed no disparity in maximum oxygen consump-tion (VO2max) of elite Kenyan and scandinavian run-ners or unqualified Kenyan runners and a group of young people from Denmark. Further research is needed.

According to Larsen [26], members of the Kalenjin tribe are described as people with a higher concentra-tion of those enzymes in skeletal muscles that stimulate better utilization of oxygen and decreased production of lactic acid. As a result of that, the Kalenjins are able to transform oxygen into energy in much more efficient manner. As some authors claim [27], abilities of increased aerobic capacity among the Kalenjins are the results of genetic transfer and odd environmental conditions. If they undergo special training and follow a healthy life-style, they become athletes of enormous endurance abili-ties and absolutely exceptional abilities to regenerate. Thus it is extremely difficult to beat an athlete who, like his ancestors, originates from the highlands of the Great Rift Valley. Generally all researchers agree that the excep-tional endurance abilities result from an interaction of genetic heritage, environmental conditions (hypoxia) as well as cultural, social and economic determinants. In view of extremely difficult living conditions, under-developed economy and lack of job opportunities, young Kenyans and Ethiopians choose to become athletes. Thanks to their strong will and hard work they be-come successful in sport all around the world, which improves their and their families’ living standard.

Conclusions

As a results of conducted study following conclu-sions were made:

1. The BMI of the examined Kenyan runners was fairly low compared to the health norms, in some cases even below the norm.


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2. The following correlations have been found:– positive (important) – the 10 km run time was cor-

related with the foot width and torso length,– positive (important) – the marathon run time was

correlated with the arm, forearm length, and the hip width,– positive (moderate) – the 10 km run time was corre-

lated with body mass, BMI, arm length, width shoul-ders,

– negative (moderate) – the 10 km run time was correlated with the thigh circumference,

– positive (moderate) – between the half-marathon run time was correlated with the arm length, lower limb length, foot length, hip width, foot width, and torso length,

– negative (moderate) – the half-marathon run time was correlated with the calf circumference,

– positive (moderate) – the marathon run time was correlated with BMI, upper limb length, torso length, and WHR index.

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24. Weston A.R., Mbambo Z., Myburgh K.H., Running econ-omy of African and caucasian distance runners. Med Sci Sports Exerc, 2000, 32 (6), 1130–1134. Available from: http://journals.lww.com/acsm-msse/pages/articleview-er.aspx?year=2000&issue=06000&article=00015&type=abstract.

25. saltin B., Larsen H., Terrados N., Bangsbo J., Bak T., Kim c.K. et al., Aerobic exercise capacity at sea level and at altitude in Kenyan boys, junior and senior runners com-pared with scandinavian runners. Scand J Med Sci Sports, 1995, 5 (4), 209–221, doi: 10.1111/j.1600-0838.1995.tb00037.x.


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26. Larsen H.B., Kenyan dominance in distance running. Comp Biochem Physiol A Mol Integr Physiol, 2003, 136 (1), 161–170, doi: 10.1016/s1095-6433(03)00227-7.

27. Harm c., Knechtle B., Rust ch.A., Rosemann T.J., Lepers R., Onywera V.O, Performance of Kenyan athletes in moun-tain versus flat marathon running – an example in switzer-land. J Hum Sport Exerc, 2013, 8 (4), 881–893, doi: 10.4100/hse.2013.84.01.

Paper received by the Editor: July 23, 2015Paper accepted for publication: March 30, 2016

Correspondence addressJerzy EksterowiczInstytut Kultury FizycznejUniwersytet Kazimierza Wielkiegoul. sportowa 285-091 Bydgoszcz, Polande-mail: [email protected]

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15

THE mulTI-funcTIonAl fooT In ATHlETIc movEmEnT: ExTrAordInAry fEATs By our ExTrAordInAry fEET

doi: 10.1515/humo-2016-0001

2016, vol. 17 (1), 15– 20


JEnnIfEr wIlson 1 *, JoHn KIEly 21 University of Derby, college of Life & Natural sciences: sport, Outdoor & Exercise science, Derby, United Kingdom2 University of central Lancashire, Institute of coaching & Performance, school of sport, Tourism and the Outdoors,

Preston, Lancashire, United Kingdom

ABsTRAcTThe unique architecture of the foot system provides a sensitive, multi-tensional method of communicating with the surrounding environment. Within the premise of the paper, we discuss three themes: complexity, degeneracy and bio-tensegrity. complex structures within the foot allow the human movement system to negotiate strategies for dynamic movement during athletic endeavours. We discuss such complex structures with particular attention to properties of a bio-tensegrity system. Degeneracy within the foot structure offers a distinctive solution to the problems posed by differing terrains and uneven surfaces allowing lower extremity structures to overcome perturbation as and when it occurs. This extraordinary structure offers a significant contribution to bipedalism through presenting a robust base of support and as such, should be given more consideration when designing athletic development programmes.

Key words: foot, degeneracy, bio-tensegrity, robustness

The overlooked role of the foot in dynamic sporting activities

conventionally, when devising conditioning strate-gies to enhance ambulant, bipedal athletic movements – run, jump, pivot, turn, change direction – much training attention is dedicated to strengthening the large power-generating muscles of the hips and upper legs. substan-tial research exists evidencing the positive contributions of various strength and conditioning strategies to ath-letic performance: to the extent that few would argue against the conventional perspective that, within reason, stronger muscles enhance movement capacity.

Within this conventional ‘muscle powers movement’ model there is, we suggest, an apparent omission. spe-cifically, observable power production, in dynamic lo-comotive activities, typically exceeds muscular force-gen-eration capabilities. As an example, during the step phase of a triple-jump, impacts of up to 15 times bodyweight and above are commonly absorbed, controlled and the propulsive forces necessary to power the next jump phase are generated, within the abbreviated time-frame af-forded by a short ground contact typically lasting less than one-fifth of a second [1]. similarly, during run-ning, impacts of multiple times bodyweight are com-fortably accommodated, by runners of all abilities, for little discernible effort. In elite sprinters very forceful ground contacts must be managed in windows of as little as 80 ms–1 [2]. In non-elite marathon runners, im-

pacts, while less forceful than those of the sprinter, never-theless typically number beyond 21 thousand contacts, again of multiple times bodyweight per leg [3].

Furthermore, during the dynamic accelerating, de-celerating, twisting and turning athletic movement per-mutations common across a broad range of sporting activities, the loadings imposed on joints and other struc-tures appear similarly excessive: exposing tissues to high shock loads, in apparently unstable, ever-varying move-ment conditions. Despite the severe challenges imposed by such dynamically-shifting movement demands, we are capable of robustly and agilely executing a broad di-versity of complex bipedal movements, under constantly shifting conditions.

A further interesting, if obvious, observation is that although many muscle groups must be skilfully activated to manage, buffer and generate propulsive powers, their net contribution to whole-body momentum can only be expressed through interaction with the ground. A fea-ture of bipedal movement is that the large forces generated through the dynamic re-positioning of the limbs during flight must be transferred between body and ground via the relatively small surface area provided by the foot. The foot serves as our only interface with the ground during walking and running, but also in the endless variety of dynamic movement permutations encoun-tered in athletic sporting activities. Hence the foot is exposed to high shock impacts and decelerations, while simultaneously and/or consecutively functioning as a brake, a spring, a buffer, a means of steering, and a stiff conduit for force transfer between the dynamically moving body, and the immovable environment. Yet de-spite this primacy, little consideration is typically afforded

J. Wilson, J. Kiely, The multi-functional foot

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to foot conditioning within our conventional training theory or practices.

Over the course of our evolutionary history, the architecture of the foot has been progressively shaped by ever-present evolutionary imperatives, constantly striving to increase movement proficiency, for mini-mum uptake of energetic and neural resources, while simultaneously reducing exposure to negative sensory feedback indicative of the mounting risk of ‘damage’ [4–8]. The aim of this piece is to highlight three evo-lutionary innovations which, in combination, under-pin the remarkable robustness of the human foot dur-ing dynamic impact activities (see Figure 1).

Extraordinary feats by our extraordinary feet

neurobiological complexity of the human foot

As the only habitually upright bipedal primate, human foot architecture differs substantially from that of our nearest relatives. With three strong arches; over 100 muscles; 26 separate skeletal elements (exempting the sesamoids) linked through 33 joints, fastened by 3 layers of ligaments; dextrously manipulated by numerous in-trinsic and extrinsic muscle-tendon units, the human foot constitutes a uniquely complex bio-composite ana-tomical module [9–11]. This design complexity is not only structural but also sensory. During locomotion the various tissues and structures of the foot are subjected to considerable deformations, in three dimensions. sen-sory information, arising from local foot deformations, emanates from multiple somatosensory receptors in the foot arch ligaments, joint capsules, intrinsic foot muscles, and cutaneous mechanoreceptors on the plantar soles: such that deformations instantaneously affect afferent outflow [9, 12–14,]. This neurobiological design com-plexity is matched by a similarly expansive functional complexity, as the foot adapts to the expansive diver-

sity of tasks imposed by the physics of landing on un-predictable surfaces.

In the past, this seemingly needless complex design was frequently considered an unfortunate legacy from our evolutionary past. Yet, despite the intricate nature of its multi-tissue, multiple sensory organ, bio-composite structure, the foot remains highly functional and adapt-able. It is remarkably robust, across an unusually diverse range of dynamic movement activities: walking, running, climbing, turning, pivoting, hopping, bounding. Further-more, not only does the foot adapt to changing move-ment demands, it also is capable of fulfilling multiple roles, frequently simultaneously, in multiple movement contexts. For example, even under the abbreviated ground contacts afforded during run/jump activities, the foot functions as a flexible structure in early stance, buff-ering, braking, and stabilizing, yet milliseconds later is a rigid structure, stiffly channelling propulsive forces; directing momentums and contributing to push-off efficiency [14].

certainly, the foot is not simply a passive, rigid base of support but a flexibly adapting, exquisitely adaptive functional unit: enabling precise control of multiple func-tions. And, far from being a potentially problematic evolutionary hangover, the complexity of the human foot endows us with a rich repository of robustness and efficiency-enabling movement innovations.

degeneracy: the adaptive agility of the ‘nearly decomposable’ human foot

The early complexity theorist Herbert simon sug-gested biological organisms could be meaningfully ap-proximated as ‘nearly decomposable’ complex systems. A purely mechanical system is, in contrast, fully decom-posable, in that each component fulfils a tightly desig-nated role within a given context [15]. Within a ‘nearly decomposable’ biological system there is obvious cross-over, overlap and integrated interplay between the func-tionality of different tissues and structures in different contexts. Yet, the entire organism is not haphazardly complex and instead exhibiting a modular design: whereby each module is composed of collections of elements more densely networked to each other than to elements within other modules.

Modularity is a crucial organizing principle, perva-sive throughout biology, greatly simplifying what would otherwise be overwhelmingly disordered complexity. Although all modules are inter-connected, they are simul-taneously partially-insulated and functionally semi-au-tonomous. Hence modularity facilitates robustness as modules can evolve, reshape, rewire and repair in tan-dem, or independently, without necessarily jeopard-izing the survivability of the entire organism [16–18].

This ‘nearly decomposable’ architecture enables com-plex neurobiological systems to reap the benefits of struc-tural specialization while simultaneously retaining

Figure 1. A depiction of the three evolutionary innovations that contribute to ‘robustness’ within the foot structure


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the adaptive agility essential to coping with demands im-posed by a chaotic, ever-changing environment. such design characteristics underpin an essential prerequi-site of biological robustness: degeneracy [19].

Degeneracy is the capacity, of alliances of modules, to collectively modify behaviours and re-combine out-puts in differing permutations to collaboratively realize equivalent outcomes through a diversity of pathways [20–24]. In biological terms, degeneracy is similar to, but differs from, the classical concept of redundancy, in that it enables collaborating communities of funda-mentally different components to produce consistently reliable outputs under diversely fluctuating conditions [19, 21].

The bio-composite design of the human foot pro-vides a prime example of a highly-degenerate biological architecture. The complex ‘nearly decomposable’ archi-tecture of the foot enables instantaneous structural re-configuration to dynamically changing contexts. Most obviously in circumstances imposed by environmental variations, such as encountered during running over broken terrains but also during the various permuta-tions of accelerations, decelerations, pivots, turns and changes of direction implicit in dynamic sporting ac-tivities. Thus the ‘nearly decomposable’ architecture of the foot facilitates immediate and flexible adaptation to changing context.

A further feature of this highly degenerate configu-ration is that seemingly identical movement cycles, re-sulting in equivalent movement outcomes, can be achieved through a multiplicity of subtly varying pathways. Thereby enabling the mechanical stresses imposed by repeti-tive impacts, such as that encountered during a mara-thon, to be dispersed amongst a broad network of col-laborating structural and material components. Hence degeneracy facilitates robustness.

Degeneracy within the foot ensures that subtle mod-ifications, in multiple permutations of positioning and/or pre-tensioning of foot structures, channels mechanical stress through ever-varying routes, thus spreading the work burden imposed by impact and diminishing the probability of repetitive strain, and subsequent tissue damage. The impact of which plays a significant role in ambulant athletic performance.

resisting deformation and channelling momentums: the bio-tensegrity solution

The foot is commonly subjected to both frequent, and large, impacts during athletic movements. The degenerate design of the foot substantially contributes to its structural robustness in the face of repetitive shock loadings, yet does not operate in isolation, and is ir-reparably entwined with another evolutionary design innovation.

The architect Buckminster Fuller originally defined tensegrity systems as structures that stabilize shape

through continuous tension rather than by continuous compression such as employed, for example, in the con-struction of a stone arch [25]. In contrast, tensegrity systems innately self-stabilize and resist structural distor-tion purely by balancing tension-imposing and compres-sion-resisting structural components within a self-sta-bilizing web of tensioning and stiffening forces [26].

The strikingly energy-efficient, perturbation-repel-ling simplicity of tensegrity designs has, recently, been recognised as a pervasive evolutionary innovation evi-dent across biological scales, from the cellular to the whole-body level [26, 27].

The bio-tensegrity model depicts the skeletal system as a non-random arrangement of compression elements knitted into the tensional fabric of the fascia [28]. Fascia provides a constant inherent tension maintaining a back-ground tautness that allows the system to respond and adapt to external force without losing the structural integrity of the organism whilst simultaneously serving as a mechano-sensitive signalling system, receptive to pressure changes [29].

The running bio-tensegrity system is composed of a hierarchy of nested subsystems. During dynamic activi-ties, the athletes body acts as a tensegrity system; as does each leg, each muscle-tendon unit (MTU), each

muscle, each muscular sub-compartment, each motor unit, each muscle fiber, each myofibril and so on [30–31]. In essence, serving as a sequence of nested tensegrity structures extending down to the level of the individu-al cell, and beyond. Each nested structure lies within greater, and is comprised of lesser, bio-tensegrity ar-chitectures; each evolutionarily designed, structurally and materially, to advantageously respond to the load-ings and deformations most relevant to our species survival. Each sub-system innately responds to defor-mation by striving to rebound to a state of homeostatic mechanical equilibrium: linking from the micro-level of the cell, through the various tissue collectives, to the macro-level of the entire organism [26, 28, 32–35].

The foot, as the structure exposed to the highest im-pact deceleration, is an exquisitely evolved bio-tenseg-rity structure. The foot is itself formed by a number of bio-tensegrity systems encased within the foot archi-tecture, and in turn serves as a sub-system of the inte-grated systemic whole. The foot is often described as being made up of floating compression elements (such as the skeletal structures of the midfoot [36]) support-ed by a tensional fabric (the plantar aponeurosis being the most cited [37]). Although it is typically considered as having two functional aims – to support body weight and to act as a lever during propulsive phases of loco-motion [9] –, thanks to its complex multi-tissue design the foot system is capable of fulfilling a wide diversity of functions: variously absorbing, decelerating, trans-ferring, steering and recycling movement powers.

As with any bio-tensegrity system, effective dispersal of forces alleviates risks of exceeding critical tissue loading


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limits. To move efficiently these forces must be chan-nelled and re-deployed to optimally contribute to sta-bilisation and propulsive power demands. Within the hierarchy of tensional systems, compression of local structures creates a ‘non-linear wave’ through the ten-sional fabric of the global construct resulting in a modi-fication to internal forces through a ‘preflexive’ response [27]. Driven by evolutionary imperatives and repeat prac-tice, we progressively become more skilled at exploiting these built-in mechanical efficiencies. We gradually become more proficient at poising ‘tensioned’ or pre-stressed tensegrity structures to more productively capitalise on ‘cheap’ sources of control and propulsion merely by matching the physics of the situation to in-nate deformation-repelling features of our integrated bio-tensegrity design [38].

Furthermore, simply by leveraging properties of the mechanical system, the coordinated harnessing of our nested bio-tensegrity design remedies the inherent information-processing and perturbation-prediction deficits implicit in top-down control [39]. This provides an instantaneous non-neurological, yet skilled, response to sudden perturbation: automatically buffering, re-di-recting and re-cycling momentums and stabilizing move-ment, for little energetic or neurological investment.

Locally, the foot must respond instantaneously, with zero delay, to variations in contact conditions [38]. When moving at speed, where conditions underfoot are pre-dictable, the variable component may assume a stiffly set posture (i.e. high efficiency but high impact). Under more uncertain conditions, the foot will be less stiffly pre-set, allowing for more flexible absorption of con-tact to overcome external perturbations.

The robust human foot: a collaboration of evolutionary innovations

During dynamic loading activities the complex, ‘nearly decomposable’ structure of the human foot provides a robust means of absorbing, distributing, channelling and re-directing the shock loads imposed by violent collision with the external environment. Upon impact the foot deforms as tissue structures variously collapse, compress and stretch under the integrated influence of gravity and ground reaction forces. These deforming forces provide both a challenge and an opportunity.

Degeneracy exploits the multi-functionality bestowed by our nested bio-tensegrity architecture, enabling us to solve inevitably unique movement problems through ever-varying movement solutions. Hence, movement variability is an outcome of degeneracy, accounting for the flexible and adaptive behaviours seen in a bio-tensegrity structure.

As with any system demonstrating degeneracy, ex-ploitation of variable configurations and behaviours promotes mechanical efficiency as the system strives for the most economical outcome. By offering more move-ment options, a degenerate system is able to facilitate stress management through variable permutations. At the level of the foot, the seamless integration of ten-sional properties regulates the poising and pre-activation of hierarchical structures so as to optimally contribute to the stabilization and energetic requirements of move-ment. In locomotive activities, particularly those that incur repetitive impacts, the foot serves multiple func-tional roles. A multi-functionality built among a platform of structural complexity. The generous movement de-generacy, afforded by the human foot, is underpinned by this structural complexity. Together this blend of bio-tensegrity and degeneracy enable the human foot to adjust, deform, dampen, absorb and productively har-ness the deformations imposed by ground contact (see Figure 2).

Theoretical implications

conventional performance training models are built upon a theoretical assumption that improving strength – specifically of the large lower limb muscles – inevitably enhances bipedal movement proficiency. Our purpose is not to dispute this presumption but to highlight its fundamental limitations as an overarch-ing conceptual framework: specifically in relation to the role of the foot in dynamic bipedal movements.

In activities that require the athlete to run, jump, land, accelerate, brake and pivot, the foot must instantane-ously respond, to inevitably idiosyncratic permutations of internal and external constraints, in a manner re-solving the twin demands of robustness and efficiency. The capacity of the foot to simultaneously fulfil multiple demands is enabled by its design complexity. A complexity underpinning the foot’s highly degenerate capacity to

Figure 2. collaboration between three evolutionary innovations


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accomplish similar outcomes through a multiplicity of ever-varying movement permutations. A complexity which, thanks to its nested bio-tensegrity design, innately responds to imposed perturbation by first absorbing, and subsequently repelling, structural and material de-formations: thus contributing to self-stabilization and momentum re-cycling.

This extraordinary structure plays a fundamental role in damping, dissipating and dispersing shock im-pacts; in channelling and directing momentums; in seam-lessly adapting to movement errors or changing surface conditions; in contributing to energy re-cycling through deformation and restitution. Yet despite the criticality of foot function in bipedal athletic activities, our foot conditioning philosophies remain poorly evolved and the potential importance of developing strategies to optimise foot functionality remain commonly overlooked. As our appreciation of the architectural and functional complexity of the foot continues to grow, so too does an awareness that perhaps conventional foot conditioning and therapy strategies need to evolve in tandem? cer-tainly, given the importance of optimised foot function to athletic bipedal movement, it seems remiss not to re-flect on how we conventionally consider, or fail to con-sider, how we might design conditioning and therapeutic interventions to specifically target the on-going health of these extraordinary structures.

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Paper received by the Editor: January 18, 2016Paper accepted for publication: March 30, 2016

Correspondence addressJennifer WilsonUniversity of Derbycollege of Life & Natural sciences:sport, Outdoor & Exercise scienceKedleston Road Derby, DE22 1GBe-mail: [email protected]

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IdEnTIfIcATIon of dETErmInAnTs of sporTs sKIll lEvEl In BAdmInTon plAyErs usIng THE mulTIplE rEgrEssIon modEl

JAnusz JAworsKI 1 *, mIcHAł ŻAK 21 Department of Theory of sport and Kinesiology, Institute of sport sciences, Faculty of Physical Education and sport,

University of Physical Education, Krakow, Poland2 Department of sports and Recreational Training, Institute of sport sciences, Faculty of Physical Education and sport,

University of Physical Education, Krakow, Poland

ABsTRAcTPurpose. The aim of the study was to evaluate somatic and functional determinants of sports skill level in badminton players at three consecutive stages of training. Methods. The study examined 96 badminton players aged 11 to 19 years. The scope of the study included somatic characteristics, physical abilities and neurosensory abilities. Thirty nine variables were analysed in each athlete. coefficients of multiple determination were used to evaluate the effect of structural and functional parameters on sports skill level in badminton players. Results. In the group of younger cadets, quality and effectiveness of playing were mostly determined by the level of physical abilities. In the group of cadets, the most important determinants were physical abili-ties, followed by somatic characteristics. In this group, coordination abilities were also important. In juniors, the most pro-nounced was a set of the variables that reflect physical abilities. Conclusions. Models of determination of sports skill level are most noticeable in the group of cadets. In all three groups of badminton players, the dominant effect on the quality of playing is due to a set of the variables that determine physical abilities.

Key words: badminton, sport training, recruitment and selection

doi: 10.1515/humo-2016-0004

2016, vol. 17 (1), 21 – 28


Introduction

Badminton is one of the most popular racket sports. The origins of badminton date back to the second half of the 19th century. Organizations and associations for badminton players are registered in over 90 countries [1]. This sport has attracted the interest of researchers in many academic fields. Numerous scientific studies have dealt with physiological, biomechanical, somatic and psychological conditions, and badminton move-ment technique [2, 3]. Other reports have demonstrat-ed health benefits of playing badminton [4].

A comprehensive development of motor abilities is needed to become a successful badminton player. Players often perform jumps, sudden directional changes on the court, a broad range of movements of the upper limbs and changes in body posture [5, 6]. From the standpoint of energy demands, badminton is characterized by move-ments with very high intensity, alternate with short pe-riods of low-intensity exercise or rest [2, 7]. During the game, energy is largely fuelled by aerobic pathways (around 60–70%), while around 30% of the energy is generated from anaerobic processes [3]. With its total time of the game and the character of exercise during individual actions, badminton can be considered as a speed and endurance sport. Anaerobic exercise during the game of badminton is observed during individual

actions, whereas aerobic exercise results from the dura-tion of the game and the number of various movement sequences repeated during the game [3, 8].

Another important factor that affects the effective-ness of the game is optimal level of somatic parameters. These problems have been documented for example in [3, 9–10]. These studies have shown that optimal body build of a badminton player is characterized by substan-tial body height and slim body. The findings obtained in many countries [3, 9] have demonstrated that mes-omorphy and ectomorphy should be preferred among badminton players.

A specific level of coordination motor abilities is also important in badminton. The complex character of the game requires a perfect performance of movement tasks with high complexity and adaptation to frequent changes in the situation on the court [10, 11–13]. Therefore, simi-lar to combat sports and other games (mainly team sports), badminton is classified in the third (the hardest) category of sports, characterized by the highest level of variability of movement structure, which is attributable to the dominance of external stimuli and open move-ment structure.

The effectiveness of the game of badminton depends on many combinations of the factors which determine the effectiveness of coaching in badminton. In the prac-tice of training, one should take into consideration interactions between genetic and training factors. There-fore, both talent identification and training optimiza-tion are of key importance for final success in the sport

J. Jaworski, M. Żak, Determinants of sports skill level in badminton players

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[14]. The basic criterion during development of this type of champion model is always the analysis of key variables in the specific sport, with strong genetic de-termination [15]. Each “champion model” implies the necessity of using only the variables which can be re-alistically anticipated over the training. Anticipation of adaptations in this field should be based not only on the knowledge of problems connected with human ontogeny but also on the awareness of individual dif-ferences in speed of development of children and young people.

Identification of the determinants of the effective-ness of actions is essential for athletic training. Unfor-tunately, few reports have attempted to find variables which should be preferred in badminton (at each stage of sports training). Furthermore, few studies have ex-amined optimization of sports training [16].

Therefore, the main aim of this study was to examine somatic and functional determinants of sports skill level at three consecutive stages in badminton training. The following questions were addressed in the study:

– Which somatic characteristics, physical abilities and neurofunctional abilities are of key importance to the sports skill level in badminton players?

– How does the configuration of determinants of badminton performance change at each consecutive stage of the training process?


The results recorded for 96 badminton players in three training categories: 40 younger cadets (aged 11 to 13 years), 32 cadets (aged 14 to 16 years) and 24 juniors (aged 17 to 19 years) were analysed. Mean experience in competition was 3.8 years in the group of younger cadets, 5.9 years in the group of cadets, and 8.2 years in the junior group. The athletes were from the following sports clubs: MKs „spartakus” from Niepołomice, UKs „Orbitek” from straszęcin, LKs „Technik” from Głub-czyce, UKs „sokół” from Ropczyce, UKs „Trójka” from Tarnobrzeg, UKs „Badmin” from Gorlice, UKs „Hubal” from Białystok, MKs „Orlicz” from suchedniów.

Their sports skill level was evaluated indirectly using the ranking lists prepared by the Polish Badminton Association. The lists are updated annually after com-pletion of cycles of tournaments. Players are awarded ranking points based upon their achievements in each tournament, and the ultimate position on the annual ranking list depends on the player’s total score. In the case of the equal number of points or other doubts, the evaluation was supplemented with the expert method.

The study was conducted according to the Declara-tion of Helsinki. Informed consent prior to participation was obtained from children’s parents or guardians and coaches. Each player was informed that they can stop the examination at any moment without giving the reasons for such a decision.

scope of the study

Martin’s technique was used to measure somatic parameters: body height, length of upper limb, height in the sitting position from the sitting level to the vertex point, range of the arm with racket during the fore-hand stroke, shoulder width and hip width. Body mass, lean body mass (LBM) and fat mass were evaluated using TANITA TBF-551 body composition analyser. Flexibility – the depth of the seated forward bend [17]. Amplitude of movements in the radiocarpal joint was measured in the four basic directions in the frontal plane and sagittal plane using a goniometer.

The analysis focused on the following tests of motor fitness:

a) long jump from standing position – explosive leg strength,

b) overhead medicine ball throw (2 kg) with both hands, with legs spread apart – explosive arm strength,

c) measurement of hand grip strength – force gen-erated under static conditions,

d) measurement of maximal force and perception of half of its value – kinaesthetic differentiation of the force,

e) run with changes of directions (envelope run) – running speed,

f) 10 × 5-metre shuttle run [17] – ability of quick muscle recruitment,

g) endurance shuttle run [17] – cardiovascular en-durance,

h) sit-ups – abdominal muscle power, i) power tests according to the procedure proposed

by spieszny et al. [18] – 10 × 3-metre shuttle run; over-head medicine ball throw (1 kg) from the kneeling po-sition; “tapping” with the medicine ball (2 kg) – 10 cycles of overhead hitting with the ball held with two hands against the wall and against the ground between the legs spread apart,

j) maximal anaerobic power (MAP) was calculated as the product of body mass and standing long jump or overhead medicine forward throw [19].

coordination motor abilities were also analysed: kinaesthetic differentiation of temporal motion param-eters, frequency of hand movements, visual-motor coor-dination, spatial orientation (free and forced modes), mean reaction time to auditory stimulus (minimal, mean, maximal), mean reaction time to visual stimulus, mean selective reaction time to visual and auditory stimuli (minimal, mean, maximal), movement rhythmization, movement integration, kinaesthetic differentiation (spa-tial-dynamic parameters).

The testing procedure, program settings and charac-terization of the equipment used for the examinations were described in the monograph by Jaworski [15].


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1. Prior to the main statistical analysis, the consist-ency of the distribution of the variables with normal dis-tribution was verified by means of the shapiro-Wilk test.

2. In order to reduce the number of variables used in the regression model, we used factor analysis performed previously in the study [20]. The variant of the analysis based on the principal component procedure developed by Hotelling with Tucker’s modification was used, sup-plemented with Varimax rotation proposed by Kaiser. The variables with factor loading of over 0.5000 were selected for further analyses.

2. coefficients of multiple determination were used to evaluate the effect of structural and functional param-eters on the sports skill level in badminton players. This study used the stepwise regression. Forward se-lection was adopted as a method for selection of vari-ables introduced to the system. Other variables were qualified only in the situation where it was possible to reject the hypothesis of zero contribution to the model (snedecor’s F-distribution meets the condition of con-fidence at the level of 95%, p < 0.05). The variables previously separated using factor analysis were con-sidered as independent, and introduced to the regres-sion model. Analysis of the results was performed by dividing all the variables into the three sets: somatic characteristics and structural-functional ones, coordi-nation abilities, and physical abilities. Each set repre-sented the basis for development of a separate model of multiple correlations with sports skill level. The pro-cedure was repeated for each age group (younger cadets, cadets, and juniors).

calculations were made using statistica 10.0 PL for Windows software package. The significance level was set at = 0.05.

Results

The problem of correlations between the sports skill level of athletes and their morphological aptitudes and motor fitness was attempted to be solved through in-depth analysis of the phenomenon based on the inter-pretation of coefficients of multiple determination. The factor analysis [20] and its pragmatic interpretation al-lowed for selection of up to 26 variables for these statis-tical procedures (see Table 1).

In the context of the research questions, the most interesting information was provided by the analysis of multiple determination that allows for evaluation of the combined effect of the structural-functional charac-teristics on the sports skill level in badminton players in different age categories. Determination of the com-bined effect of variables found through factor analysis seems to be more justified than seeking individual cause-and-effect correlations between isolated variables.

The results were analysed using the typology that allows for division of all the parameters into the three sets: somatic aptitudes, structural and functional char-acteristics; coordination abilities; and physical abili-ties. Each of them represented the basis for develop-ment of a separate model of multiple correlations with sports skill level. The procedure was repeated for each age groups (younger cadets, cadets and juniors).

In the group of younger cadets (see Table 2), quality and effectiveness of playing are mostly determined by the level of physical abilities. This model is based on the results of two speed and strength tests that evaluate lower limb fitness. They explain 33% of the sports skill level. This system of variables is also reinforced (to a slightly lower extent) by the endurance variable and, to an insignificant extent, by the parameters that de-termine MAP of the upper limbs and static strength. It is noticeable that most of the tests formed a factor which was conventionally (in previous analyses) termed as com-prehensive anaerobic power. The whole system of physical

Table 1. set of variables introduced to the multiple regression model

No. Variable No. Variable

1. Body height 14. Visual-motor coordination (free mode)2. LBM 15. spatial orientation (free mode)3. shoulder width 16. spatial orientation (forced mode) 4. Arm range (with racket) 17. Differentiation of force parameters of motion5. Flexibility 18. standing long jump6. Wrist mobility 19. 10 × 5-meter shuttle run7. Kinaesthetic differentiation of temporal parameters 20. cardiorespiratory endurance8. Frequency of movements 21. Envelope run9. Visual reaction time 22. MAP, lower limbs

10. Auditory reaction time 23. MAP, upper limbs11. selective reaction time 24. Abdominal muscle power12. Rhythmization 25. Forward medicine ball throw13. Movement integration 26. static strength


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Table 2. coefficients of multiple determination between sports skill level and morphofunctional variables in the group of younger cadets

Group of variables Variable introduced to the model R R2 R2pop. F

somatic and structural-functional characteristics

Wrist mobility 0.28 0.08 0.05 3.04Arm range (with racket) 0.37 0.13 0.09 2.83shoulder width 0.47 0.22 0.15 3.27*

coordination abilitiesspatial orientation (forced mode) 0.27 0.07 0.04 2.80Visual reaction time 0.32 0.10 0.05 2.07Movement integration 0.36 0.13 0.06 1.79

Motor physical abilities

10 × 5-meter shuttle run 0.53 0.28 0.26 14.26***MAP, lower limbs 0.61 0.37 0.33 10.53***cardiorespiratory endurance 0.66 0.44 0.388 9.02***MAP, upper limbs 0.67 0.45 0.389 7.06***static strength 0.69 0.47 0.393 5.92***

The results statistically significant * p < 0.05; ** p < 0.01; *** p < 0.001

Table 3. coefficients of multiple determination between the sports skill level and morphofunctional variables in the group of cadets



Flexibility 0.67 0.45 0.43 18.18***Body height 0.69 0.48 0.43 9.74***Arm range (with racket) 0.71 0.51 0.44 7.06***

coordination abilities

spatial orientation (forced mode) 0.46 0.21 0.18 5.91*Rhythmization 0.55 0.31 0.24 4.62*Differentiation of force parameters of motion 0.64 0.41 0.33 4.70*Visual-motor coordination (free mode) 0.68 0.46 0.34 4.07*Frequency of movements 0.71 0.50 0.36 3.46*

Motor abilitiesof physical nature

Envelope run 0.66 0.42 0.39 15.71***Abdominal muscle power 0.75 0.57 0.53 13.87***cardiorespiratory endurance 0.79 0.63 0.57 11.16***


Table 4. coefficients of multiple determination between the sports skill level and morphofunctional variables in the group of juniors



Wrist mobility 0.40 0.16 0.10 2.68Body height 0.57 0.32 0.22 3.12shoulder width 0.68 0.47 0.331 3.47Arm range (with racket) 0.72 0.51 0.337 2.91LBM 0.75 0.56 0.340 2.54

coordination abilities

selective reaction time 0.42 0.17 0.12 2.96spatial orientation (forced mode) 0.54 0.29 0.18 2.66Movement integration 0.62 0.39 0.23 2.53Kinaesthetic differentiation of temporal parameters 0.68 0.47 0.27 2.40

Motor abilitiesof physical nature

MAP, upper limbs 0.68 0.46 0.43 12.11**Envelope run 0.77 0.59 0.52 9.26**MAP, lower limbs 0.80 0.64 0.55 7.03**Abdominal muscle power 0.82 0.67 0.556 5.59**



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ability variables explains around 40% of the quality of playing in the group of beginners.

In the somatic model, three variables emerge as more indicative than others: wrist mobility, arm range (with racket) and shoulder width. However, it should be em-phasized that only the combination of these three vari-ables is statistically significant and explains 15% of the sports skill level.

The effectiveness of playing is even less determined by the structure of coordination ability variables (ca. 6% in general). In this model, the first place is occupied by the spatial orientation test, i.e. reaction to the moving objects, the second by the test of reaction time to visual stimuli, with the variable of movement integration being the least relevant.

A diametrically different construction of all the three models is observed in the group of cadets (see Table 3). It is true that the highest explanation percentage for variability of sports skill level concerned the complex of physical abilities, but it consisted of only three pa-rameters. The first was the factor of MAP for the low-er limbs, however, in the other test: envelope run. The motor effect for the results of the test explains 39% of the quality of playing at the level of 39%. composition with the parameter of abdominal muscle power signifi-cantly increases the level of the coefficient of determi-nation (53%), whereas integration of another value that determines the cardiorespiratory endurance leads to an insignificant increase in this index. In this form, it ex-plains around 57% of the variance of the sports skill level.

configuration of the somatic model in the group of cadets in the context of the previous sequence of vari-ables that determine the level of motor preparation seems to be relatively logical. The first place in the model was taken by body flexibility. correlations between the next two parameters, body height and the range of arm with racket, are logical for the discussed coefficient of deter-mination. However, they do not significantly change the level of explanation for the sports skill level which in the whole composition is at the level of 44%. Presence of the characteristics of body height in the model may be also correlated with high variability of morphologi-cal age in this group of study participants.

The variables which determine coordination abili-ties also seem to be interesting. The first variable in the model is spatial orientation (forced mode) but with much greater loading that explains sports skill level compared to the group of younger cadets (18%). The whole model is explained by the quality of playing (36%), reinforced by the following variables: movement rhythmization, differentiation of strength motion parameters, visual-motor coordination (free mode), and movement frequen-cy. The significant effect on the level of playing from such a substantial number of factors of motor coordi-nation is symptomatic for this period of development and represents an interesting material for discussion.

In the group of juniors, complexation of variables that

form the individual models is also interesting compared to the previously characterized groups (see Table 4). The composition of variables that represent physical abilities is most noticeable and accounts for 55% of the quality of playing. The most important component in the model is anaerobic power of the lower limbs, which seems to be logical since at this stage of training process, the suc-cess may be determined by speed and force the shut-tlecock is hit with. The parameters that determine the efficient movements on the court (envelope tests and MAP test for the lower limbs) are also important. On the one hand, they can determine successful results in the competition, and on the other hand, their lower level may be compensated by the parameters of body size (mainly the range of the arm with racket) or very efficient movements of the racket that result from high mobility (range of motion) of the wrist.

The reality of this phenomenon can be supported by the structure of the somatic model, with the first place (10%) taken by the variable that determines the am-plitude of wrist movements and body size parameters (body height, shoulder width and range of motion of the arm with racket). In general, the combination of these variables accounts for 34% of the sports skill level.

The effect of coordination abilities is weaker at this stage of training. However, it is worth noting that this composition of variables contains parameters of motor coordination with higher degree of organization. The first place is taken in this sequence by selective reaction time, followed by spatial orientation and movement integration and kinaesthetic differentiation of tempo-ral parameters of movement. The whole model deter-mines the sports skill level in juniors at 27%.

Discussion

The observations conducted in the study were aimed to bridge the gap in the area of complex explorations in terms of multi-aspect determinants of sports skill level of young badminton players. They concerned in partic-ular the effect of structural aptitudes, physical abilities and coordination abilities on the development of com-petitive competencies with age. This complex concept was supposed to gradually lead to identification, struc-turization and hierarchization of the determinants of proper status of sports skill level at each stage of the athletic training process in badminton.

The principal interpretation of the results was pre-ceded by multidimensional statistical procedures: factor analysis and the Ward’s method [20]. This was used to reduce the initial number of variables and select the relatively independent factors that guarantee high sports skill level. This was connected with the need for identi-fication of “shared factors” necessary to identify a set of variables which lead to a reduction in the dimension and indication of the higher order factors until they are logically explained. Eventually, due to these statistical


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procedures, 26 variables were selected and analysed with-in three complexes at each stage of the training process.

The selected complexes that determine sports skill level in the group of younger cadets indicate that mainly physical abilities contribute to the positive picture of the game, of which the most important is the player’s ability to move on the court. They are connected with performing both the anaerobic and aerobic exercise [3, 8].

In the case of somatic variables constituting the model, it is the whole composition of this group of char-acteristics that affects sports skill level at a statistically significant level. The importance of these characteris-tics to the player’s effectiveness was indicated in the literature review in the Introduction section. It was essential for the sake of the analysed problems to have identified the cause-and-effect relationships between physical abilities and morphological characteristics. similar relationships were emphasized by subramanian [21]. In this group, the factor of motor coordination is getting to be more pronounced but mainly in terms of spatial orientation and reaction time to visual stimuli. In general, playing in the group of younger cadets is based on strong physical abilities.

A completely different structure of the model was observed in cadets. The number of components of mo-tor coordination in this group rose to five. The impor-tance of coordination abilities for badminton players is also confirmed by the findings published by many authors. Jaworski and Żak [10] analysed morphofunc-tional models in three groups of experience level. In the model obtained for younger cadets, only the results of movement integration and mean reaction time to visu-al stimulus were above the mean obtained for the whole module. These results demonstrate that the above coor-dination abilities are essential for recruitment of ath-letes, whereas sports skill level is determined mainly by physical abilities and wrist mobility. The dominant abilities in the group of cadets were spatial orientation and visual-motor coordination. In the group of juniors, an average level of contribution to the development of sports skill level was observed for spatial orientation, mean selective reaction time, movement integration and kinaesthetic differentiation. Badminton is numbered among one of the fastest racket sports. Therefore, reac-tion time is one of the most important neurofunction-al abilities that affect playing efficiency. Badminton players (both boys and girls) have better results com-pared to untrained peers [13]. As presented by the au-thors of the above study, the findings may have been caused by playing badminton. The importance of visual information processing and time needed to anticipate movement, as well as determination of intercorrela-tions between these variables in elite badminton players was emphasized by Poliszczuk and Mosakowska [12]. In their study, the researchers used two tests from the Vienna Test Battery: anticipation of movement (ZBA)

and visual field (PP). They found a relatively extensive range of vision in badminton players (172.9°, with 89.99° for the left eye and 82.86° for the right eye) and significant correlations between the base indices for both tests. Badminton is a sport where players have to respond to strong and fast shots performed by the op-ponents using the upper limbs. The results of many studies have shown that shorter reaction time in elite athletes compared to other badminton players may be a key variable to distinguish between players at differ-ent sports skill levels. Furthermore, the results of the studies concerning the relationships of simple and com-plex reaction time with muscular strength show that only complex reaction time was significantly correlated with the strength of the right and left arm and was not correlated with the strength of the lower limbs [22–25]. The review of some selected findings suggests the ne-cessity of paying particular attention to development and improvement of technique in this period of training. coordination exercises are known to stimulate develop-ment of special fitness, which, based on feedback, im-proves the level of coordination skills. In particular, this might concern spatial orientation, which is essential for evaluation of the trajectory of the shuttlecock in space and observation of the current situation on the court. In the context of the game, it also seems essential to maintain the specific rhythm of actions and the action-related frequency of movements. These may include very fast sequences of repeated actions. Good differentiation of force parameters of movement revealed in the factor helps using the racket, whereas visual-motor coordina-tion makes it easy to anticipate the shuttlecock trajec-tory and hit the shuttlecock with the racket.

The most substantial contribution in this group was observed for the complex of physical abilities, but it was dominated by another test, i.e. the envelope test. How-ever, it should be emphasized that the result of this test is associated not only with the speed of recruitment of energy sources but also with motor coordination (fast and rhythmic changes in the direction of movements). This phenomenon can be associated with the struc-ture of the model in the area of coordination abilities. Also the contribution of the abdominal muscle strength test should be regarded as logical as it is associated with improvement in smashes and clears. The dominant orien-tation of training towards technique development is insufficient to fully utilize the factor of endurance, which in this phase of development starts playing an essential role in the game [3].

The somatic model of a cadet showed substantial differences in the components of body size. The atten-tion should be paid to the component of flexibility, which was located at the first place. This element seems to be useful for solving tasks on the court. The importance of flexibility for playing effectiveness was also empha-sized by subramanian [21]. In the multiple regression model, this variable explained around 10% of the de-


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pendent variable. The second place in the proposed model was taken by speed (around 8%). The analysed model also included arm length and quality of service and attack. All the variables introduced to the model explained around 33% of the playing effectiveness.

The importance of somatic aptitudes and flexibility for the quality of playing was also emphasized by Jeyara-man and Kalidasan [26]. In their multiple regression model, the whole model explained around 81% of the playing effectiveness.

It should also be emphasized that the age of cadets extends over the puberty period, when a decline in the value of this anatomical and functional parameter is more pronounced. consequently, this might cause a high dispersion of results. correlation between body size and sports skill level points to a significant role of the developmental age in earlier achievement of better re-sults in competition. This thesis is reinforced by the strongly accentuated views on the variation of the mor-phological age and its effect on the results achieved in terms of performance of motor tasks. The greatest vari-ation of physical development was observed in the pu-berty period, which, in extreme cases, may reach the span of eight years. since the group of juniors was aged from 14 to 16 years, the relationships found in the study seem to be obvious. slightly better sports results in this group were obtained by accelerants and individuals who were genetically programmed to be tall. Therefore, the factor of the morphological age must be taken into considera-tion in the athletic training to understand the causes of developmental delay or accelerations. This problem was also emphasized in studies by Waddell and In Hong [27]. They highlighted the importance of adjust-ing the exercises to developmental abilities of children and reasonable (rational) development of the technique which is consistent with physical abilities of young badminton players.

The system of variables in the models that describe the determinants of the sports skill level in the group of juniors also turned out to be interesting and slightly different than in younger groups of badminton players. At this stage of training process, physical abilities remain to be essential, which is especially noticeable in the dom-inant variable of MAP of the arms. This phenomenon is logical since juniors do not only have well-developed technique but also the speed and force of hitting the shuttlecock that are necessary at this stage. Further-more, the efficient shots require fast moving on the court in order to adopt a specific position in time and space. This determines a high level of MAP of the lower limbs, which manifests itself in, for example, the enve-lope run [19]. The movement actions typical of perfor-mance of these tests are immanent in the effective playing.

The composition of variables in the somatic model of junior was connected with the range of arm motion, which can often compensate for the deficiencies in effec-tive movements on the court. However, the variable of

wrist mobility was dominant. This can be justified by the fact that this helps a player to generate initial speed and force applied to the shuttlecock.

There is also the problem of coordination abilities which are slightly weakened at this stage of training. This might be the effect of lower dispersion of the results and consequently, equalization of their level in this group of players, although it should be also emphasized that these abilities are of higher level of organization like selective reaction time, reaction to the moving ob-ject, movement integration and kinaesthetic differen-tiation. These abilities have a leading effect on develop-ment of technique of movements of higher order, typical of the effective playing at this level of training process.

Conclusions

1. All the models of sports skill level determination are most pronounced in the group of cadets, less pro-nounced in the group of juniors and the least in younger cadets.

2. In all three groups of young badminton players, the dominant effect on the quality of playing is due to a complex of variables that determines physical abilities.

3. The model of coordination abilities slightly deter-mines the sports skill level on the initial level of training process, and its contribution in this area rapidly in-creases in the group of cadets and insignificantly de-clines in the group of juniors. It should also be empha-sized that its structure changes not only in quantitative but also in qualitative terms.

4. At the initial stage of training process, sports skill level is determined by a comprehensive fitness. At the next stage, it largely depends on body size and efficiency of moving on the court and a wide set of variables that determine movement coordination. In the group of jun-iors, this level is more determined by maximal anaerobic power of the upper limbs, wrist mobility and a complex of coordination abilities with higher degree of motor organization.

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9. Poliszczuk T., Mosakowska M., Anthropometric profile of Polish elite badminton players [in Polish]. Medycyna Sportowa, 2010, 1 (6), 26, 45–55.

10. Jaworski J., Żak M., The structure of morpho-functional conditions determining the level of sports performance of young badminton players. J Hum Kinet, 2015, 47 (1), 215–223, doi: 10.1515/hukin-2015-0077.

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13. Bańkosz Z., Nawara H., Ociepa M., Assessment of simple reaction time in badminton players. Trends in Sport Sci-ences, 2013, 1 (20), 54–61.

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process and sports competition in team games (hand-ball) [in Polish]. MTNGs, Wrocław 2009, 12, 76–83.

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25. Dube s.P., Mungal s.U., Kulkarni M.B., simple visual re-action time in badminton players: a comparative study. Natl J Physiol Pharm Pharmacol, 2015, 5 (1), 18–20, doi: 10.5455/njppp.2015.5.080720141.

26. Jeyaraman R., Kalidasan R., Prediction of playing abil-ity in badminton from selected anthropometrical phys-ical and physiological characteristics among inter col-legiate players. Int J Adv Innov Res, 2012, 2 (3), 47–58.

27. Waddell D.B, Badminton for children based on biomecha-nical and physiological principles. In: Hong Y., Johns D.P., sanders R. (eds.) 18th International symposium on Bio-mechanics in sports. Hong Kong June 25–30. Department of sports science and Physical Education. The chinese University of Hong Kong, Hong Kong 2000, 837.

Paper received by the Editor: January 27, 2016Paper accepted for publication: March 31, 2016

Correspondence addressJanusz JaworskiZakład Teorii sportu i AntropomotorykiWydział Wychowania Fizycznego, Instytut sportuAkademia Wychowania Fizycznegoal. Jana Pawła II 7831-571 Kraków, Polande-mail:[email protected]

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2016, vol. 17 (1), 29– 35

Body sTABIlITy And supporT scull KInEmATIc In syncHronIzEd swImmIng

AlIcJA ruTKowsKA-KucHArsKA*, KArolInA wucHowIczDepartment of Biomechanics, University school of Physical Education, Wrocław, Poland

ABsTRAcTPurpose. The aim of this study was to examine the dependencies between support scull kinematics and body stability in the vertical position. Methods. The study involved 16 synchronized swimmers. Twelve markers were placed on the pubic symphysis, head, middle fingers, and transverse axes of upper limb joints. support scull trials were recorded at 50 fps by cameras placed in watertight housings. calculated measures included: excursion of the sculling movement; flexion and extension angle of the elbow and wrist joints; adduction and abduction angle of the shoulder joint; adduction and abduction angle of the forearm to/from the trunk; ranges of movement of the wrist, elbow, and shoulder joints; range of movement of forearm adduction towards the trunk; and the range of movement of shoulder adduction towards the trunk. Results. The length of the trajectory taken by the marker on the pubic symphysis was longer if the range of movement of the wrist joint was larger. The movement of the body in the right-left and upwards-downwards direction increased together with a greater range of movement of the wrist joint. It was also found that a greater sculling angle produced greater body displacement in the forwards-backwards direction. The head marker was characterized by a significantly larger range of displacement in the forwards-backwards and right-left directions than the pubic symphysis. Conclusions. The findings indicate that the ability to maintain body stability in the vertical position is associated with the range of movement of the radial wrist joint, angle of forearm adduction, and a newly-introduced measure – sculling angle.

Key words: sculling, vertical position, swimmer

doi: 10.1515/humo-2016-0008


Introduction

The relatively small (compared with other sports) num-ber of scientific publications on synchronized swimming can be explained by the fact that it is still a new, albeit rapidly growing, discipline. A review of the available litera-ture finds reports that have attempted to: determine the total duration and number of times swimmers spend underwater during a solo routine [1], measure the effects of propulsive sculling action in horizontal body displace-ment [2], compare the efficiency of repetitive arm move-ments by synchronized swimmers and artistic gym-nasts [3], measure the force produced in standard and contra-standard sculling [4], search for a relationship between eggbeater kicking skills with leg and trunk muscle strength and the technical skills needed to main-tain the vertical position [5], determine unhealthy be-haviors in swimmers and examine the relationships between perfectionism, body esteem dimensions, and restrained eating [6], assess the effects of vibration and stretching on passive and active forward split ranges of motion [7], and evaluate the dynamic asymmetry of support sculling [8]. However, few studies have dealt exclusively with analyzing the synchronized swimming technique. One reason may stem from the necessary albeit complex demands of recording synchronized swim-ming movements underwater.

synchronized swimming is a branch of swimming in which swimmers compete by executing a specific move-ment routine composed of numerous technical elements. This discipline is dominated primarily by movement sequences performed in an upright (vertical) position, with the head above or under water. A more compre-hensive literature review found a limited number of studies analyzing lower limb movements such as the egg-beater and boost kicks, techniques which allow swim-mers to move or rise out of the water or maintain the body in the vertical position [9–11]. some congruency between these swimming techniques and those used in water polo was found [12]. However, few have exam-ined the employment of the upper limbs in synchro-nized swimming. Although the use of the upper limbs when underwater (termed as sculling) is not subject to scoring during competition, the upper limbs are essen-tial in synchronized swimming performance as they allow a swimmer to execute various movement routines and figures in both static and dynamic conditions. Two commonly executed sculls are the standard scull and support scull. The standard scull (and contra-stand-ard) is used to align the swimmer’s body in the layout position whereas the support scull is employed to main-tain the vertical position, with the head above or under the water. support scull has been described as one of the most difficult techniques in synchronized swimming since it involves steadily and smoothly displacing the body while maintaining a part of it above the water [13]. During vertical position maintenance, with head above

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HUMAN MOVEMENTA. Rutkowska-Kucharska, K. Wuchowicz, Body stability in synchronized swimming

the water, correct sculling technique requires an elbow flexion angle of 90° while maintaining the arm in a rela-tively stationary position with the forearm performing the sculling motion [14]. conversely, in order to keep the swimmer’s body in the vertical position with head under the water, swimmers hold their elbows und up-per arms stationary whereas the forearms are kept horizontally at 110–145° of elbow flexion [13]. Analysis of support scull kinematics in the vertical position (head under water) was found to differ depending on the length of the lower limbs [15]. During sculling the hands of swimmers typically execute a “figure 8”, egg-shaped oval, or ellipse movement [2, 16]. Another alter-native is to use hand dorsiflexion. some sculls, such as the reverse, dolphin, and alligator sculls use a technique involving palmar flexion. sculls performed with both palmar and dorsal flexion allow swimmers to rotate and twist when in the vertical position [17]. One study to date has attempted to determine the most efficient hand configuration for generating maximal lift by hy-drodynamic analysis [16]. Additional interest in scull-ing technique stems from the fact that synchronized swimming is a subjectively judged sport, where criteria such as the accuracy in executing various figures as well as the ability to maintain the body in a high and stable position above the water are very important. Further-more, the difficulty in learning the necessary skills to support the body in the inverted vertical position, which takes up to two years according to coaches, warrants additional research on synchronized swimming tech-nique and the ability of the swimmer to maintain body stability in the water.

A review of the available literature shows no inves-tigation on the correlations between the kinematic vari-ables associated with support scull technique and balance. One available publication has analyzed the kinematic variables of sculling in elite synchronized swimmers able to maintain nearly perfect body balance, leading them to create an elite movement model but this is based on swimmers that demonstrated proficient and balanced support scull [10]. The difficulty in learning the necessary skillset to support the body in the inverted vertical position can take up to 2 years according to coaches and therefore warrants the need for additional research on support scull technique in order to ascer-tain technique efficacy.

Therefore, the aim of the present study was to search for correlations between support scull kinematics (with the introduction of a new angular variable to quantify the support scull movement cycle) and the ability to maintain balance in the inverted vertical position. Al-though the biomechanical investigation of synchronized swimming technique – in contrast with competitive swimming [18] – is not directly associated with achiev-ing competitive success, it can aid in the identification of the factors responsible for technique execution and therefore contribute to enhanced performance.


The sample consisted of 16 female synchronized swimmers with varying levels of performance, from be-ginners (juniors) to experts (master class). Mean (± SD) age, body mass, and body height was 15.9 ± 3.5 years, 51.9 ± 6.2 kg, and 160.6 ± 6.2 cm, respectively. Written informed consent was obtained from the guardians of the participants as was approval from the local ethics advisory committee.

Optimum conditions were ensured in order to pro-vide high-quality data acquisition [19]. Two digital JVs video cameras recording at 50 fps and 100 Hz, placed in watertight housings, were affixed perpendicularly to the walls of a pool. A frame of reference in the shape of a rigid cube (1 m/1 m/1 m) with six selected reference points was used during filming. Both cameras were syn-chronized with a flash of light. Twelve markers (Figure 1) were drawn on the swimmers’ bodies corresponding to the transverse axes of the shoulder, elbow, wrist, and hip joints and on the pubic symphysis, head, and right and left middle fingers. The markers were 1 cm in diameter and drawn with a waterproof pen directly on the body. Each participant was then filmed performing

Figure 1. Location of body markers to define flexion and extension angle of the wrist joint ( ), flexion

and extension angle of the elbow joint ( ), adduction and abduction angle of the shoulder joint ( ), adduction

and abduction angle of the forearm to/from the trunk ( ), sculling angle( )

31


three trials of eight support scull cycles with both lower limbs extending out of the water. The experiment was preceded by a warm-up and all participants wore swim-suits, caps, swimming goggles, and nose clips.

support scull kinematics was quantified using sIMI Motion® software by assessing individual move-ment cycles. since sculling is performed in all three ana-tomical planes, the breakdown of this movement based on only the angle created by the elbow joint was consid-ered insufficient. Therefore, we adopted the angular motion made at both the elbow and wrist joints (meas-ured by the shoulder, elbow, and middle finger markers). This angle was defined herein as the sculling angle ( ). The sculling movement cycle was then delineated by the changes in the sculling angle, where the first phase of the sculling movement cycle was treated as the minimum to maximum sculling angle and the second phase of the sculling movement cycle as the maximum to mini-mum value. Based on these phases, the following tempo-ral and kinematic characteristics of the sculling move-ment cycle were considered:

– duration of the sculling movement cycle [s]– duration of the first and second sculling cycle

phases [s]– trajectory length of the sculling movement (based

on the displacement of the middle finger marker) [m]– flexion (palmar flexion) and extension (dorsi-

flexion) angles of the wrist joint ( ) [°]– flexion and extension angles of the elbow joint ( ) [°]– adduction and abduction angles of the shoulder

joint ( ) [°]– adduction and abduction angles of the forearm

to/from the trunk ( ) [°]– sculling angle ( ) [°]– ranges of movement of the radial wrist, elbow,

and shoulder joints [°]– range of movement during forearm adduction to-

wards the trunk [°]– range of movement during shoulder adduction

towards the trunk [°]The angles defined in the study are shown in Fig-

ure 1. Body stability during the support scull was as-sessed by measuring:

– trajectory created by the head and pubic symphysis markers (over subsequent scull cycles)

– marker displacement in the forward–backward (frontal plane), right–left (sagittal plane), and upward–downward (transverse plane) directions (for each scull cycle) [m].

statistical analysis was performed using statistica v 9.1 software. Means and standard deviation were calculated for all variables. The one-sample Kolmogorov–smirnov test was used to examine the normality of data distribution. Non-parametric measures were then applied (Wilcoxon signed-rank and spearman’s rank correlation tests). Differences were considered signifi-cant when the probability was at p 0.05.

Results

For this purpose, the mean displacement of the two markers placed on the pubic symphysis and on the head was calculated in three anatomical planes. Additionally, another criterion was the measurement of the length of the trajectory taken by the markers located on the pubic symphysis and head (Table 1).

To research the relationship between the kinemat-ic variables of sculling and body stability the criteria for assessing body stability should be determined. The first criterion was the displacement of the swimmer’s body in three directions. Differences in upward–downward displacement and trajectory length of the head and pubic symphysis markers were not statisti-cally significant. However, the head marker was char-acterized by significantly (p 0.05) greater range of displacement in the forward–backward and right–left directions than the pubic symphysis. This finding sug-gests the important role of head movement in correcting sway when submerged under the water. For the remainder of the present study we assessed body stability with the pubic symphysis marker.

Analysis of the angles as well as ranges of movement found the largest range of movement was exhibited in forearm adduction (Table 2). This movement was also found to feature the smallest variability among the swimmers. The smallest range of movement yet with the

Table 1. Mean displacements and trajectory lengths (per scull cycle) by the pubic symphysis and head markers

Variable Direction Mean ± SD coefficient of variation (%)

Displacement (m)

Head marker

Pubic symphysis marker

Forwards–backwards Right–leftUpwards–downwardsForwards–backwards Right–leftUpwards–downwards

0.044 ± 0.010 0.028 ± 0.007 *0.034 ± 0.0150.028 ± 0.0160.023 ± 0.010 0.034 ± 0.010

*

23.5425.3343.6658.0045.6629.67

Trajectory length (m)Head marker 0.13 ± 0.06 51.19Pubic symphysis marker 0.12 ± 0.09 65.52

* statistically significant difference p 0.05

32


greatest amount of variability was found in the wrist joint angles.

For the sculling angle, the first phase (lateral shoulder movement) was significantly (p 0.05) shorter in du-ration than the second phase (medial shoulder move-ment) (Table 3).

correlational analyses were performed between the range of displacement and the trajectory of the pubic symphysis marker (Table 1) and scull kinematics (Ta-ble 2). A statistically significant relationship (spearman’s r = 0.621, p < 0.01) was found between the trajectory of the pubic symphysis marker and radial wrist joint range of movement. The range of displacement of the pubic symphysis marker (and thus the body of the swimmer) in the right–left direction was positively cor-related (spearman’s r = 0.602, p < 0.013) with the range of movement of the wrist joint and negatively correlated (spearman’s r = –0.720, p < 0.001) with forearm adduc-tion towards the trunk. Movement in the forward–back-ward direction correlated (spearman’s r = 0.547, p < 0.028) with sculling angle, whereas upward–downward move-ment correlated (spearman’s r = 0.614, p < 0.011) with the range of movement of the radial wrist joint.

comparisons were made between the angular kine-matics of those who presented the least (A) and most (B) sway (best and worst stability, respectively) in order to determine a frame of reference for support scull tech-nique. The trajectory length of the pubic symphysis marker in one support scull cycle in the least stable swimmer (B) was 0.10 m, whereas the swimmer with

the greatest stability (A) showed only 0.05 m sway. The displacement of the pubic symphysis marker in swim-mer B in all three anatomical planes was twice as large as that in swimmer A. The differences in sculling tech-nique by swimmers A and B are illustrated in Figure 2, which presents the trajectories of the right and left middle fingers in all three anatomical planes. Differ-ences between both swimmers were also found in the shape of the trajectories as well as in the amount of upper limb asymmetry.

Discussion

The purpose of this study was to describe the move-ment technique used in sculling and determine the kine-matic variables associated with maintaining stability in the inverted vertical position. For this purpose, we proposed the division of the sculling movement into cycles and phases by the use of a newly introduced measure, the sculling angle, calculated by the movement of the elbow and wrist joints. The minimum and max-imum angular values were used to quantify the entire sculling movement into an initial phase (abduction and second phase (adduction). However, the linear and an-gular values we obtained are difficult to compare with the results of other authors as different criteria were used to quantify the sculling movement. Nonetheless, a com-parison of the duration of the sculling movements found that the present support scull cycle times were similar to the ones reported in other papers [20, 21, 15]. The

Table 2. Range of movement (º) for the right and left limb during a sculling movement

Range of movement

Right upper limb Left upper limb

Mean ± SD (º) coefficient of variation (%) Mean ± SD (º) coefficient

of variation (%)

sculling ( ) 57.05 ± 10.96 19.20 56.38 ± 13.30 23.6Elbow joint ( ) 50.61 ± 10.77 21.27 49.99 ± 19.15 38.3Wrist joint ( ) 26.80 ± 5.65 21.07 31.15 ± 9.6 30.72Forearm abduction/adduction ( ) 91.67 ± 7.65 7.66 91.77 ± 7.8 8.5Arm abduction/adduction ( ) 30.84 ± 4.25 13.76 30.83 ± 4.82 15.65

Table 3. Linear variables of upper limb movements during a sculling movement

Variable Upper limb Mean ± SDcoefficient

of variation (%) Relative time (%)

Duration of sculling (s)Duration of the first phase of sculling (s)Duration of the second phase of sculling (s)Trajectory length of the hand (m)

Right0.72 ± 0.050.31 ± 0.060.40 ± 0.061.74 ± 0.21

*7.32

17.9614.4315.15

10043

55.5–

Duration of sculling (s)Duration of the first phase of sculling (s)Duration of the second phase of sculling (s)Trajectory length of the hand (m)

Left

0.73 ± 0.050.28 ± 0.050.44 ± 0.051.64 ± 0.25

*6.98

18.1811.9115.21

1003860–

* statistically significant difference p 0.05

33


Figure 2. Hand movement trajectory lengths (m) (based on the right and left middle finger marker) for each anatomical plane in the swimmers with the best and worst support scull body stability

34


present sample of synchronized swimmers showed little variability in sculling movement cycle duration. However, the time of the first and second sculling cycle phases were found to substantially differentiate the swimmers. A comparison of the swimmers with the greatest and least amount of stability indicated that the swimmer with the most sway presented prolonged movement cycle and phase duration. For comparison purposes, the Olym-pic silver medalists examined by Homma and Homma [13] featured a shorter sculling movement cycle (0.69 s) than the best swimmer in this study, indicating a rela-tionship between scull cycle duration and competitive level. In addition, Rostkowska et al. [21] also demon-strated an association between the duration of the entire movement cycle and performance level, suggesting that swimmers who have trained for a longer period of time and achieved greater success exhibit reduced support scull movement time.

Analysis of the angular kinematics in sculling was delineated to the examined ranges of movement. The greatest range of movement was observed in the adduc-tion and abduction of the forearm. This range of move-ment was also characterized by the smallest variability among the swimmers. Homma and Homma [15] inves-tigated the minimum and maximum angular values and ranges of movement in synchronized swimming. While their results on wrist joint flexion are congruent with that observed in the present study, a number of differ-ences were found between both studies regarding the movement ranges of the elbow joint. This may be ex-plained by differences in the skill level of the samples, where the elite athletes exhibited greater palmar and dorsal flexion whereas the lower-level swimmers in the present study showed no dorsal flexion [15]. This finding high-lights the importance of training hand dorsiflexion, as it likely to influence sculling efficacy.

To our knowledge, no studies have yet analyzed the kinematic factors that affect body stability in synchro-nized swimming. This is surprising, as judges assess the ability to maintain the non-submerged parts of the body in a stable upright position over the water [17]. We as-sumed that one valid measure of body stability in support scull may be the displacement and ranges of movement of the pubic symphysis in all three anatomical planes, as this anatomical location is the closest to the body’s overall center of gravity. We found that this point on the body was characterized by greater movement vari-ability than the head, although the head marker was characterized by significantly greater displacement in the forward–backward and right–left directions than the pubic symphysis. This may indicate the important role of head movement in correcting the body’s stability when upside down underwater. The present findings confirm the importance of fine hand movements in maintaining stability in the vertical position. In particu-lar, we found that an increase in the excursion of the pu-bic symphysis marker was paralleled with an increased

range of movement of the wrist joint, as was the move-ment of the body in the right-left and upward-downward directions. Furthermore, a larger sculling angle was as-sociated with greater body displacement in the forward–backward direction. This finding implies that excessive flexion of the upper limbs at the elbow and wrist joints during support scull results in a loss of forward–back-ward stability. In turn, reduced range of movement of the forearm in relation to the trunk correlated with greater displacement in the right–left direction. These findings were confirmed regardless of whether they were performed by the swimmers featuring the greatest or least stability in the vertical position (albeit the latter was characterized by greater sculling asymmetry).

Conclusions

The use of a sculling angle, as proposed herein, can serve as a valid measure for dividing the upper limb movements of support scull into phases. Additionally, the trajectory and range of displacement of the pubic symphysis can also quantify body stability in the verti-cal position. Body stability in the vertical position was associated with the range of movement of the radial wrist joint, angle of forearm adduction, and sculling angle.

AcknowledgementsThis study was made possible by the financial support of the Polish Ministry of science and Higher Education (Grant Nr. 0338 /B/P01/2010/39).

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10. Homma M., Homma M., Three-dimensional analysis of the eggbeater kick in synchronized swimming. In: Vilas-Boas J.P., Alves F., Marques A. (eds.), Xth International sym-posium for Biomechanics and Medicine in swimming, Porto, Portugal. Biomechanics and medicine in swim-ming X. Port J Sport Sci, 2006, 6 (suppl 2), 40–42. Avail-able from: http://www.fade.up.pt/rpcd/_arquivo/RPcD_vol.6_supl.2.pdf.

11. Kubo Y., Homma M., Homma M., Takamatsu J., Ito K., Ichi kawa H., Biomechanical analysis of a “boost” in synchronized swimming. In: chatard J.c. (ed.), Biome-chanics and medicine in swimming IX. Proceedings of the IXth International symposium for, saint Etienne, France. University of saint-Etienne, saint-Etienne 2003, 535–538. Available from: https://www.iat.uni-leipzig.de/datenbanken/iks/open_archive/bms/9_535-538_Kubo.pdf.

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17. Gray J., coaching synchronized swimming figure tran-sitions. standard studio, Berkshire 1993.

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20. Hall s.J., support scull kinematics in elite synchronized swimmers. In: Bauer T. (ed.), Proceedings of the XIIIth Inter-national symposium on Biomechanics in sports. Lake-head University, school of Kinesiology, Thunder Bay, 1995, 44–47.

21. Rostkowska E., Habiera M., Antosiak-cyrak K., Angular changes in the elbow joint during underwater movement in synchronized swimming. J Hum Kinet, 2005, 14, 51–66. Available from: http://www.johk.pl/files/05rostkowskain.pdf.

Paper received by the Editor: November 4, 2015Paper accepted for publication: February 8, 2016

Correspondence addressAlicja Rutkowska-KucharskaDepartment of BiomechanicsUniversity school of Physical Educational. I.J. Paderewskiego 3551-612 Wrocław, Polande-mail: [email protected]

HUMAN MOVEMENT

36

A compArIson of sTATIc And dynAmIc mEAsurEs of lowEr lImB JoInT AnglEs In cyclIng: ApplIcATIon To BIcyclE fITTIng

rodrIgo rIco BInI 1, 2 *, pATrIA HumE 21 school of Physical Education of the Army, center for Physical Training of the Army, Rio de Janeiro, Brazil2 sport Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand

ABsTRAcTPurpose. configuration of bicycle components to the cyclist (bicycle fitting) commonly uses static poses of the cyclist on the bi-cycle at the 6 o’clock crank position to represent dynamic cycling positions. However, the validity of this approach and the po-tential use of the different crank position (e.g. 3 o’clock) have not been fully explored. Therefore, this study compared lower limb joint angles of cyclists in static poses (3 and 6 o’clock) compared to dynamic cycling. Methods. Using a digital camera, right sagittal plane images were taken of thirty cyclists seated on their own bicycles mounted on a stationary trainer with the crank at 3 o’clock and 6 o’clock positions. Video was then recorded during pedalling at a self-selected gear ratio and pedalling cadence. sagittal plane hip, knee and ankle angles were digitised. Results. Differences between static and dynamic angles were large at the 6 o’clock crank position with greater mean hip angle (4.9 ± 3°), smaller knee angle (8.2 ± 5°) and smaller ankle angle (8.2 ± 5.3°) for static angles. Differences between static and dynamic angles (< 1.4°) were trivial to small for the 3 o’clock crank position. Conclusions. To perform bicycle fitting, joint angles should be measured dynamically or with the cyclist in a static pose at the 3 o’clock crank position.

Key words: bike fitting, joint kinematics, photogrammetry, videogrammetry

doi: 10.1515/humo-2016-0005

2016, vol. 17 (1), 36– 42


Introduction

Optimal body position on the bicycle has been sug-gested to reduce injury risk and improve cycling per-formance [1, 2]. The configuration of bicycle components to the cyclist (bicycle fitting) has been usually conducted using tape measures and plumb bobs [3] with the dimen-sions of bicycle components related to anthropometric dimensions of the cyclist [4, 5]. For the configuration of bicycle components (e.g. vertical and horizontal posi-tions of the saddle), joint angles have been preferably recommended in comparison to anthropometric refer-ences [6]. The reason is that length based references for saddle height configuration does not take into account particular differences in thigh, shank and foot length. The effectiveness of the “optimum” relationship between bicycle components and body dimensions failed to result in similar body positions because joint angles have not been taken into account. An optimal combination of hip, knee and ankle joint angles would indeed result in op-timal power production from the lower limb muscles.

In cycling the use of video analysis to optimize the configuration of bicycle components is increasing [7, 8]. However, all guidelines are based on measurements of the cyclist in static poses without information on po-tentially optimum joint angles from dynamic assessments. Burke and Pruitt [3] suggested that knee flexion angle should be between 25–30° when the pedal is static at the

bottom of the crank cycle (6 o’clock crank position) for an optimum saddle height configuration. Yet, Peveler et al. [7] showed that the knee flexion angle measured statically at the 6 o’clock crank position underestimated the knee flexion angle taken during cycling motion by ~17%. Their result indicates that another approach should be taken to ascertain the saddle height by using either a dynamical assessment or a static measure in a different crank position (whenever video analysis is not possible). Assuming that the peak crank torque is ap-plied close to the 3 o’clock crank position [9] and that leads to peak patellofemoral compressive force [10], this position could be used rather than the 6 o’clock crank position. Also, the 3 o’clock crank position has been used to ascertain the forward-backward saddle position [11] and that is closer to the knee joint angle of optimal quadriceps muscle force production for cyclists [12].

Given previous studies showed that knee flexion angles are larger at dynamic compared to static assessments of cyclists [7, 8], a comparison between static and dynamic analyses of joint angles for optimization of bicycle com-ponents have not fully being explored. This comparison could show that a static position of cyclists (i.e. at 3 o’clock crank angle) could be valid to replicate joint angle ob-served during cycling motion. clinicians that do not have access to motion analysis systems could then benefit by using a single digital still camera to capture images from cyclists at a given position on their bicycles. Bicycle saddle position (vertical and fore-aft) could then be con-figured more properly, leading to an improvement in bike fitting methods.

R.R. Bini, P. Hume, comparison of static and dynamic angles in cycling

37

HUMAN MOVEMENT

Thus, the aim of this study was to compare lower limb joint angles of cyclists in static postures compared to dynamic cycling. This comparison would indicate if joint angles taken during static poses at the 3 o’clock crank position would replicate a dynamic cycling mo-tion. The hypothesis was that cyclists would replicate similar joint angles in static poses only at the 3 o’clock crank position.


Design

All cyclists attended one evaluation session (cross-sec-tional) where anthropometric measures, images from static postures (photogrammetry) and dynamic cycling from video (videogrammetry) from their right sagittal plane were collected. They did not have the configura-tion of their bicycles changed throughout the study to avoid changing their preferred set up and affect their preferred muscle recruitment.

Participants

Thirty cyclists with experience ranging from recrea-tional to competitive volunteered to participate in the study. The characteristics of the cyclists were (mean ± SD) 39 ± 10 years old, 80 ± 15 kg body mass, 177 ± 8 cm height, 7.3 ± 3.8 hours/week cycle training, and 8 ± 7 years cycle experience. Prior to the study participants were informed about possible risks and signed a consent form approved by the Ethics committee of Human Re-search where the study was conducted in accordance to the declaration of Helsinki.

Procedures

As landmarks for the hip, knee and ankle joint axes, reflective markers were placed on the right side of the cyclists at the greater trochanter, lateral femoral con-dyle, and lateral malleolus (see Figure 1). Two markers were attached to the pedal to compute the pedal axis and one marker was attached to the bottom bracket to determine the crank axis. Two markers were taped at a known distance on the bicycle frame for linear image calibration in metric units. The distance from the camera to the bicycle and zoom setting were defined to reduce the motion of the cyclists in the edges of the image frame as an attempt to reduce non-planarity errors in angle computation (for details see Page et al. [13] and Olds and Olive [14]).

cyclists had their own bicycles mounted on a wind trainer (Kingcycle, Buckinghamshire, UK), and were asked to assume a position as similar as possible to out-doors cycling. A digital camera (samsung Es15, seoul, south Korea) recorded three high resolution images

(3600 × 2400 pixels of resolution) from the sagittal plane with the cyclists standing on the floor (calibration image), cyclists seated on the bicycle with the right crank in the most forward position (3 o’clock) and the right crank in the lowest position on the crank cycle (6 o’clock). One image was recorded at each position to simulate common procedures used in bicycle fitting configuration when a cyclist’s knee flexion angle is measured using a manual goniometer [3, 15]. cyclists were then asked to select a gear ratio and assume ped-alling cadence as similar as possible to steady state cruis-ing road cycling for five minutes simulating regular long distance training. After three minutes of riding, video was recorded for 20 s using the same digital camera (30 Hz, 640 × 480 pixels of resolution) which was shown to provide reliable measurements of rearfoot timing variables (e.g. time of maximal eversion) during running in a previous study [16]. The digital camera used in our study enabled picture capture in high resolution and video recording at regular frame rate and resolution simi-lar to cameras used in motion analysis systems (i.e. 1 mega pixel). Assuming that cyclists would freely choose ped-alling cadence close to 90 rpm, we expected that our resolution for crank angle definition would be of 18° per crank revolution and consequently of 3.6° for averages of five crank revolutions.

Hip, knee and ankle joint angles were manually digi-tized from the static postures and video files using ImageJ (National Institute of Health, UsA) by the same rater for the 30 cyclists. Joint angles definitions are illustrated in Figure 1. For dynamic cycling, frames taken from five consecutive crank revolutions where cyclists were at the 3 o’clock and at the 6 o’clock crank positions were visually selected to compute joint angles. The average of five revolutions of each joint angle was used for com-parison with static poses. The rater’s reliability in digit-ising was determined using images from static poses ana-lysed on day one and day seven (see results in Table 1). Average pedalling cadence was computed for each cyclist from the time difference taken to cover five consecutive revolutions.

statistical analyses

Inferential statistics can be prone to error. Low power of tests would preclude extrapolation of results to a wider population using inferential statistics. Therefore, we used effect sizes opting for a threshold of large effects (Es = 1.0) for substantial changes. This is a more conservative approach than previously described [17], but it would ensure a non-overlapping in distribution of scores greater than 55% [18]. For comparison of measures taken in each image, typical errors were computed as the ratio between the standard deviation from the differences between days and the square root of “2” (TE = sDdiff/√2 – see Hopkins [19] for details).


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cyclists’ means and confidence limits (computed for p < 0.05) were reported for both static and dynamic hip, knee and ankle angles. To compare static and dy-namic angles (i.e. hip, knee and ankle), cohen‘s effect sizes (Es) were computed for the analysis of magni-tudes of the differences between the two methods and were rated as trivial (d < 0.25), small (d = 0.25–0.5), moderate (d = 0.5–1.0), and large (d > 1.0) [20]. Mean differences and standard deviation from the differ-ences between the joint angles measured in static and dynamic positions were computed to illustrate the agree-ment between methods, following description from Bland and Altman [21].

Results

Differences in measuring joint angles were trivial between days (< 4.5%) for hip, knee and ankle angles

based on analysis of cohen‘s effect sizes (see Table 1). Within cyclists coefficient of variation of joint angles taken across five crank revolutions was lower than 5%. Errors in determination of the 3 o’clock and the 6 o’clock crank positions in video files were < 1° (< 1%) and 3° (2%), respectively.

Freely chosen pedalling cadence was 85 ± 11 rpm for all cyclists. The differences between static and dynam-ic angles were large at the 6 o’clock crank position with greater hip angle (4.9 ± 1°), smaller knee angle (8.1 ± 2°) and smaller ankle angle (8.5 ± 2°) for static angles.

The differences between static and dynamic angles (< 2.5°) were trivial to small for the 3 o’clock crank position (see Figure 1 and Table 2). In Figure 2, we illus-trate the mean differences between joint angles measured in static and dynamic positions and the standard devi-ation from differences for the 6 o’clock and the 3 o’clock crank positions using the Bland–Altman’s plot [21].

Table 1. Intra-rater variability (between days comparison) in the analysis of images from static postures reported as typical error of measurements and effect sizes of the hip, knee and ankle angles at the 6 o’clock and at the 3 o’clock

positions of the pedal

Between day difference(degrees)

Between day difference

(%)

Typical error(degrees) Es Es – magnitude

inference

3 o’clock position

Hip angle 0.03° 0.61 0.14 0.01 TrivialKnee angle 0.05° 0.46 0.09 0.01 TrivialAnkle angle 0.98° 4.51 1.25 0.13 Trivial

6 o’clock position

Hip angle 0.05° 0.48 0.12 0.03 TrivialKnee angle 0.25° 0.42 0.12 0.01 TrivialAnkle angle 0.84° 4.01 0.58 0.17 Trivial

Figure 1. Illustration of reflective marker placement on the right side of the cyclist at the greater trochanter, lateral femoral condyle and lateral malleolus to indicate hip, knee and ankle joint angles. Markers attached to the pedal were used

to compute the pedal axis for ankle joint measurement. Mean hip, knee and ankle joint angles are shown for the 30 cyclists for static (s) and dynamic (D) measurements at the 3 o’clock (A) and 6 o’clock (B) crank positions.


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Table 2. Hip, knee and ankle angles (mean ± confidence interval – cI) at the 3 o’clock and 6 o’clock crank positions for 30 cyclists. comparison of the angles determined by static and dynamic methods using effect sizes (Es)

Difference between static and dynamic angles

static angle (degrees)

Dynamic angle (degrees) Degrees Es Es – magnitude

inference

3 o’clock crank position

Hip angle 38 ± 1.3 38 ± 1.1 0.3 ± 1.1 0.1 TrivialKnee angle 62 ± 1.7 63 ± 1.5 1.1 ± 1.6 0.3 TrivialAnkle angle 125 ± 2.4 122 ± 2.2 2.5 ± 2.5 0.4 small

6 o’clock crank position

Hip angle 67 ± 1.8 62 ± 1.4 4.9 ± 1.1 1.1 LargeKnee angle 30 ± 2.4 38 ± 1.5 8.1 ± 1.9 1.5 LargeAnkle angle 131 ± 2.1 139 ± 2.4 8.5 ± 1.9 1.4 Large

Figure 2. Differences between measures (individual scores), mean differences between joint angles measured in static and dynamic positions and the standard deviation from differences for the 6 o’clock and the 3 o’clock crank

positions using the Bland–Altman’s plot [21]


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Discussion

In bicycle shops, clinics and bicycle research, con-figuration of bicycle components to the cyclist (bicycle fitting) takes into account lower limb joint angles deter-mined from a static position of cyclists at the 6 o’clock crank position measured once [3, 11]. However, cycling is a dynamic movement, so bicycle configuration should ideally be based on dynamic assessment looking at the average of consecutive pedal revolutions. Our study re-ported differences between lower limb joint angles gathered from cyclists in static postures compared to dynamic cycling. cyclists in our study did not repli-cate similar angles in static postures as those observed in video analysis when the crank was at the 6 o’clock crank position. Given the fact that the static 6 o’clock crank angle method is commonly used in bicycle shops and clinics, the results of the current study showed that the 3 o’clock position would be a better method to set-up a cyclist on a bicycle if dynamic cycling angles are not available.

The measurement of joint angles in images of cyclists on their own bicycles has the potential to improve the existing techniques for bicycle configuration components optimization [15]. Joint angles are important variables for the configuration of bicycle components to help re-duce injury risk and optimize performance [6, 22], but the assessment of joint angles of cyclists may depend on exercise conditions. Previous studies presented the de-pendence of joint angle on workload level [23], pedal-ling cadence [24], fatigue state [25] and experience in cycling [26]. Therefore, these factors should ideally be taken into account when providing a bicycle set-up.

Farrell et al. [27] reported that configuring saddle height to elicit 25–30° of knee flexion using a goniometer with the cyclist in a static pose at the 6 o’clock crank posi-tion resulted in 30–45° knee flexion at the same 6 o’clock crank position in video analysis. The larger knee flexion angles (~10°) in dynamic cycling reported by Farrell [27] and Peveler et al. [7] using the goniometer method were also evident in our study (8.2 ± 5°) using the digitisation of the static pose to determine knee flexion angle at the 6 o’clock crank position. Therefore, one has to be careful that the static recommended angles might result in dif-ferent joint angles than the ones intended for cycling motion.

Greater hip angle (smaller flexion), smaller knee angle (smaller flexion) and smaller ankle angle (greater flexion) were observed in static poses at the 6 o’clock crank position compared to the dynamic assessment in our study. Looking at the main driving muscles of cycling (hip and knee joint extensors and ankle plantar flex-ors), hip and knee joint extensors may be shorter and ankle plantar flexors may be longer in the static pose at the 6 o’clock crank position compared to the one during dynamic cycling due to smaller flexion angles. These differences may affect muscle tendon-unit length and force production [28].

Differences in joint angles between static and dynam-ic analysis may be related to the lack of angular mo-mentum at the 6 o’clock crank position during static poses, which is contrary to what is observed during dynamic cycling. For pedalling at 90 rpm, cyclists usually present ~27% greater angular velocity of the crank at the 12 o’clock and 6 o’clock crank positions compared to the average angular velocity of the revolution [29]. Two reasons may explain the similarities of the static and dynamic joint angles at the 3 o’clock crank position: 1) There is ~28% lower angular velocity in dynamic cycling at the 3 o’clock crank position than the average angular velocity over the entire revolution of the crank [29]; and 2) To sustain the cranks horizontally at the 3 o’clock crank position, cyclists need to balance the mass of the ipsilateral and contralateral legs.

In terms of saddle height adjustment, a range of 25–30° of knee flexion has been recommended to im-prove efficiency and reduce the risk of injuries in cy-clists [22]. Reductions of ~8° may be expected for the knee flexion angle of cyclists assessed statically at the 6 o‘clock position in comparison to dynamic assessment. Therefore setting the saddle height by a static pose of the cyclist taken at the 6 ‘clock position would generally result in a lower saddle height than the one taken dy-namically. Depending on the existing saddle height, suboptimal muscle length for force production and in-creased compressive knee forces would be observed using a lower saddle height [22]. Although the goal of the current study was not to determine recommendations for bicycle fitting, it would be ideal to match the knee flexion angle for optimal torque production (~60–80°, see Folland and Morris [30]) to the one observed at the optimal crank angle for torque production (i.e. 3 o’clock). Future research should be conducted to ascertain on what ranges of hip, knee and ankle angles taken together would optimize cycling performance.

The choice of using the same camera to acquire video and capture images of the cyclists in static poses had positive and negative effects in our study. One benefit was that there was no effect from different lenses on image distortion. However, the camera used in the pre-sent study was not capable of recording images and video at the same resolution (which would be similar to cameras used by bicycle shops providing bicycle configuration services). Video images had ~19% of the resolution of the static images, which may have reduced the precision of tracking markers in video images compared to im-ages from static poses. However, the choice for analysis of mean results of joint angles over five crank revolu-tions increased the accuracy of crank angle determi-nation for joint angle computation.

sources of error using sagittal plane video may be out of plane movements and linear image calibration. In cycling, most movement can be assessed via sagittal plane analysis, but up to 10% of differences may be expected for the hip angle when measuring from the


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sagittal plane compared to 3D analysis [31]. Pelvic mo-tion during cycling may also affect the comparison of images from static and dynamic analyses. Horizontal (± 5 cm) and vertical (± 2 cm) motion of the hip joint occurs during stationary cycling [32] which may affect lower limb joint angles especially for cyclists using a higher saddle height. Therefore, bicycle set-up should ideally use images from both sagittal and frontal planes or 3D analyses.

Conclusions

cyclists did not replicate in a static pose at the 6 o’clock crank position similar hip, knee and ankle joint angles as measured in dynamic cycling. To perform configu-ration of bicycle components using joint angles, meas-urements should be taken dynamically or with the cyclists in static poses at the 3 o’clock crank position, instead of the usually recommended 6 o’clock crank position.

AcknowledgementsThe first author acknowledges capes-Brazil for his PhD schol-arship. The authors acknowledge AUT University for sup-porting this research Thanks are given to the cyclists who participated in the study

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Paper received by the Editor: December 31, 2015Paper accepted for publication: March 18, 2016

Correspondence addressRodrigo BiniDivisão de Pesquisa e ExtensãoEscola de Educação Física do Exércitocentro de capacitação Física do ExércitoAv. João Luiz Alves s/n, Urca, Rio de Janeiro, Brazile-mail: [email protected]

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43

JoInT-AnglE spEcIfIc sTrEngTH AdApTATIons InfluEncE ImprovEmEnTs In powEr In HIgHly TrAInEd ATHlETEs

doi: 10.1515/humo-2016-0006

2016, vol. 17 (1), 43– 49


mATTHEw r. rHEA1 *, JosEpH g. KEnn 2, mArK d. pETErson 3, drEw mAssEy 4, roBErTo sImão 5, pEdro J. mArIn 6, mIKE fAvEro 7, dIogo cArdozo 5, 8, dArrEn KrEIn 91 A.T. still University, Mesa, Arizona, UsA 2 carolina Panthers, National Football League, charlotte, North carolina, UsA 3 University of Michigan, Ann Arbor, Michigan, UsA 4 Game Time sports and Training, columbia, Tennessee, UsA5 Rio de Janeiro Federal University, Rio de Janeiro, Brazil6 cYMO Research Institute, Valladolid, spain 7 Logan High school, Logan, Utah, UsA8 Granbery Methodist college, Juiz de Fora, Brazil 9 Indianapolis colts, National Football League, Indianapolis, Indiana, UsA

ABsTRAcTPurpose. The purpose of this study was to examine the influence of training at different ranges of motion during the squat exercise on joint-angle specific strength adaptations. Methods. Twenty eight men were randomly assigned to one of three training groups, differing only in the depth of squats (quarter squat, half squat, and full squat) performed in 16-week training intervention. strength measures were conducted in the back squat pre-, mid-, and post-training at all three depths. Vertical jump and 40-yard sprint time were also measured. Results. Individuals in the quarter and full squat training groups improved significantly more at the specific depth at which they trained when compared to the other two groups (p < 0.05). Jump height and sprint speed improved in all groups (p < 0.05); however, the quarter squat had the greatest transfer to both outcomes. Conclusions. consistently including quarter squats in workouts aimed at maximizing speed and jumping power can result in greater improvements.

Key words: vertical jump, speed, squat depth, performance enhancement, sports conditioning

Introduction

The ultimate goal of a sports conditioning program is to enhance each individual athlete’s athletic potential through a structured program of physical development and injury prevention [1]. To this end, specificity of train-ing is a concept that should be of great importance to sports conditioning professionals. The body will adapt in very specific ways to meet the demands of a specific, re-occurring stress [2]. Resistance training that mimics the movements and demands of a given sport may en-hance performance in that sport through specific ad-aptations in neuromuscular performance.

siff [2] detailed this concept in a more complex, neurophysiologic manner stating that “it is vital to re-member that all exercise involves information process-ing in the central nervous and neuromuscular systems, so that all training should be regarded as a way in which the body’s extremely complex computing systems are programmed and applied in the solution of all motor tasks”. It is important to consider how the specific stress applied to an athlete’s body in conditioning will effect

or stimulate the neuromuscular system, as well as how conditioning can result in improved information pro-cessing and physiological performance in specific sport skills.

Accordingly, alterations in the range of motion for a given exercise may, theoretically, result in different adap-tations. squat depth has been a topic of much discussion in the field and literature [3–11] with primary focus centering on strength improvements at different training depths. More broadly, this debate is an issue of joint-angle specificity, which has been examined for comparable strength improvements [12–17]. The topic of joint-an-gle specificity was initially examined with isometric and isokinetic training, which was shown to increase strength at or near the angles trained, and at or near angular velocities trained, with little or no adaptation at other angles/velocities [17].

Three primary squat depths have been characterized and discussed in the literature [18], including partial/quarter squats (40–60 degree knee angle), parallel/half squats (70–100 degree knee angle), and deep/full squats (greater than 100 degree knee angle). Range of motion variation during the squat exercise influences various biomechanical factors that relate to specificity of move-ment pattern, and can affect the development of force, rate of force development, activation and synchroniza-

M.R. Rhea et al., Joint-angle specific strength adaptations

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tion of motor units, and dynamic joint stability. There-fore, the manner in which an exercise changes based on range of motion is an important concept to examine.

The purpose of this study was to examine the in-fluence of training at different squat depths on joint-angle specific strength as well as transfer to several sports-related performance variables. Understanding the effects of training at different ranges of motion can help the strength and conditioning professional to apply the most effective training strategy and further the performance enhancement advantages of evidence-based training prescriptions.


subjects

Male college athletes of all sports at various schools (Division I, II, III and Junior college) were invited to participate in this research. Inclusion criteria included: 1) minimum of 2 years of consistent year-round training, 2) a minimum parallel squat 1RM of at least 1.5 times body weight, and 3) no physical condition that would impair aggressive sports conditioning and high-intense resistance training. A total of 38 athletes volunteered to participate. Of those, 32 met the minimum strength requirement. Two subjects experiencing tendonitis in the knee were excluded prior to group assignment. Two subjects withdrew during the initial testing peri-od, resulting in 28 total subjects entering the training portion of the study. The methods and procedures for this study were evaluated and approved by an Institu-tional Review Board for research with Human subjects and all participants provided informed consent. The majority (n = 24) of the subjects were football players, with track (n = 1), basketball (n = 2), and wrestling (n = 1) completing the sport backgrounds. Random assignment resulted in 3 groups with similar anthropometric meas-ures, strength, and training experience. Descriptive data are presented in Table 1.

Procedures

Trained staff familiar with proper testing procedures and data handling performed all testing. Those con-ducting the pre-, mid-, and post-tests were blinded to the group assignment of each subject to avoid any po-tential bias. Experienced coaches implemented and over-

saw the training program to ensure proper execution, tempo, and adherence to the prescribed program.

strength testing was performed in accordance with published guidelines of National strength and condi-tioning Association [19]. subjects performed one rep-etition maximum (1RM) testing at each of the three squat depths (quarter, half, and full) in three separate sessions, randomized in order, with a minimum of 72 hours between testing sessions. All 1RM values were achieved within 3 attempts. In a fourth and final testing session designed to examine the reliability of the strength data, each subject repeated the 1RM testing procedures for each depth (Intraclass correlation coefficient rang-ing from 0.95–0.98). Non-significant differences (p > 0.05) were found between 1RM values on the different testing days at each specific depth tested; however, the highest 1RM for each depth was utilized for data analysis. Testing at week 8 was performed in a 7-day period with each depth randomly tested on a separate day a minimum of 48 hours apart. Post-intervention testing was per-formed according to the same protocols explained for the pre-testing.

Vertical jump testing was performed according to protocols previously published [19]. Immediately fol-lowing the dynamic warm-up in the first two testing sessions, all subjects were tested for their vertical jump using the Vertec (Vertec sports Imports, Hilliard, OH). subjects were given 3 attempts with the maximum height recorded. Non-significant differences were found be-tween the two testing sessions (p > 0.05) but the highest jump height was recorded for data analysis.

sprint testing was performed according to protocols previously published [19]. Following the dynamic warm-up in the first two testing sessions, all subjects performed a 40-yard sprint test. Electronic timing for the sprint was conducted with a wireless timing system (Brower Timing systems, Draper, Utah). subjects were given 2 attempts in each session with the maximum speed re-corded. Non-significant differences were found between the two testing sessions (p > 0.05) but the fastest speed was recorded for data analysis.

All aspects of the training program were identical for each group with the exception of squat depth and absolute load. Within subject strength differences at each depth, due to the biomechanical disadvantage with increased depth, resulted in greater absolute loads being used at quarter and half squat depths. However, relative loads were the same for each group. The program

Table 1. Baseline Descriptive Data

Group Age (years)

Weight (kg)

Pre-Quarter 1RM (kg)

Pre-Half 1RM (kg)

Pre-Full 1RM (kg)

Pre-VJ (cm)

Pre-40 (sec)

QTR 21.4 (3.2) 86.5 (25.6) 167.67 (13.95) 151.51 (15.12) 129.54 (17.23) 75.92 (15.06) 4.68 (0.18)HALF 20.7 (2.1) 95.7 (32.1) 162.12 (12.22) 146.72 (11.54) 125.50 (14.09) 77.03 (11.05) 4.73 (0.18)FULL 21.3 (1.3) 92.1 (23.8) 164.09 (13.18) 151.82 (12.80) 125.91 (18.38) 73.91 (14,25) 4.76 (0.20)

1RM – 1 repetition maximum, VJ – vertical jump, 40 – 40 yard sprint


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followed a daily undulating periodization sequence with intensity progressing from 8RM, 6RM, 4RM, to 2RM then reverting back to 8RM. Training weight was esti-mated using 1RM prediction equations based on the 1RM measures at the specific depth of training group, with notations made for rep ranges in each workout that required adjustments to the predicted values.

A split training routine was implemented to enable greater monitoring and control of lower body exercises. Lower body exercises (squats, power cleans, lunges, re-verse hamstring curls, and step ups) were performed on Monday and Thursday, and upper body exercises per-formed on Tuesday and Friday. squats (65%) and pow-er cleans (25%) made up 90% of the training volume for the lower body with the other exercises added for general athletic preparation but at low volumes in each session (1–3 sets) and were identical for all three groups. Exercise order was kept constant for all groups and subjects. Wednesday, saturday, and sunday were designated as rest days with no exercise prescribed or allowed.

Lower body workouts included 4–8 sets of squats, at the prescribed depth, followed by each of the other exercises. A linear periodization adjustment in volume was made throughout the training program (weeks 1–2: 8 sets; weeks 3–4: 6 sets; weeks 5–6: 4 sets; weeks 7–10: 8 sets; weeks 11–14: 6 sets; weeks 15–16: 4 sets). A three-minute rest was provided between each set. This re-sulted in total volume, relative intensity, and workout sessions that were equated across the 16-week training intervention for all groups.

squat depth was taught and monitored via video-taping throughout the training program. The first group performed full squats (FULL) with range of motion de-termined by the top of the thigh crossing below parallel to the floor and knee angles exceeding 110 degrees of flexion. The half squat group (HALF) trained at depths characterized by the top of the thigh reaching parallel to the floor with knee angles approximately 85–95 de-grees of flexion. The final group performed quarter squats (QTR) with range of motion involving a squat to approximately 55–65 degrees of knee flexion. Dur-ing the initial sessions, and during all testing, a goni-ometer (Orthopedic Equipment company, Bourbon, Indiana) was used to measure the appropriate depth. safety bars were raised or lowered in the squat rack for each subject to provide a visual gauge of the depth required. The coach provided immediate feedback if a slight alteration in depth was needed within a set.

A minimum of 30 workouts (out of 32) was required to be included in the final data analysis. This ensured that all subjects included in the analysis had completed roughly the same amount of work throughout the pro-gram. All 28 subjects met this requirement.

statistical analyses

Data were analyzed using PAsW/sPss statistics 20.0 (sPss Inc, chicago, IL, UsA). The normality of the data

was checked and subsequently confirmed with the sha-piro–Wilk test. Dependent variables were evaluated with a repeated measures analysis of variance (ANOVA) on group (QTR; HALF; FULL) × time (Baseline; Mid; Post). When a significant F-value was achieved, pairwise com-parisons were performed using the Bonferroni post hoc procedure. The level of significance was fixed at p 0.05. Partial Eta squared statistics ( 2) were analyzed to de-termine the magnitude of an effect independent of sam-ple size. Pre/Post effect sizes were calculated for each group and performance measure [20]. The coefficient of the transfer was then calculated from squat result gains to vertical jump and sprinting speed via a calcu-lation reported by Zatsiorsky [21]:

Transfer = Result Gain in nontrained exercise/Re-sult Gain in trained exercise

Result Gain = Gain in performance/standard de-viation of performance

The associations between different measures were assessed by Pearson product moment correlation at base-line time. Values are expressed as mean ± sD in the text, and as mean ± sE in the figures.

Results

Quarter squat – 1RM-test

A group × time interaction effect was noted for quar-ter squat test (p = 0.002; 2 = 0.545; see Figure 1a). A main effect of the group was observed (p < 0.001; 2 = 0.652), as well as a main effect of the time was noted (p = 0.012;

2 = 0.322).

Half squat – 1RM-test

A group × time interaction effect was noted for half squat test (p < 0.001; 2 = 0.563; see Figure 1b). However, there was no significant a main effect of the group was observed (p > 0.05; 2 = 0.002). A main effect of the time was noted (p < 0.001; 2 = 0.930).

Full squat – 1RM-test

A group × time interaction effect was noted for full squat test (p < 0.001; 2 = 0.647; see Figure 1c). However, there was no significant a main effect of the group was observed (p = 0.074; 2 = 0.278). A main effect of the time was noted (p < 0.001; 2 = 0.623).

Vertical Jump Test

A group × time interaction effect was noted for ver-tical jump test (p < 0.001; 2 = 0.689; see Figure 2). However, there was no significant a main effect of the group was observed (p > 0.05; 2 = 0.146). A main ef-fect of the time was noted (p < 0.001; 2 = 0.795).


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sprint Test

A group × time interaction effect was noted for ver-tical jump test (p < 0.001; 2 = 0.615; see Figure 3). How-ever, no significant main effect of the group was observed (p > 0.05; 2 = 0.232). A main effect of the time was noted (p < 0.001; 2 = 0.836).

Percent change (Table 2) and effect size calculations (Table 3) demonstrated the greatest changes in strength at the specific depth at which each group trained. QTR squat improved 12% in the quarter squat 1RM, HALF 14% at half 1RM, and FULL improved 17% in the full squat 1RM. For VJ and 40-sprint, the QTR squat group

showed the greatest treatment effect (VJ: 0.75; sprin: –0.58), followed by HALF (VJ: 0.48; sprint: –0.35), with FULL showing the lowest magnitude of training effect (VJ: 0.07; sprint: –0.10). Transfer calculations (Table 4) somewhat mimicked the other trends in the data with QTR showing the greatest transfer to VJ (0.53), with HALF next (0.28), and FULL showing the least amount of transfer (0.06). For sprinting speed, QTR showed the greatest transfe (–0.41) with HALF second (–0.20) and FUL (–0.09) again showing the least trans-fer. Finally, correlation analysis (Table 5) demonstrated stronger relationships between the QTR squat group and both VJ (r = 0.64) and sprint (r = –0.74) perfor-mances followed by HALF (r = 0.43 and r = –0.57) and FULL (r = 0.31 and r = –0.49).

Discussion

Taken collectively, these findings support the use of shortened ranges of motion during squat training for improvements in sprint and jump performance among highly trained college athletes. This conclusion should stimulate further consideration among strength and con-

* significantly different from Baseline (p < 0.05)# significantly different from Mid (week 8) (p < 0.05)† significantly different compared with the QTR group (p < 0.05)‡ significantly different compared with the HALF group (p < 0.05)

Figure 1. squat tests. Values are mean ± sE (QTR Group, n = 9; HALF Group, n = 9; FULL Group, n = 10)

* significantly different from Baseline (p < 0.05)# significantly different from Mid (week 8) (p < 0.05)† significantly different compared with the QTR group (p < 0.05)

Figure 2. Vertical Jump Test. Values are mean ± sE (QTR Group, n = 9; HALF Group, n = 9;

FULL Group, n = 10)

* significantly different from Baseline (p < 0.05)# significantly different from Mid (week 8) (p < 0.05)† significantly different compared with the QTR group (p < 0.05)

Figure 3. sprint test. Values are mean ± sE (QTR Group, n = 9; HALF Group, n = 9; FULL Group, n = 10)


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ditioning coaches regarding the use of quarter squats in a sports conditioning program. Further examination of the risks, benefits, and implementation of squats of var-ious depths is warranted, and will be discussed here.

Weiss et al. [7] conducted a study examining deep and shallow squat (corresponding to half and quarter squats in our study) and leg press training on vertical jump among untrained college students. Their study failed to find any significant changes in vertical jump for either group regardless of squat depth but two transfer calculations suggested greater transfer from the half squat training program to vertical jump. They did find statistically significant improvements in 1RM squat at the angle of training. The half squat group also improved 1RM at the quarter squat depth; however, the quarter squat training group did not improve 1RM performance in the half squat test. Our findings concur with the joint-angle specific improvement in strength relative to the angle where training occurred but differ in that

our study did not show an improvement in quarter squats in the half or full squat training groups. Addi-tionally, we found far less transfer from deep squat training to vertical jump. several distinct differences exist be-tween these two studies, perhaps accounting for the dif-ferent findings. Our study utilized very highly trained athletes training with free weights instead of untrained college students who trained with machines. Our study was also nearly twice the length (16 weeks compared to 9 weeks). It is notable that in our study, the mid-test data (8 weeks) showed no significant findings, highlight-ing the need for longer studies to examine these impor-tant training issues more critically. It is also possible that as an individual becomes more highly trained, joint-angle specific adaptations are more pronounced and detectable.

Joint-angle specificity has been suggested to relate to neurological control [17]. Thepaut-Mathieu et al. [14] found increases in EMG activity at trained joint angles

Table 2. Percet changes in performane measures

Group Quarter squat Half squat Full squat VJ 40 sprint

QTR 0.12 0.06 0.02 0.15 –0.02HALF 0.07 0.14 0.00 0.07 –0.01FULL 0.00 0.05 0.17 0.01 0.00

VJ – vertical jump; 40 – 40 yard sprint

Table 3. Effect size calculations based on squat depth

Group Quarter 1RM Half 1RM Full 1RM VJ 40 sprint

QTR 1.41 0.62 0.12 0.75 –0.58HALF 0.88 1.76 0.02 0.48 –0.35FULL 0.05 0.59 1.14 0.07 –0.10

Es – (post-pre)/pre-test sD

Table 4. coefficient of transfer calculations


QTR 1.00 0.44 0.08 0.53 –0.41HALF 0.51 1.00 0.01 0.28 –0.20FULL 0.05 0.52 1.00 0.06 –0.09

coefficient of transfer – result gain in nontrained exercise/result gain in trained exercise

Table 5. Bivariate correlations between strength capacities at different squat depths, vertical jump height, and sprint speed (n = 28)


Quarter 1RM 1 0.847** 0.722** 0.640** –0.740**Half 1RM 0.847** 1 0.693** 0.428* –0.567**Full 1RM 0.722** 0.693** 1 0.309 –0.490**

VJ –0.640** 0.428* 0.309 1 –0.779**sprint 0.740** –0.567** –0.490** –0.779** 1

** correlation is significant at the 0.01 (2-tailed)


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compared to untrained joint angles suggesting an increase in neural drive at the specific angles trained. Those data highlight the complexity of the nervous system pro-cesses for gathering information and responding to motor challenges. It appears that the nervous system gathers information relative to joint angles, contraction type, and angular velocities during training, responding with adap-tations specific to those training demands.

An examination of the differences in squat 1RM at the three different depths in the current study provides valuable information relative to joint-angle specific loads and may assist in the development of an explanation of why quarter squats transfer more to jumping and sprinting speed. First, the quarter squat range of motion matches more closely the hip and knee flexion ranges observed in jumping and sprinting. That said, on average, athletes were able to squat 30–45% more in a quarter squat compared to the full squat depth (10–20% more when compared to half squat depth). Using 1RM test-ing at full squat depths to calculate and apply training loads through a full squat range of motion, results in training loads at the top of the range of motion repre-senting less than 70% of maximum lifting capacity in that range of motion. consistently training at 60–80% of maximum capacity may promote strength gains in less trained populations but would not be considered sufficient for optimal strength development among more highly trained populations [22]. Quarter squats would not be expected to improve full squat strength due to the lack of stress applied in full squat joint angles and the data in the current study supports that assertion. But the load during full squats appears to be insufficient to promote significant gains in strength in the quarter squat joint angles in highly trained populations. Thus, the loads that are calculated for training are specific to the joint angles at, or near, the angle at which testing occurs. They do not represent optimal training loads for all angles in the range of motion.

Isometric research [15] has shown that strength im-provements only occur at or near the joint-angles where training occurs. Our data support this concept, as all of our groups were similar in gains at the half squat depth; however, significant differences were found at quarter and deep squats based on the training depths. The con-cept of joint-angle specificity as it relates to resistance training has generally been described as improvements in function at the joint-angles where training occurs. Under this philosophy, conventional thought has sug-gested that athletes must train through a full range of motion to ensure adaptations at all joint-angles. Given the data of the current study, it seems that strength im-provements are specific to joint-angles that are sufficiently overloaded, not just joint-angles where training occurs. Therefore, we propose a change in perspective, based on the current data and theory, to reflect the concept of joint-angle overload.

It is suggested that improvements in muscular fit-ness will occur at the joint-angles that are sufficiently

overloaded by the load placed upon them. In the con-ventional approach to measuring 1RM values at either a parallel or deep squat depth, and then performing squats at a certain percentage of that 1RM through a parallel or deep squat range of motion, the joint-angles involved in jumping and sprinting may not be sufficiently overloaded for maximal gains. Returning to the con-cepts proposed by siff [2] regarding information pro-cessing during training, it is suggested that the neuro-muscular system perceives, and adapts to, stresses applied during quarter squats much differently than full squats.

It is also important that the strength and condition-ing professional differentiate between transfer and value. If the goal of a specific workout were to enhance sprint-ing or jumping, quarter squats would be the most ef-fective range of motion based on the current data. But other squat depths may have value in preparing the athlete for competition, and coaches should examine the benefits, and risks, associated with squats of varying depths. If or when value exists, regardless of the amount of transfer directly to a given sports skill, an exercise or range of motion should be used to ensure that the athlete gains the full value of that exercise.

Different EMG activation patterns have been shown with various squat depths [10] and may provide evidence of specific value outside of transfer to sport skills. Full squats were shown to result in greater gluteus maximus activation with decreased hamstring involvement. Thus, squat depth may preferentially target recruitment of dif-ferent muscle groups. Understanding the exact benefits or drawbacks of different exercises and ranges of motion is imperative to optimal training and strength and con-ditioning professionals should place high value on edu-cating themselves and their clients regarding the pros and cons of a certain exercise or range of motion.

An additional consideration when selecting squat variations is the different stresses that each variation presents to the athlete. schoenfeld [18] provides a de-tailed review of the various stresses that occur at the ankle, knee, and hip joints during the squat exercise at various depths. With changing loads and ranges of mo-tion, stress appears to vary substantially. The increased load in a quarter squat, combined with the increased anterior shear force in that range, could present added risk of overuse injury if athletes only performed quar-ter squats. The same could be said of all squat depths and the best approach for health and performance en-hancement may be to include different squat variations (i.e. back, front, split) at all three squat depths. squats of different depths may need to be considered as sepa-rate exercises, or tools, employed for various purposes or to target specific muscles. A mixture of different squat depths, much like the use of various different exercises throughout a training program, may be the optimal ap-proach to developing the total athlete. However, based on the data from this study, it is clear that the use of quar-ter squats is not only helpful, but also necessary for pro-moting maximal sprinting and jumping capabilities.


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Conclusions

In summary given the significantly greater transfer to improvements in sprinting and jumping ability, the use of quarter squats during sports conditioning is recom-mended. Including quarter squats in workouts aimed at maximizing speed and jumping power can result in greater improvements in sport skills. While squats through a full range of motion may be useful in a general sports conditioning regimen, strength and conditioning pro-fessionals should consider the integration of quarter squats for maximizing sprinting and jumping ability.

References1. Kenn J., The coach’s strength training playbook. coaches

choice, Monterey 2003.2. siff M.c., supertraining. supertraining Institute, Denver,

colorado 2003.3. chandler T.J., Wilson G.D., stone M.H., The squat exer-

cise: attitudes and practices of high school football coaches. Natl Strength Cond Assoc J, 1989, 11 (1), 30–36.

4. chandler T.J., Wilson G.D., stone M.H., The effect of the squat exercise on knee stability. Med Sci Sports Exerc, 1989, 21 (3), 299–303. Available from: http://journals.lww.com/acsm-msse/pages/articleviewer.aspx?year=1989&issue=06000&article=00012&type=abstract

5. Klein K.K., The deep squat exercise as utilized in weight training for athletes and its effects on the ligaments of the knee. JAPMR, 1961, 15 (1), 6–11.

6. Wilson G.J., Newton R.U., Murphy A.J., Humphries B.J., The optimal training load for the development of dynamic athletic performance. Med Sci Sports Exerc, 1993, 25 (11), 1279–1286. Available from: ournals.lww.com/acsm-msse/pages/articleviewer.aspx?year=1993&issue=11000&article=00013&type=abstract.

7. Weiss L.W., Frx A.c., Wood L.E., Relyea G.E., Melton c., comparative effects of deep versus shallow squat and leg-press training on vertical jumping ability and related factors. J Strength Cond Res, 2000, 14 (3), 241–247.

8. Escamilla R.F., Knee biomechanics of the dynamic squat exercise. Med Sci Sports Exerc, 2001, 33 (1), 127–141. Available from: http://journals.lww.com/acsm-msse/pages/ articleviewer.aspx?year=2001&issue=01000&article=00020&type=abstract.

9. Rogers L., sherman T., Leg press versus squat. Strength Cond J, 2001, 23 (4), 65–69.

10. caterisano A., Moss R.F., Pellinger T.K., Woodruff K., Lewis V.c., Booth W. et al., The effect of back squat depth on the EMG activity of 4 superficial hip and thigh mus-cles. J Strength Cond Res, 2002, 16 (3), 428–432.

11. Drinkwater E.J., Moore N.R., Bird s.P., Effects of changing from full range of motion to partial range of motion on squat kinetics. J Strength Cond Res, 2012, 26 (4), 890–896, doi: 10.1519/Jsc.0b013e318248ad2e.

12. Lindh M., Increase of muscle strength from isometric quadriceps exercises at different knee angles. Scand J Rehabil Med, 1979, 11 (1), 33–36.

13. Knapik J.J., Mawdsley R.H., Ramos M.U., Angular speci-ficity and test mode specificity of isometric and isokinetic strength training. J Orthop Sports Phys Ther, 1983, 5 (2), 58–65, doi: 10.2519/jospt.1983.5.2.58.

14. Thepaut-Mathieu c., Van Hoecke J., Maton B., Myoelec-trical and mechanical changes linked to length speci-ficity during isometric training. J Appl Physiol, 1988, 64 (4), 1500–1505.

15. Kitai T.A., sale D.G., specificity of joint angle in isometric training. Eur J Appl Physiol Occup Physiol, 1989, 58 (7), 744–748, doi: 10.1007/BF00637386.

16. Weir J.P., Housh T.J., Weir L.L., Electromyographic evalu-ation of joint angle specificity and cross-training after iso-metric training. J Appl Physiol, 1994, 77 (1), 197–201.

17. Weir J.P., Housh T.J., Weir L.L., Johnson G.O., Effects of unilateral isometric strength training on joint angle specificity and cross-training. Eur J Appl Physiol Occup Physiol, 1995, 70 (4), 337–343, doi: 10.1007/BF00865031.

18. schoenfeld B.J., squatting kinematics and kinetics and their application to exercise performance. J Strength Cond Res, 2010, 24 (12), 3497–3506, doi: 10.1519/Jsc.0b013e3181bac2d7.

19. Baechle T.R., Earle R.W., Essentials of strength training and conditioning. 3rd edition. Human Kinetics, cham-paign 2008.

20. Rhea M.R., Determining the magnitude of treatment effects in strength training research through the use of the effect size. J Strength Cond Res, 2004, 18 (4), 918–920.

21. Zatsiorsky V.M., science and practice of strength train-ing. Human Kinetics, champaign 1995.

22. Rhea M.R., Alvar B.A., Burkett L.N., Ball s.D., A meta-analysis to determine the dose response for strength devel-opment. Med Sci Sports Exerc, 2003, 35 (3), 456–464, doi: 10.1249/01.Mss.0000053727.63505.D4.

Paper received by the Editor: september 22, 2015Paper accepted for publication: March 21, 2016

Correspondence addressMatthew RheaKinesiology DepartmentA.T. still University5850 East still circle, MesaAZ 85206, UsAe-mail: [email protected]

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50

AnAEroBIc ExErcIsE AffEcTs THE sAlIvA AnTIoxIdAnT/oxIdAnT BAlAncE In HIgH-pErformAncE pEnTATHlon ATHlETEs

mArcElo dE lImA sAnT’AnnA1, 2, gusTAvo cAsImIro-lopEs 1, 3, gABrIEl BoAvEnTurA1, 3, sErgIo TAdEu fArInHA mArquEs 4, mArTHA mErIwETHEr sorEnson 1, roBErTo sImão 1, vErônIcA sAlErno pInTo 1 *1 Department of Biosciences Physical Activity, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil2 Instruction center Almirante sylvio de camargo, Rio de Janeiro, Brazil3 Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil4 Navy sports commission, Rio de Janeiro, Brazil

ABsTRAcTPurpose. Investigate free radical production and antioxidant buffering in military pentathletes’ saliva after their performance of a standardized, running-based anaerobic sprint test (RAsT). Methods. seven members of the Brazilian Navy pentathlon team were recruited to perform a running-based anaerobic test (~90 sec). The participants provided samples of saliva before and after the test that were analyzed for biomarkers of oxidative stress such as lipid peroxidation, total antioxidant capacity and the quantity of two specific antioxidants, glutathione and uric acid. Results. The lipid peroxidation increased ~2 fold after RAsT, despite an increase in total antioxidant capacity (46%). The concentration of reduced glutathione did not change, while the uric acid concentration increased by 65%. Conclusions. The evaluation in saliva following a sprint test that lasted no more than 90 sec was sensitive enough to reveal changes in redox state.

Key words: saliva, physical exercise, oxidative stress, GsH, lipid peroxidation

doi: 10.1515/humo-2016-0003

2016, vol. 17 (1), 50– 55


Introduction

Free radicals are not intrinsically harmful to health: low-to-moderate concentrations play multiple regula-tory roles in gene expression, cell signaling, and skele-tal muscle force production [1, 2]. However, if there is an imbalance between production of free radicals and antioxidant capacity, oxidative stress occurs and can provoke tissue damage [3, 4].

Anaerobic and aerobic exercise can both increase free radical formation. Prominent among mechanisms of free radical production during anaerobic exercise are mitochondrial leakage, ischemia-reperfusion response and leukocyte activation [5, 6], so a short burst of in-tense anaerobic exercise can be effective in generating oxidative stress as assessed by xanthine oxidase activity and markers for lipid peroxidation, protein carbonyla-tion, and DNA oxidation, as well as total antioxidant capacity [5]. strenuous aerobic exercise induces an in-crease in lipid peroxidation in human plasma [1], likely generated by hydroxyl radical attack on polyunsatu-rated fatty acids [5].

Providing blood samples increases stress in athletes that can limit their willingness to participate in scien-tific studies, especially during competition. This study examines oxidative stress, for the first time in military

athletes training for an international competition called the naval pentathlon, using a non-invasive analysis of saliva. The naval pentathlon consists of five different tests performed on consecutive days. The tasks require in-tense anaerobic effort and in some cases apnea. There is very little published about reactive oxygen species (ROs)/antioxidant balance in saliva of high-level anaerobic athletes. We hypothesized that saliva samples are suit-able as biological material to monitor changes in bio-markers for free radical generation and total antioxi-dant capacity. saliva samples were collected before and after a short test, RAsT (running-based anaerobic sprint test), and used to assess anaerobic performance during the training period [7].


subjects

subjects were seven military athletes of the Brazilian Navy, all of them experienced in international compe-tition in naval pentathlon. They were engaged in the final weeks of training for a series of international tour-naments. The team with five men and two women volunteered to participate in the study. Their written informed consents were obtained after explanation of the purpose, benefits and potential risks to the subjects. All military personnel are submitted to periodic medical and odontological examinations. The results of the oral health evaluation were used to exclude any athletes

M. de Lima sant’Anna et al., Redox balance in athlete’s saliva

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showing symptoms of oral inflammation, periodontitis or gingivitis.

The diet of all participants during the week prior to testing was the same and obtained from the military facility, which was controlled by a military nutricionist to meet the energy demands of the armed services. sub-jects were instructed not to ingest supplemental vitamins or antioxidants. In addition, each was instructed to avoid smoke and heavy physical exercise for 1h prior to testing. The experimental protocol was approved by the Ethics committee of clementino Fraga Filho Hospital of the Federal University of Rio de Janeiro.

Aerobic capacity and anthropometric measurements Maximal oxygen consumption (VO2max) was estimated

on a synthetic outdoor track several days before the RAsT, applying the distance run in 12 min to the cooper [8] regression equation. The results are presented in relative rate in milliliters of oxygen per kilogram of body weight per minute (Table 1). skinfold thickness was measured as described in Pollock and Jackson [9]. Body fat per-centage was determined using the siri [10] equation.

Exercise test

The RAsT, a single set applied individually, was per-formed outdoors on grass. It consisted of 5 min of very light warm-up (stretching and jogging) followed by 6 × 35-m sprints as fast as possible, with 10 s between sprints, and the last sprint followed by 5 min of cool-down. The power generated in each sprint was calculated by the formula Power (W) = (Body mass × Distance2)/Time3, normalized to body weight (Table 2).

collection of saliva

To avoid contamination, the subjects washed their mouths with deionized water before the collection and then chewed a piece of cotton wool for 1 min. saliva samples were collected before and 5 min after the RAsT as suggested by several papers [11–13]. After being collected, the samples were transported on ice to the laboratory and centrifuged at 3,000 × g for 10 min at 4°c. supernatants were separated from pellets and stored at – 20°c.

Lipid peroxidation assay

The lipid peroxidation assay was performed as de-scribed by Zalavras et al. [14] with slight modification. One hundred microliters of saliva supernatant was mixed with 500 µL TcA (35%, w/v) and 500 µL Tris-Hcl (200 mM, pH 7.4) and incubated for 10 min at room temperature. One milliliter of a solution containing 55 mM thiobarbituric acid in 2 M Na2sO4 was added and the samples were incubated at 95°c for 45 min and then cooled on ice for 5 min. After the addition of 1 mL TcA (70%, w/v) they were vortexed and centri-fuged at 15,000 × g for 3 min. The absorbance of the supernatant was read at 530 nm and TBARs concen-tration was calculated using an extinction coefficient of e = 0.156 µM–1 · cm–1. Values were expressed in µM.

Total antioxidant capacity

The total antioxidant capacity was measured as in Georgakouli et al. [15], using 20 µL saliva, 480 µL sodi-um-potassium phosphate (10 mM, pH 7.4) and 500 µL 2,2-diphenyl-1-picrylhydrazyl (DPPH, 0.1 mM), incu-bated in the dark for 30 min and centrifuged for 3 min at 20,000 × g. The absorbance Ac was read at 520 nm and compared with A0, absorbance of a reference sample containing only 20 µL water, DPPH and buffer. Per-centage reduction of the DPPH (Q) was defined by Q = 100(A0 – Ac)/A0 [16].

Determination of GSH in saliva

One hundred microliters of saliva was added to 200 µL of a 10% solution of TcA, vortexed and cen-trifuged at 4,000 × g for 10 min at 10°c. To 200 µL of the supernatant was added 700 µL of 400 mM Tris-Hcl buffer, pH 8.9, followed by 100 µL of 2.5 mM DTNB dissolved in 40 mM Tris-Hcl buffer, pH 8.9. The sam-ples were incubated for 10 min at room temperature and the absorbance was measured at 412 nm. Blanks contained water instead of saliva. The concentration of GsH in the samples was read from a GsH standard curve (0.8 µM – 4 µM) [17].

Table 1. Anthropometric characteristics and aerobic capacity

Mean ± SD Range

Age (yr) 27.1 ± 5.4 21–31Body mass (kg) 65.3 ± 6.6 53.8–72.2Height (cm) 170 ± 10 160–185BMI* (kg/m2) 21.9 ± 0.8 20.7–23.2Body fat (%) 10.2 ± 5.6 3.9–20.3VO2max (mL/kg · min) 61.9 ± 12.0 44.6–73.7

* body mass index = mass(kg)/(height(m))2

Table 2. Measures of performance in the RAsT

Mean ± SD Range

Peak power per weight (W/kg) 6.5 ± 1.4 4.4–7.9Average power per weight (W/kg) 5.4 ± 1.1 3.8–6.7Minimum power per weight (W/kg) 4.6 ± 1.1 3.0–5.9

Power (in watts) is normalized to body weight (kg).


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Uric acid in saliva

Urate concentration in saliva was analyzed by a uric acid assay kit (Doles Urato 160, Goiania, GO, Brazil) based on the amount of H2O2 produced when urate is converted to allantoin by uricase.


Pre- and post-test samples were compared using stu-dent’s paired t-test. Data normality was verified with the shapiro-Wilk test, which showed that non-parametric test was not required. The power of the performed tests with an = 0.05 was 1.000 to TBARs, 0.735 to DPPH, 0.999 to uric acid and 0.098 to GsH. correlation be-tween variables were assessed by Pearson’s correlation coefficient. For all analyses, statistical significance was indicated when p < 0.05. standard errors are reported, except for anthropometric characteristics, aerobic ca-pacity and measures of performance in the RAsT.

Results

correlation between aerobic and anaerobic performance

The subjects showed a high VO2max, as presented in Table 1. Anaerobic power was assessed during each RAsT sprint (Table 2). The correlation coefficient between peak anaerobic power and previously determined VO2max for each subject was high (r = 0.94, Figure 1).

Lipid peroxidation in saliva

In this study the peroxidation of fatty acids was assessed by an assay for thiobarbituric acid-reactive substances (TBARs). After the RAsT, the lipid peroxi-dation was ~2 times higher than at rest (Figure 2). In

the pre-test condition the value obtained was 0.9 µM ± 0.2 µM and five minutes after six sprints the value was 1.9 µM ± 0.2 µM.

Total antioxidant capacity

To evaluate the overall antioxidant response to the RAsT, which as shown above generated a substantial lipid oxidation, we measured the quenching of DPPH absorbance after the addition of saliva. This measure of total antioxidant capacity increased by 46.6% (Figure 3).

Non-enzymatic antioxidant system

To evaluate the contribution of the non-enzymatic antioxidant system to the increment observed in total antioxidant capacity, we evaluated the salivary glutathione and uric acid. There was no significant change in glu-tathione status (Figure 4A), but uric acid increased by 65.6%, from 178.9 µM ± 21.4 µM to 293.5 µM ± 9.4 µM (Figure 4B).

Peak power per kg (W/kg)

4 5 6 7 8 9

VO2m

ax (m

L/kg

.min

)

30

40

50

60

70

80

90

TB

ARS

(µM

)

*

PRE POST

2.5

2.0

1.5

1.0

0.5

0.0

Figure 2. The anaerobic test RAsT induces oxidative stress. Mean ± s.E. (n = 7), *p < 0.05

Figure 1. correlation between aerobic and anaerobic power for each athlete presented a R2 = 0.8885

and a correlation coefficient of 0.94 (n = 7), p < 0.05

% Q

UEN

CH

IN D

PPH

0

2

4

6

8

10

*

PRE POSTFigure 3. RAsT increases the total antioxidant capacity

in athletes’ saliva. Mean ± s.E. (n = 7), *p < 0.05


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Discussion

The aim of this study was to investigate free radical production and antioxidant buffering in military pen-tathletes’ saliva after an anaerobic test, RAsT. The run-ning-based anaerobic sprint test is designed to assess anaerobic power in sports that mostly use running [7].

The athletes evaluated had a high VO2max, commonly accepted as a key indicator of the endurance capacity. The two women averaged 45.0 ± 0.5 mL/kg · min and the men 69.0 ± 4.0 mL/kg · min. The values for the men were equivalent to those reported for male triathletes (67.6 ± 4.5 mL/kg · min) [18] and a European team of naval pentathlon athletes (74.0 mL/kg · min) [19].

The naval pentathlon is an intense sequence of five anaerobic tasks performed on consecutive days: obstacle race, life-saving swimming race, utility swimming race, seamanship race and amphibious cross-country race. They range from about 60 s (life-saving race) to 10–12 min (cross-country race). The RAsT is an intense anaerobic test but it is short and the effort level is lower than the actual naval pentathlon competition. Other authors have studied metabolic parameters after application of a modified RAsT protocol, but they did not meas-

ure redox status [20]. The RAsT has not been exploited for assessment of biochemical changes in athletes, al-though it is frequently used to predict running perfor-mance, with high correlations for 35, 50, 100, 200 and 400 meters [7]. During a pentathlon competition the distance covered by running varies in different tests from 280 to 900 meters. Although the RAsT is shorter it was able to provide a measure of pro-oxidant and anti-oxidant status in well-trained athletes in a controlled test condition.

In an intermittent high-intensity test such as the RAsT, major sources for ATP replacement are initially phos-phocreatine hydrolysis and glycolysis, but a shift toward oxidative metabolism to replenish ATP has been demon-strated for later trials in a sequence of sprints [21]. We observed a high correlation between VO2max and an-aerobic power, consistent with a role for aerobic power in anaerobic performance, and suggesting the impor-tance of such a shift during the RAsT, as observed for other anaerobically trained athletes, for example, judo players performing an anaerobic judo test that lasted 60 s [22].

Very few studies have proposed saliva as an alterna-tive source to evaluate oxidative stress biomarkers and antioxidant adaptation induced by exercise [11], and Deminice et al. [12] emphasized the differences between redox profiles of plasma and saliva. However, the main finding in our study was that saliva of trained athletes, following an anaerobic test, reveals an increase in lipid peroxidation (TBARs) and at the same time an increase in the antioxidant capacity that can be attributed pri-marily to uric acid (UA) – consistent with published data obtained using serum or plasma. Under hydroxyl radical attack the double bonds in polyunsatured fatty acid of biological membranes can degrade membrane structure with loss in physiological function and cellular disrup-tion [2, 23]. The increase in lipid peroxidation after six sprints shows that mechanism for free radical produc-tion can override antioxidant defenses even in highly trained athletes, and this can be seen clearly in saliva.

After the RAsT, the quenching of DPPH, a measure of total antioxidant capacity, was 46% higher than at rest (Figure 3). These data show that although these athletes undergo substantial lipid peroxidation (Fig-ure 2), the total antioxidant capacity was not used up.

Wayner et al. [24] have assigned total peroxyl trap-ping in human plasma to uric acid (35–65%) and the thiols of plasma proteins (10–50%), with minor roles for ascorbic acid and vitamins. An increase in TBARs and/or UA concentrations post-exercise has been found in other studies [11, 12, 25], but in agreement with our observations there were no large changes in GsH. It is worth noting that a large decrease in GsH was record-ed in the cases where whole blood was analyzed [25], suggesting that the use of saliva has the advantage of avoiding artifacts due to hemolysis or contamination with erythrocytes.

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Figure 4. Antioxidant biomarkers. A) Glutathione (GsH); B) Uric acid. Mean ± s.E. (n = 7), *p < 0.05


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In our study the GsH concentration did not change (Figure 4A), as also reported by Deminice et al. [12], who tested saliva of healthy well-trained males after a 40-min session of anaerobic resistance exercise. Even prolonged aerobic exercise of moderate intensity was not able to alter GsH concentration in skeletal muscle in healthy adults [26]. Thus GsH appears to be tightly reg-ulated, with secretion from liver to plasma designed to ensure homeostasis in blood [27]; in our study the concentration in saliva also appeared to be tightly con-trolled. In another study that assessed anaerobic resist-ance training, Margonis et al. [25] found a decrease in GsH concentration in the blood only in association with overtraining. Wiecek et al. [28] did not measure any alteration in GsH plasma concentration 3 min after the anerobic exercise, which is in line with the saliva meau-rements presented here, although the authors showed a reduction after 15 min up to 24h. since our data only includes a collection at 5 min post aerobic exercise, this time dependent effect cannot be ruled out. Further ex-periments need to be performed to evaluate the time dependent behavior of GsH levels in saliva.

Physical exercise triggers antioxidant adaptations [1, 29] that upregulate expression of endogenous anti-oxidant enzymes such as eNOs, MnsOD and iNOs expression [1, 30] as well as increases the non-enzymatic antioxidants [2]. Foti and Amorati [31] showed that uric acid accounted for one-third of the increase in antioxi-dant capacity suggesting that our observed increment in uric acid content in saliva represented an increase in total antioxidant capacity. Electron spin resonance and chemical studies indicate that uric acid can react with peroxyl radical, providing scavenging abilities [31]. This chemical feature may mean that uric acid helps to con-trol oxidative stress generated by exercise, at the same time reflecting greater ATP flux associated with elevated energy requirements. Purine catabolism increases and the higher concentrations of sub-products of this me-tabolism are formed [32]. Xanthine oxidoreductase is a key intracellular enzyme of purine metabolism. Its oxi-dase form is responsible for converting hypoxanthine to xanthine and xanthine to acid uric [33]. The purine cycle generates superoxide, hydrogen peroxide, and the reactive hydroxyl molecule [34], but uric acid itself is a potent non-enzymatic antioxidant [25]. Formed in the liver from hypoxanthine, it is released to the blood and either excreted or taken up by muscle, where it scav-enges hydroxyl radical [35].

Conclusions

Based on the results of this study, it can be concluded that this study shows that it is possible to obtain a pro-file of redox state using a non-invasive approach associ-ated with a short anaerobic test. RAsT triggers free radical production, as evaluated by lipid peroxidation in saliva, and at the same time reveals an increasead antioxidant

capacity as a sub-acute adaptation to a short series of sprints.

AcknowledgementsThis work was supported by grants from Fundação de Am-paro à Pesquisa do Estado do Rio de Janeiro (FAPERJ). We wish to thank capt. cyro coelho (coach) and the Brazilian pentathlon naval’s team for their sincere cooperation.

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Paper received by the Editor: October 26, 2015Paper accepted for publication: February 8, 2016

Correspondence addressVeronica Pinto salernoLaboratório de Bioquímica do Exercícioe Motores Moleculares (LaBEMMol)Avenida carlos chagas Filho, 549cidade UniversitáriacEP 21941-599, Rio de Janeiro, Brazile-mail: [email protected]

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11. The author (authors) receives no royalty for publica-tion. The author for correspondence receives through e-mail a PDF file with the article and full volume in which it was published.

12. Authors of research papers are obliged to protect per-sonal data of the research participants. If the information included in the paper makes it possible to identify the sub-jects, authors have to obtain their written consent for publi-cation of the research outcomes, photographs included (the appropriate form can be downloaded from the Internet) be-fore submitting papers to the Editor.

13. The editor does not accept papers that make use of ghostwriting and guest authorship. If detected, such practices will be disclosed. The Editor requires the principal author of joint publications to complete a declaration which specifies the contribution of each co-author in the research paper.

14. In order to initiate the publishing procedures of the paper, the author has to submit its electronic version to the email address [email protected]. The paper has to be prepared according to the submission requirements enclosed to the Guide for Authors, accompanied by the signed license, the principal author’s declaration (if it is a joint paper) as well as the consents of the photographer and the photographed persons (if there are any).

15. The moment authors submit papers to the Editor, they agree to accept the procedures of article qualification for publication employed in HM Editorial Office.

16. After the corrections are introduced by the reviewers, authors are obliged to send the paper back within 3 weeks.

17. Authors are obliged to cooperate with the editorial staff: native speaker, HM editor and proofreaders (language and statistical data) in order to eliminate ambiguities and errors. In case of no response to the editorial observations within a week, the author’s consent for introduction of the suggested changes is taken for granted.

18. Authors should list all the people or institutions that contributed to the article preparation factually, financially or technically.

19. The Editor accepts advertisements that can be placed in an advertising inserts next to the cover pages. Prices of ad-vertising are negotiated individually.

20. The original version of the journal is its paper issue.

detailed guidelines for submitting articles to Human Movement

1. The article should be written in English.2. Empirical research articles, together with their summa-

ry and any tables, figures or graphs, should not exceed 20 pages in length; comparative articles are limited to 30 pages. Page format is A4 (about 1800 characters with spaces per page). Pages should be numbered.

3. Articles should be written using Microsoft Word with the following formats:– Font: Times New Roman, 12 point– Line spacing: 1.5– Text alignment: Justified– Title: Bold typeface, centered


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4. strona tytułowa powinna zawierać:– tytuł pracy w języku angielskim;– skrócony tytuł artykułu w języku angielskim (do 40 zna-

ków ze spacjami), który zostanie umieszczony w żywej paginie;

– imię i nazwisko autora (autorów) z afiliacją zapisaną według następującego schematu:• nazwauczelni,nazwamiejscowości,nazwakraju,

np. Akademia Wychowania Fizycznego, Wrocław, Polska;

– adres do korespondencji (imię i nazwisko autora, jego adres, e-mail oraz numer telefonu).

5. Następna strona powinna zawierać:– tytuł artykułu;– streszczenie w języku angielskim (około 200 wyra-

zów) składające się z następujących części: Purpose, Methods, Results, conclusions;

– słowa kluczowe w języku angielskim (3–6) – ze słow-nika i w stylu MesH.

6. Trzecia strona powinna zawierać:– tytuł artykułu;– tekst główny.

7. Tekst główny pracy empirycznej należy podzielić na na-stępujące części:

wstęp We wstępie należy wprowadzić czytelnika w tematykę

artykułu, opisać cel pracy oraz podać hipotezy, stan badań (przegląd literatury).

materiał i metody W tej części należy dokładnie przedstawić materiał badaw-

czy (jeśli w eksperymencie biorą udział ludzie, należy podać ich liczbę, wiek, płeć oraz inne charakterystyczne cechy), omó-wić warunki, czas i metody prowadzenia badań oraz opisać wykorzystaną aparaturę (z podaniem nazwy wytwórni i jej adresu). sposób wykonywania pomiarów musi być przed-stawiony na tyle dokładnie, aby inne osoby mogły je powtó-rzyć. Jeżeli metoda jest zastosowana pierwszy raz, należy ją opisać szczególnie precyzyjnie, przedstawiając jej trafność i rzetelność (powtarzalność). Modyfikując uznane już metody, trzeba omówić, na czym polegają zmiany, oraz uzasadnić ko-nieczność ich wprowadzenia. Gdy w eksperymencie biorą udział ludzie, konieczne jest uzyskanie zgody komisji etycznej na wykorzystanie w nim zaproponowanych przez autora me-tod (do maszynopisu należy dołączyć kopię odpowiedniego dokumentu). Metody statystyczne powinny być tak opisane, aby można było bez problemu stwierdzić, czy są one poprawne. Autor pracy przeglądowej powinien również podać metody poszukiwania materiałów, metody selekcji itp.

wyniki Przedstawienie wyników powinno być logiczne i spójne

oraz ściśle powiązane z danymi zamieszczonymi w tabelach i na rycinach.

dyskusja W tym punkcie, stanowiącym omówienie wyników, autor

powinien odnieść uzyskane wyniki do danych z literatury (innych niż omówione we wstępie), podkreślając nowe i zna-czące aspekty swojej pracy.

4. The main title page should contain the following:– The article’s title– A shortened title of the article (up to 40 characters in

length including spaces), which will be placed in the running head

– The name and surname of the author(s) with their affi-liations written in the following way: the name of the university, city name, country name. For example: The University of Physical Education, Wrocław, Poland

– Address for correspondence (author’s name, address, e-mail address and phone number)

5. The second page should contain:– The title of the article– An abstract of approximately 200 words divided into

the following sections: Purpose, Methods, Results, con-clusions

– Three to six keywords to be used as MesH descriptors (terms)

6. The third page should contain:– The title of the article– The main text

7. The main body of text in empirical research articles should be divided into the following sections:

IntroductionThe introduction prefaces the reader on the article’s sub-

ject, describes its purpose, states a hypothesis, and mentions any existing research (literature review)

material and methodsThis section is to clearly describe the research material

(if human subjects took part in the experiment, include their number, age, gender and other necessary information), dis-cuss the conditions, time and methods of the research as well identifying any equipment used (providing the manufacturer’s name and address). Measurements and procedures need to be provided in sufficient detail in order to allow for their re-producibility. If a method is being used for the first time, it needs to be described in detail to show its validity and relia-bility (reproducibility). If modifying existing methods, de-scribe what was changed as well as justify the need for the modifications. All experiments using human subjects must obtain the approval of an appropriate ethnical committee by the author in any undertaken research (the manuscript must include a copy of the approval document). statistical meth-ods should be described in such a way that they can be easily determined if they are correct. Authors of comparative re-search articles should also include their methods for finding materials, selection methods, etc.

resultsThe results should be presented both logically and con-

sistently, as well as be closely tied with the data found in tables and figures.

discussionHere the author should create a discussion of the obtained

results, referring to the results found in other literature (besides those mentioned in the introduction), as well as emphasizing new and important aspects of their work.


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wnioski Przedstawiając wnioski, należy pamiętać o celu pracy oraz

postawionych hipotezach, a także unikać stwierdzeń ogólni-kowych i niepopartych wynikami własnych badań. stawiając nowe hipotezy, trzeba to wyraźnie zaznaczyć.

podziękowaniaNależy wymienić osoby lub instytucje, które pomogły au-

torowi w przygotowaniu pracy, udzieliły konsultacji bądź wsparły go finansowo lub technicznie.

BibliografiaBibliografię należy uporządkować i ponumerować według

kolejności cytowania publikacji w tekście, a nie alfabetycznie. Odwołania do piśmiennictwa należy oznaczać w tekście nu-merem i ująć go w nawias kwadratowy, np. Bouchard et al. [23].

Bibliografia (powołania zawarte tylko w bazach danych, np. sPORTDiscus, Medline) powinna się składać najwyżej z 30 pozycji (dopuszcza się powołanie na 2 publikacje książ-kowe), z wyjątkiem prac przeglądowych. Niewskazane jest cytowanie prac nieopublikowanych.

Opis bibliograficzny artykułu z czasopismaOpis bibliograficzny artykułu powinien zawierać: na-

zwisko autora (autorów), inicjał imienia, tytuł artykułu, tytuł czasopisma w przyjętym skrócie, rok wydania, tom lub nu-mer, strony, numer doi, np.

Tchórzewski D., Jaworski J., Bujas P., Influence of long-lasting balancing on unstable surface on changes in balance. Hum Mov, 2010, 11 (2), 144–152, doi: 10.2478/v10038-010-0022-2.

Gdy autorami artykułu jest sześć lub mniej osób, należy wy-mienić wszystkie nazwiska, jeżeli jest ich siedem i więcej, należy podać sześć pierwszych, a następnie zastosować skrót „et al.”;

Tytuł artykułu w języku innym niż angielski autor po-winien przetłumaczyć na język angielski, a w nawiasie kwa-dratowym podać język oryginału, tytuł czasopisma należy zostawić w oryginalnym brzmieniu, np.

Jaskólska A., Bogucka M., Świstak R., Jaskólski A., Mecha-nisms, symptoms and after-effects of delayed muscle sore-ness (DOMs) [in Polish]. Med Sportiva, 2002, 4, 189–201.

W pracy powinny być uwzględnianie tylko artykuły pu-blikowane ze streszczeniem angielskim.

Opis bibliograficzny książkiOpis bibliograficzny książki powinien zawierać: nazwisko

autora (autorów) lub redaktora (redaktorów), inicjał imienia, tytuł pracy przetłumaczony na język angielski, wydawcę, miejsce i rok wydania, np.

Osiński W., Anthropomotoric [in Polish]. AWF, Poznań 2001.Heinemann K. (ed.), sport clubs in various European coun-tries. Karl Hofmann, schorndorf 1999.

Opis bibliograficzny rozdziału w książce powinien zawie-rać: nazwisko autora (autorów), inicjał imienia, tytuł rozdziału, nazwisko autora (autorów) lub redaktora (redaktorów), tytuł pracy, wydawcę, miejsce i rok wydania, strony, np.

McKirnan M.D., Froelicher V.F., General principles of exer-cise testing. In: skinner J.s. (ed.), Exercise testing and exercise prescription for special cases. Lea & Febiger, Philadelphia 1993, 3–28.

conclusionsIn presenting any conclusions, it is important to remember

the original purpose of the research and the stated hypotheses, and avoid any vague statements or those not based on the results of their research. If new hypotheses are put forward, they must be clearly stated.

AcknowledgementsThe author may mention any people or institutions that

helped the author in preparing the manuscript, or that pro-vided support through financial or technical means.

BibliographyThe bibliography should be composed of the article’s cita-

tions and be arranged and numbered in the order in which they appear in the text, not alphabetically. Referenced sources from literature should indicate the page number and en-close it in square brackets, e.g., Bouchard et al. [23].

The total number of bibliographic references (those found only in research databases such as sPORTDiscus, Medline) should not exceed 30 for empirical research papers (citing a maximum of two books); there is no limit for compara-tive research papers. There are no restrictions in referencing unpublished work.

Citing journal articlesBibliographic citations of journal articles should include:

the author’s (or authors’) surname, first name initial, arti-cle title, abbreviated journal title, year, volume or number, page number, doi, for example:

Tchórzewski D., Jaworski J., Bujas P., Influence of long-lasting balancing on unstable surface on changes in balance. Hum Mov, 2010, 11 (2), 144–152, doi: 10.2478/v10038-010- 0022-2.

If there are six or less authors, all the names should be mentioned; if there are seven or more, give the first six and then use the abbreviation “et al.”

If the title of the article is in a language other than Eng-lish, the author should translate the title into English, and then in square brackets indicate the original language; the journal title should be left in its native name, for example:

Jaskólska A., Bogucka M., Świstak R., Jaskólski A., Mecha-nisms, symptoms and after-effects of delayed muscle sore-ness (DOMs) [in Polish]. Med Sport, 2002, 4, 189–201.

The author’s research should only take into considera-tion articles published in English.

Citing booksBibliographic citations of books should include: the au-

thor (or authors’) or editor’s (or editors’) surname, first name initial, book title translated into English, publisher, place and year of publication, for example:

Osiński W., Anthropomotoric [in Polish]. AWF, Poznań 2001.Heinemann K. (ed.), sport clubs in various European coun-tries. Karl Hofmann, schorndorf 1999.

Bibliographic citations of an article within a book should include: the author’s (or authors’) surname, first name initial, article title, book author (or authors’) or editor’s (or editors’) surname, first name initial, book title, publisher, place and year of publication, paga number, for example:

McKirnan M.D., Froelicher V.F., General principles of exer-cise testing. In: skinner J.s. (ed.), Exercise testing and exercise prescription for special cases. Lea & Febiger, Philadelphia 1993, 3–28.


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Opis bibliograficzny materiałów zjazdowychOpis bibliograficzny materiałów zjazdowych (umiesz-

czanych tylko w międzynarodowych bazach danych, np. sPORTDiscus) powinien zawierać: nazwisko autora (auto-rów), inicjał imienia, tytuł, nazwisko autora (autorów) lub redaktora (redaktorów), tytuł pracy, wydawcę, miejsce i rok wydania, strony, np.

Rodriguez F.A., Moreno D., Keskinen K.L., Validity of a two-distance simplified testing method for determining criti-cal swimming velocity. In: chatard J.c. (ed.), Biomechan-ics and Medicine in swimming IX, Proceedings of the IXth World symposium on Biomechanics and Medicine in swim-ming. Université de st. Etienne, st. Etienne 2003, 385–390.

Opis bibliograficzny artykułu w formie elektronicznejOpis bibliograficzny artykułu w formie elektronicznej po-

winien zawierać: nazwisko autora (autorów), inicjał imienia, tytuł artykułu, tytuł czasopisma w przyjętym skrócie, tom lub numer, rok wydania, adres strony, na której jest dostępny, numer doi, np.

Donsmark M., Langfort J., Ploug T., Holm c., Enevold - sen L.H., stallknech B. et al., Hormone-sensitive lipase (HsL) expression and regulation by epinephrine and exer-cise in skeletal muscle. Eur J Sport Sci, 2 (6), 2002. Available from: URL: http://www.humankinetics.com/ejss/bissues.cfm/, doi: 10.1080/17461391.2002.10142575.

8. Tekst główny w pracach innego typu powinien zachować logiczną ciągłość, a tytuły poszczególnych części muszą odzwierciedlać omawiane w nich zagadnienia.

9. przypisy (objaśniające lub uzupełniające tekst)– powinny być numerowane z zachowaniem ciągłości

w całej pracy i umieszczone na końcu tekstu głównego. 10. Tabele, ryciny i fotografie

– należy opatrzyć numerami i podpisami;– należy umieścić w tekście artykułu;– dodatkowo ryciny i fotografie trzeba dołączyć w po-

staci osobnych plików zapisanych w formacie *.jpg lub *.pdf (gęstość co najmniej 300 dpi);

– nie można powtarzać tych samych wyników w tabe-lach i na rycinach;

– materiał ilustracyjny powinien zostać przygotowany w wersji czarno-białej lub w odcieniach szarości (w taki sposób jest drukowane czasopismo Human Movement);

– symbole, np. strzałki, gwiazdki, lub skróty użyte w tabe-lach czy na rycinach należy dokładnie objaśnić, tak by były czytelne i zrozumiałe niezależnie od tekstu pracy.

Przed drukiem autor otrzyma swój artykuł do akceptacji w formie pliku pdf. Obowiązkiem autora jest niezwłoczne przesłanie do Redakcji Human Movement informacji o akcep-tacji artykułu do druku. Na tym etapie będą przyjmowane tylko drobne poprawki autorskie.

Citing conference materialsciting conference materials (found only in international

research databases such as sPORTDiscus) should include: the author’s (or authors’) surname, first name initial, arti-cle title, conference author’s (or authors’) or editor’s (or edi-tor’s) surname, first name initial, conference title, publisher, place and year of publication, page number, for example:

Rodriguez F.A., Moreno D., Keskinen K.L., Validity of a two-distance simplified testing method for determining criti-cal swimming velocity. In: chatard J.c. (ed.), Biomechan-ics and Medicine in swimming IX, Proceedings of the IXth World symposium on Biomechanics and Medicine in swim-ming. Université de st. Etienne, st. Etienne 2003, 385–390.

Citing articles in electronic formatciting articles in electronic format should include: au-

thor’s (or authors’) surname, first name initial, article title, abbreviated journal title, year of publication, journal volume and number, website address where it is available, doi num-ber, for example:

Donsmark M., Langfort J., Ploug T., Holm c., Enevold - sen L.H., stallknech B. et al., Hormone-sensitive lipase (HsL) expression and regulation by epinephrine and exer-cise in skeletal muscle. Eur J Sport Sci, 2002, 2 (6). Available from: URL: http://www.humankinetics.com/ejss/bissues.cfm/, doi: 10.1080/17461391.2002.10142575.

8. The main text of any other articles submitted for consid-eration should maintain a logical continuity and that the titles assigned to any sections must reflect the issues dis-cussed within.

9. footnotes/Endnotes (explanatory or supplementary to the text). Footnotes should be numbered consecutively through-out the work and placed at the end of the main text.

10. Tables, figures and photographs– Must be numbered consecutively in the order in which

they appear in the text and provide captions– should be placed within the text– Additionally, figures or photographs must be attached

as separate files in .jpg or .pdf format (minimum reso-lution of 300 dpi)

– May not include the same information/data in tables and also figures

– Illustrative materials should be prepared in black and white or in shades of gray (Human Movement is pub-lished in such a fashion and cannot accept color)

– symbols such as arrows, stars, or abbreviations used in tables or figures should be clearly defined using a legend.

Prior to printing, the author will receive their article in .pdf format. It is the author’s responsibility to immediately inform the Editorial Office if they accept the article for publi-cation. At such a point in time, only minor corrections can be accepted from the author.

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