Human Movement - Akademia Wychowania Fizycznego we Wrocławiu

Transcription

University School of Physical Education in Wrocław
University School of Physical Education in Kraków
vol. 17, number 1 (March), 2016
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
quarterly
vol. 17, number 1 (March), 2016, pp. 1– 60
Editor-in-Chief Alicja Rutkowska-Kucharska
University School of Physical Education, Wrocław, Poland
Associate EditorEdward Mleczko
University School of Physical Education, Kraków, Poland
Editorial Board
Physical activity, fitness and health
Wiesław Osiński
University School of Physical Education, Poznań, Poland
Applied sport sciences
Zbigniew Trzaskoma Józef Piłsudski University of Physical Education, Warszawa, Poland
Biomechanics and motor control
Tadeusz Bober
Kornelia Kulig
University of Southern California, Los Angeles, USA
Physiological aspects of sports
Andrzej Suchanowski
Józef Rusiecki Olsztyn University College, Olsztyn, Poland
Psychological diagnostics of sport and exercise
Andrzej Szmajke
Opole University, Opole, Poland
Advisory Board
Wojtek J. Chodzko-Zajko
Gudrun Doll-Tepper Józef Drabik
Kenneth Hardman
Andrew Hills
Zofia Ignasiak
Slobodan Jaric
Han C.G. Kemper Wojciech Lipoński
Gabriel Łasiński
Robert M. Malina Melinda M. Manore Philip E. Martin Joachim Mester Toshio Moritani
Andrzej Pawłucki John S. Raglin Roland Renson
Tadeusz Rychlewski
James F. Sallis James S. Skinner
Jerry R. Thomas
Karl Weber
Peter Weinberg
Marek Woźniewski
Guang Yue Wladimir M. Zatsiorsky Jerzy Żołądź
University of Illinois, Urbana, Illinois, USA
Free University, Berlin, Germany
University School of Physical Education and Sport, Gdańsk, Poland
University of Worcester, Worcester, United Kingdom
Queensland University of Technology, Queensland, Australia
University of Delaware, Newark, Delaware, USA
Vrije University, Amsterdam, The Netherlands
University of Texas, Austin, Texas, USA
Oregon State University, Corvallis, Oregon, USA
Iowa State University, Ames, Iowa, USA
German Sport University, Cologne, Germany
Kyoto University, Kyoto, Japan
Indiana University, Bloomington, Indiana, USA
Catholic University, Leuven, Belgium
San Diego State University, San Diego, California, USA
Indiana University, Bloomington, Indiana, USA
University of North Texas, Denton, Texas, USA
German Sport University, Cologne, Germany
Hamburg, Germany
Cleveland Clinic Foundation, Cleveland, Ohio, USA
Pennsylvania State University, State College, Pennsylvania, USA
University School of Physical Education, Kraków, Poland
Translation: Agnieszka Piasecka
Design: Agnieszka Nyklasz
Copy editor: Beata Irzykowska
Statistical editor: Małgorzata Kołodziej
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HUMAN MOVEMENT
2016, vol. 17 (1)
contents
ph y sic a l ac t i v i t y, f i t n e s s a n d h e a lt 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
applied sport science
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
biomechanics and motor control
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
3
HUMAN MOVEMENT
2016, vol. 17 (1), 4– 7
Exercise and academic achievement in children:
Effects of acute class-based circuit training
doi: 10.1515/humo-2016-0007
Ben D. Dickinson 1 *, Michael J. Duncan 2 , Emma L.J. Eyre 2
1
2
University of Central Lancashire, Preston, United Kingdom
Centre for Applied Biological and Exercise Science, Coventry University, Coventry, United Kingdom
Abstract
Purpose. For schools, the increasingly imposed requirement to achieve well in academic tests puts increasing emphasis on improving 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. Standardised 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
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 exercise to have beneficial effects on cognition and subsequently 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 academic classes has been reported for children who participate 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 wholeclass 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
* Corresponding author.
4
effects on cognitive function [8], while cycling ergometer use produced stronger effect sizes than treadmill
running [9]. This study argued that cycling uses less
metabolic energy compared with running and that running resulted in greater ‘neural interference’ and more
cognitive demands for movement. Duncan and Johnson [10] also used cycle ergometer training at differing
intensities and found that spelling and reading were
improved, arithmetic impaired and sentence comprehension unaffected. While the potential for acute exercise 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 exercise might have a similar impact on academic achievement. Immediate recall scores were higher following
submaximal intensity lessons involving both team games
and aerobic training. This can be attributed to exerciseinduced increases in physiological arousal and the cognitive activation induced by the exercise demands. Circuit 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 translate to the school setting in a practical way.
The current study sought to address this gap by examining the effects of class-based exercise on preadolescent
academic performance.
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B.D. Dickinson, M.J. Duncan, E.L.J. Eyre, Exercise and academic achievement in children
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 Warrington, UK, participated in the study following institutional ethics approval and informed parent and child
and school consent. A pre-exercise Physical Activity Readiness 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 recruited voluntarily following a presentation given by
the researchers to children and parents attending the
school concerned.
Procedures
This study employed repeated measures design whereby 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 administered. 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 arithmetic, now includes an assessment of sentence comprehension. 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 threeletter 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. ‘assiduous’) 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 comprehend 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 employed 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 recorded for all participants after a 5-minute rest period
in a supine position.
A 30-minute circuit-based exercise session was conducted 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 exercises selected were body weight focused, compound,
whole body exercises, chosen as the children were familiar 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, ‘Mountain 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 normality (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 sentence 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 So5
HUMAN MOVEMENT
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, p2 = 0.597. Gender was not significant
(p > 0.05) in any of the analyses and is therefore not discussed further. Analysis of each individual dependent
variable, with Bonferroni correction, indicated that standardised scores for word reading were significantly higher
post exercise (F(1,18) = 49.9, p = 0.0001, p2 = 0.735) compared to control. In contrast, standardised scores for sentence comprehension (F(1,18) = 0.078, p = 0.783, p2 =
0.004), spelling (F(1,18) = 4.07, p = 0.06, p2 = 0.185),
mathematics (F(1,18) = 1.257, p = 0.277, p2 = 0.065),
and reading (F(1,18) = 2.09, p = 0.165, p2 = 0.104) were
not significantly different in control and exercise conditions. Mean ± SD of standardised WRAT scores in control 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) compared to rest on academic performance (WRAT 4). The
findings of the present study, that only word reading
scores were significantly different between rest and exercise, matches similar studies using the WRAT test exercise 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 interpreted in another way. The Word reading test is the first
Figure 1. Mean ± SD of standardised WRAT scores
in control and exercise conditions (*p = 0.001)
6
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 exercise-induced increases in memory storage and physiological 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 certainly important to acknowledge that the order of testing 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 clarification 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 measurement 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 control of exercise intensity may be a factor for consideration. 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 ergometer, 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 induced by memory tasks and visual stimulation [15] and
this may be the mechanism whereby cognitive perfor-
HUMAN MOVEMENT
mance is increased. Endurance exercise, such as circuit
style exercise and running, has been proposed to produce a deregulation of the highest level of consciousness
associated with the prefrontal cortex and an adverse
effect on executive control during exercise [17]. This hypothesis also proposes that all motor cortex activation
will cease, and functioning restored, immediately as
soon as the altered state, such as that produced by exercise, 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 interference’ and more cognitive demands for movement reported 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 positive relations between fitness and standardised achievement 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 interference before it affects cognitive function after exercise.
In summary, the present study provides no strong evidence that exercise intensity moderates the improvement in pre-adolescent post-exercise academic ability.
Exercise was found to improve word reading independent of intensity. Exercise did not improve sentence comprehension, arithmetic, spelling or reading, with the
relationship with exercise intensity requiring further
investigation.
References
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activity and cognition in children: a meta-analysis. Pediatr
Exerc Sci, 2003, 15 (3), 243–256. Available from: https://
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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.humankinetics.com/AcuCustom/Sitename/Documents/DocumentItem/2575.pdf.
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mss.0000227537.13175.1b.
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8. Hillman C.H., Pontifex M.B., Raine L.B., Castelli D.M.,
Hall E.E., Kramer A.F., The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children. Neuroscience, 2009, 159 (3), 1044–
1054, doi: 10.1016/j.neuroscience.2009.01.057.
9. Lambourne K., Tomporowski P., The effect of exerciseinduced arousal on cognitive task performance: a metaregression analysis. Brain Res, 2010, 1341, 12–24, doi:
10.1016/j.brainres.2010.03.091.
10. Duncan M., Johnson A., The effect of differing intensities of acute cycling on preadolescent academic achievement. 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., Physical 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:
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physical activity among children and adolescents: a review 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
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15. Delp M.D., Armstrong R.B., Godfrey D.A., Laughlin M.H.,
Ross C.D., Wilkerson M.K., Exercise increases blood flow
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Paper received by the Editor: November 4, 2015
Paper accepted for publication: March 25, 2016
Correspondence address
Ben D. Dickinson
University of Central Lancashire
Preston, United Kingdom
e-mail: [email protected]
7
HUMAN MOVEMENT
2016, vol. 17 (1), 8 – 14
How the Kenyan runner’s body structure
affects sports results
doi: 10.1515/humo-2016-0002
Jerzy Eksterowicz *, Marek Napierała, Walery Żukow
Faculty of Physical Education, Health and Tourism, Kazimierz Wielki University, Bydgoszcz, Poland
Abstract
Purpose. 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 anthropometric 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 selection of candidates for a particular sport discipline
and somatic features. For instance, the taller the basketball 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. Predisposition 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 activists and coaches alter their selection criteria and choose
the ones that promise masterful results. Particularly interesting with regard to what has been said is the phenomenon of extreme endurance abilities of Kenyan runners 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
8
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 oxidized. The consequence of extremely intensive training
and selection of athletes, as not all Kenyans are predestinate for endurance events, is a specific body type that
tends to be extremely thin, low in body mass, low in adipose 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 particular body parts.
The aim of this study was to determine the dependency between some somatic parameters of selected Kenyan 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 Poland 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-
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J. Eksterowicz, M. Napierała, W. Żukow, How the Kenyan runner’s body structure affects sports results
ments and calculations were done in July 2013 during
the athletes’ presence in Poland, in the civilian-military sports club “Zawisza” in Bydgoszcz. The following
anthropometric measurements were taken: length measurements (cm): body height (V–B), arm length (a–r), forearm length (r–sty), upper limb length (a–da III), lower
limb length (tro–B), foot length (ap–pte); width measurements: 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 circumferences of: fully expanded/deflated chest, waistline, hipline, 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), horizontal 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 measurements were taken using an anthropometric apparatus. 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 (Switzerland). All measurements were taken by the same investigator, applying standard anthropometric methods according to the procedure of the International Biological
Programme [10]. The study was performed according
to the Declaration of Helsinki. Written informed consents 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 characteristics 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 significance of the Student t-test can be used for correlation 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 correlation, 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 correlation table.
Results
Table 1 reports the results of anthropological measurements and the results of long-distance events. In
Table 2 the results of measurements of tested circumferences and some anthropological features of Kenyan runners 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 materiality 0.05) – between results obtained in 10,000 meters 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 moderate 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 (negative correlation, r = –0.46). The same moderate correlation (important statistically significant dependency at
the level of materiality 0.05) was shown in relationship 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 circumference (negative correlation, r = –0.43). Moderate correlation (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 index (r = 0.41). No relationship was observed between results 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 longdistance runners in the world. Kenyan runners’ superiority in long-distance runs is often linked to the advantage 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.
9
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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)
Half-marathon (s)
Marathon (s)
Body height (cm) (B–V)
Body mass (kg)
Fat mass FM (%)
Fat free mass FFM (%)
1730.43
3753.61
8080.30
169.18
55.98
5.41
94.59
33.24
67.84
158.59
4.15
4.84
1.75
1.75
1791.0
3840.16
7800.57
161.0
48.0
4.56
90.72
1698.47
3600.15
8280.25
177.0
63.1
9.28
96.83
Sum of skinfolds (mm):
– subscap
– triceps
– suprial
13.97
5.46
4.09
4.42
1.96
1.70
0.81
1.10
11.7
3.5
3.0
3.0
18.5
9.6
5.0
5.0
Length measurements (cm):
– arm (a–r)
– forearm (r–sty)
– upper limb (a–da III)
– lower limb (tro–B)
– foot (ap–pte)
– torso (tro–a)
33.04
26.38
80.51
90.02
25.72
50.96
1.93
2.99
3.80
2.77
0.88
3.20
30.50
23.40
76.40
85.60
24.00
46.00
35.80
27.20
87.10
97.70
26.60
54.30
Width measurements (cm):
– shoulder (a–a)
– hip (ic–ic)
– pelvis (is–is)
– hand (mm–mu)
– palm (mr–mu)
– foot (mtt–mtf)
38.66
28.73
23.02
10.04
8.00
9.77
2.72
1.47
1.21
0.56
0.56
0.68
33.40
26.20
20.80
9.50
7.00
9.00
41.50
31.00
24.60
10.50
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 capillary 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 mitochondria 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 counterparts. This enables them to improve their endurance especially 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 highaltitude 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 vegetable sauces, bean, corn, fruit or parts of plant sprouts
and sometimes meat. Such a diet contains a lot of carbohydrates, mineral components, vitamins and fibre
10
but lacks fats, especially animal ones. It is worth mentioning 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 production of energy, up to 20–50%. Jeukendrup [17] notices
that high physical effort that leads to intensive carbohydrates 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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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)
– chest measurement – expiration (cm)
– waist measurement (cm)
– hip measurement (cm)
– arm measurement – tensed (cm)
– arm measurement – relaxed (cm)
– thigh measurement (cm)
– calf measurement (cm)
87.28
82.53
70.33
85.33
26.06
23.56
47.66
37.84
3.88
4.63
4.52
3.25
2.81
2.16
6.29
6.43
83.00
78.00
64.50
81.00
22.00
21.50
46.00
33.00
94.50
90.00
76.00
91.00
32.50
29.00
47.00
54.10
Indexes
BMI
AMC Index
WHR Index
19.55
22.27
0.82
1.51
2.10
0.05
17.50
20.24
0.78
22.90
27.56
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
Height
Body mass
BMI
Sum of fat-skin folds
Adipose tissue %
Fat free mass %
Arm length
Forearm length
Upper limb length
Lower limb length
Foot length
Shoulder breadth
Hip width
Foot breadth
Torso length
WHR
AMC
Thigh circumference
Calf circumference
0.26
0.49*
0.43*
–0.36
–0.36
0.36
0.54*
–0.04
0.14
–0.34
0.36
0.53*
0.30
0.76**
0.75**
–0.38
0.13
–0.46*
–0.19
Half-marathon
–0.13
0.17
0.25
–0.06
–0.06
0.06
0.50*
0.08
0.45*
–0.37
0.51*
–0.15
0.43*
0.54*
0.40*
–0.15
–0.05
–0.26
–0.43*
Marathon
–0.03
0.34
0.40*
0.16
0.16
–0.16
0.73**
0.75**
0.58*
–0.13
0.57
0.25
0.77**
0.29
0.46*
0.41*
–0.08
0.01
–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)
teristics of black runners: lower body mass, significantly
lower adipose tissue that results in much lower BMI, longer lower limbs, smaller calf circumference and shorter
torso [18]. They certainly increase endurance abilities,
especially in endurance events. In our study all the Kenyan 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,
11
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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 technique Erdman [21]. If a runner of a certain height of the
body has a too long torso, his limbs are relatively shorter. 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 correlation between its length and run time.
The negative correlation between the thigh circumferences 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 physiological 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
12
population. In recent years Kenyan athletes have dominated 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 members, 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 compensate 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 consumption (VO2max) of elite Kenyan and Scandinavian runners 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 concentration 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 lifestyle, they become athletes of enormous endurance abilities 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 exceptional 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, underdeveloped economy and lack of job opportunities, young
Kenyans and Ethiopians choose to become athletes.
Thanks to their strong will and hard work they become successful in sport all around the world, which
improves their and their families’ living standard.
Conclusions
As a results of conducted study following conclusions 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 correlated 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 correlated with body mass, BMI, arm length, width shoulders,
– 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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Paper received by the Editor: July 23, 2015
Jerzy Eksterowicz
Instytut Kultury Fizycznej
Uniwersytet Kazimierza Wielkiego
ul. Sportowa 2
85-091 Bydgoszcz, Poland
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2016, vol. 17 (1), 15– 20
The multi-functional foot in athletic movement:
extraordinary feats by our extraordinary feet
doi: 10.1515/humo-2016-0001
Jennifer Wilson 1 *, John Kiely 2
1
University of Derby, College of Life & Natural Sciences: Sport, Outdoor & Exercise Science, Derby, United Kingdom
University of Central Lancashire, Institute of Coaching & Performance, School of Sport, Tourism and the Outdoors,
Preston, Lancashire, United Kingdom
2
Abstract
The 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 strategies to enhance ambulant, bipedal athletic movements –
run, jump, pivot, turn, change direction – much training
attention is dedicated to strengthening the large powergenerating muscles of the hips and upper legs. Substantial research exists evidencing the positive contributions
of various strength and conditioning strategies to athletic 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. Specifically, observable power production, in dynamic locomotive activities, typically exceeds muscular force-generation 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 afforded by a short ground contact typically lasting less
than one-fifth of a second [1]. Similarly, during running, impacts of multiple times bodyweight are comfortably 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, nevertheless typically number beyond 21 thousand contacts,
again of multiple times bodyweight per leg [3].
Furthermore, during the dynamic accelerating, decelerating, twisting and turning athletic movement permutations common across a broad range of sporting
activities, the loadings imposed on joints and other structures appear similarly excessive: exposing tissues to high
shock loads, in apparently unstable, ever-varying movement conditions. Despite the severe challenges imposed
by such dynamically-shifting movement demands, we
are capable of robustly and agilely executing a broad diversity 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 feature 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 encountered 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 despite this primacy, little consideration is typically afforded
15
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J. Wilson, J. Kiely, The multi-functional foot
Figure 1. A depiction of the three evolutionary innovations
that contribute to ‘robustness’ within the foot structure
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 minimum 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 evolutionary innovations which, in combination, underpin the remarkable robustness of the human foot during 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 intrinsic and extrinsic muscle-tendon units, the human
foot constitutes a uniquely complex bio-composite anatomical 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. Sensory 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 complexity is matched by a similarly expansive functional
complexity, as the foot adapts to the expansive diver16
sity of tasks imposed by the physics of landing on unpredictable 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 adaptable. It is remarkably robust, across an unusually diverse
range of dynamic movement activities: walking, running,
climbing, turning, pivoting, hopping, bounding. Furthermore, not only does the foot adapt to changing movement 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, buffering, 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 functions. 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 suggested biological organisms could be meaningfully approximated as ‘nearly decomposable’ complex systems.
A purely mechanical system is, in contrast, fully decomposable, in that each component fulfils a tightly designated role within a given context [15]. Within a ‘nearly
decomposable’ biological system there is obvious crossover, overlap and integrated interplay between the functionality 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, pervasive throughout biology, greatly simplifying what would
otherwise be overwhelmingly disordered complexity.
Although all modules are inter-connected, they are simultaneously partially-insulated and functionally semi-autonomous. Hence modularity facilitates robustness as
modules can evolve, reshape, rewire and repair in tandem, or independently, without necessarily jeopardizing the survivability of the entire organism [16–18].
This ‘nearly decomposable’ architecture enables complex neurobiological systems to reap the benefits of structural specialization while simultaneously retaining
HUMAN MOVEMENT
the adaptive agility essential to coping with demands imposed by a chaotic, ever-changing environment. Such
design characteristics underpin an essential prerequisite of biological robustness: degeneracy [19].
Degeneracy is the capacity, of alliances of modules,
to collectively modify behaviours and re-combine outputs 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 fundamentally different components to produce consistently
reliable outputs under diversely fluctuating conditions
[19, 21].
The bio-composite design of the human foot provides a prime example of a highly-degenerate biological
architecture. The complex ‘nearly decomposable’ architecture of the foot enables instantaneous structural reconfiguration 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 permutations of accelerations, decelerations, pivots, turns and
changes of direction implicit in dynamic sporting activities. Thus the ‘nearly decomposable’ architecture of
the foot facilitates immediate and flexible adaptation
to changing context.
A further feature of this highly degenerate configuration is that seemingly identical movement cycles, resulting in equivalent movement outcomes, can be achieved
through a multiplicity of subtly varying pathways. Thereby
enabling the mechanical stresses imposed by repetitive impacts, such as that encountered during a marathon, to be dispersed amongst a broad network of collaborating structural and material components. Hence
degeneracy facilitates robustness.
Degeneracy within the foot ensures that subtle modifications, 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 irreparably 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 construction of a stone arch [25]. In contrast, tensegrity
systems innately self-stabilize and resist structural distortion purely by balancing tension-imposing and compression-resisting structural components within a self-stabilizing web of tensioning and stiffening forces [26].
The strikingly energy-efficient, perturbation-repelling simplicity of tensegrity designs has, recently, been
recognised as a pervasive evolutionary innovation evident 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 background 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 activities, 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 individual cell, and beyond. Each nested structure lies within
greater, and is comprised of lesser, bio-tensegrity architectures; each evolutionarily designed, structurally
and materially, to advantageously respond to the loadings and deformations most relevant to our species
survival. Each sub-system innately responds to deformation 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 impact deceleration, is an exquisitely evolved bio-tensegrity structure. The foot is itself formed by a number of
bio-tensegrity systems encased within the foot architecture, and in turn serves as a sub-system of the integrated systemic whole. The foot is often described as
being made up of floating compression elements (such
as the skeletal structures of the midfoot [36]) supported 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 locomotion [9] –, thanks to its complex multi-tissue design
the foot system is capable of fulfilling a wide diversity
of functions: variously absorbing, decelerating, transferring, steering and recycling movement powers.
As with any bio-tensegrity system, effective dispersal
of forces alleviates risks of exceeding critical tissue loading
17
HUMAN MOVEMENT
limits. To move efficiently these forces must be channelled and re-deployed to optimally contribute to stabilisation and propulsive power demands. Within the
hierarchy of tensional systems, compression of local
structures creates a ‘non-linear wave’ through the tensional fabric of the global construct resulting in a modification to internal forces through a ‘preflexive’ response
[27]. Driven by evolutionary imperatives and repeat practice, we progressively become more skilled at exploiting
these built-in mechanical efficiencies. We gradually
become more proficient at poising ‘tensioned’ or prestressed tensegrity structures to more productively
capitalise on ‘cheap’ sources of control and propulsion
merely by matching the physics of the situation to innate 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-directing and re-cycling momentums and stabilizing movement, 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 predictable, 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 contact 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 biotensegrity structure.
As with any system demonstrating degeneracy, exploitation of variable configurations and behaviours
promotes mechanical efficiency as the system strives for
the most economical outcome. By offering more movement options, a degenerate system is able to facilitate
stress management through variable permutations. At
the level of the foot, the seamless integration of tensional properties regulates the poising and pre-activation
of hierarchical structures so as to optimally contribute
to the stabilization and energetic requirements of movement. In locomotive activities, particularly those that
incur repetitive impacts, the foot serves multiple functional roles. A multi-functionality built among a platform
of structural complexity. The generous movement degeneracy, afforded by the human foot, is underpinned by
this structural complexity. Together this blend of biotensegrity and degeneracy enable the human foot to
adjust, deform, dampen, absorb and productively harness 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 overarching 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 instantaneously respond, to inevitably idiosyncratic permutations
of internal and external constraints, in a manner resolving 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
18
HUMAN MOVEMENT
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 deformations: thus contributing to self-stabilization and
momentum re-cycling.
This extraordinary structure plays a fundamental
role in damping, dissipating and dispersing shock impacts; in channelling and directing momentums; in seamlessly 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? Certainly, given the importance of optimised foot function
to athletic bipedal movement, it seems remiss not to reflect on how we conventionally consider, or fail to consider, 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, 2016
Jennifer Wilson
University of Derby
College of Life & Natural Sciences:
Sport, Outdoor & Exercise Science
Kedleston Road
Derby, DE22 1GB
HUMAN MOVEMENT
2016, vol. 17 (1), 21 – 28
Identification of determinants of sports skill level
in badminton players using the multiple regression model
doi: 10.1515/humo-2016-0004
Janusz Jaworski 1 *, Michał Żak 2
1
Department of Theory of Sport and Kinesiology, Institute of Sport Sciences, Faculty of Physical Education and Sport,
University of Physical Education, Krakow, Poland
2
Department of Sports and Recreational Training, Institute of Sport Sciences, Faculty of Physical Education and Sport,
University of Physical Education, Krakow, Poland
Abstract
Purpose. 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 abilities, followed by somatic characteristics. In this group, coordination abilities were also important. In juniors, the most pronounced 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
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 movement technique [2, 3]. Other reports have demonstrated 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 movements with very high intensity, alternate with short periods 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 duration of the game and the number of various movement
sequences repeated during the game [3, 8].
Another important factor that affects the effectiveness 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 substantial body height and slim body. The findings obtained
in many countries [3, 9] have demonstrated that mesomorphy 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, similar 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 movement 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 practice of training, one should take into consideration
interactions between genetic and training factors. Therefore, both talent identification and training optimization are of key importance for final success in the sport
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J. Jaworski, M. Żak, Determinants of sports skill level in badminton players
[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 determination [15]. Each “champion model” implies the
necessity of using only the variables which can be realistically 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 differences in speed of development of children and
young people.
Identification of the determinants of the effectiveness of actions is essential for athletic training. Unfortunately, few reports have attempted to find variables
which should be preferred in badminton (at each stage
of sports training). Furthermore, few studies have examined 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 completion 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 Declaration 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.
22
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 forehand 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 generated 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 endurance,
h) sit-ups – abdominal muscle power,
i) power tests according to the procedure proposed
by Spieszny et al. [18] – 10 × 3-metre shuttle run; overhead medicine ball throw (1 kg) from the kneeling position; “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 parameters, frequency of hand movements, visual-motor coordination, 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 (spatial-dynamic parameters).
The testing procedure, program settings and characterization of the equipment used for the examinations
were described in the monograph by Jaworski [15].
HUMAN MOVEMENT
Results
1. Prior to the main statistical analysis, the consistency of the distribution of the variables with normal distribution 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, supplemented 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 parameters on the sports skill level in badminton players.
This study used the stepwise regression. Forward selection was adopted as a method for selection of variables 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 confidence at the level of 95%, p < 0.05). The variables
previously separated using factor analysis were considered as independent, and introduced to the regression model. Analysis of the results was performed by
dividing all the variables into the three sets: somatic
characteristics and structural-functional ones, coordination abilities, and physical abilities. Each set represented the basis for development of a separate model
of multiple correlations with sports skill level. The procedure 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.
The problem of correlations between the sports skill
level of athletes and their morphological aptitudes and
motor fitness was attempted to be solved through indepth analysis of the phenomenon based on the interpretation of coefficients of multiple determination. The
factor analysis [20] and its pragmatic interpretation allowed for selection of up to 26 variables for these statistical 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 characteristics on the sports skill level in badminton players
in different age categories. Determination of the combined effect of variables found through factor analysis
seems to be more justified than seeking individual causeand-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 characteristics; coordination abilities; and physical abilities. Each of them represented the basis for development 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 determine 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 comprehensive anaerobic power. The whole system of physical
Table 1. Set of variables introduced to the multiple regression model
No. Variable
No. Variable
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
Body height
LBM
Shoulder width
Arm range (with racket)
Flexibility
Wrist mobility
Kinaesthetic differentiation of temporal parameters
Frequency of movements
Visual reaction time
Auditory reaction time
Selective reaction time
Rhythmization
Movement integration
Visual-motor coordination (free mode)
Spatial orientation (free mode)
Spatial orientation (forced mode)
Differentiation of force parameters of motion
Standing long jump
10 × 5-meter shuttle run
Cardiorespiratory endurance
Envelope run
MAP, lower limbs
MAP, upper limbs
Abdominal muscle power
Forward medicine ball throw
Static strength
23
HUMAN MOVEMENT
Table 2. Coefficients of multiple determination between sports skill level and morphofunctional variables
in the group of younger cadets
R
R2
Wrist mobility
Shoulder width
0.28
0.37
0.47
0.08
0.13
0.22
0.05
0.09
0.15
3.04
2.83
3.27*
Coordination abilities
Visual reaction time
0.27
0.32
0.36
0.07
0.10
0.13
0.04
0.05
0.06
2.80
2.07
1.79
Motor physical abilities
10 × 5-meter shuttle run
MAP, lower limbs
MAP, upper limbs
Static strength
0.53
0.61
0.66
0.67
0.69
0.28
0.37
0.44
0.45
0.47
0.26
0.33
0.388
0.389
0.393
Group of variables
Variable introduced to the model
Somatic and structuralfunctional characteristics
R 2pop.
F
14.26***
10.53***
9.02***
7.06***
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
R
R2
R 2pop.
F
Flexibility
Body height
0.67
0.69
0.71
0.45
0.48
0.51
0.43
0.43
0.44
18.18***
9.74***
7.06***
Rhythmization
Differentiation of force parameters of motion
Visual-motor coordination (free mode)
Frequency of movements
0.46
0.55
0.64
0.68
0.71
0.21
0.31
0.41
0.46
0.50
0.18
0.24
0.33
0.34
0.36
5.91*
4.62*
4.70*
4.07*
3.46*
Motor abilities
of physical nature
Envelope run
0.66
0.75
0.79
0.42
0.57
0.63
0.39
0.53
0.57
15.71***
13.87***
11.16***
Group of variables
Table 4. Coefficients of multiple determination between the sports skill level and morphofunctional variables
in the group of juniors
R
R2
R 2pop.
F
Wrist mobility
Body height
Shoulder width
LBM
0.40
0.57
0.68
0.72
0.75
0.16
0.32
0.47
0.51
0.56
0.10
0.22
0.331
0.337
0.340
2.68
3.12
3.47
2.91
2.54
Selective reaction time
Kinaesthetic differentiation of temporal
parameters
0.42
0.54
0.62
0.17
0.29
0.39
0.12
0.18
0.23
2.96
2.66
2.53
0.68
0.47
0.27
2.40
MAP, upper limbs
Envelope run
MAP, lower limbs
0.68
0.77
0.80
0.82
0.46
0.59
0.64
0.67
0.43
0.52
0.55
0.556
12.11**
9.26**
7.03**
5.59**
Group of variables
Motor abilities
of physical nature
24
HUMAN MOVEMENT
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 emphasized that only the combination of these three variables 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 parameters. The first was the factor of MAP for the lower 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 significantly increases the level of the coefficient of determination (53%), whereas integration of another value that
determines the cardiorespiratory endurance leads to an
insignificant increase in this index. In this form, it explains 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 variables 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 determination. 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 morphological age in this group of study participants.
The variables which determine coordination abilities 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, visualmotor coordination (free mode), and movement frequency. The significant effect on the level of playing from
such a substantial number of factors of motor coordination 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 success may be determined by speed and force the shuttlecock 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 amplitude 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 temporal parameters of movement. The whole model determines 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 particular the effect of structural aptitudes, physical abilities
and coordination abilities on the development of competitive competencies with age. This complex concept
was supposed to gradually lead to identification, structurization 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 preceded 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 identification 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
25
HUMAN MOVEMENT
procedures, 26 variables were selected and analysed within 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 characteristics that affects sports skill level at a statistically
significant level. The importance of these characteristics 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 motor coordination in this group rose to five. The importance of coordination abilities for badminton players
is also confirmed by the findings published by many
authors. Jaworski and Żak [10] analysed morphofunctional 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 visual stimulus were above the mean obtained for the whole
module. These results demonstrate that the above coordination abilities are essential for recruitment of athletes, 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, reaction time is one of the most important neurofunctional abilities that affect playing efficiency. Badminton
players (both boys and girls) have better results compared to untrained peers [13]. As presented by the authors 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 intercorrelations 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)
26
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 opponents 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 different sports skill levels. Furthermore, the results of the
studies concerning the relationships of simple and complex 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 necessity of paying particular attention to development
and improvement of technique in this period of training.
Coordination exercises are known to stimulate development of special fitness, which, based on feedback, improves 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 actionrelated 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 coordination makes it easy to anticipate the shuttlecock trajectory 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. However, 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 structure 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 orientation 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 attention 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 emphasized by Subramanian [21]. In the multiple regression
model, this variable explained around 10% of the de-
HUMAN MOVEMENT
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 Jeyaraman 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 results in competition. This thesis is reinforced by the
strongly accentuated views on the variation of the morphological age and its effect on the results achieved in
terms of performance of motor tasks. The greatest variation of physical development was observed in the puberty 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 consideration 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 adjusting 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 dominant 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. Furthermore, 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 envelope run [19]. The movement actions typical of performance 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 effective 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 object, movement integration and kinaesthetic differentiation. These abilities have a leading effect on development 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 pronounced 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 determines the sports skill level on the initial level of training
process, and its contribution in this area rapidly increases in the group of cadets and insignificantly declines in the group of juniors. It should also be emphasized 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 juniors, 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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Paper received by the Editor: January 27, 2016
Janusz Jaworski
Zakład Teorii Sportu i Antropomotoryki
Wydział Wychowania Fizycznego, Instytut Sportu
Akademia Wychowania Fizycznego
al. Jana Pawła II 78
31-571 Kraków, Poland
e-mail:[email protected]
HUMAN MOVEMENT
2016, vol. 17 (1), 29– 35
Body stability and support scull kinematic
in synchronized swimming
doi: 10.1515/humo-2016-0008
Alicja Rutkowska-Kucharska*, Karolina Wuchowicz
Department of Biomechanics, University School of Physical Education, Wrocław, Poland
Abstract
Purpose. 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
Introduction
The relatively small (compared with other sports) number 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 literature 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 displacement [2], compare the efficiency of repetitive arm movements by synchronized swimmers and artistic gymnasts [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 maintain the vertical position [5], determine unhealthy behaviors 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 swimming movements underwater.
Synchronized swimming is a branch of swimming in
which swimmers compete by executing a specific movement 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 comprehensive literature review found a limited number of
studies analyzing lower limb movements such as the eggbeater and boost kicks, techniques which allow swimmers 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 examined the employment of the upper limbs in synchronized swimming. Although the use of the upper limbs
when underwater (termed as sculling) is not subject to
scoring during competition, the upper limbs are essential 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-standard) is used to align the swimmer’s body in the layout
position whereas the support scull is employed to maintain 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
29
HUMAN MOVEMENT
A. 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 relatively 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 upper 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”, eggshaped oval, or ellipse movement [2, 16]. Another alternative 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 hydrodynamic analysis [16]. Additional interest in sculling 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. Furthermore, 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 technique and the ability of the swimmer to maintain body
stability in the water.
A review of the available literature shows no investigation on the correlations between the kinematic variables 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 ascertain 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. Although the biomechanical investigation of synchronized
swimming technique – in contrast with competitive
swimming [18] – is not directly associated with achieving competitive success, it can aid in the identification
of the factors responsible for technique execution and
therefore contribute to enhanced performance.
30
The sample consisted of 16 female synchronized
swimmers with varying levels of performance, from beginners (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 provide 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 synchronized 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( )
HUMAN MOVEMENT
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 swimsuits, caps, swimming goggles, and nose clips.
Support scull kinematics was quantified using
SIMI Motion® software by assessing individual movement cycles. Since sculling is performed in all three anatomical planes, the breakdown of this movement based
on only the angle created by the elbow joint was considered insufficient. Therefore, we adopted the angular
motion made at both the elbow and wrist joints (measured 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 minimum value. Based on these phases, the following temporal and kinematic characteristics of the sculling movement 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 (dorsiflexion) 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 towards the trunk [°]
– range of movement during shoulder adduction
towards the trunk [°]
The angles defined in the study are shown in Figure 1. Body stability during the support scull was assessed 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 significant 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 kinematic 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 statistically significant. However, the head marker was characterized by significantly (p 0.05) greater range of
displacement in the forward–backward and right–left
directions than the pubic symphysis. This finding suggests 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
Head marker
Displacement (m)
Trajectory length (m)
Pubic symphysis marker
Head marker
Pubic symphysis marker
* statistically significant difference p
Forwards–backwards
Right–left
Upwards–downwards
Forwards–backwards
Right–left
Upwards–downwards
Mean ± SD
0.044 ± 0.010
0.028 ± 0.007 *
0.034 ± 0.015
*
0.028 ± 0.016
0.023 ± 0.010
0.034 ± 0.010
0.13 ± 0.06
0.12 ± 0.09
Coefficient of variation (%)
23.54
25.33
43.66
58.00
45.66
29.67
51.19
65.52
0.05
31
HUMAN MOVEMENT
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 duration than the second phase (medial shoulder movement) (Table 3).
Correlational analyses were performed between the
range of displacement and the trajectory of the pubic
symphysis marker (Table 1) and scull kinematics (Table 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 correlated (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 adduction towards the trunk. Movement in the forward–backward direction correlated (Spearman’s r = 0.547, p < 0.028)
with sculling angle, whereas upward–downward movement 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 kinematics 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 technique. 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 swimmer B in all three anatomical planes was twice as large
as that in swimmer A. The differences in sculling technique 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. Differences 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 movement technique used in sculling and determine the kinematic 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 maximum angular values were used to quantify the entire
sculling movement into an initial phase (abduction and
second phase (adduction). However, the linear and angular 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 comparison 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
Right upper limb
Range of movement
Sculling ( )
Elbow joint ( )
Wrist joint ( )
Forearm abduction/adduction ( )
Arm abduction/adduction ( )
Left upper limb
Mean ± SD (º)
Coefficient
of variation (%)
Mean ± SD (º)
Coefficient
of variation (%)
57.05 ± 10.96
50.61 ± 10.77
26.80 ± 5.65
91.67 ± 7.65
30.84 ± 4.25
19.20
21.27
21.07
7.66
13.76
56.38 ± 13.30
49.99 ± 19.15
31.15 ± 9.6
91.77 ± 7.8
30.83 ± 4.82
23.6
38.3
30.72
8.5
15.65
Table 3. Linear variables of upper limb movements during a sculling movement
Variable
Upper limb
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)
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)
* statistically significant difference p
32
0.05
Right
Left
Coefficient
of variation (%)
Relative time (%)
0.72 ± 0.05
0.31 ± 0.06 *
0.40 ± 0.06
1.74 ± 0.21
7.32
17.96
14.43
15.15
100
43
55.5
–
0.73 ± 0.05
0.28 ± 0.05 *
0.44 ± 0.05
1.64 ± 0.25
6.98
18.18
11.91
15.21
100
38
60
–
Mean ± SD
HUMAN MOVEMENT
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
33
HUMAN MOVEMENT
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 Olympic 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 relationship between scull cycle duration and competitive
level. In addition, Rostkowska et al. [21] also demonstrated 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 adduction and abduction of the forearm. This range of movement was also characterized by the smallest variability
among the swimmers. Homma and Homma [15] investigated 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 differences were found between both studies regarding the
movement ranges of the elbow joint. This may be explained 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 highlights 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 synchronized 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 assumed 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 variability 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 particular, we found that an increase in the excursion of the pubic symphysis marker was paralleled with an increased
34
range of movement of the wrist joint, as was the movement of the body in the right-left and upward-downward
directions. Furthermore, a larger sculling angle was associated 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–backward 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 vertical 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.
Acknowledgements
This 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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Symposium for Biomechanics and Medicine in Swimming, Porto, Portugal. Biomechanics and medicine in
swimming X. Port J Sport Sci, 2006, 6 (Suppl 2), 45–48.
Available from: http://www.fade.up.pt/rpcd/_arquivo/
RPCD_vol.6_supl.2.pdf.
17. Gray J., Coaching synchronized swimming figure transitions. Standard Studio, Berkshire 1993.
18. Strzała M., Krężałek P., The body angle of attack in front
crawl performance in young swimmers. Hum Mov, 2010,
11 (1), 23–28, doi: 10.2478/v10038-010-0003-5.
19. Grimshaw P., Lees A., Fowler N., Burden A., Instant notes.
Sport and exercise biomechanics. Taylor & Francis Group,
New York, Abingdon, 2007.
20. Hall S.J., Support scull kinematics in elite synchronized
swimmers. In: Bauer T. (ed.), Proceedings of the XIIIth International Symposium on Biomechanics in Sports. Lakehead 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, 2015
Paper accepted for publication: February 8, 2016
Alicja Rutkowska-Kucharska
Department of Biomechanics
University School of Physical Education
al. I.J. Paderewskiego 35
51-612 Wrocław, Poland
35
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2016, vol. 17 (1), 36– 42
A comparison of static and dynamic measures of lower limb
joint angles in cycling: Application to bicycle fitting
doi: 10.1515/humo-2016-0005
Rodrigo Rico Bini 1, 2 *, Patria Hume 2
1
School of Physical Education of the Army, Center for Physical Training of the Army, Rio de Janeiro, Brazil
Sport Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
2
Abstract
Purpose. Configuration of bicycle components to the cyclist (bicycle fitting) commonly uses static poses of the cyclist on the bicycle at the 6 o’clock crank position to represent dynamic cycling positions. However, the validity of this approach and the potential 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
Introduction
Optimal body position on the bicycle has been suggested to reduce injury risk and improve cycling performance [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 dimensions of bicycle components related to anthropometric
dimensions of the cyclist [4, 5]. For the configuration of
bicycle components (e.g. vertical and horizontal positions of the saddle), joint angles have been preferably
recommended in comparison to anthropometric references [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 optimal 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 potentially 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
36
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 applied 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 components 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 observed 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 configured more properly, leading to an improvement in
bike fitting methods.
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R.R. Bini, P. Hume, Comparison of static and dynamic angles in cycling
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 motion. 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-sectional) 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 configuration 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 recreational 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 Research 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 condyle, 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 outdoors 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 pedalling cadence as similar as possible to steady state cruising 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 similar to cameras used in motion analysis systems (i.e. 1 mega
pixel). Assuming that cyclists would freely choose pedalling 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 digitized 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 comparison with static poses. The rater’s reliability in digitising was determined using images from static poses analysed 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).
37
HUMAN MOVEMENT
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 dynamic angles (i.e. hip, knee and ankle), Cohen‘s effect
sizes (ES) were computed for the analysis of magnitudes 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 differences between the joint angles measured in static and
dynamic positions were computed to illustrate the agreement 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 dynamic 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 illustrate the 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].
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
0.01
0.01
0.13
Trivial
Trivial
Trivial
0.03
0.01
0.17
Trivial
Trivial
Trivial
3 o’clock position
Hip angle
Knee angle
Ankle angle
0.03°
0.05°
0.98°
0.61
0.46
4.51
0.14
0.09
1.25
6 o’clock position
Hip angle
Knee angle
Ankle angle
0.05°
0.25°
0.84°
0.48
0.42
4.01
0.12
0.12
0.58
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.
38
HUMAN MOVEMENT
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
0.1
0.3
0.4
Trivial
Trivial
Small
1.1
1.5
1.4
Large
Large
Large
3 o’clock crank position
Hip angle
Knee angle
Ankle angle
38 ± 1.3
62 ± 1.7
125 ± 2.4
38 ± 1.1
63 ± 1.5
122 ± 2.2
0.3 ± 1.1
1.1 ± 1.6
2.5 ± 2.5
6 o’clock crank position
Hip angle
Knee angle
Ankle angle
67 ± 1.8
30 ± 2.4
131 ± 2.1
62 ± 1.4
38 ± 1.5
139 ± 2.4
4.9 ± 1.1
8.1 ± 1.9
8.5 ± 1.9
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]
39
HUMAN MOVEMENT
Discussion
In bicycle shops, clinics and bicycle research, configuration of bicycle components to the cyclist (bicycle
fitting) takes into account lower limb joint angles determined 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 reported differences between lower limb joint angles
gathered from cyclists in static postures compared to
dynamic cycling. Cyclists in our study did not replicate 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 reduce injury risk and optimize performance [6, 22], but
the assessment of joint angles of cyclists may depend on
exercise conditions. Previous studies presented the dependence of joint angle on workload level [23], pedalling 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 position 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 different 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 flexors), 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].
40
Differences in joint angles between static and dynamic analysis may be related to the lack of angular momentum 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 improve efficiency and reduce the risk of injuries in cyclists [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 dynamically. Depending on the existing saddle height,
suboptimal muscle length for force production and increased 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 present 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 images from static poses. However, the choice for analysis
of mean results of joint angles over five crank revolutions increased the accuracy of crank angle determination 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
HUMAN MOVEMENT
sagittal plane compared to 3D analysis [31]. Pelvic motion 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 configuration of bicycle components using joint angles, measurements 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.
Acknowledgements
The first author acknowledges Capes-Brazil for his PhD scholarship. The authors acknowledge AUT University for supporting this research Thanks are given to the cyclists who
participated in the study
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17 (1), 55–62. Available from: http://journals.humankinetics.com/AcuCustom/Sitename/Documents/DocumentItem/2280.pdf.
32. Neptune R.R., Hull M.L., Methods for determining hip
movement in seated cycling and their effect on kinematics and kinetics. J Appl Biomech, 1996, 12 (4), 493–
507.
Paper received by the Editor: December 31, 2015
Rodrigo Bini
Divisão de Pesquisa e Extensão
Escola de Educação Física do Exército
Centro de Capacitação Física do Exército
Av. João Luiz Alves s/n, Urca, Rio de Janeiro, Brazil
42
HUMAN MOVEMENT
2016, vol. 17 (1), 43– 49
JOINT-ANGLE SPECIFIC STRENGTH ADAPTATIONS INFLUENCE
IMPROVEMENTS IN POWER IN HIGHLY TRAINED ATHLETES
doi: 10.1515/humo-2016-0006
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 9
1
A.T. Still University, Mesa, Arizona, USA
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, USA
5
Rio de Janeiro Federal University, Rio de Janeiro, Brazil
6
CYMO Research Institute, Valladolid, Spain
7
Logan High School, Logan, Utah, USA
8
Granbery Methodist College, Juiz de Fora, Brazil
9
Indianapolis Colts, National Football League, Indianapolis, Indiana, USA
2
Abstract
Purpose. 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 training 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 enhance performance in that sport through specific adaptations in neuromuscular performance.
Siff [2] detailed this concept in a more complex,
neurophysiologic manner stating that “it is vital to remember that all exercise involves information processing 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 processing and physiological performance in specific sport
skills.
Accordingly, alterations in the range of motion for
a given exercise may, theoretically, result in different adaptations. 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-angle 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 movement pattern, and can affect the development of force,
rate of force development, activation and synchroniza43
HUMAN MOVEMENT
M.R. Rhea et al., Joint-angle specific strength adaptations
tion of motor units, and dynamic joint stability. Therefore, 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 influence of training at different squat depths on jointangle specific strength as well as transfer to several sportsrelated 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 period, 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 Institutional 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 measures, 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 conducting the pre-, mid-, and post-tests were blinded to
the group assignment of each subject to avoid any potential 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 Conditioning Association [19]. Subjects performed one repetition 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 ranging 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 performed according to the same protocols explained for
the pre-testing.
Vertical jump testing was performed according to
protocols previously published [19]. Immediately following 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 between 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 warmup 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 recorded. 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
HALF
FULL
21.4 (3.2)
20.7 (2.1)
21.3 (1.3)
86.5 (25.6)
95.7 (32.1)
92.1 (23.8)
167.67 (13.95)
162.12 (12.22)
164.09 (13.18)
151.51 (15.12)
146.72 (11.54)
151.82 (12.80)
129.54 (17.23)
125.50 (14.09)
125.91 (18.38)
75.92 (15.06)
77.03 (11.05)
73.91 (14,25)
4.68 (0.18)
4.73 (0.18)
4.76 (0.20)
1RM – 1 repetition maximum, VJ – vertical jump, 40 – 40 yard sprint
44
HUMAN MOVEMENT
followed a daily undulating periodization sequence with
intensity progressing from 8RM, 6RM, 4RM, to 2RM
then reverting back to 8RM. Training weight was estimated 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, reverse hamstring curls, and step ups) were performed on
Monday and Thursday, and upper body exercises performed on Tuesday and Friday. Squats (65%) and power 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 threeminute rest was provided between each set. This resulted 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 videotaping throughout the training program. The first group
performed full squats (FULL) with range of motion determined 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 degrees of flexion. The final group performed quarter
squats (QTR) with range of motion involving a squat
to approximately 55–65 degrees of knee flexion. During the initial sessions, and during all testing, a goniometer (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 program. 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 Shapiro–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 comparisons 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 determine the magnitude of an effect independent of sample 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 calculation reported by Zatsiorsky [21]:
Transfer = Result Gain in nontrained exercise/Result Gain in trained exercise
Result Gain = Gain in performance/Standard deviation of performance
The associations between different measures were
assessed by Pearson product moment correlation at baseline 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 quarter 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 vertical 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 effect of the time was noted (p < 0.001; 2 = 0.795).
45
HUMAN MOVEMENT
Sprint Test
A group × time interaction effect was noted for vertical jump test (p < 0.001; 2 = 0.615; see Figure 3). However, 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 transfer. Finally, correlation analysis (Table 5) demonstrated
stronger relationships between the QTR squat group
and both VJ (r = 0.64) and Sprint (r = –0.74) performances 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)
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 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)
46
* significantly different from Baseline (p < 0.05)
#
†
Figure 3. Sprint test. Values are mean ± SE (QTR Group,
n = 9; HALF Group, n = 9; FULL Group, n = 10)
HUMAN MOVEMENT
Table 2. Percet changes in performane measures
Group
Quarter Squat
Half Squat
Full Squat
VJ
40 sprint
QTR
HALF
FULL
0.12
0.07
0.00
0.06
0.14
0.05
0.02
0.00
0.17
0.15
0.07
0.01
–0.02
–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
HALF
FULL
1.41
0.88
0.05
0.62
1.76
0.59
0.12
0.02
1.14
0.75
0.48
0.07
–0.58
–0.35
–0.10
ES – (post-pre)/pre-test SD
Table 4. Coefficient of transfer calculations
Group
QTR
HALF
FULL
Quarter 1RM
Half 1RM
Full 1RM
VJ
40 sprint
1.00
0.51
0.05
0.44
1.00
0.52
0.08
0.01
1.00
0.53
0.28
0.06
–0.41
–0.20
–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)
Group
Quarter 1RM
Half 1RM
Full 1RM
VJ
40 sprint
Quarter 1RM
Half 1RM
1
0.847**
0.847**
1
0.722**
0.693**
0.640**
0.428*
–0.740**
–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)
ditioning coaches regarding the use of quarter squats in
a sports conditioning program. Further examination of
the risks, benefits, and implementation of squats of various 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. Additionally, we found far less transfer from deep squat training
to vertical jump. Several distinct differences exist between these two studies, perhaps accounting for the different 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, highlighting the need for longer studies to examine these important training issues more critically. It is also possible that
as an individual becomes more highly trained, jointangle 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
47
HUMAN MOVEMENT
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 processes 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 adaptations 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 testing 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 representing 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 improvements 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 concept 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 suggested 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 improvements 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 fitness will occur at the joint-angles that are sufficiently
48
overloaded by the load placed upon them. In the conventional 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 concepts proposed by Siff [2] regarding information processing during training, it is suggested that the neuromuscular system perceives, and adapts to, stresses applied
during quarter squats much differently than full squats.
It is also important that the strength and conditioning professional differentiate between transfer and value.
If the goal of a specific workout were to enhance sprinting or jumping, quarter squats would be the most effective 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 different muscle groups. Understanding the exact benefits
or drawbacks of different exercises and ranges of motion
is imperative to optimal training and strength and conditioning professionals should place high value on educating 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 detailed 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 motion, 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 quarter squats. The same could be said of all squat depths
and the best approach for health and performance enhancement 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 separate 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 approach to developing the total athlete. However, based
on the data from this study, it is clear that the use of quarter squats is not only helpful, but also necessary for promoting maximal sprinting and jumping capabilities.
HUMAN MOVEMENT
Conclusions
In summary given the significantly greater transfer
to improvements in sprinting and jumping ability, the
use of quarter squats during sports conditioning is recommended. 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 professionals should consider the integration of quarter
squats for maximizing sprinting and jumping ability.
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Paper received by the Editor: September 22, 2015
Matthew Rhea
Kinesiology Department
A.T. Still University
5850 East Still Circle, Mesa
AZ 85206, USA
49
HUMAN MOVEMENT
2016, vol. 17 (1), 50– 55
ANAEROBIC EXERCISE AFFECTS THE SALIVA ANTIOXIDANT/OXIDANT
BALANCE IN HIGH-PERFORMANCE PENTATHLON ATHLETES
doi: 10.1515/humo-2016-0003
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, Brazil
Instruction Center Almirante Sylvio de Camargo, Rio de Janeiro, Brazil
3
Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
4
Navy Sports Commission, Rio de Janeiro, Brazil
2
Abstract
Purpose. 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
Introduction
Free radicals are not intrinsically harmful to health:
low-to-moderate concentrations play multiple regulatory roles in gene expression, cell signaling, and skeletal 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 intense anaerobic exercise can be effective in generating
oxidative stress as assessed by xanthine oxidase activity
and markers for lipid peroxidation, protein carbonylation, and DNA oxidation, as well as total antioxidant
capacity [5]. Strenuous aerobic exercise induces an increase in lipid peroxidation in human plasma [1], likely
generated by hydroxyl radical attack on polyunsaturated fatty acids [5].
Providing blood samples increases stress in athletes
that can limit their willingness to participate in scientific studies, especially during competition. This study
examines oxidative stress, for the first time in military
50
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 intense 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 suitable as biological material to monitor changes in biomarkers for free radical generation and total antioxidant 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 competition in naval pentathlon. They were engaged in the
final weeks of training for a series of international tournaments. 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
HUMAN MOVEMENT
M. de Lima Sant’Anna et al., Redox balance in athlete’s saliva
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. Subjects 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 percentage was determined using the Siri [10] equation.
Exercise test
The RAST, a single set applied individually, was performed 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).
Table 1. Anthropometric characteristics
and aerobic capacity
Age (yr)
Body mass (kg)
Height (cm)
BMI* (kg/m2)
Body fat (%)
VO2max (mL/kg · min)
Mean ± SD
Range
27.1 ± 5.4
65.3 ± 6.6
170 ± 10
21.9 ± 0.8
10.2 ± 5.6
61.9 ± 12.0
21–31
53.8–72.2
160–185
20.7–23.2
3.9–20.3
44.6–73.7
* body mass index = mass(kg)/(height(m))2
Table 2. Measures of performance in the RAST
Mean ± SD
Peak power per weight (W/kg)
6.5 ± 1.4
Average power per weight (W/kg)
5.4 ± 1.1
Minimum power per weight (W/kg) 4.6 ± 1.1
Range
4.4–7.9
3.8–6.7
3.0–5.9
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 described 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 centrifuged at 15,000 × g for 3 min. The absorbance of the
supernatant was read at 530 nm and TBARS concentration 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 sodium-potassium phosphate (10 mM, pH 7.4) and 500 µL
2,2-diphenyl-1-picrylhydrazyl (DPPH, 0.1 mM), incubated 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. Percentage 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 centrifuged 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 samples 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].
Power (in watts) is normalized to body weight (kg).
51
HUMAN MOVEMENT
Uric acid in saliva
2.5
Pre- and post-test samples were compared using Student’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 between 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 capacity and measures of performance in the RAST.
Results
1.5
1.0
0.5
0.0
PRE
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 peroxidation was ~2 times higher than at rest (Figure 2). In
90
Figure 2. The anaerobic test RAST induces oxidative stress.
Mean ± S.E. (n = 7), *p < 0.05
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.
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 glutathione 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).
80
10
*
70
8
% QUENCH IN DPPH
60
50
40
30
4
5
6
7
8
POST
Total antioxidant capacity
Correlation between aerobic and anaerobic
performance
VO2max (mL/kg.min)
*
2.0
TBARS (µM)
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.
9
6
4
2
Peak power per kg (W/kg)
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
52
0
PRE
POST
Figure 3. RAST increases the total antioxidant capacity
in athletes’ saliva. Mean ± S.E. (n = 7), *p < 0.05
HUMAN MOVEMENT
a
50
GSH (µM)
40
30
20
10
0
b
PRE
POST
350
*
300
URIC ACID (µM)
250
200
150
100
50
0
PRE
POST
Figure 4. Antioxidant biomarkers. A) Glutathione (GSH);
B) Uric acid. Mean ± S.E. (n = 7), *p < 0.05
Discussion
The aim of this study was to investigate free radical
production and antioxidant buffering in military pentathletes’ saliva after an anaerobic test, RAST. The running-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, although it is frequently used to predict running performance, 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 antioxidant 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 phosphocreatine hydrolysis and glycolysis, but a shift toward
oxidative metabolism to replenish ATP has been demonstrated for later trials in a sequence of sprints [21]. We
observed a high correlation between VO2max and anaerobic power, consistent with a role for aerobic power
in anaerobic performance, and suggesting the importance 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 alternative 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 primarily 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 disruption [2, 23]. The increase in lipid peroxidation after six
sprints shows that mechanism for free radical production 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 (Figure 2), the total antioxidant capacity was not used up.
Wayner et al. [24] have assigned total peroxyl trapping 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 recorded 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.
53
HUMAN MOVEMENT
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 regulated, 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 controlled. In another study that assessed anaerobic resistance 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 meaurements 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 experiments 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 antioxidant 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 antioxidant 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 control 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 metabolism are formed [32]. Xanthine oxidoreductase is
a key intracellular enzyme of purine metabolism. Its oxidase 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 scavenges 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 profile of redox state using a non-invasive approach associated 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
54
capacity as a sub-acute adaptation to a short series of
sprints.
Acknowledgements
This work was supported by grants from Fundação de Amparo 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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muscle adaptation. Exp Physiol, 2010, 95 (1), 1–9, doi:
10.1113/expphysiol.2009.050526.
30. Ji L.L., Gomez-Cabrera M.C., Vina J., Role of nuclear factor kappaB and mitogen-activated protein kinase signaling in exercise-induced antioxidant enzyme adaptation. Appl Physiol Nutr Metab, 2007, 32 (5), 930–935,
doi: 10.1139/H07-098.
31. Foti M.C., Amorati R., Non-phenolic radical-trapping antioxidants. J Pharm Pharmacol, 2009, 61 (11), 1435–1448,
doi: 10.1211/jpp/61.11.0002.
32. Gerber T., Borg M.L., Hayes A., Stathis C.G., High-intensity intermittent cycling increases purine loss compared
with workload-matched continuous moderate intensity
cycling. Eur J Appl Physiol, 2014, 114 (7), 1513–1520,
doi: 10.1007/s00421-014-2878-x.
33. Whidden M.A., McClung J.M., Falk D.J., Hudson M.B.,
Smuder A.J., Nelson W.B. et al., Xanthine oxidase contributes to mechanical ventilation-induced diaphragmatic
oxidative stress and contractile dysfunction. J Appl Physiol
(1985), 2009, 106 (2), 385–394, doi: 10.1152/japplphysiol.91106.2008.
34. Cantu-Medellin N., Kelley E.E., Xanthine oxidoreductasecatalyzed reactive species generation: a process in critical
need of reevaluation. Redox Biol, 2013, 1, 353–358, doi:
10.1016/j.redox.2013.05.002.
35. Morales-Alamo D., Calbet J.A., Free radicals and sprint
exercise in humans. Free Radic Res, 2014, 48 (1), 30–42,
doi: 10.3109/10715762.2013.825043.
Paper received by the Editor: October 26, 2015
Paper accepted for publication: February 8, 2016
Veronica Pinto Salerno
Laboratório de Bioquímica do Exercício
e Motores Moleculares (LaBEMMol)
Avenida Carlos Chagas Filho, 549
Cidade Universitária
CEP 21941-599, Rio de Janeiro, Brazil
55
HUMAN MOVEMENT
PUBLISHING GUIDELINES – Regulamin publikowania prac
1. Human Movement (abb.: HM) is a peer-reviewed quarterly journal published by the University School of Physical
Education (abb.: AWF).
2. The Editorial Office accepts for publication original empirical papers and review ones on various aspects of human
movement, e.g. sports medicine, exercise physiology, biomechanics, motor control, psychology. Letters to the Editor, reports from scientific meetings and book reviews are also welcome. Publication of articles in Human Movement is free
of charge.
3. Papers are accepted for publication after being reviewed
favorably by at least two independent reviewers nominated by
the Editor and who are not affiliated in the same research unit
as the author of the reviewed manuscript. Authors can suggest
reviewers, but the Editor reserves the right to final selection.
4. Review procedures are set forth in accordance with the
guidelines of the Polish Ministry of Science and Higher Education which are consultable on website: https://pbn.nauka.gov.pl/
static/doc/wytyczne_dotyczace_procedury_recenzowania.pdf
5. Reviews are written by completing a paper review form
(available on the HM website) where reviewers have to expli
citly express whether the manuscript is accepted for publication or rejected.
6. The review process is double-blind. Otherwise reviewers
are obliged to sign a conflict of interest declaration (conflict
of interest occurs when there are close personal relationships
between the author and the reviewer, professional superiorsubordinate relationships, direct research cooperation for the
two years prior to the manuscript reviewing.
7. Names of the reviewers are not revealed. Once a year the
Editor provides a general list of the cooperating reviewers.
8. After the article is accepted for publication, the author
transfers copyright to AWF by signing the Creative Commons
license, and consequently giving his or her consent to publish
the article in printed, magnetic and digital form, and to make
it accessible on the Internet (the appropriate form is available
online). If the article is an output of cooperation of more
authors, the principal author is entitled by the other co-authors to sign the license on their behalf and is also obliged to
inform the co-authors of the license terms and the journal
submission requirements. Papers accepted for publication
become the property of AWF and cannot be published elsewhere without AWF’s written permission. Publication is subject to copyright due to the Berne Convention and the Universal Copyright Convention, with few exceptions admitted
by the local law. No part of the paper (except for the abstract)
may be reproduced by readers, stored and transmitted in any
form and by any means without the copyright holder’s permission.
9. Authors retain copyright of their papers, are allowed
to store, propagate it according to the legally permitted private use and can use the paper’s content in their future works
only if the complete bibliography source information is
provided.
56
1. Kwartalnik Human Movement (dalej: HM) jest recenzowanym czasopismem naukowym Akademii Wychowania
Fizycznego we Wrocławiu (dalej: AWF).
2. Redakcja przyjmuje do publikacji oryginalne prace
empiryczne oraz przeglądowe dotyczące ruchu człowieka
z zakresu medycyny sportu, fizjologii wysiłku fizycznego,
biomechaniki, antropomotoryki, psychologii. Przyjmowane są również listy do Redakcji, sprawozdania z konferencji
naukowych i recenzje książek. Publikowanie prac w Human
Movement jest bezpłatne.
3. Do druku zatwierdzane są tylko prace, które uzyskają
pozytywną opinię co najmniej dwóch, powołanych przez Redakcję, niezależnych recenzentów spoza jednostki naukowej
afiliowanej przez autora publikacji. Autor może zaproponować
recenzentów, lecz Redakcja zastrzega sobie prawo ich doboru.
4. Procedury recenzowania są zgodne z wytycznymi Ministerstwa Nauki i Szkolnictwa Wyższego, umieszczonymi na
stronie: https://pbn.nauka.gov.pl/static/doc/wytyczne_dotyczace_procedury_recenzowania.pdf
5. Recenzje mają formę pisemną i są sporządzane na arkuszu
recenzenckim (dostępny na stronie internetowej czasopisma),
zobowiązującym recenzenta do sformułowania jednoznacznego
wniosku o dopuszczeniu pracy do publikacji lub jej odrzuceniu.
6. Autor i recenzent pozostają względem siebie anonimowi
(double-blind review process). W pozostałych przypadkach
recenzent jest zobowiązany do podpisania deklaracji o niewystępowaniu konfliktu interesów (za konflikt interesów uznaje
się zachodzące między recenzentem a autorem: bezpośrednie
relacje osobiste – pokrewieństwo, związki prawne, relacje podległości zawodowej, bezpośrednia współpraca naukowa w ciągu
ostatnich dwóch lat poprzedzających przygotowanie recenzji.
7. Nazwiska recenzentów nie są ujawniane. Raz w roku
Redakcja podaje do publicznej wiadomości listę recenzentów
współpracujących.
8. Po akceptacji artykułu do druku autor przekazuje prawa
autorskie na rzecz AWF, podpisując licencję Creative Commons,
tym samym zgadzając się na druk artykułu w postaci drukowanej, na nośnikach magnetycznych, cyfrowych i upowszechnie
nia w internecie (formularz do pobrania ze strony internetowej).
Jeśli artykuł powstał we współpracy z innymi autorami, główny
autor jest upoważniony przez wszystkich współautorów do
podpisania licencji w ich imieniu i zobowiązuje się do poinformowania współautorów o warunkach zawartych w licencji oraz
Regulaminie czasopisma. Przyjęty artykuł staje się własnością
AWF i nie może się ukazać w innym wydawnictwie bez jej
pisemnej zgody. Publikacja podlega prawu autorskiemu wynikającemu z Konwencji Berneńskiej i z Międzynarodowej Konwencji Praw Autorskich, poza wyjątkami dopuszczanymi przez
prawo krajowe. Żadna część publikacji (z wyjątkiem abstraktu)
nie może być reprodukowana przez czytelników, archiwizowana ani przekazywana w jakiejkolwiek formie ani żadnymi
środkami bez pozwolenia właściciela praw autorskich.
9. Autor zachowuje prawa autorskie dotyczące artykułu,
ma prawo go archiwizować, rozpowszechniać zgodnie z prawem dozwolonego użytku prywatnego oraz może wykorzystywać treści tego artykułu w przyszłych swoich pracach
pod warunkiem podania pełnego adresu bibliograficznego.
HUMAN MOVEMENT
Publishing guidelines – Regulamin publikowania prac
10. The Editor reserves the right to introduce corrections in the paper and prevent its publication in case of confirmed plagiarism. The submitted articles which are not conform to the requirements will be returned to authors for
corrections.
11. The author (authors) receives no royalty for publication. 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 personal data of the research participants. If the information
included in the paper makes it possible to identify the subjects, authors have to obtain their written consent for publication of the research outcomes, photographs included (the
appropriate form can be downloaded from the Internet) before 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 advertising are negotiated individually.
20. The original version of the journal is its paper issue.
10. Redakcja zastrzega sobie prawo do wprowadzenia poprawek w artykule oraz niedopuszczenia do jego publikacji
w razie stwierdzenia plagiatu. Artykuł przygotowany niezgodnie z regulaminem będzie odsyłany autorowi do poprawy.
11. Za artykuł opublikowany w HM autor (autorzy) nie
otrzymuje honorarium. Autor do korespondencji otrzymuje
za pośrednictwem poczty e-mail plik PDF z opublikowanym
artykułem i tomem, w którym został opublikowany artykuł.
12. Autor pracy naukowej ma obowiązek ochraniać dane
osobowe badanych osób. Jeżeli zawarte w artykule informacje
umożliwiają w jakikolwiek sposób ustalenie tożsamości badanych osób, autor musi uzyskać ich pisemną zgodę na opublikowanie wyników, w tym zdjęć fotograficznych (formularz do
pobrania ze strony internetowej), przed wysłaniem artykułu
do Redakcji.
13. Redakcja nie przyjmie artykułu, w którym występują
zjawiska „ghostwriting” i „guest authorship”, a wszelkie nieprawidłowości będzie ujawniać. Od głównego autora pracy
zbiorowej Redakcja wymaga wypełnienia stosownego oświadczenia, pozwalającego określić wkład współautorów w powstanie artykułu.
14. Warunkiem rozpoczęcia prac redakcyjnych nad artykułem jest dostarczenie na adres [email protected]
wersji elektronicznej, przygotowanej zgodnie z wytycznymi
zawartymi w załączniku niniejszego Regulaminu, podpisanej
licencji, oświadczenia głównego autora (w wypadku pracy
zbiorowej) oraz zgody autora fotografii i osoby fotografowanej (w wypadku załączonego materiału ilustracyjnego).
15. Autor, składając artykuł do czasopisma, tym samym
zgadza się na obowiązujące w Redakcji HM procedury kwalifikowania pracy do publikacji.
16. Po naniesieniu poprawek po recenzji autor zobowiązuje się odesłać poprawiony artykuł w ciągu 3 tygodni.
17. Autor jest zobowiązany współpracować z native spea
ker, redaktorem wydawniczym i korektorami (językowym
i statystycznym) w celu wyjaśnienia wszelkich niejasności lub
uzupełnienia braków w tekście. Brak odpowiedzi na uwagi
redakcyjne w ciągu tygodnia będzie oznaczać zgodę na wprowadzenie proponowanych poprawek.
18. Autor powinien wymienić osoby lub instytucje, które
pomogły mu w przygotowaniu pracy, udzieliły konsultacji
bądź wsparły go finansowo lub technicznie.
19. Redakcja przyjmuje zamówienia na reklamy, które
mogą być umieszczane na dodatkowych kartach sąsiadujących
z okładką. Ceny reklam będą negocjowane indywidualnie.
20. Wersją pierwotną czasopisma jest wersja papierowa.
Detailed guidelines for submitting articles
to Human Movement
Szczegółowe zasady przygotowania artykułu
do Human Movement
1. The article should be written in English.
2.Empirical research articles, together with their summary 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
1. Redakcja przyjmuje prace wyłącznie w języku angielskim.
2. Tekst prac empirycznych wraz ze streszczeniem, rycinami
i tabelami nie powinien przekraczać 20, a prac przeglądowych – 30 stron znormalizowanych formatu A4 (ok. 1800
znaków ze spacjami na stronie). Strony powinny być ponumerowane.
3.Artykuł należy przygotować w edytorze tekstu Microsoft
Word według następujących zasad:
– krój pisma: Times New Roman, 12 pkt;
– interlinia: 1,5;
– tekst wyjustowany;
– tytuł zapisany pogrubionym krojem pisma, wyśrodkowany.
57
HUMAN MOVEMENT
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 affiliations 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:
4.Strona tytułowa powinna zawierać:
– tytuł pracy w języku angielskim;
– skrócony tytuł artykułu w języku angielskim (do 40 znaków ze spacjami), który zostanie umieszczony w żywej
paginie;
– imię i nazwisko autora (autorów) z afiliacją zapisaną
według następującego schematu:
• nazwa uczelni, nazwa miejscowości, nazwa kraju,
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 wyrazów) składające się z następujących części: Purpose,
Methods, Results, Conclusions;
– słowa kluczowe w języku angielskim (3–6) – ze słownika i w stylu MeSH.
6. Trzecia strona powinna zawierać:
– tytuł artykułu;
– tekst główny.
7. Tekst główny pracy empirycznej należy podzielić na następujące części:
Introduction
The introduction prefaces the reader on the article’s subject, describes its purpose, states a hypothesis, and mentions
any existing research (literature review)
Wstęp
We wstępie należy wprowadzić czytelnika w tematykę
artykułu, opisać cel pracy oraz podać hipotezy, stan badań
(przegląd literatury).
This 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), discuss 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 reproducibility. If a method is being used for the first time, it
needs to be described in detail to show its validity and reliability (reproducibility). If modifying existing methods, describe 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 methods should be described in such a way that they can be easily
determined if they are correct. Authors of comparative research articles should also include their methods for finding
materials, selection methods, etc.
Materiał i metody
W tej części należy dokładnie przedstawić materiał badawczy (jeśli w eksperymencie biorą udział ludzie, należy podać
ich liczbę, wiek, płeć oraz inne charakterystyczne cechy), omówić warunki, czas i metody prowadzenia badań oraz opisać
wykorzystaną aparaturę (z podaniem nazwy wytwórni i jej
adresu). Sposób wykonywania pomiarów musi być przedstawiony na tyle dokładnie, aby inne osoby mogły je powtórzyć. 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 konieczność ich wprowadzenia. Gdy w eksperymencie biorą
udział ludzie, konieczne jest uzyskanie zgody komisji etycznej
na wykorzystanie w nim zaproponowanych przez autora metod (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.
Results
The results should be presented both logically and consistently, as well as be closely tied with the data found in
tables and figures.
Discussion
Here 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.
58
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 znaczące aspekty swojej pracy.
HUMAN MOVEMENT
Conclusions
In 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.
Wnioski
Przedstawiając wnioski, należy pamiętać o celu pracy oraz
postawionych hipotezach, a także unikać stwierdzeń ogólnikowych i niepopartych wynikami własnych badań. Stawiając
nowe hipotezy, trzeba to wyraźnie zaznaczyć.
Acknowledgements
The author may mention any people or institutions that
helped the author in preparing the manuscript, or that provided support through financial or technical means.
Podziękowania
Należy wymienić osoby lub instytucje, które pomogły autorowi w przygotowaniu pracy, udzieliły konsultacji bądź
wsparły go finansowo lub technicznie.
Bibliography
The bibliography should be composed of the article’s citations 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 enclose 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 comparative research papers. There are no restrictions in referencing
unpublished work.
Bibliografia
Bibliografię należy uporządkować i ponumerować według
kolejności cytowania publikacji w tekście, a nie alfabetycznie.
Odwołania do piśmiennictwa należy oznaczać w tekście numerem 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 książkowe), z wyjątkiem prac przeglądowych. Niewskazane jest
cytowanie prac nieopublikowanych.
Citing journal articles
Bibliographic citations of journal articles should include:
the author’s (or authors’) surname, first name initial, article title, abbreviated journal title, year, volume or number,
page number, doi, for example:
Opis bibliograficzny artykułu z czasopisma
Opis bibliograficzny artykułu powinien zawierać: nazwisko autora (autorów), inicjał imienia, tytuł artykułu, tytuł
czasopisma w przyjętym skrócie, rok wydania, tom lub numer, 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.
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 English, 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:
Gdy autorami artykułu jest sześć lub mniej osób, należy wymienić 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 powinien przetłumaczyć na język angielski, a w nawiasie kwadratowym podać język oryginału, tytuł czasopisma należy
zostawić w oryginalnym brzmieniu, np.
Jaskólska A., Bogucka M., Świstak R., Jaskólski A., Mechanisms, symptoms and after-effects of delayed muscle soreness (DOMS) [in Polish]. Med Sport, 2002, 4, 189–201.
Jaskólska A., Bogucka M., Świstak R., Jaskólski A., Mechanisms, symptoms and after-effects of delayed muscle soreness (DOMS) [in Polish]. Med Sportiva, 2002, 4, 189–201.
The author’s research should only take into consideration articles published in English.
W pracy powinny być uwzględnianie tylko artykuły publikowane ze streszczeniem angielskim.
Citing books
Bibliographic citations of books should include: the author (or authors’) or editor’s (or editors’) surname, first name
initial, book title translated into English, publisher, place and
year of publication, for example:
Opis bibliograficzny książki
Opis 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.
Osiński W., Anthropomotoric [in Polish]. AWF, Poznań 2001.
Heinemann K. (ed.), Sport clubs in various European countries. Karl Hofmann, Schorndorf 1999.
Heinemann K. (ed.), Sport clubs in various European countries. 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:
Opis bibliograficzny rozdziału w książce powinien zawierać: 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 exercise testing. In: Skinner J.S. (ed.), Exercise testing and exercise
prescription for special cases. Lea & Febiger, Philadelphia
1993, 3–28.
McKirnan M.D., Froelicher V.F., General principles of exercise testing. In: Skinner J.S. (ed.), Exercise testing and exercise
prescription for special cases. Lea & Febiger, Philadelphia
1993, 3–28.
59
HUMAN MOVEMENT
Citing conference materials
Citing conference materials (found only in international
research databases such as SPORTDiscus) should include:
the author’s (or authors’) surname, first name initial, article title, conference author’s (or authors’) or editor’s (or editor’s) surname, first name initial, conference title, publisher,
place and year of publication, page number, for example:
Opis bibliograficzny materiałów zjazdowych
Opis bibliograficzny materiałów zjazdowych (umieszczanych tylko w międzynarodowych bazach danych, np.
SPORTDiscus) powinien zawierać: nazwisko autora (autorów), 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 twodistance simplified testing method for determining critical swimming velocity. In: Chatard J.C. (ed.), Biomechanics and Medicine in Swimming IX, Proceedings of the IXth
World Symposium on Biomechanics and Medicine in Swimming. Université de St. Etienne, St. Etienne 2003, 385–390.
Rodriguez F.A., Moreno D., Keskinen K.L., Validity of a twodistance simplified testing method for determining critical swimming velocity. In: Chatard J.C. (ed.), Biomechanics and Medicine in Swimming IX, Proceedings of the IXth
World Symposium on Biomechanics and Medicine in Swimming. Université de St. Etienne, St. Etienne 2003, 385–390.
Citing articles in electronic format
Citing articles in electronic format should include: author’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 number, for example:
Opis bibliograficzny artykułu w formie elektronicznej
Opis bibliograficzny artykułu w formie elektronicznej powinien 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., Enevoldsen L.H., Stallknech B. et al., Hormone-sensitive lipase
(HSL) expression and regulation by epinephrine and exercise 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.
Donsmark M., Langfort J., Ploug T., Holm C., Enevoldsen L.H., Stallknech B. et al., Hormone-sensitive lipase
(HSL) expression and regulation by epinephrine and exercise 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. The main text of any other articles submitted for consideration should maintain a logical continuity and that the
titles assigned to any sections must reflect the issues discussed within.
9. Footnotes/Endnotes (explanatory or supplementary to the
text). Footnotes should be numbered consecutively throughout 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 resolution 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 published 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.
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 postaci osobnych plików zapisanych w formacie *.jpg lub
*.pdf (gęstość co najmniej 300 dpi);
– nie można powtarzać tych samych wyników w tabelach 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 tabelach czy na rycinach należy dokładnie objaśnić, tak by
były czytelne i zrozumiałe niezależnie od tekstu pracy.
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 publication. At such a point in time, only minor corrections can be
accepted from the author.
Przed drukiem autor otrzyma swój artykuł do akceptacji
w formie pliku pdf. Obowiązkiem autora jest niezwłoczne
przesłanie do Redakcji Human Movement informacji o akceptacji artykułu do druku. Na tym etapie będą przyjmowane
tylko drobne poprawki autorskie.
SUBSCRIBING to THE HUMAN MOVEMENT JOURNAL
ZASADY PRENUMERATY CZASOPISMA HUMAN MOVEMENT
http://www.awf.wroc.pl/pl/article/1003/5954/Prenumerata_subscription/
60

Human Movement - Akademia Wychowania Fizycznego we Wrocławiu

Transcription

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