Somatic constitution and the ability to maintain dynamic body equilibrium in girls practicing rhythmic gymnastics

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1 ORYGINAL ARTICLES / Prace oryginalne Pediatric Endocrinology, Diabetes and Metabolism 21, 16, 2, ISSN X Somatic constitution and the ability to maintain dynamic body equilibrium in girls practicing rhythmic gymnastics Budowa somatyczna oraz zdolność zachowania równowagi dynamicznej dziewcząt uprawiających gimnastykę artystyczną Tatiana Poliszczuk, Daria Broda Department of Theory and Practice of Sports for All, The Józef Piłsudski University of Physical Education in Warsaw Zakład Teorii i Praktyki Sportu dla Wszystkich Akademii Wychowania Fizycznego Józefa Piłsudskiego w Warszawie Address for correspondence: Tatiana Poliszczuk PhD Zakład Teorii i Praktyki Sportu dla Wszystkich Akademii Wychowania Fizycznego Józefa Piłsudskiego w Warszawie ul. Marymoncka 4; -968 Warszawa 45; skr. pocz. 55; Poland; phone: (+48 22) / 7, 61; tatiana.poliszczuk@awf.edu.pl Abstract Introduction: The greatest similarities in body constitution were noted in competitors practising the same discipline. The similarities increase with the training level. A typical body constitution for a given discipline not only favourably affects athletic performance, but is also the factor preventing sportsrelated contusions. The ability to maintain body equilibrium, together with somatic constitution, are the basic selective criteria in rhythmic gymnastics. Aim of the study: The objective of this paper was to determine somatotypes, to evaluate the ability to maintain dynamic body equilibrium in girls practicing rhythmic gymnastics and to develop model characteristics enabling early diagnosis of the disorders equilibrium system function. Material and methods: The sample comprised 19 girls aged 8-11 years, practising rhythmic gymnastics. For the evaluation of the competitors somatotypes, the Heath-Carter method was used, based on the classic concept of Sheldon s body constitution components. Body equilibrium level was evaluated by means of posturography. Results: The mean values of the endomorphic component I, mesomorphic component II and ectomorphic component III in the gymnasts were 2.65±1.29, 2.45±.7 a nd. 95±.64 r espectively. T he m ean b ody m ass i ndex (B MI) v alue f or th is co hort w as 15.2, w hich m eans a dvanced s limness. T he l evel of dynamic equilibrium is determined by the following mean values: the time of reaching the equilibrium, the way of reaching it and the duration of stay at the defined point. The model of above mentioned indicates was developed based on the analysis of it s best results Conclusion: Body co nstitution t ype in th e q ualified g ymnasts is ch aracterised by th e p revalence o f th e e ctomorphic co mponent. T he s tudy r esults indicate that female gymnasts are generally slim and lean. It is necessary to monitor BMI in order to exclude weight-related disorders and to observe the changes with age. The poorest result was found when the gymnasts bent in the backward direction as this body position is most difficult to assume and to maintain body equilibrium as compared to all other directions. KEY WORDS: rhythmic gymnastics, dynamic body equilibrium, body build types, posturography Streszczenie Wprowadzenie: Największe podobieństwo budowy ciała zaobserwowano u zawodników reprezentujących tę samą dyscyplinę, przy czym podobieństwo wzrasta wraz z poziomem sportowym. Charakterystyczna, odpowiadająca specyfice dyscypliny budowa ciała nie tylko sprzyja osiągnięciom sportowym, ale może być jednocześnie czynnikiem zapobiegającym kontuzjom. Zdolność zachowania równowagi ciała razem z budową somatyczną są podstawowymi kryteriami przy wstępnym doborze do gimnastyki artystycznej. Cel p racy: Celem b adań by ło o kreślenie s omatotypu, o cena p oziomu z dolności z achowania równowagi d ynamicznej ciała d ziewcząt uprawiających gimnastykę artystyczną oraz opracowanie modelowych charakterystyk, pozwalających na wczesne diagnozowanie sprawności układu równowagi. Materiał i metody: Badaniami objęto 19 dziewcząt w wieku 8-11 lat uprawiających gimnastykę artystyczną. Do oceny somatotypu zawodniczek wykorzystano metodę Heath-Cartera opartą na klasycznej koncepcji ko mponentów budowy ciała Sheldona. Oceny poziomu równowagi ciała dokonano metodą posturografii. Wyniki: Średnia wartości komponentu I endomorfii u gimnastyczek wyniosła 2,65±1,29, II komponentu mezomorfii 2,45±,7 oraz III komponentu ektomorfii,95±,64. Średnia wartość wskaźnika body mass index (BMI) w tej grupie wyniosła 15,2, co wskazuje na zaawansowaną smukłość. Poziom równowagi dynamicznej badanych gimnastyczek określają średnie wartości: czasu dojścia, drogi dojścia, czasu pobytu w określonym punkcie. Na podstawie analizy najlepszych wyników wymienionych wskaźników w różnych kierunkach, stworzono model. Wnioski: Typ budowy ciała kwalifikowanych gimnastyczek artystycznych charakteryzuje przewaga elementu ektomorficznego. Badania wskazują, że gimnastyczki artystyczne cechują się smukłą i szczupłą sylwetką. Konieczne jest monitorowanie ich BMI, w celu wykluczenia zaburzeń masy ciała zawodniczek oraz dalsza obserwacja zmian zachodzących wraz z wiekiem. Najsłabszy wynik w modelu równowagi dynamicznej zaznaczono w kierunku w tył, gdyż jest to najtrudniejsza pozycja do uzyskania i utrzymania równowagi ciała w porównaniu ze wszystkimi innymi kierunkami. SŁOWA KLUCZOWE: gimnastyka artystyczna, równowaga dynamiczna, budowa somatyczna, posturografia 94

2 Budowa somatyczna oraz zdolność zachowania równowagi dynamicznej dziewcząt uprawiających gimnastykę artystyczną Introduction One of th e m ost imp ortant f actors af fecting athle tic p erformance is s omatic c onstitution, w hich is als o an imp ortant f actor influencing p hysical f itness ( 1). It s variabilit y de termines in terpersonal variations in human m otorics. T he result s of num erous studies on this issue indic ate that m orphological tr aits de termine a thletes res ults wit h dif fering s ignificance, dep ending on a giv en di scipline. E vidence s uggests t hat s uccessful a thletes have a dis tinct b ody c onstitution, re lated t o th e re quirements of a giv en discipline or c ompetition (2-4). The greatest similarities in b ody c onstitution, f urther in creasing w ith th e tr aining l evel (5), were obser ved in competitors prac tising the s ame discipline. A t ypical b ody c onstitution for a giv en dis cipline not onl y f avourably af fects athletic performance, but i s also the factor preventing sports-related contusions (6). Therefore, it should be included in th e basic selective criteria. The level of athle tic p erformance in g ymnastic sp orts (rhythmic and ar tistic g ymnastics, acrob atics) is highl y dep endent on coordination m otor ab ilities and f lexibility. T he s tudies c arried out among w orld-class s port r epresentatives s uggest t he c orrelation b etween th e ab ove tr aits and s omatic c onstitution ( 7). One of th e most essential coordination traits of m otor abilities in rhythmic g ymnastics is b ody e quilibrium. T here are thre e for ms of e quilibrium: s tatic, d ynamic and e quilibrium w hile th e obje cts are balancing (8). The positions of g ymnasts are mainl y based on dynamic e quilibrium. M aintaining a d ynamic e quilibrium w hen performing exercises in dif ferent directions and around th e gymnast s b ody a xis re quires high sk ills ( 9). T he ab ility t o main tain equilibrium is th e ab ility t o main tain a b alanced b ody p osition (static equilibrium) and to maintain or regain this position (dynamic e quilibrium) w hile m oving or imm ediately af ter th e m ovement (8). Steering is a continuous and dynamic process. It consists in unin terrupted a djustment of various b ody s egments t o ever changing e xternal and in ternal conditions (1) and it is c onsidered one of t he most specific coordinative properties (11). The basic crit eria for th e s election of g ymnasts inclu de: b ody constitution, physical f itness, motor abilities, aesthetics of movements, musical hearing, age and th e state of health. Somatic constitution is us ually evaluat ed v isually b y trainer s. T he c andidates for rh y- thmic g ymnasts should ha ve a slender and aes thetic b ody build, long upp er and lo wer limbs, a c orrect b ody p osture and a high foot arch ( 12). U sually, si x y ear o ld children are s elected for th e participation in c ompetitive rhythmic gymnastics. Aim of the study The objective of th e s tudy was t o de termine s omatotypes, evaluate th e lev el of th e ab ility t o main tain d ynamic b ody e quilibrium in girl s prac tising rh ythmic g ymnastics and t o de velop model c haracteristics enabl ing ea rly diagnosis of y he dis orders of the equilibrium system function. Material and methods The s ample c omprised 19 girls age d 8-11, engage d in rh ythmic g ymnastics. T he tr aining re cord of th e s tudy subje cts was kept for 2 t o 5 y ears. The characteristics of th e studied cohort are presented in t able I. T he s tudy was a pilot. It was desir able that the study group consisted of a great er number of p eople. For this reason, f urther s teps were t aken in this dire ction t o obt ain th e most reliable results. The subje cts s omatotypes were ass essed using H eath-carter s method based on the classic Sheldon s concept of three body constitution c omponents and b ody mass inde x ( BMI) values ( 1, 14). The met hod i s ba sed on d irect me asurements, p erformed at b oth b ody sides and on th e c alculated (corrected) values. T he measurements were p erformed at b oth sides of th e b ody t o determine th e de gree of s tructural as ymmetry. T he s tudied fea - tures inclu ded: b ody mass, b ody h eight, f at fo lds: on th e ar ms, under s capulae and on th e cr us, w idth of th e e lbow and k nee, arm c ircumference in t ension an d cr us circumference. th e m ethod de termines b ody build c omponents, nam ely: c omponent I endomorphy body fat is assessed based on sk in fat folds (on the ar ms, under th e s capulae and o ver th e iliac ala ); c omponent II m esomorphy is th e measure of build massiv eness or s tockiness (it is b ased on th e measurements of b ody height, elbow and knee w idth and c orrected circumferenc es of th e ar m and cr us); c omponent III e ctomorphy ass esses b ody slimn ess b ased on th e slimn ess in dex. O n th e b asis of th ese thre e c omponents (endo-, m eso- and e ctomorphy, th e s omatotypes were ass essed using thre e numb ers in a 9 -grade s cale. P oint values of indi - vidual components are read from special tables (14). Body build distribution in th e s tudied c ompetitors is gr aphically illus trated on th e s omatogram. B asic m easuring dev ices de termining for human somatotype characteristics, also in this study, included: an an thropometer for b ody h eight and ar m length m easurement; b ig cur ved compasses for m easuring b ody diam eters (e.g. shoulder width and ch est girth) and limb s egments; small cur ved compasses for th e m easurement of hands, fe et and th e w idth of bone epiphyses; a metal or oilcloth metric tape for measuring body circumferences; a l inear slider for m easuring hands and fe et and a c alliper for m easuring skin fat folds. The d ynamic e quilibrium was evaluat ed using th e P ro-med Posturograph sy stem, c onsisting o f a po sturographic pl atform of small dim ensions( cm) and a s oftware (15) ( This m ethod is used in different modifications, not only in sciences related to physical culture, but als o in re habilitation and th e studies on p osture control system (16, 17). The movement test consists in moving the centre of mass (COM) so that its projection on the platform surface is maintained in a s quare-shaped p oint m oved on th e m onitor. T he subje ct Table I: Anthropometric characteristics of the studied girls practicing rhythmic gymnastics (n=19) Tabela I: Charakterystyka antropometryczna badanych dziewcząt uprawiających gimnastykę artystyczną (n=19) Parameter / Parametr Mean / Średnia SD Age [years] / Wiek [lata] Body height [cm] / Wysokość ciała [cm] Body mass / Masa ciała [kg]

3 Somatic constitution and the ability to maintain dynamic body equilibrium in girls practicing rhythmic gymnastics Pediatric Endocrinology, Diabetes and Metabolism 21, 16, 2 can obs erve tr ansient C OM p ositions on th e m onitor s creen in a prop er s cale lik e on a map. T he s quare m oves in th e c entre of the monitor in 8 dire ctions respectively, returning to the baseline p osition. T he subje ct obs erves th e ac tual C OM p osition on the m onitor and c orrect his/ her p osture s o as t o main tain this point in th e pres et limiting area. T he subje ct has t o reach th e target by p roperly inclining his/ her b ody an d maint aining this position for a de fined p eriod of tim e, c ontrolling at th e s ame time his/her postural equilibrium. The next stage of th e posturographic task is reaching th e target. In th e study, the monitor was placed at th e distance of m f rom the subject and at th e height of h er ey es. T he m ovement t est was p erformed under fe edback conditions with the subject selecting an optimal m ovement limit (fig. 1). T he obs ervation of on e s o wn gr avity c entre enab les th e subject to maintain herself/himself in th e preset place by mak ing conscious m ovements, in order t o c orrect his/ her p osture. T he task performance depends on o culomotor coordination. The task enabled t o c alculate th e tim e of reaching th e t arget (s), th e way to reach th e pre defined t arget and th e dur ation of s tay at that point (expressed in %) were c alculated. Afterwards, th e obt ained result s were subj ected to s tatistical analysis using b asic m ethods of des criptive s tatistics. T he evalu - ation of th e c orrelation b etween th e t wo quan titative variab les was made u sing P earson s ( with normal di stributions) or S pearman s ( distributions dif ferent f rom th e nor mal on es) c orrelation coefficient. Then, the results were subjected to s tatistical analysis using Statistica 8. package. Results The mean val ue of t he f irst, endomorphic c omponent (b ody fat c ontent), th e s econd, m esomorphic c omponent ( stockiness) 4 2 Front back / Przód tył [cm] and th e third, e ctomorphic c omponent ( slimness) in th e g ymnasts were 2.65±1.29, 2.45±.7 and. 95±.64 resp ectively. T he somatotype made up of these components is marked on the somatograph with a b lack square. The mean BMI value was kg/m 2, w hich m eans a dvanced slender ness. T he indiv idual sub - jects somatotypes were p lotted on Sh eldon s somatotype (b lack points). T hey are on th e e ctomorphic f ield w ith is olated c ases in t he c entre and t he endomorphic f ield ( fig. 2 ). On t he c entile charts of P olish girls p opulation th e values for b ody h eight and body mass of th e s tudied g ymnasts were p lotted as we ll as th e arithmetic m eans of th ese values for th e w hole group, mark ed with b lack s quares. 1 6 out of 1 9 s tudied girls are shor ter than % of th e p opulation (fig. ). A s re gards b ody mass, th e values of 18 subje cts are b etween th e 1 th and 5 th ce ntile, li kewise th e average value de termined for th e studied group (fig. 4). The level of d ynamic equilibrium with the subjects feedback is de fined by a verage values of : th e tim e of reaching th e t arget point. 62±1.76 s, the length of th e distance necessary to reach the t arget p oint 5.79±16.6% and th e dur ation of s tay at the t arget p oint ±11.58%. B ased on th e anal ysis of th e best result s of th e ab ove m entioned indic es repres ented by th e competitors in dif ferent dire ctions, th e m odels of d ynamic e quilibrium m ovement t ests were dev eloped for female g ymnasts aged 8-11 y ears ( fig. 5-7). T he c omparison of th e result s for th e time of reachin g th e t arget p lace w ith th e m odel sh owed di fferences in s everal p oints, in dicating er rors an d a p oorer p otential to maintain a d ynamic balance in th ese directions. Both the time and the distance covered to reach th e target point indicate a b etter result w hen they are shor ter. The c omparison of th e m odel w ith th e result s obt ained by the girl w hose result for th e distance covered to reach th e target was the best, also showed multiple similarities. Unlike the presented indices, the higher the percentage of th e stay time the better the result. P art of th e result s obt ained by th e girl w ith th e b est results constitute th e m odel and th ese are of ten ma ximum valu - es (1%). The d ynamic e quilibrium t est using fe edback sho wed that poorer result s are obt ained w hile reaching th e t arget p oint than left right / lewo prawo [cm] 96 Fig. 1. An example of standard dynamic equilibrium test with feedback in a 1 year old female competitor Ryc. 1. Przykład standardowego badania r ównowagi dynamicznej z e spr zężeniem zwrotnym zawodniczki w wieku 1 lat Fig. 2. Sheldon s somatograph with somatotype of examined girls Ryc. 2. Somatogram Sheldona z uwzględnieniem somatotypów badanych dziewcząt

4 Budowa somatyczna oraz zdolność zachowania równowagi dynamicznej dziewcząt uprawiających gimnastykę artystyczną during the return to th e baseline position af ter that, and that th e worst results were noted in the right, backward and left direction, both for the time and distance of reaching th e target, and during the stay at th e target point. Discussion It is ob vious that ap art f rom t alent, an adequate for a giv en discipline somatic constitution is th e basic factor warranting success in sports. Body build is to a large extent determined by the human genot ype, but w ithin th e de fined limit s it is als o subje ct to en vironmental imp act. T he e xtent of s ensitivity t o e xternal environment is also genetically conditioned. The t ype of b ody c onstitution in th e s tudied g ymnasts was mainly characterised by th e prevalence of th e ectomorphic component. T he subje cts are h ealthy and f it girls although th e mean BMI value is f ar b elow th e nor m. D ue t o such alar ming result s, Body M ass Inde x should b e m onitored re gularly am ong a w ider group of girls pr acticing rhythmic g ymnastics. S uch ac tions may contribute to earl y de tection of dis orders of b ody mass and cre - ate an opp ortunity t o reac t. T he danger ass ociated w ith high training lo ad ( rhythmic g ymnasts tr ain four tim es a we ek for two hours with high lo ads) is v ery high at this age s o prevention of disorders of body mass is an important aspect of health that allows to continue their sporting careers without the destruction of the body due t o malnutrition. It is als o obvious that g ymnasts are char acterised by th e latest m enarche age as c ompared t o th e c ompetitors pr actising other sport disciplines. It is a b iological property connected with a very slim and e xtremely slim b ody constitution, desire d in this sport discipline (18). The studies of M enezes and F ilho indicate that Br azilian gymnasts are als o characterised by th e prevalence of th e ectomorphic component i n soma totype de velopment. In Brazi lian c hampion gymnasts (n=1) w hose m ean age was 1.7 y ears th e m ean val - ues of t he endomorphic, mesomo rphic and e ctomorphic components were 2.72±.99, 2.65±.87 and 4.17±.92 respectively (9). The studies confirm the selectors conclusions that rh ythmic gymnasts should be characterised mainly by a slim and slender build ( 19). In athle tes th e s omatotypes are de finitely less dif ferentiated a s c ompared t o t he d ifferentiated s omatotypes a mong t he non-training p opulation. It is th e result of s election and tr ainingrelated changes. Training brings ab out physiological and mor phological e ffects. T he changes w ithin th e mus cular s ystem, induced by p hysical e xercise, consist mainl y in mus cle mass dev elopment as a result of th e increas e in s arcoplasma in mus cle f ibres. T he changes within muscles depend principally on the sort of training, its intensity and dur ation. It is de finitely harder t o shape the skel cm Body height girls / Wysokość ciała dziewcząt polish population / populacja polska n=6 19 % kg Body mass girls / Masa ciała dziewcząt polish population / populacja polska n=6 19 % calendar age [years] / wiek kalendarzowy [lata] Fig.. The c omparison of the individual v alues of body heigh t of the competitors with polish girls population Ryc.. Wartości wysokości ciała zawodniczek w stosunku do populacji polskich dziewcząt calendar age [years] / wiek kalendarzowy [lata] Fig. 4. The comparison of individual v alues of body mass of c ompetitors with polish girls population Ryc. 4. Wartości masy ciała za wodniczek w st osunku do populacji polskich dziewcząt 97

5 Somatic constitution and the ability to maintain dynamic body equilibrium in girls practicing rhythmic gymnastics Pediatric Endocrinology, Diabetes and Metabolism 21, 16, 2 98 etal system as it is p articularly rigid and not subje ct to changes. The results of s tudies conducted in world class athle tes in different sp ort dis ciplines indic ate a clos e re lationship b etween different body constitution indices and coordinative abilities includ - ing an ab ility to maintain body equilibrium (7-9 12). The analysis of th e results of this s tudy allows us t o conclude that in indiv iduals aged 8-11 years with a lo w training level there Left Lewo Front-left Przód-lewo Back-left Tył-lewo / Przód/Front Back / Tył / Front- right Przód-prawo Back-right Tył-prawo Right Prawo model AS Fig. 5. The comparison between the model value of the time to reach the target point [s] and the correspondent value obtained by the best gymnast Ryc. 5. Porównanie w artości czasu dojścia [s] do okr eślonego punktu gimnastyczki, która uzyskała najlepsze wyniki, do modelu Front-left Przód-lewo Left Lewo Back-left Ty ł-lewo Front / Przód Back / Tył Front- right Przód-prawo Back-right Ty ł-p rawo Right Prawo model Fig. 6. Comparison between the model v alue of the distanc e covered to reach the target point [%] and the correspondent value obtained by the best gymnast Ryc. 6. Porównanie w artości dr ogi dojścia [%] do okr eślonego punktu gimnastyczki, która uzyskała najlepsze wyniki, do modelu MM is no c orrelation b etween d ynamic e quilibrium and on e of th e most imp ortant features d etermining su ccess in rh ythmic g ymnastics: b ody c onstitution. T his ma y result f rom th e subje cts age, as th e age of 7-11 years is a s ensitive p eriod in th e development of th e ability to maintain e quilibrium. D ynamic e quilibrium can b e we ll tr ained in girls age d years, however, it is m ore genetically conditioned than th e static equilibrium (2). There are few p apers in lit erature on rh ythmic g ymnastics, especially thos e p ertaining t o th e ab ility t o main tain b ody e quilibrium. T he author s claim that this ab ility develops by p articipation in sp orts (9, 2 ). T he s tudy c onducted by Hir tz als o depic ts the dev elopment of d ynamic e quilibrium in girls subje cted t o training pro cess (11). K ioumourtzoglou e t al. in th eir s tudy found significant differences in the results determining dynamic equilibrium among gymnasts and non -training individuals (21). Fotiadou et al. showed a significant effect of training in rhythmic gymnastics on th e improvement of main taining a d ynamic equilibrium in blind children (22). Feedback p osturography enab les us t o develop th e d ynamic equilibrium m odel (an imaginar y ar rangement th e t ask of w hich is to imitate the best values obtained during the movement test, presented by each c ompetitor as a w hole). The comparison of the results obt ained by th e c ompetitors age d 8-11 y ears w ith th e model may b e th e b aseline for obje ctive diagnos tics of d ynamic equilibrium f unction and for de termining th e dire ction and c orrection level of th e studied properties. To mak e sure that th e result s are th e m ost re liable and up to date such research should be continued. The plan of scientific ac tivity involves conducting s ystematic s tudy an d e xtension of the themes of th e measurements of b ody composition of gir ls practicing rhythmic gymnastics. Front-left Przód-lewo Left Lewo Back-left T ył-lewo Front / Przód 1 Back / Tył Front- right Przód-prawo Back-right Tył-prawo model ET Right Prawo Fig. 7. Comparison bet ween the model v alue of the dur ation of sta y a t the target poin t [%] and the c orrespondent v alue obtained b y the best gymnast Ryc. 7. Porównanie w artości czasu pob ytu [%] w okr eślonym punk cie gimnastyczki, która uzyskała najlepsze wyniki, do modelu

6 Budowa somatyczna oraz zdolność zachowania równowagi dynamicznej dziewcząt uprawiających gimnastykę artystyczną The obtained results may be an imp ortant source of infor mation for sports physicians and physiotherapists, and serve as comparative data for oth er researchers. Conclusions 1. The girls pr acticing rh ythmic g ymnastics are char acterised by a high lev el of th e ab ility t o main tain d ynamic e quilibrium. B ased on th e dev eloped m odels of s elected m ovement test indices, model values of d ynamic equilibrium were determined in the gymnasts aged 8-11 years. However, it is necessary t o m onitor this indic ator in order t o e xclude disorders of b ody mass am ong p layers and f urther obs ervation of changes with age. 2. The ectomorphic component is the main component involved in the development of female g ymnasts somatotype.. The m ean BM I value was k g/m 2 in th e s tudied c ohort of gymnasts which indicates advanced slenderness. 4. In female gymnasts aged 8-11 there is no correlation between the s elected b ody c onstitution c omponents an d d ynamic equilibrium level. The paper is part of statutory studies s ubject No DS.-121, granted by the M inistry of Scienc e and H igher Education. References 1. Reilly T., S tratton G.: Children and adolesc ent in spor t: ph ysiological c onsiderations. Sport Exerc. Inj., 1995, 1, Claessens A.L., B eunen G, Malina R.M.: Anthropometry, ph ysique, body c omposition and maturity. [in:] Pediatric Exercise Science and Medicine. (ed.) N. Armstrong, W. Van Mechelen. Oxford University Press, Oxford, 2, Gualdi-Russu E.G., Gruppioni G., Guer esi P. et al.: Skinfolds and body c omposition of spor t participants. J. Sports Med. Phys. Fitness, 1992, 2, Leone M., Lariviere G., Comtois A.S.: Discriminant analysis of anthropometric and biometr y variables among elite adolescent female athletes in four sports. J. Spor ts Sci., 22, 6, Charzewski J., Głaz A., K uźnicki S.: Somatotype characteristics of elit e European wrestlers. Biology of Sport, 1991, 4, Backx F.J.G.: Epidemiology of pediatric sports-related injuries. [in:] Child and adolescent athlete. Encyclopedia of sports Medicine. (ed) O. Bar-Or, Blackwell Scientific, Oxford, Starosta W.: Motoryczne z dolności k oordynacyjne (znacz enie, struktur a, uw arunkowania, kształtowanie). International Association of Sport Kinetics, Warszawa, Raczek M., Mynarski W., Ljach W.: Kształtowanie i diagnozowanie koordynacyjnych zdolności motorycznych. AWF, Katowice, Starosta W.: Globalna i lokalna koordynacja ruchowa w w ychowaniu fizycznym i w spor cie. International Association of Sport Kinetics, Warszawa, 26, Saulicz E., Nowotny J.: Niektóre zaburzenia statyki ciała i ich korekcja. AWF, Katowice, Hirtz P.: Koordinative Fähigkeiten im Schulsport. Volk und Wissen, Berlin Kuźmińska O.: Struktura somatyczna dziewcząt uprawiających gimnastykę artystyczną. Kult. Fiz., 197, 2, Carter J.E.L., Heath B.H.: Somatotyping: development and applications. Cambridge University Press, Cambridge, Łaska-Mierzejewska T.: Ocena budo wy somat ycznej czło wieka. [in:] Zastosowanie met od naukowych na potrzeby sportu. Tom XI, (ed.) T. Ulatowski. PTNKF, Warszawa, 22, Olton J.: Posturograf. S ystem, badania i oc eny układu r ównowagi k oordynacji wzrokoworuchowej Instrukcja. Pro-Med, Warszawa, Błaszczyk J.W., Czerwosz L.: Stabilność posturalna w procesie starzenia. Gerontologia Polska, 25, 1, Bosek M., Gr zegorzewski B.: The par tition of the fluctuation strength of the h uman center of pressure. Med. Biol. Sci., 28, 22, Łaska-Mierzejewska T.: Antropologiczne a spekty selekcji spor towej dzieci i młodzieży. [in:] Zastosowanie met od nauk owych na potrz eby spor tu. Tom XI ( ed.) T. Ula towski. PTNKF, Warszawa,22, Menezes L., Filho J.: Identification and comparison of dermatoglyfics, somatotype and basic physical aptitude characterístics of rhythmic gymnasts of different qualification levels. Fitness and Performance, 26, doi:1.9/fpj p. 2. Prus G.: Wytrenowalność zdolności motorycznych u kobiet. AWF, Katowice, Kioumourtzoglou E., Derri V., Mer tzanidou O. et al.: Experience with per ceptual and mot or skills in rhythmic gymnastics. Percept. Mot. Skill., 1997, 84, Fotiadou E., Giagazoglou P., Kokaridas D. et al.: Effect of rhythmic gymnastics on the dynamic balance of children with deafness. Eur. J. Spec. Needs Educ., 22, 17, 1-9. Recived: Accepted: Conflicts of interest: none declared 99