Release mechanics in the triple tucked backward salto dismount from high bar

Abstract

s-International Society of Biomcchanics XIII Congress 1991 107 RELEASE MECHANICS IN THE TRIPLE TUCKED BACKWARD SALT0 DISMOUNT FROM HIGH BAR Michael J. Harwood, David G. Kerwin and Maurice R. Yeadon Biomechanics Research Laboratory, Department of Sports Science, Loughborough University, Loughborough, England. The precise point of release for triple tucked backward salto dismounts from high bar is the subject of some debate among coaches and biomechanists. Some experienced observers are convinced that many gymnasts release with their mass centres above bar level while others maintain that this is impossible if the gymnasts are to travel away from the bar in flight. Six gymnasts performing triples at the 1988 Olympic Games were filmed at IO frames per second using two cameras. Twenty one frames around release were digitized twice from each view, with release defined as the point at which the wrists began to move away from the bar. Three dimensional coordinates of 12 body landmarks were calculated and the mass centre location determined using an inertia model. Velocity values were obtained using quintic splines, and the horizontal mass centre velocity was partitioned into four components: bar relative to it's neutral position, bar to wrist (due to movement of the wrist around the bar), wrist to mass centre radially and wrist to mass centre tangentially. Although some gymnasts' mass centres were very close to bar level at release, none were above it. Despite these differing mass centre heights at release, all gymnasts had similar in flight horizontal velocities. For gymnasts releasing close to bar level the greatest contributor to horizontal velocity was the bar to wrist component. This suggests that gymnasts used wrist flexor/extensor control to begin to move away from the bar in anticipation of letting go. The release mechanics are more complex than simply letting go at the right moment, and include a number of preparatory movements. THE EFFECT OF BRAKING LOAD ON MAXIMAL ANAEROBIC MUSCLE POWER OUTPUT DURING SHORT-TERM CYCLING EXERCISE Yuichi Hirano, Takehiro Tagawa and Mitsumasa Miyashita Lab. for Exert. and Sports Sci., Faculty of Education, The Univ. of Tokyo, Tokyo, JAPAN The purpose of the present study was to investigate the effect of braking load on maximal anaerobic muscle power output (maxP) during shortterm exercise performed on a cycle ergometer. Eight healthy males made a series of 4.5sec maximal efforts at 5 different low loads (0.4, 0.6, 0.8, 1.0, and 1.2kp) on a cycle ergometer. Exerted anaerobic muscle power output during each cranking was calculated as the summation of the power for the braking load and the power for the acceleration of the wheel. MaxP was determined by the regression analysis of power output in each cranking. One-way ANOVA revealed no significant effect of 5 different loads on both maxP and the revolution at maxP. In case of the measurement of maxP estimated from each power output during repetitive contractions of specific muscles such as cycling, it may be the determinant factor whether optimal revolution for maxP was obtained during a short-term exercise. THE MXHANICAL MODELOFLF~SANDAFNS.ANDTHE DEFINITIONSOF THE STFUKE CENTFtE OF BFUDGES AND &P-LEGS IN TBE WlLsHu Li Hui, Zeng Weimin, Zbonguan University of Finance and Ecamada wuhall. china Wang Juan, The Deprvtmeat of Physicd-Training, Jbghan U&en&y, WI&&. China Wushu is a trad&naJ cultureinChina.ThktraditaadcubremaybcdatcdbacJt for thousands of years. In this paper, WC! apply the manybody dynamim to the wushu, and good results are obtabed. We simpliiy the kgs & m to two 3igids bodks. We can get the mechanical model of legs and arms. It we have data about a spo&man. We can obtain the strike cenlres of the upper arms (or thinks) and the fcuwums calcdats to obtain the following data ahout the spatmen Wu’s (or shanks). we masum and wu xkng Weight 64b right hand:135 light f orearm:26.3 right upperrums left hand90 kft forearm5?8.1 kft uppua~m&2 right foot93, right shank%.5 m&It tiQd3.s left fcow27.5 left shank:47.5 kft thkhzs39.s stnie cmtremWu.brright arm:(-o.63~92) kft &n:(-o.~l6.41) right kgz(3.41.24.31) kft kg:(4.61,26.64) Thess iu4goodreeuIt8thateaIlbeusaliuthe~,~~ ~.~~ts IN\~~~a~tothenanqnanaadtbc~hthe~u.