A METHOD FOR DETERMINING THE INDMDUAL SPORT TECHNIQUE IN JAVELIN

Abstract

INTRODUCTION. The javelin throwing skill is within the movement pattern which objective is to reach the maximum velocity of human body chain free end at the release instant. It has been proved for numerous researchers that segments reach the maximum speed consecutively and beginning for the proximal segments. This one has done to think that throwing pattern is based in the energy transmission among segments. However, nobody has found until to day quantitative relations among energy exchanges which allow to establish, in an objective way, differences among throws of one subject. Also, the trunk has been considered normally like a bar, that is, no differing thorax, abdomen and pelvis. Finally, to remark that it has not been found any research which calculates the kinetic energy of segments considering them with their six degrees of freedom. Therefore, the main objective of this work will be to develop individual technique patterns based in the energy exchange among segments. This model should allow to assess the performance objectively. The methology has been based in the filming of the movement by mean two highspeed cine-camaras and the latter determination of the 3D coordinates of the body landmarks. DLT algorithm was used. Previously to the experimental phase, a theorical model was develop for the computation of human body kinetic energy. The model considers the body like a solid rigid (six degrees of freedom)system and takes like input the 3D coordinates of body markers. The model determines a local reference system in each segment and after calculates the kinetic energy of the 17 segments which define the human body (included the javelin). The kinetic energy is considered like the addition of a traslational and arotational terms. Two elite thowers were the subjects. 36 throws were analyzed. The energy increments of segments and groups of segments in the registered throws were the variables. Each subject was considered separately. RESULTS. The linear regression study confirmed the energy exchange among segments general pattern in both athletes. The discriminate analysis proved the existence of an individual pattern -mathematical model- for each thrower. The discriminate function allowed to differ objectively between good a bad throws. Also it informed about the technique used for the subject. CONCLUSIONS. A new model for calculating the kinetic energy of segments has been developed. A procedure for a quantitative determination of the individual pattern of movement in throwing, based on the using of discriminant analysis, has been developed REFERENCES. -Bartlett, R.M. y Best,R.J. (1988) The biomechanics of javeling throwing: a review. J. Sports Sci. 6(1), 1-38.-Caldwell, G.E. y Fonester, L.W. (1992)Estimates of mechanical work and energy transfers: demostration of a rigid bodypower model of the recovery leg in gait.Med. Sci. Sports Exerc. 24(12). 1396-1412.-Menzel, H.J. (1987) Transmission ofpartial momenta in javelin throw. EnBiomechanics X-6, (Editado por Jonsson,B.) Human Kinetics Publishers,Champaign, 643-647.