Biophysics

ABSTRACT. In this article we perform theoretical analysis of long jumps with the purpose to find the contribution of different biomechanical parameters to the final results. The graphical diagrams show how the result changes when the parameters change. The calculated diagrams may be useful for trainers and athletes in order to predict and improve their achievements. © 2009 Bull. Georg. Natl. Acad. Sci. Key words: biomechanical analysis, video-computer modeling, long jumps. In the recent publications [1-4] we presented a new markerless method for video-computer modeling based on the well-known principle of forward kinematics. This method was successfully applied to video-computer modeling of long jumps [2, 4]. The method may be more effective when combined with a well- developed theoretical model. In this article we investigate how the result of long jumping depends on the basic parameters which characterize the push-off phase, namely, on the value and direction of the sportsman’s start speed and the start point coordinates. The start point is the position of the sportsman’s center of gravity at the push-off moment when his pushing-off leg comes off the ground. The motion of the sportsman’s center of gravity in the gravitation field can be described by the following formulas. L = L0 + L1+ L2; (1) x0 = L0 = r cosβ; y0 = r sinβ; r = (x02+ y02)1/2; (2) V0x=V0 cosα; V0y=V0 sinα; (3) T1=V0y/g; y1=Hmax=y0+V0y2/2g; (4