STUDY OF LEG MOVEMENT IN ONE- AND TWO-LEGGED HOPPING

Abstract

This study was based on the previous research where mechanics of the leg-pushing phase in shot put was studied. The present paper examined the functional mechanics of leg movements during the ground contact of the jumps on one leg and on two legs. The principle of the measuring method was to photograph the movement in series of subject images on one frame where the marker lights attached to the subject can be seen as broken light-lines. The measuring accuracy of the system (time and distance) proved to be very high. This new measuring method is a useful complement to the existing methods. The aim of the study was to approximate the measured points by a suitable curve. Two equations (representing damped oscillatory motion and sine-formed motion) derived for the path of the center of gravity in jump on one leg and on two legs fitted well the experimental results while the equation of strengthening oscillatory motion did not match the measured paths of motion. However, it was hypothesized that vertical displacement-time curve may become a strengthening oscillatory motion as the leg force exertion increases. The model of leg movement of the present paper was compared with the earlier model of the same equation of motion.