(School of Physical Education,Southwest University,Chongqing 400715,China) Abstract: In order to reveal the biomechanical mechanism of goal shooting with instep front at different heights, the authors recruited 12 testees to carry out goal shooting with instep front at ground height, 1/2 knee height and knee height, with and without the ball respectively for 10 times, carried out synchronized kinetic and dynamic measure-ment by using two JVC9800 cameras and a domestic JP6060 multidimensional force measurement platform, and revealed the following findings: multi-factor variance analysis showed that the ball speed and foot speed were sig-nificantly different during goal shooting at ground height, 1/2 knee height and knee height, the speed of the ball shot at ground height was the fastest, followed by the speed of the ball shot at 1/2 knee height, tailed by the speed of the ball shot at knee height; various kinetic indexes of the testees in the experiment group, such as forward and back-ward swinging of the thigh, backward swinging of the shank, had no significant difference during goal shooting at different heights, while forward swinging of the shank as a kinetic datum was significantly different during goal shooting at different heights; the vertical distance from the supporting leg to the ball was significantly correlative with the speed of the ball shot at various heights, the speed of the swinging leg, knee angle right at the moment the ball was kicked, angular speed of forward swinging of the shank, amplitude of forward swinging of the shank, and time of forward swinging of the shank, while there was no linear relation between the speed of the ball shot at 3 heights and the ground reacting force born by the supporting leg. The said findings indicate the followings: the lower the ball shooting height during goal shooting with instep front, the faster the ball speed; therefore, if a player wants to get a faster ball speed during goal shooting with instep front, he/she should kicked the ball when it is at a relatively low height; a player can control ball speed, ball flying path and action time during goal shooting with in-step front by controlling the perpendicular distance from the supporting leg to the ball; the ground reacting forced born by the supporting leg is irrelevant to the speed of the ball kicked, hence, the main function of the supporting leg during ball kicking is to fix the support and maintain balance, so that the swinging leg exerts its power more thoroughly. Key words: sports biomechanics;goal shooting with instep front;different heights;goal shooting;ball speed;supporting leg |