An Analysis On Features Of Lower Limbs Velocity Put By Chinese Excellent Women Shot Putters

The technique of back slide step is mainly used by Chinese female shot putters. Many researches on it have been conducted both at home and abroad, but there is little documentation on lower limbs velocity analysis and research. The author studies the top 8 female shot putters in the National Track and Field Championships held in Yutong Stadium in Shijiazhuang, a capital city in Hebei province, on October 11, 2008. By means of two JVC9800 high speed camera by the 50 Hertz speed synchronization photography, and an"Ariel"3-D kinematics analytic system which gives the picture analysis, a kinematic analysis on the features of lower limbs velocity will be expounded from three stages: gliding, transitional, delivery. Through the analysis of body—shot system's shot put velocity, barycenter velocity, lower limbs velocity and other parameters, the author tries to find the correct features of lower limbs velocity in the athlete's act of putting the shot, which will provide reference standard for shot put teaching and training.The result shows that:(1) at the gliding stage,the vertical speed of the swing leg is too fast, which has an influence on the speed of the horizontal movement of body barycenter and the shot. The right hipbone moves down first and then moves up, which shows that the horizontal body barycenter velocity declines, and the right leg do not draw back actively;(2) at the transitional stage, when the right foot is landing Li Fengfeng'left hipbone velocity is slow and the left hipbone velocity is slower than the right hipbone velocity, which will have a detrimental effect on surmounting the instrument sufficiently; when the left foot is landing, some athletes'right hipbone velocity is slower than the left hipbone velocity, it means that their left legs do not apply the brake timely, which is detrimental to gliding and the transition to final forceful stage. The transitional time is obviously too long;(3) at the finally forceful stage, the changing features of hip-knee-ankle velocity are not ideal, so it does not achieve a good effect. The release velocity of domestic athlete is lower than the foreign excellent athlete. The difference between shot put velocity and body barycenter velocity is lower compared with the foreign excellent athletes. The final forceful technique needs to be improved. (4) the correct features of lower limbs velocity in the technique of back slide step is as follows: at the gliding stage, the right hipbone velocity increases first and then decreases, and finally increases again, while the swinging leg should not swing too much; at the transitional stage, the left knee's velocity increases first and then decreases; at the finally forceful stage, the left lower limb velocity decreases sharply, while the right lower limb velocity increases sharply.