The Three-dimensional Kinematics Analysis On Rotational Shot Put Technique Of Two Elite Athletes In China

This paper adopted the Arial three-dimensional analysis system imported in USA to do the work of three-dimensional filming, trimming of films, resolution of films and the calculating and comparing of the data. The subject of the paper is the elite shot put athletes of China who took part in the National Track and Field Championship of China in December, 2008.The two athletes, both right-hand, rotational shot put technique and master sportsman at all, are selected as the subject who are the top of ten of the nation in China .The film of the shot put competition, firstly, was digitized. Then a document of 3D-stick was composed by Arial three-dimensional analysis system. At last, the data can be exported at anytime. The paper divided the trajectory of rotational shot put at six time-space spots as follow: the biggest angle of shoulder-hip axis spot, the right foot up spot, the left foot up spot, the right foot down spot, the left foot down spot and the delivery spot.One of the joint points of athlete's body was traced, so the trajectory of the joint point can be used as technique diagnosis as well as the analysis of time-space points. The top-view and side-view of CG, ball and left knee of the athletes were compared.Conclusions of the paper are as follow:Firstly, the paper analyzed the kinematics characteristics of the two elite athletes, structured the kinematics parameters of rotational shot put and laid a foundation of kinematics research in future.Secondly, the ratio of the displacement of ball and CG at pre-flight phase was named as the Back 7 Deflection Rate, and the Back 7 Deflection Rate of Zhang Jun is 1.5 and Zhao Zhongjun is 1.2.Thirdly, the outside swing motion of right leg is an offset motion to keep the CG balance of body and it also transform the inertness of body. The acceleration of body made by the outside swing motion of right leg is named the Outside Swing Motion Acceleration.The last but not the least, the paper deduced the formula of right leg moment of couple, .The variable M andωin formula are inversely-proportional relationship, so to increase the angular velocity of the right leg is to reduce the right leg moment of couple.