Kinematics Analysis On The Final Delivery Techniques Of Women Discus Athletes In The 11^th National Games

Discus throwing is a sport of complex techniques including two different nature motions, which are continuous rotating and straight line forward moving. The result of discus throwing can be influenced by original release speed, release angle, release height, aerodynamic effects and elevation angle, among which the original release speed is most predominant. The discus throwing techniques can be analyzed in four phases:discus grip, initial stance and preliminary swings, rotation, delivery and balance recovery. Rotation and delivery are critical to the discus throwing result.In recent years, the research on discus throwing techniques and training has been attached more importance especially in countries which advance in the event. According to the literature review, the related research is mainly based on the biomechanics and electromyographic studies on throwing techniques, or aerodynamic evaluation on the outer condition. The present research has two elements to be improved:female discus thrower and the final delivery phase. Kinematic and kinetic measures are more promising and efficient methods to analyze the discus throwing techniques. Research results are listed as below:1. The thesis chooses the top 6 female discus throwers of the 11th National Games as research subjects, and conducts 3-dimansional kinematic research on their throwing techniques of best distance trial throwing at the final delivery phase. The gold medal winner Li Yanfeng reached a throwing distance of 66.40m, and Song Aiming wins silver medal with a distance of 65.44m. Actually their throwing results surpass the best results in 2008 Beijing Olympics, which is significant and non-typical and encourages the author to carry out a kinematic research on them and other 4 female discus throwers of the 11th National Games. The research aims to understand the merits and shortcomings of discus throwing techniques of the top 6 female discus throwers applied in the final delivery phase and provide suggestions to improve the throwing techniques to a magnificent level. The result may contribute to the development of the female discus event in our country.2. Some of the top 6 female discus throwers of the 11th National Games have lower ability in speed acceleration at the final delivery phase which influences the last delivery whip, as the data shows that they have longer discus duration at final delivery phase. Only by improving the control ability in discus throwing and enlarging discus distance at final delivery phase can the female discus throwers improve their speed acceleration.3. Data on the top 6 female discus throwers of the 11th National Games indicates that the initial acceleration period duration decides the discus speed acceleration trajectory from high point to low point in initial acceleration period and influences the discus speed acceleration trajectory from low point to high point in final acceleration period. In the final acceleration period, the shorter the discus duration within certain trajectory, the faster the release speed can be realized.4. It can be concluded from the analysis on data of the top 6 female discus throwers of the 11th National Games that the higher odds ratio between initial and final acceleration periods can lead to longer discus throwing distance. But if thrower's body move over forward, the last delivery whip may be influenced and lead to a lower discus throwing result. So the higher odds ratio may indicate the better technique application of the discus thrower at the final release phase.5. Concerning the top 6 female discus throwers of the 11th National Games, smaller shoulder and hip angle of some throwers means that the unsatisfied performance in body screw and discus surpass in final delivery preparation, which may caused by haste landing or early moving forward to the throwing direction.6. Some of the top 6 female discus throwers of the 11th National Games have impropriate foot distance at the beginning of the final delivery phase (the moment of left foot landing). The wrong foot position has a negative influence on the muscle contraction strength and the complete of last delivery whip. Feet distance should not be too small and the left foot should be set on the extension line of throwing area axle and be kept one and a half shoulder distance from the right foot.