Kinematics Analysis Of Chinese Women's Discus Thrower Su Xinyue's Throwing Technique

Study objective:On July 3, the Chinese contestant Su Xinyue won the women's discus champion with 55.88m in the Asian track and field championships held in India. In 2014,the national track and field throwing open women's junior discus final sino,Su Xinyue won the championship with 60.34m.Su Xinyue fully performed her personal characteristics by strengthening the personal special ability and refining with the intensice training. This paper obtains her discus action video. By analyzing and evaluating the data obtained, this paper sums up the kinematics characteristics of technical action. The rotation is good and the formation of the reverse position is stronger which keep hip beyond shoulder posture.In this study, by the video we acquired about Su Xinyue at the game site, through qualitative and quantitative analysis, we aimed at reveal the kinematics principle and technical characteristics of discus throwing. We compared and analyzed the kinematics parameters of Su Xinyue to world elite athletes, thus to provide theoretical basis and technical reference for athletes and teach trainer to improve and develop the technique of the action.Research methods:We used two JVC9800 high speed cameras to record the whole process of women's discus throw at the national track and field throwing open on March 29,2014. Used 3-D signal Tec V1.OC 3D video analytical system to analysis the best technical actions of Su Xinyue, and then obtained the relevant kinematic parameters.Results:(1) pre swing stage:in the pre placed the greatest moment, Su affectionately left hip angle is 133.6°, right hip angle is 125.4°, left knee angle is 134.5°,right Knee angle was 124.3°; at pre swing phase of his right foot off from ground time (T1), velocity of left shoulder is 3.24m/s, right shoulder speed is 1.76m/s.; right hip joint velocity is 1.49m/s, the speed of the left hip joint is 0.67m/s. Left and right hip joint velocity difference is up to 0.82m/s, right hip speed significantly higher than speed in the left hip, right leg in the process of stretching inadequate failed to obtain larger ground reaction force, thus affecting the increase of rotational speed. Su Xinyue on his right foot from the moment the discus speed 6.42m/s, Su Xinyue pre swing phase 0.40s, pre swing moment of maximum speed of the center of gravity of the body 2.78m/s. Right foot off from ground moment, the velocity of the center of gravity of the body 5.12m/s, Su Xinyue pre swing time is shorter, lead to discus the acting distance decreases, which is not conducive to the discus speed increase.(2) left single support rotary stage:left foot off from the ground moment, the rotation speed of left and right shoulder joint are 2.45m/s and 3.16m/s, left and right hip joint velocity are 2.86m/s 3.78m/s respectively, the speed of the right hip is bigger than the left hip. Su Xinyue ipsilateral joint velocity difference is small and; from T1 to T2 time, Su Xinyue increment in the discus speed is 2.39m/s Sue Xinyue left single support phase 0.38s, which is slightly shorter than the excellent athletes; in this phase discus running distance is 2.88m, smaller than the elite female athletes running distance mean value 3.03m, her average speed at this stage is7.61m/s.(3) the flight stage:Su Xinyue right foot touch the ground moment, the angle between shoulder and hip is 36.5°, pull lead angle is 15.68°, less than outstanding athletes, vacated small pulling angle can make athletes rapid hip rotation, effectively shorten the time of the whole stage. During the flight, speed of the center of gravity of the stage from 2.93m/s decreases to 2.32m/s, loss of speed is larger; vacated stage (T2-T3) Su Xinyue when 0.15s, slightly longer and elite athletes, rotational speed is slow in this stage, Su Xinyue, is not conducive to the speed transition to further action.(4) transition stage:right foot touch the ground moment,the speed of her left and right shoulder are 1.41m/s and 2.24m/srespectively. Su rejoices in the right moment left shoulder joint velocity, right shoulder joint velocity, the left and right hip joint velocity were 3.25m/s 2.07m/s more time Su Xinyue shoulder the right shoulder, and left hip and right hip speed 3.30m/s 1.89m/s 1.41m/s 1.88m/s.Su Xinyue hip, shoulder joint velocity increasing, T4 moments left shoulder joint velocity increases to 3.30m/s Xinyue transition stage time is slightly longer; the left foot with instantaneous (T4), Su Xinyue shoulder hip is 32.6°, lead angle is 146.7°.(5) finally forcibly stage:Su Xinyue in T5 moment shot speed is 23.21m/s. Less than the mean value 25.0m/s of the last shot speed of excellent athletes in the world; angle of shot is 38.45°, larger than the mean value of 35°of excellent athletes in the world; release height is1.57m; the exertion Su Xinyue with 0.22s, slightly longer than the time of world elite athletes in the last exertion 0.10-0.20s. The discus moment angle between shoulder and hip is 19.5°, pull lead angle is 165.3°,relationship to discus the acting distance; distance between the feet is 0.72m.