Three-Dimensional Kinematics Analysis Of The Starting Technique Of Chinese Elite Female Hammer Throwers

The 2020 Tokyo Olympics is imminent.As a member of the team of "National Team Preparing for the Track and Field Hammering Project to Prepare for the Tokyo Olympics(2020)Scientific and Technological Research and Service".This study in order to improve the performance of China's women's hammer throws,Wang Zheng,Luo Na,Zong Dan and Liu Tingting's characteristics of the starting technical movements in the 2019 National Athletics Championships are the object of study.Learning the theoretical knowledge of the starting technology by consulting the literature,and obtain the relevant parameters of the starting technology of the four athletes by combining the video shooting technology and the 3D kinematic analysis technology.Then using mathematical statistics to analyze these parameters,the aim is to find the technical characteristics of the four athletes' starting techniques,and to find the problems and deficiencies in the connection process of the pre-swing and rotation stages,in order to fully prepare for the 2020 Tokyo Olympics Provide technology support services.The main research conclusions are as follows:1.Regarding the time parameters— the time difference between the four athletes in the starting technique is relatively small.Among them,the longer time is Wang Zheng and Liu Tingting.Compared with Liu Tingting,Wang Zheng ?s technical time accounts for a large proportion of total time.Luo Na and Zong Dan's turning technology takes a relatively short time.Compared with Zong Dan,Luo Na's turning technology accounts for a larger proportion of the time spent in the chain throw.2.Regarding the speed parameters— the maximum speed of the four athletes during the pre-swing phase is in the spin-up technology,and the maximum value of the spin-up technology is at the moment when the right foot of the first rotation is off the ground,indicating that the ability to accelerate the hammer is stronger overall,but the ability to control the hammer is different.Wang Zheng always maintained a large increase in ball speed in the spin technology.She completed the control and acceleration of the speed of the hammer.Luo Na's ball speed was relatively small during the pre-swing phase,the task of accelerating the chain ball was better completed in the spin technology.But the ball speed increment decreased when entering the first rotation,and the ball speed increase was not maintained.In the starting technique,Zong Dan has a big difference in ball speed increment from the first rotation,which disrupts the rotation rhythm of the hammer.Liu Tingting has a good acceleration effect on the hammer during the pre-swing phase.However,because the speed of the hammer that she obtained during the first rotation and before is too small,This puts greater pressure on her subsequent processes.3.Regarding the trajectory parameters—the trajectory parameters of the four athletes in the starting technique are different.Wang Hao and Zong Dan's starting point of the chain ball trajectory has a large difference in height and trajectory tilt angle.Longer,it means that the rotation radius of the hammer is relatively long in the spin technique.Luo Na and Liu Tingting have relatively small differences in the height and low of the hammer ball trajectory,and the trajectory inclination angle is relatively small,which is not conducive to the acceleration of the rotation of the chain ball into the rotation phase.4.Regarding the angle parameters—the shoulder and hip twist angles,shoulder chain angles,and torso angles of the four athletes in the starting technique meet the requirements of the starting technique.The left hip angle and the left knee angle of support of support decreased in the first lap of the rotation.Wang's various angle parameters are relatively reasonable,and he has a strong ability to control the chain ball,creating a good basic condition for the rotation phase;Luo Na's torso is smaller,and the shoulder chain angle is smaller when the right foot is off the ground.And when entering the rotation phase,the left shoulder lags behind the left hip,which is not conducive to her left hip surpassing the left shoulder in the single support of the first circle of rotation.When the single support is about to enter the first turn of the rotation,Zong Dan's various angle parameters in the rotation technology vary greatly,which is not conducive to the increase of the ball speed during the rotation.The maximum value of Liu Tingting's shoulder and hip twist angle is too small,resulting in weak acceleration of the hammer,which did not reach a larger radius of rotation.