Kinematic Research On The Key Link Of Wang Zheng's Hammer Throw Technique

Wang Zheng,as one of China's top female hammer throwers,achieved a good result of 77 m 68 in the 2014 National Open throw event,and became the current record holder of Asian women's hammer.As one of the members of the research group of "preparing for the 2020 Tokyo Olympic Games women's hammer project research and tackling key problems",I selected the key technology of the best performance throwing in the 2019 national throwing events group competition and the 2019 national track and field championship participated by Wang Zheng as the research object,and took the three-dimensional kinematic parameters of the key links in Wang Zheng's complete throwing technology as the main research content The purpose of this paper is to reveal the kinematic characteristics of Wang Zheng's throwing technique and provide a theoretical basis for improving his throwing technique.In this study,the methods of documentary,video shooting,threedimensional video analysis,mathematical statistics and comparative analysis are used to analyze the key links of Wang Zheng's throwing techniques in the two competitions,and the following results are obtained:1.Time parameters: Wang Zheng's single and double support time in 2019 national throwing events group match is 1s and 0.95 s respectively,and the single support time is longer than the double support time;in 2019 national track and Field Championships,the single and double support time is 0.92 s and 0.97 s respectively.2.Speed parameters: Wang Zheng's second rotation ball speed increment in 2019 national throwing events group match is obviously smaller than the third;the equipment speed increment in 2019 national track and Field Championships is consistent with the equipment acceleration trend in hammer sport.3.Angle parameters: when the left leg is rotated as the axis in the 2019 national track and field throwing events group competition,the right leg does not touch the ground actively,resulting in the increase of shoulder hip rotation angle in the fourth round of rotation.In the two games,Wang Zheng's maximum body tilt angle in the rotation phase is not much different.4.Track parameters: Wang Zheng's shoulders are not relaxed enough and his center of gravity is slightly higher than that of the back field in 2019 national track and field throwing events group competition.In the trial of 2019 national track and Field Championships,the throwing rhythm is obvious,and the arms are fully extended.5.Release parameters: the rotation of the second and third laps in 2019 national throwing events group match does not conform to the regularity of ball speed increment,which affects the initial release speed.During the fourth round of rotation,Wang Zheng's upper body didn't extend enough,which affected the height of his hand.The final shooting angle of the two matches is in line with the best shooting angle in the industry,37 °-43 °.The conclusion is as follows:1.From the perspective of time parameters,Wang Zheng did not create favorable conditions for the rotation stage in the 2019 national track and field throwing events group competition due to the unreasonable distribution of single and double support time;in the 2019 national track and Field Championships,the rotation time distribution of each rotation circle was good,which provided great help for the acceleration of the equipment.2.From the perspective of speed parameters,the ball speed increment in 2019 national track and field throwing events group match does not conform to the rule of equipment speed increment;the hammer speed increment trend in 2019 national track and Field Championships is consistent with previous studies.3.From the angle of parameters: Wang Zheng in the 2019 national throwing events group match,the fourth lap shoulder hip twist angle increased,affecting the acceleration of hammer.In the two games,the maximum value of trunk inclination is not much different,because Wang Zheng's throwing style and waist abdomen strength are better,and he has grasped the control of hammer.4.From the perspective of trajectory parameters: there is no good body posture in the rotation process of 2019 national track and field throwing events group competition,which affects the throwing distance.5.From the perspective of release parameters: in 2019 national track and field throwing events group competition,the upper body range extension is not enough in the fourth round of rotation double support stage,the body center of gravity is on the high side,and the final release height is not enough.The track of the two games is relatively smooth,so it is more conducive to create the best angle of hand.