The Kinematic Analysis Of Technical Characteristics Of The Combination Of The Last Four Steps And Take-off Of The Chinese Junior Women's Long Jump

Research objective:From the kinematics analysis of the technical characteristics of the top eight junior women long jump athletes in our country at present,we can find out the technical characteristics,sports level and current development situation of the outstanding junior women long jump athletes in our country.The author excavates the female long jump reserve talents in our country,and carries on the pertinence training.Based on the contrast research,the author finds out the existing difference and the individual characteristics of the long jump technique of these outstanding junior women athletes in our country so that the paper can clearly affect he kinematics factors of the development of junior women athletes' long jump in our country.Below the premise of mastering the technical theory of excellent athletes,the scientific service and the objective reference is provided to promote the improvement and great development of the special achievements of the junior women athletes' long jump in our country.Research methods:According to the final results of the National Youth Championships(Ordos)in2017,this paper takes the top eight junior women long jump athletes' s the research object,and adopts the documentation method,Delphi technique,kinematics analysis,mathematical statistics,comparative analysis and other research methods to study their run-up four steps and takeoff technical characteristics.Research results:1.In the study of the last four steps of the run-up,Wang Tiantian and Zhong Jiawei had the most stable changes in the step size;Wang Ping's last four steps showed the longest step length.The biggest length of the last two steps is 2.31 meters and the shortest length of the last step is 1.92 meters,which shows the greatest variation.Yu Yaxin's last four steps are all the shortest steps.Her four steps and two steps are the same.The longest length of the four steps is 1.82 meters,and the shortest length of the last three steps is 1.63 meters.2.Chinese junior women long jumpers all have their own technical styles in the last four steps of the run-up,but the time used on the last step of the last four steps of the run-up is the shortest.Among them,Zhong Jia-wei shows the most regular characteristics in the time used,that is to say,the ratio of the used time gradually decreases and the reduction degree of the time taken in the last step is the most obvious;while compared with other athletes the reduction degree of the time taken byLiu Jiahui in the last step of the run-up shows the biggest variation.3.Wang Tiantian,who won the first place in this competition,was the fastest in the last four steps of the run-up,and she alone was the only one whose run-up speed was higher than 9m / s.Besides,Wang Tiantian and Ye Xiaoqin had a significant decrease in the speed of the last step of the run-up;while the speed of other athletes increased gradually;and the last step reached the fastest speed.Chen Liwen's last step was the slowest among the seven athletes,and the value was 8.25 m / s.The slow run-up speed was the main factor that affects her performance.4.At the take-off stage of the long jump,Liu Jiahui had the smallest landing angle,with a value of 59.4 °.Yu Yaxin had the largest landing angle,with a value of65.3 °.Zhong Jiawei had the smallest landing angle with a value of 65.6 °.Ye Xiaoqin had the largest landing angle with value of 75.7 °,and the sector angle of Ye Xiaoqin is the smallest with the value of 42.1 °.The sector angle of Zhong Jiawei is the largest,which is 53.9 °.Research conclusion:1.The overall special achievement of young women long jumpers in China is not ideal,mainly because the speed of run-up level is generally low that also is the main factor affecting the overall long jump results.But the overall speed change of their final four steps showed a reasonable upward trend.The results are in accordance with the biomechanics basis of the run-up and take-off of the long jump event.2.Although the last four steps of the run-up are characterized by the reasonable change in step size,that is,"big?small" pattern that is conducive to the run-up forward effect,the overall performance of the four steps is not stable.3.The overall trend of step frequency change is reasonable,that is,the step frequency can reach the peak level in the last step.Although this rhythm characteristic accords with the development trend of modern long jump technology,it sometimes appears the jagged rhythm disorder.The run-up and take-off can not maintain the coherence,which is also a hidden danger to the normal effect of takeoff.4.The landing angle of the take-off is smaller than the angle from the ground,and the offset direction of the whole sector angle(opening direction)tends to the opposite direction of the run-up,and the overall performance is within a reasonable angle range.The angle of central elevation of the proximal hip joint is relatively small,with an angle range from 14.5 °to 18.3°.