| In all stages of long jump,run-up is not only a prerequisite for efficient take-off,but also a technical link with the longest time and the highest stability requirements.However,in China’s competitions at all levels,athletes still often have problems such as "broken step","big step" and "small step" in front of the board caused by the unstable run-up rhythm.The chain effect induced by these problems interferes with the overall coherence and fluency in the process of long jump run-up,thus affecting the exertion of competitive level.In order to solve the existing problems in the long jump run-up,this study,through literature,expert interviews,questionnaires,image analysis and mathematical statistics,takes the kinematics characteristics of the optimal run-up rhythm of the first jump of the top eight male long jump athletes in 2021 Zhaoqing National Track and Field Invitational Games as the research object,Based on the analysis of kinematics,this paper finds the laws of each athlete’s approach rhythm and the differences between individuals in the changes of time,space,and time,and summarizes the advantages and disadvantages,so as to provide a better theoretical basis and reference for the development of the long jump event.Research indicates:（1）The starting stage is the stage with the largest rhythm difference among athletes.Due to individual differences in initial speed,8 athletes have different initial rhythm.In this stage,Tao Junhui and Li Chengbin’s run-up rhythm belongs to slow rhythm,and the other six belong to fast rhythm.（2）In the acceleration stage,the overall rhythm difference of the 8 athletes gradually narrowed after adjustment in the starting stage,and the performance of time,space and space-time rhythm gradually approached.The dispersion degree of individual rhythm performance narrowed in this stage,and the rhythm gradually tended to be stable.（3）In the speed maintenance stage,the rhythm performance of the 8 players was very close,and all of them reached their own fastest rhythm.At the same time,this stage is the most stable of the four run-up stages.（4）In the stage of boarding,8 athletes inverted 3 steps due to the influence of early rhythm performance,the fluctuation range increased,and individual athletes suffered loss of speed.Research Conclusions:（1）The structural ratio of speed distribution to the overall ratio of 8 athletes in four stages is 1.1:1.1:1.4:1.4.Rhythm has similar changing characteristics in each stage.In the overall division of backward 18-step run-up stage,although the change of rhythm in the early stage has individual characteristics,the fastest rhythm of each athlete all appears in T12-T18.（2）In the run-up process of the long jump,the overall performance of rhythm gradually accelerated,and the change of performance gradually narrowed.The rhythm of the four stages of starting,accelerating,maintaining speed and boarding is "slow-fast-fastest-fast",and the change is "big-small-minimum-small".（3）In the four stages of backward 18 steps in the run-up,the athletes’ rhythm performance in each stage affects each other.Early too fast and loss of a steady rhythm will prolong the speed to maintain the stage distance.The steady and progressive rhythm is conducive to delaying the maximum personal speed to the stage of boarding,promoting the benign transformation of the speed in the last stage,weakening the internal friction of nerves and muscles,and reducing the speed loss.（4）In the run-up process of 8 athletes,tao Junhui and Tao Yege’s rhythm was the most consistent with the overall rule,and their rhythm performance was relatively ideal.Li Chengbin,He Xilong and the overall rhythm of the big difference,not conducive to the level of play. |
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