| Research objectives:The main purpose of this paper is to study the technique of the last two steps of the run-up and the movement of the take-off technique,Analyze the relevant technical actions,To find out the relationship between the steps length,step time,step frequency,the Angle of ankle,knee,hip joint,the Angle of two thighs,the angular velocity of swinging leg,the height of center of gravity and other parameters and the sports performance of six athletes in the long jump run-up process.It also finds out the technical problems existing in the long jump of young women in shaanxi province,and the key indexes that affect the distance of jump in the technical stage of run-up and take-off,clarifies the kinematics factors that affect the development of young women’s long jump,and puts forward reasonable suggestions to improve the technical problems in the long jump process.Research objects and methods:This paper takes six outstanding young female long jumpers from Shaanxi Province who will participate in the national U series communication competition in 2020 as the research object.Using a variety of research methods such as literature review,expert interview,testing,mathematical statistics and comparative analysis,The kinematics parameters related to the last two steps of the run-up and the take-off process are analyzed and studied.Research results:1.The average of the penultimate step length,step time and step speed are1.91 m,0.222 s and8.61 m /s respectively,and the average of the penultimate step length,step time and step speed are1.84 m,0.212 s and 8.52 m /s respectively.The average of the penultimate step length,step time and step speed of first-level athletes are 1.96 m,0.222 s and 8.84 m/s respectively,and the average of the penultimate step length,step time and step speed are 1.89 m,0.205 s and 8.76 m/s respectively.The average of the penultimate step length,step time and step speed of second-level athletes are 1.86 m,0.222 s and 8.38 m /s respectively,and the average of the penultimate step length,step time and step speed are 1.79 m,0.218 s and 8.27 m /s respectively.2.The average Angle of ankle,knee and hip joint is 117.50 °,161.94 ° and 160.98 °respectively,the average Angle between two thighs is 51.03°,and the average angular velocity of swinging leg is 598.17 °/s at the moment when the athlete takes off the jump foot and hits the board.The average Angle of ankle,knee and hip joint of first-level athletes is 120.60°,164.05°and 161.88°respectively,the average Angle between two thighs is 48.68°,and the average angular velocity of swinging leg is 621.59 °/s.The average Angle of ankle,knee and hip joint of second-level athletes is 114.40 °,159.83 ° and 160.08 ° respectively,the average Angle between two thighs is 53.37°,and the average angular velocity of swinging leg is 574.75 °/s.3.The average Angle of ankle,knee and hip is 129.58 °,164.72 ° and 184.59 °,respectively,the average Angle between two thighs is 103.00° and the average Angle of lift is17.58°at the moment when the athlete takes off from the ground.The average Angle of ankle,knee and hip joint of first-level athletes is 132.62°,166.71°and 186.86°,respectively.The average Angle between the two thighs is 104.16°,and the average lifting Angle is 18.10 °/s.The average Angle of ankle,knee and hip joint of second-level athletes at the moment of striking the board is 126.53°,162.72°and 182.31°,respectively.The average Angle between the two thighs is 101.85°,and the average lifting Angle is 17.06 °/s.4.The average landing Angle,pedal Angle and takeoff fan Angle of the athletes are 61.35°,71.45°and 47.21°respectively.The mean values of all angles for Level 1 athletes were 62.63°,72.01 ° and 45.37 °,respectively.The average Angle of second-level athletes was 60.06 °,70.88°and 49.05°respectively.5.In the process of taking off,the average horizontal velocity at the moment of landing,horizontal velocity at the moment of taking off,vertical velocity at the moment of taking off,initial velocity of jump and the loss rate of horizontal velocity are respectively 8.40 m /s,7.52 m /s,2.52 m /s,7.80 m /s and 10.36%.The average speed of first-level athletes at the moment of striking the board is 8.45 m /s,7.59 m /s,2.56 m /s,8.15 m /s and 10.12%,respectively.The average speeds of second-class athletes are 8.34 m /s,7.46 m /s,2.48 m /s,7.45 m /s and 10.63%,respectively.Research conclusions:1.Shaanxi province outstanding young women’s long jump athletes run-up last two steps are to present the reasonable structure of "big and small",but its run-up speed as a whole is low,especially the secondary athletes,the last two steps overall longer,stride length,step speed slower,appropriately increase the last two step distance,speed up the pace of the improvement of performance has a certain advantage.2.The ceiling board moments of ankle,knee,hip Angle smaller overall,both knees movements,among them,the secondary athletes performance is more apparent,the seed is relatively small,push stude screws is relatively reasonable,therefore sectored Angle is relatively large,go against tion of cohesion,appropriately increase the seed reduce sectoral horn was beneficial to the improvement of the performance.3.The small Angle of ankle and knee at the moment when the foot is off the ground is not conducive to the acquisition of vertical velocity and rising Angle at the moment of taking off and the full completion of the push and stretch.The Angle of the hip joint is small,which is not conducive to the athletes to increase the range of take-off and affect the performance of the long jump.4.In the take-off process,the swing leg is insufficient,the lift Angle is relatively low,the athlete’s acceleration ability is relatively low,and the horizontal velocity at the moment of striking the board is relatively low.At the same time,when taking off,the vertical velocity of the lift is low,the loss rate of the horizontal velocity is too large,and the initial speed of the lift is small,which eventually leads to the small Angle of the lift and affects the performance of the long jump. |
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