A Kinematic Analysis Of The Back Jump High Jump Technique Of Outstanding Female High Jumpers In My Country

Research Objective: This paper analyzes the three-dimensional video of the top six athletes in Women's High Jump Competition,2018 National Track and field Grand Prix(Chongqing Station)to get the data of the athletes' Fosbury-Flop technical motion,and analyzes the derived kinematic data in detail,to find out the main issue of the technical motion of China's elite women high jumpers in Fosbury Flop,to expect to provide a reference to promote the action techniques of China's elite women high jumpers.Research Methods: Literature review method,Three-dimensional video analysis method and Mathematical statistics method.Research Results:(1)The final step speed of Hu,Linpeng(6.71m/s)has reached the level of world.At the same time,her body leaning angle in the final step is within the reasonable range(75°-80°).While the final step speed of the rest five jumpers is lower than the level of world and their body leaning angle is bigger than the reasonable range.(2)The ratio of the final step length to height of the six women high jumpers(0.98±0.01)is smaller than that of the world elite women high jumpers.(3)At the T4 moment,the hip joint angle(165.32±2.56 °),knee-joint angle(161.83±1.90°)and ankle joint angle(142.58±3.86°)of the six women high jumpers' take-off leg are lower than those of the world elite women high jumpers,and their H1(1.23±0.03m)and the vertical speed of their body center of gravity at the T4 moment(3.48±0.10m/s)are lower than the world level as well.(4)The take-off stretching time of Hu,Linpeng,Liu,Sang and Ding,Jiayi is long,and both the take-off buffer time and stretching time of Wang,Xueyi,Zhang,Yu and Jin,Yiwen are long.(5)Among the six high jumpers,Zhang,Yu and Jin,Yiwen's hip joint angle at the T4 moment is smaller than 90°;Wang,Xueyi's arm swing speed is the fastest one(7.65m/s).(6)The H2 of the six women high jumpers(0.66±0.02m)is lower than the world level,and their H3(0.09±0.02m)is bigger than that of the world elite women high jumpers.The maximum height of their body center of gravity does not show on the directly above or below the bar.Research Conclusion:(1)The final step speed of Hu,Linpeng is fast,while that of the rest five jumpers is slow.The speed of the final step is an important factor to the body leaning angle of the final step and the vertical speed of body center gravity at the T4 moment.(2)The length of the final step of the six women high jumpers is short,which is against the fully stretching of swing leg.(3)The main reason why the six women high jumpers' H1 is lower than the world level is that the hip,knee and ankle joints of their take-off legs are not fully stretched.At the same time,this also has adverse effect on the vertical speed of body center gravity at the T4 moment.(4)Due to the long take-off time taken by the six high jumpers,the elastic potential of the leg muscles cannot be fully exerted,which would further influence the take-off effect.(5)All the six women high jumpers use bent-leg mode when swing their legs.Among them,only Zhang,Yu and Jin,Yiwen's swing leg effect is good.Compared with others,the swing arm effect of Wang,Xueyi works best.(6)The main reason why the six women high jumpers' H2 is small is their vertical speed of body center gravity is slow at the T4 moment.In addition,the six high jumpers don't fully arch their back when flying over the bar,and they don't fully use the H2,which indicates their crossbar technique needs further improvement.