| With the continuous development of modern competitive gymnastics technology and rules,the movement difficulty of the men’s horizontal bar is also becoming more and more difficult.Through consulting relevant information and watching the video of the men’s horizontal bar finals in recent years,the current Chinese men’s horizontal bar project is in a backward state compared with the world’s advanced level,and the lack of high difficulty flight movements is an important reason,And in the past decade,few scholars have studied the highly difficult "flying movements" of the horizontal bar,more of which are the technical movements of horse vaulting.Under this background,this paper analyzes the horizontal bar "two straight back somersaults and 360 ° turn over the bar and then grip" movement completed by Zhang Boheng and Sun Wei,the main gymnasts of the national team,by using the method of sports literature,expert interview,video analysis and comparative analysis.Through SIMIMOION sports video analysis system,the two people can obtain the 270 °rotation of the vertical back somersaults in the lower hem,shoulder sinking,leg curling,and straight back somersaults And the specific kinematics parameters of the five stages of holding the bar and rotating 90 ° in turn,combined with the relevant knowledge of sports biomechanics,reveal the internal movement rules of the movement,analyze the advantages and disadvantages of the two athletes,and summarize their technical characteristics.On this basis,it provides theoretical basis for the development of more difficult movements,so as to improve the level of China’s men’s horizontal bar and enrich the theoretical research of the horizontal bar.Research results:1.Zhang Boheng and Sun Wei took 1.91 s and 1.96 s to complete the whole movement,respectively.Zhang Boheng spent 0.44 s,0.26 s,0.44 s,0.66 s and 0.11 s in each stage of the movement,and Sun Wei spent 0.47 s,0.26 s,0.45 s,0.64 s and 0.14 s in each stage of the movement.Sun Wei spent more time than Zhang Boheng in the stage of "straight back somersault and turn 270 °" and "two hands holding the bar and turn 90 °".2.The height change of the two people’s body center of gravity is basically the same.At the beginning,the curve slowly drops,and then rapidly rises to the highest point after falling to the lowest point(the slope of the curve at the rising stage of Zhang Boheng’s body center of gravity is significantly greater than Sun Wei,and the highest point is slightly higher than Sun Wei).Under the dual function of gravity,the curve starts to drop from the highest point to the completion of the action.3.At the beginning of the hem stage,Zhang Boheng’s shoulder angle,hip angle and knee angle are 177 °,178 ° and 178 ° respectively,and Sun Wei’s shoulder angle,hip angle and knee angle are 174 °,175 ° and 177 ° respectively.When the hem is at the shoulder level,Zhang Boheng’s shoulder angle,hip angle and knee angle are 165 °,161 ° and 179 ° respectively,and Sun Wei’s shoulder angle,hip angle and knee angle are 158 °,155 ° and 178 ° respectively.The increasing values of the velocity of the body center of gravity of Zhang Boheng and Sun Wei on the Z axis are 1.59m/s and3.27m/s respectively,and the average angular velocity of the body center of gravity of the two people at this stage is 3.57rad/s and 3.35rad/s respectively4.At the vertical plane position under the bar in the shoulder sinking stage,Zhang Boheng’s hip angle and shoulder angle are 223 ° and 177 ° respectively,and Sun Wei’s hip angle and shoulder angle are 217 ° and 175 ° respectively.The average angular velocity of the center of gravity of Zhang Boheng and Sun Wei is 5.8 rad/s and 5.3 rad/s respectively,which is larger than that of the previous stage and conforms to the laws of kinematics.5.At the end of the round leg stage,Zhang Boheng’s hip and shoulder angles were 155 ° and 95 ° respectively,and Sun Wei’s hip and shoulder angles were 134 °and 117 ° respectively.The ankle joint velocities of Zhang Boheng and Sun Wei were8.45m/s and 8.1m/s respectively at the time of letting go.6.In the stage of "straight back somersault and turn 270 °",Zhang Boheng and Sun Wei’s relative height of body center of gravity were 0.97 m and 0,91 m respectively,and the time of take-off was 0.66 s and 0.64 s respectively.Zhang Boheng’s rotation angular velocity increased from 6.06 rad/s to 12.11 rad/s,and Sun Wei’s rotation angular velocity increased from 5.65 rad/s to 9.84 rad/s.7.Zhang Boheng and Sun Wei held the bar in turn for 0.18 s and 0.20 s,respectively.The vertical distance of their body center of gravity was 0.23 m and0.12 m when they held the bar with their left hand,and the angle of their left elbow joint was 128 ° and 114 °.Research conclusion:1.The ratio of time spent in the five stages of completing the "Casina" movement,namely,the lower hem,shoulder sinking,leg covering,straight backward somersault and turn 270 °,and two hands holding the turn 90 ° in turn,is about3.6:2.1:3.6:5.2:1,and the change trend of the height of the body’s center of gravity is basically the same.2.In the stage of large loop hemming,the shoulder angles of Zhang Boheng and Sun Wei at the moment of handstand are close to the ideal state(180 °).During the process of hemming,the hip angle and shoulder angle of the two men are reduced,and the speed of ankle and Shoulder joint is increasing.The fluctuation of Zhang Boheng’s hip angle is greater than that of Sun Wei,which is not conducive to the completion of the movement.During the shoulder sinking stage,the hip angles of both individuals continue to increase,resulting in knee flexion.The shoulder angle and hip angle of the two men began to decrease during the leg driving phase,and Zhang Boheng’s leg driving speed was greater than that of Sun Wei.3.In the 270 ° phase of straight back somersault,the distance between the highest point of Zhang Boheng’s body center of gravity and the ground is slightly larger than that of Sun Wei,and the flying time is slightly longer.The rotation angular speed of the athletes around the longitudinal axis of the body is increasing.Sun Wei’s body center of gravity is not as high as Zhang Boheng’s,and the highest point of the body center of gravity is close to the horizontal distance of the bar axis,resulting in a bent arm when the right hand holds the bar,4.During the 90 ° rotation stage of holding the bar with both hands in sequence,the athlete turns the vertical axis to the left and grasps the bar with his right hand,actively extending and expanding his body to reduce the speed of his body descent.Zhang Boheng’s body posture control is better when he holds the bar with his right hand,and the movement range is larger.Sun Wei’s body bends its arms when he holds the bar.Sun Wei’s two hands hold the bar at a longer interval than Zhang Boheng’s,and the rotation angle around the longitudinal axis of his body is insufficient.The height of the body’s center of gravity is lower than Zhang Boheng’s,which is not conducive to the body’s greater movement speed. |
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