Biomechanical Comparative Analysis Of Serving Techniques Of Male Tennis Players Of Different Levels

This article selected the first serve skill of college student athlete Gao(the men team and singles champion of the 2019 National Sports College Tennis Championship)and the professional athlete Cao(the third runner-up of the tennis menteam competition of the 13th National Games in 2017),the biomechanical data were obtained by consulting the domestic and foreign literature and by synchronizing the three-dimensional Photography and the three-dimensional force measurement of the serve technique of the two players,from the angle of Sports biomechanics,this paper makes a comparative analysis of the serve skills of the two players to understand the biomechanics characteristics of the players of different levels.The following conclusions are obtained from the study:(1)Throwing and racking stage:T1 Moment,the height of the ball left hand of Gao and Cao was close to the height of the ball,and the height of the ball left hand of Cao(2.62 m)was 1.41 times of the height of the ball,which was beneficial to the control of the ball.The wrist joints of Cao and Gao were straight when the ball left the hand,and the wrist joints of Cao were extended greatly(162.4 °,167.3 °),which was beneficial to the stability of throwing the ball.The greater the angle of the same side hip joint of the throwing arm,the more fully the hip joint is extended.Compared with Cao,Cao extended the angle of the HIP joint to the maximum(164.0 °).Gao and Cao compared to the ball out of the hands of the moment,the ball out of Cao faster(4.97 m/s)is conducive to the stability of the upward movement.T2 Moment,Gao and Cao around the bent knee angle close to the two legs under even force.The minimum flexion angle(100.6 °,97.2 °)of Cao lower limbs indicates that the elastic potential energy is stored more fully.(2)Back beat stage:T3 Moment,compared with Cao knee extension and hip extension,Cao left and right knee extension were the largest(69.7 °,79.2 °),and the left and right hip extension were also the largest(45.1 °,19.4 °),which means his lower body provides the most power for the swing.Compared with the elbow angle and shoulder speed of Gao and Cao,the shoulder angle and elbow angle of Cao hold the racquet arm are the largest(148.6 °,94.9 °),which shows that he has the largest range of arch and back,and has the most full store of strength,and the shoulder elbow speed is also the biggest(5.18 m/s,9.42 m/s)that he hits the ball at the moment to obtain the biggest explosive force.(3)Batting stage:T3 Moment,the shoulder angle of the arm of Gao and Cao was larger than that of Cao(133.4 °),which showed that the full extension of Cao was beneficial to the full exertion in the final stage.The ipsilateral hip angle of the racquet arms of Gao and Cao is larger than that of the opposite hip angle,which indicates that the back legs of the two players actively push up and forward when hitting the ball.T4 Moment,the ratio of the height of Cao hitting point to the height of Cao hitting point is the largest(1.40),which is helpful to get more effective area.And the drop between the highest point of throwing ball and the hitting point of Cao is less than 0.50 m,which shows that his serve has a coherent action and a high cohesion.The speed of the arm,shoulder,elbow,wrist,hand and head of Gao and Cao were increased in turn,the increasing speed of each link of Cao in turn(2.96 m/s,7.20 m/s,12.12 m/s,14.45 m/s,28.98 m/s)shows that his serve has more advantages in the match.(4)Volatilization stage:T5 Moment,Gao and Cao shoulder hip rotation is full,use bend knee bend hip to complete buffer.The knee joint bending angle of Cao landing foot is the biggest(165 °),which indicates that his movement is advantageous to the next racket fast stroke.And Cao from T1 time to T5 time to use the least time(1.08 s)that his fast-paced serve,explosive power.(5)3D force measurement:Through the three-dimensional force analysis,it is found that the ground force of both Gao and Cao in the left and right direction(Fx)does not fluctuate too much when they push the ball off the ground,which indicates that the center of gravity of the two players is relatively stable when they serve,Cao serve in the front and back direction(FY),the Vertical Direction(Fz)push-off force is higher,that Cao serve in the forward and upward push-off force is better,the ball is more offensive.IIn a word,compared with Gao,Cao serve technique is superior,which is worthy to be used for reference by college athletes.