Research On The Relationship Between Lower Limb Kinematics And Racket Speed In Tennis Forehand

Tennis forehand stroke is one of the most important hitting techniques and one of the most basic techniques in tennis.The forehand stroke is a typical whipping action.In the forehand stroke,depending on the coordination between the lower limbs,the trunk and the upper limbs,the speed of the end of the whipping link-the racket can be maximized to transfer more energy from the racket to the ball,so as to achieve the best hitting effect.In this study,8 male national level 2 tennis players from shaanxi normal university and xi 'an university of architecture and technology were selected as subjects.The Qualisys infrared high-speed motion capture system was used to capture the characteristics of human body movement in the indoor simulation of hard ground conditions.The shooting frequency was 200Hz,and the kinematics parameters of the main joints of the lower limb,hip,knee and ankle,as well as the kinematics related parameters of the racket were recorded.Infrared high-speed motion capture system with its own analysis software and Excel,SPSS and other statistical tools software for the relevant data statistics and analysis.The following conclusions are drawn:(1)In the swing stage,the right ankle joint has obvious braking action,and the maximum speed appears before the moment of hitting.At the moment of hitting,the Angle of the right ankle joint of the players is about the'peak value.The force action of left ankle joint kicking off the ground is not obvious,which mainly plays a role of supporting and maintaining balance.The Angle of li**'s left ankle joint fluctuates slightly before hitting the ball.(2)The Angle and speed of the knee joint are relatively stable in the racquet leading stage.In the swing stage,both sides of the knee joint are in the fast extension force,the speed increases in a straight line.Only fan hit the ball at the beginning of the knee joint extension,there is the problem of hitting too early.Li xu**,zheng**,tao ac***raise the left leg to coordinate with the right leg to send the force,only wang**and hou***in the force when both feet land at the same time,are involved in the legs stretch,the technical action is more reasonable.The left knee joint is the non-main force generating side,mainly cooperating with the right knee joint to generate force,as well as maintaining the body balance and maintaining the coordination of limbs.(3)In the swing stage,the Angle and speed of hip joint change linearly,and the effect is the largest.The hip joint has obvious deceleration braking action before hitting the ball,and the speed reaches the maximum.Lee had the most obvious hip movement.Only wang**hip joint maximum speed is far earlier than the moment of hitting the ball,affecting the effect of the power of the hip joint.(4)The velocity change of each link of the lower limb in the racquet leading stage was ankle joint>knee joint>hip joint.In the swing stage,the ankle joint pushes against the ground rapidly,the knee joint extends rapidly,and pushes the hip joint to rotate.The order of power generation conforms to the biomechanical principle of human body.(5)There was no significant difference in bat speed between players(P>0.05).In the swing stage,the racquet speed rises in a straight line,and there is an obvious deceleration before hitting.The speed in this stage is much higher than that in the lead-in stage and the follow-through stage.During the follow-up phase,the ball's rotation and landing point can be fine-tuned by controlling the racket.(6)The three joints of lower limbs,hip,knee and ankle,have a certain correlation in power generation,and have a great promoting effect on the rotation of the trunk.There was a significant correlation with the racquet speed(P<0.05),and the influence on the swing stage was the largest,followed by the swing stage,and the racquet leading stage was the smallest.(7)The center of gravity moves to the right,downward,upward and forward in the whole process of hitting the ball.In the swing stage,the center of gravity of the body is rapidly raised and moved forward through the kicking and stretching action of the lower limbs to complete the transmission process of energy from the bottom up.Only li**through the body quickly forward pressure,obvious center of gravity forward to achieve better batting effect.(8)There was a significant correlation between center of gravity change and trunk rotation on racket speed(P<0.05).Through the change of the center of gravity and the rotation of the trunk,the racquet guiding effect and the hitting effect can be enhanced,which is conducive to the upward conduction of the force velocity generated by the hip,knee and ankle joints of the lower limbs,affecting the swinging speed and the final hitting effect.Advice:(1)Strengthen the strength training of lower limbs' hip,knee and ankle joints,and improve the ability of stretching and generating power of lower limbs.At the same time,strengthening the consistency training of the lower limbs' three joints is helpful to improve the efficiency of the lower limbs' power generation and the racquet speed.Want to strengthen the hair force action of left joint.(2)In the racquet drawing stage,the shoulder and hip angles should be increased,and the racquet should be pulled backward through the rotation of the trunk to reduce excessive control of the racquet by the upper limbs.At the same time,the center of gravity should be lowered to complete the process of force accumulation before hitting,so as to store more elastic potential energy for the swing stage.(3)In the batting stage,the driving force should be rapidly pushed and stretched,and the driving force of each link should be consistent with the batting time of the swing,so as to avoid hitting the ball too early or too late.(4)The center of gravity should have obvious upward and forward movement,so as to enhance the racket up and forward speed.(5)Before hitting the ball,each link should have braking action to transfer kinetic energy efficiently to the next link and accelerate the racket.(6)During the follow-up phase,the racquet should be relaxed to avoid excessive use of the upper limbs to control the racquet speed.