Research Of The Correlation Between Kinetic Chain Of Tennis First Serve And Muscles' Mobilization

Purpose:This study analyzed the kinetic chain of tennis first serve and the work load and activation of muscle and wanted to find the key link of serving kinetic chain for improving serve ball speed, doing physical ability training and avoiding injury.Methods:7 tennis professional athletes (All male).It used 3D videographic analysis to capture the serve and used Me6000 machine to record the sEMG of 16 muscles to obtain the model and the key link of serve chain.Results:1. The angle of left knee flexion is 101.2±16.2 degree which is significant negatively correlated with ball speed (r=-0.694);2. The angle between hip and shoulder is -13.8±6.9 degree which is significant negatively correlated with ball speed (r=-0.733) at the end of backswing;3. The movement distance of gravity on the Y axis and ball velocity were positive correlated (r=0.658);4.The acceleration and braking of every link were correlated, the difference max velocity time between hip and knee, shoulder and hip, racket and wrist were negative correlated with ball speed;5.The order of each muscle's max IEMG was the same to the kinetic chain's and it appeared in the corresponding link acceleration phase;6. The value of contribution of lower limb muscles, hip muscles and abdominal muscle were much bigger, but shoulder muscles and upper limb muscle were smaller;7.The value of contribution of wrist flexor muscles, the deltoid, the left rectus, the left gluteus and the strands rectus were postive correlated with ball speed.Conclusion:1. Tennis serve kinetic chain model:Starting with the knee extension, hip, shoulder, elbows, wrist would speed up and brake to transfer the energy to the racquet in turn;2. The knee, trunk and wrist were the key factor of the chain. Reducing the angle of knee at the point of the end of backswing and enhancing the rotation of trunk and flexion of wrist could improve the ball speed;3. The order of each muscle's max IEMG was the same to the kinetic chain's and it appeared in the corresponding link acceleration phase. The difference time of the peak IEMG is the important factor to transfer energy;4. The core strength is important for improving ball speed;5.To increase the contribution of wrist flexor muscle, the deltoid, the left rectus, the left gluteus and the strands rectus was good for ball speed...