| This study uses kinematics principles to study the skills of the tennis backhands of boys in the Guangzhou Tennis Academy's tennis selection class.The first application is Vicon's three-dimensional motion capture system.9 of the sports training professions,referred to as group A,are tennis national secondary athletes and physical education.The 9 professional players were referred to as the B group's backhand batter technique and then tested with the Vicon Nexus system and the Polygon software.The three best shots of each subject were analyzed to find out the technical actions of the two groups of subjects.The same points and differences are analyzed according to the principle of kinematics to find out the main factors and kinematic characteristics that affect the technique of two-handed backhand,and provide theoretical basis for teaching and training for tennis teachers and coaches.Research results:(1)In the swing shot time,the time spent in group A was less than group B(0.17±0.03 V 0.21±0.05,P=0.04).(2)In the center-of-gravity movement feature,the trend of the center of gravity movement of the A and B groups during the backhand shot of the entire hand was similar,p>0.05,but the A group showed a center of gravity movement speed and a movement acceleration greater than B during the backswing and the hitting stage.In the group A,the center of gravity displacement and the swinging center of gravity movement speed and acceleration are smaller than that of the group B.(3)The angles of left and right elbow joints in group A were greater than those in group B at the end of post-climbing(86.22±12.29 V 64.02±15.38,P=0.004),(60.94±10.74 V 45.45±10.49,P=0.007);At time point,the left and right elbow angles in group A were also greater than those in group B(69.61±15.68 V 52.91±11.96,P=0.02)(70.61±12.83 V 59.32±7.66,P=0.03).(4)In the phase of swinging,the left and right shoulder joint angular velocity in group A is greater than that in group B in the coronal and sagittal axes,while the angular velocity of left shoulder in group B is greater than that in group A in the coronary axis,and the right shoulder angular velocity in group B is smaller than that in group A in the vertical axis.In the swing shot stage,the angle of the shoulder joint of the group A is greater on the vertical axis than in the group B.The acceleration of the left wrist angle in the group B is smaller than that of the group A in the backward swing phase.(5)Kinematic characteristics of the lower limb joints: In the swing shot stage,the right hip angle in group A was smaller than that in group B(164.80±11.54 V197.75±11.67,P=0.049).The left knee angles in group A and B were larger than those in group B.In the right knee angle,the right knee angular velocity,right hip angular velocity,and left ankle joint angular acceleration and trunk torsional angular velocity in group B were all smaller than those in group A.The left ankle angle,angular acceleration,and left knee angular velocity were all reflected during follow-up.Significant differences.conclusions:(1)Compared with group B,the higher level A group has a shorter swing time,faster swing,and can effectively increase the power of hitting the ball.(2)In the course of the backhand shot of both hands,the speed of the left shoulder,elbow and wrist of the A group is greater than that of the B group,and the shoulders and wrists show an increasing trend(wrist> elbow> shoulder).The left shoulder,elbow and wrist joints are fast and can increase the impact.The speed and effect of the ball.(3)At the end of the post-climbing,regardless of the level of skill,the angle of the left knee of the athlete is lower than that of the right knee,and the center of gravity is on the left leg.However,the lower limbs of the group A have lower joints,which is more conducive to turning.The body transfers the force to the trunk in the form of rotational momentum and transmits it to the upper limbs and racquets.It exerts the transmission efficiency of the joint chain,thereby striking a fast and powerful ball. |
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