Biomechanics Study On The Backhand Movement Of The Flat Stroke And The Top Spin

In 2019,70% of the top ten ATP athletes use the basic technique of backhand stroke.In the baseline attack of tennis,the backhand with both hands plays the topspin ball and the backhand with high stability,attack and reliability.More and more players pay attention to it and it becomes one of the important technical actions.The purpose of this paper is to study and analyze the biomechanical characteristics of two handed backhand close baseline spin and flat shot in detail.The author hopes to provide the athletes with an effective analysis of the structure of technical movements,so as to play more correct and standardized technical movements with the best body shape.This paper hopes to provide significant data for tennis teaching,training and competition.The method adopted in this paper is to select 19 joints and 8 muscles of human body with 6 national second level athletes as experimental objects,and to use APAs software to carry out digital processing and data analysis on the motion video of six athletes;Using Mega win2.4 software to process and analyze the EMG test data;through the two software,the results of node speed,joint angle,root mean square EMG and integral EMG value will be obtained.In this experiment,excellent tennis players are invited to feed the ball.The distance between the feeding point and the tested athlete is about 5 meters,which is40 ° to the left front of the test subject.The whole feeding process has a uniform transport capacity,which is guided by a senior tennis professional professor and watched to make a qualified judgment.In this study,six tennis players from Xi’an Institute of physical education were selected as the subjects,and two Panasonic m9000 high-speed cameras were used with the frequency of 120 Hz,Using megawin600 portable electromyography tester in Finland,the sampling frequency is 1000 Hz as the sampling instrument,and using APAs software and magawin software to analyze the obtained data.Results of this study:(1)The change of center of gravity in z-axis is that when the topspin ball is played,it starts to be higher than the flat shot at the moment of hitting,and the peak valueappears.(2)The angle of the left and right joints is slightly smaller than that of the flat shot when the topspin ball is played in the maximum leading racket stage,and the joint point velocity is not different in this stage.It can be seen from the increasing degree of joint angle from the maximum leading time to the moment of hitting that the increasing range of joint angle of the topspin technique is higher than that of the flat shot technique,and the joint point speed of the topspin technique in this stage is significantly higher than that of the flat shot.At the end of the swing,the difference of the joint angle of the lower limbs between the two techniques is due to the forward movement of the body center of gravity towards the opposite area when the flat shot is played,while the center of gravity of the topspin is shifted to the right,and the direction of the center of gravity is different,resulting in the difference of the body posture.(3)The RMS and i EMG of the two technical movements are the same from the moment of maximum leading to the moment of hitting.The value of the other muscles except the left tibial anterior muscle and the right fascial dilator is greater than that of the topspin.During the period from the moment of hitting to the end of the swing,the maximum value of the standardized value of each muscle of the topspin is the right anterior tibial muscle,and the minimum value is the left rectus femoris muscle.The standardized value of each muscle except the right gastrocnemius muscle and the right anterior tibial muscle is greater than the standardized value of each muscle of the topspin.The conclusions of this study are as follows:(1)The height of the center of gravity of the swing up ball is much higher than that of the swing up ball.(2)In the process of forward swing,there are obvious differences in the direction of the two strokes when the lower limbs start to push on the ground.The joint of the lower limbs has obvious forward pressure action,which makes the body use more force forward,and the center of gravity moves forward from the back;the upper spin ball is played with the right side of the body by the closed backhand of both hands Forthe axis,rotate it,cooperate with the upper limb,exert force forward and upward,fully extend the body,and lift it off the ground.(3)The results of electromyography showed that the force of gastrocnemius and tibialis anterior muscle was greater than that of topspin during the period from the maximum racking to the moment of hitting.The left gastrocnemius and right tibialis anterior muscle were the main force groups of lower limbs.The force of right tibialis anterior muscle,right rectus femoris and right fascial dilator were less than that of hitting up during the period from the moment of hitting to the end of swinging Spin ball.(4)The technical force sequence of the two hands backhand close type to hit the flat shot and the topspin is consistent with the principle of the force sequence of the body link.