On Serve Quality And SEMG Characteristics Of Tennis Majors With Different Levels

The speed of serve and the accuracy of the drop point are important reflection of the differences in the quality of tennis serve,and the surface electromyography(SEMG)in the process of serving can intuitively show the characteristics of each muscle force.Purpose: According to the measurement results of serving speed,falling point and surface electromyography(SEMG)of students with different levels of tennis,the paper analyzes the surface electromyography characteristics of students of different levels,such as the size of serving speed,falling point accuracy and main muscle groups.This paper aims to provide certain theoretical basis for tennis service training,be helpful to classroom teaching and training of tennis majors in general universities,and contribute to the scientific development of tennis major in general universities.Methods: With the methods of literature,measurement,mathematical statistics and so on,24 students majoring in tennis divided into three groups according to their levels in college of physical education of Sichuan Normal University,whose speed of serving,falling point and the surface electromyography of the muscle will be measured.The Bushnell service speedometer is going to be used to measure the speed,recording the drop point meanwhile.The Noraxon3.10 16-channel wireless EMG system will be used to measure the EMG of 10 muscles on both sides of the body chosen according to the characteristics of the delivery of service,and discharge sequence,EMG value,RMS value will be the measure or index.In addition,MATLAB(R2016a)system will be used to calculate the EMG and RMS of muscles.Results: 1.The order of serving speed:students who are second grade sportsman are the fastest,followed by students in school team,and then students in elective class;and there is a significant difference in service speed between students of different levels(P < 0.01).2.The order of the success rate of service point:students who are second grade sportsman are the most successful,followed by students in school team,and then students in select class;in Flat Serve,the success rates of students who are second grade sportsman,students in school team and students in elective class are 71.25%,51.25% and 35.00%,respectively;in Topspin Serve,the success rates of students who are second grade sportsman,students in school team and students in elective class are 85.00%,71.25% and 55.00%,respectively.There is also asignificant difference in service placement between students of different levels(P < 0.05).3.For students of different levels,the discharge sequence of each muscle part is different,while what is the common rule is that the deltoids and brachioradialis discharge first,while the pectoralis major and gastrocnemius muscles discharge finally.4.For students majoring in tennis at different levels,the contribution rate of each part of the muscle in the process of serving is different.As for students who are second grade sportsman have the largest proportion of the EMG of deltoids,brachioradialis and trapezius,and make the largest contribution to the EMG.As for students in school team,their deltoids,rectus abdominis and obliqus externus abdominis have the largest proportion,and make the largest contribution to the EMG.As for students in elective class,their latissimus dorsi and deltoids have the largest proportion and make the largest contribution to the EMG.5.RMS of the rectus femoris(P >0.05)is not significantly different between the students who are second grade sportsman and students in school team;There is no significant difference in the EMG values of the rectus femoris,trapezius,rectus abdominis,pectoralis major,external oblique(P > 0.05),and no significant difference in the RMS values of latissimus dorsi,rectus abdominis,external oblique,rectus femoris(P > 0.05)between the students who are second grade sportsman and students in elective class.The EMG values of deltoids and rectus femoris(P > 0.05),and the RMS values of brachioradialis muscle and rectus femoris(P > 0.05)are not significantly different between the students in school team and students in elective class.Conclusion:1.The higher the level of tennis majors is,the faster the students will serve,the higher the success rate will be,and the more accurate the landing point will be.2.The higher the level of tennis students is,the smaller the time difference between the onset of discharge of each muscle will be.3.The higher the level of tennis majors is,the stronger the ability to use brachioradialis and trapezius to exert force during serving will be.4.It is impossible to reflect the level of tennis majors by measuring the value of EMG and RMS during the serve.