Biomechanical Analysis Of The Knee Joint Of College Male Tennis Players In Forehand Volley Stop Motion

Research objective:In the process of tennis volley,the knee joint suffers a great impact,the knee joint is in the state of semi-flexion for a long time,and the load of flexion support is higher than that in the upright position,which is easy to cause muscle fatigue,thus leading to insufficient muscle strength.In the long run,this will eventually lead to the appearance of pathological symptoms.Therefore,this research mainly using biomechanics experimental research method,using QUALISYS infrared high-speed video capture system,the three dimension test force platform and electromyographic measuring instrument compressors synchronous measurement method,to obtain lower limb kinematics of each link,a foot 3 d support reaction force and related muscle group recorded electrical diagram(s EMG)as a result,the purpose is to tennis forehand crust from the Angle of sports biomechanics interception across urgent stopping the stress of the knee joint and knee joint muscle activity characteristics is analyzed,To better understand the force condition of knee joint and the activity force characteristics of relevant muscles involved in tennis forehand volley stop.It provides theoretical basis for college athletes to master scientific training and correct hitting movement and protect knee joints from sports injuries.Research methods: In this paper,8 national second-level tennis players(male)from xi ’an institute of physical education were selected as experimental subjects.Kinematics,dynamics and surface emg data were collected synchronously using QUALISYS infrared high-speed camera capture system(200Hz),NORAXON electromyography tester(1500Hz)and KISTLER force measuring platform(2000Hz).Research results: Kinematics: 1.The time changes in each movement stage are respectively in the upper step stage: the horizontal zone is 0.340.05s;The occupied area is 0.320.04 s.Buffer stage: the flat partition is 0.190.06s;The occupied area is 0.170.06 s.Kicking and stretching stage: the flat area is 0.350.10s;The occupied area is0.350.12 s.2.At the beginning of the buffer,the adductor and abductor Angle of the knee joint was 11.38 9.95°,and the dominant area was 4.16 2.23°.The independent sample T test showed a significant difference(P<0.05).The normal division of the internal and external rotation angles of the ankle joint was 18.1411.46°,and the dominant region was 14.906.28°.The independent sample T test showed a significant difference(P<0.05).Dynamics: 1.In the upper volley,the vertical bearing force of the sole of the flat zone and the dominant zone is 2.91 times of the body weight.2.The bearing force of plantar in the front and rear directions of the flat zone is 1.21 times of the body weight,and the bearing force of plantar in the front and rear directions of the dominant zone is1.06 times of the body weight.Surface emg: 1.The standardized RMS value of the muscle is 1.10 uv-s at most for the vastus lateralis muscle in the flat region.The occupying area of the vastus lateralis muscle is 0.84 uv-s at most.2.The maximum value of tibial anterior muscle in the plain region is 263.79 uv-s;The vastus medialis muscle in the preoccupation zone is 273.73 uv-s at most.3.The muscle contribution rate of tibial anterior muscle in the plain region was 31.02%;The contribution rate of the occupying semitendinosus muscle was 35.59%.Research conclusions:1 、 In the three action stages of interception,the cushioning stage takes the shortest time,indicating that the foot braking is the strongest during the cushioning,and the impact force on the lower limbs(including joints)is large,especially the force on the knee joint will be relatively direct.2.The Angle of the knee joint in the bisection area was significantly larger than the occupied area,indicating that the knee joint in the flat area was more likely to cause injury of the lateral collateral ligament.3.The foot volley in the flat section bears more force in the forward and backward direction than in the occupied section.The greater the force on the foot,the greater the force on the knee,more likely to lead to knee injuries.4.、During the volley in the upper step,the discharge and contribution rate of the tibial anterior muscle and vastus lateralis muscle in the flat area were the most prominent,and the semitendinosus muscle and vastus medialis muscle in the dominant area were the most prominent.