Analysis On Kinematics And Surface Electromyography Of Volleyball Double-handed Ball

Research objectives: With different pellation effects and corresponding action structures as the restrictive conditions,the parameters of key technical links of service receiving were obtained through the three-dimensional motion capture system and surface electromyography acquisition system,and the difference of action structure and the characteristics of force rule under the association between action and effect were compared to reveal the causes of the problems.In order to correctly understand the key points of technical movements of service receiving,Standardize the application of technical action to provide reference basis.Research methods: Taking Hebei men’s volleyball team as the experimental subjects,Qualisys infrared motion capture system(sampling frequency: 200Hz/s)and Delsys surface electromyography acquisition system(sampling frequency: 2000Hz/s)were used to monitor the technical movements of the players’ jump serve receiving,from which the relevant index data of kinematics and electromyography were obtained.Combined with the method of literature,expert interview and mathematical statistics,the measured data are processed and analyzed to reveal the difference of action mechanism of different service receiving effects.Research results:(1)Kinematic index: there was no significant difference in the kinematic index at the time of receiving the ball(P > 0.05),but the horizontal distance between the two feet showed a general rule of longest distance when the ball was not in place,shortest distance when the ball was wrong,and moderate distance when the ball was in place.Compared with the preparation time,the height of center of gravity and the Angle of lower limb joint decreased to different degrees.There was no significant difference in all indexes between the ball in place and not in place at the moment of hitting(P > 0.05).There were significant differences in flexion Angle of right hip joint and flexion Angle of right elbow joint when the ball was in place compared with when the ball was in error(P < 0.05).There were significant differences between the center of gravity index,flexion Angle of right hip joint,flexion Angle of right knee joint,flexion Angle of left shoulder joint and flexion Angle of right elbow joint(P < 0.05).The difference of flexion angles of bilateral joints is small when the ball is in place,but large when the ball is missed.The proportion of activity time in each action stage corresponding to different receiving effects is as follows: when receiving the ball in place,the preparation stage accounts for 42%,the attack stage accounts for 20%,and the accompanying stage accounts for 38%;When the catch is not in place,the preparation stage accounted for 44%,the attack stage accounted for 19%,and the accompanying stage accounted for 37%;The preparation phase accounted for 42%,the attack phase accounted for 18%,and the accompanying phase accounted for 40%.As a whole,the preparation stage takes the longest time,followed by the accompanying stage,and the attack stage takes the shortest time.(2)electromyographic indexes: In the preparation stage,the integrated electromyographic values of the main muscle groups when the ball was in place were from large to small: gastnemius > tibialis anterior > vastus medialis > vastus lateralis > trapezius,etc.;When the ball is not in place,it is: gastrocnemius > vastus medialis > vastus lateralis >tibialis anterior > trapezius,etc.When the ball was missed: tibialis anterior muscle >trapezius muscle > vastus medialis muscle > gastrecnemius muscle > semitendinosus muscle,etc.In the attacking stage,the integrated electromyography value of the main muscle groups when the ball was in place was from large to small: wrist extensor > deltoid tract > gastrocnemius > tibialis anterior > vastus lateralis,etc.When the ball is not in place,it is: wrist extensor > deltoid tract > tibialis anterior > gastrocnemius > vastus lateralis,etc.When the ball is missed: biceps brachii > deltoid tract = tibia anterior few > wrist extensor >gastrocnemius and so on.When the ball is in place,it is successively: gastrecnemius → tibialis anterior → vastus medialis → vastus lateralis → semitendinosus,etc.When the ball is not in place,it is successively: trapezius muscle → rectus abdominis → semitendinosus → rectus femoris →medialis muscle,etc.When the ball is missed,the order is: gastrecnemius muscle → lateral femoris muscle → trapezius muscle → medial femoris muscle → rectus abdominis and so on.Research conclusion:(1)Reasonable matching of hip,knee and shoulder joint angles is an important factor to determine the effectiveness of movement structure.Only bend the knees without bending the hips,the Angle of the knee joint is too small than the Angle of the hip joint will lead to the center of gravity,the upper body backward.Only bend the hip and not bend the knee,the Angle of the hip joint is too small than the Angle of the knee will lead to the upper body tilt,the center of gravity forward,will affect the support of the feet,resulting in root,center of gravity instability.If the shoulder Angle is too large,it will cause the hitting point to rise,and make the contact part beyond the natural center of gravity stability threshold range formed by the opening of the feet,thus affecting the control force.(2)From the moment of preparation to the moment of batting,most of the players adopt the action of fine-tuning the pace and readjusting the center of gravity,which plays a role in activating the muscle tissue again and naturally adjusting the body posture and center of gravity,which is crucial to ensure the correct force and control during batting.(3)There are significant differences in the contribution degree of the same muscle group in the process of completing the three kinds of receiving technical movements with the effect of in position,out of position and error.When the ball is in place at the preparation stage,gastrocnemius,tibialis anterior,vastus medialis and vastus lateralis play the main role.When the ball is in place during the batting phase,the extensor wrist,deltoid anterior tract,gastrocnemius,tibialis anterior,vastus lateralis and vastus medialis play the dominant role.(4)In the process of service receiving,the dislocation of the time sequence of muscle force is the main reason affecting the effect of service receiving.When receiving the ball in place,the discharge sequence of the muscles involved was as follows: gastrocnemius →tibialis anterior → vastus medialis → vastus lateralis → semitendinosus → rectus femoris→ rectus abdominis → latissimus dorsi → gluteus maximus → trapedus → deltoid anterior bundle → biceps brachii → triceps brachii → extensor wrist.The power process follows the transmission process from the lower limb to the core and then from the core to the upper limb.There is a significant difference between the main muscle group of the first power and that of the first service when the service is not in place and when the service is in place.