| Objective:Badminton is a competitive sport in the net category.It has the characteristics of fierce competition and strong confrontation.With the rapid increase in the number of people participating in badminton,the injuries rates have been gradually increasing.In badminton,single-leg landing is one of the most common sports modes,especially single-leg landing after Overhead stroking of badminton,which causes the lower extremity joints to bear greater joint load and increase the probability of injury.Studies have shown that women have a higher incidence of injuries than men in badminton.Therefore,this study attempted to analyze the biomechanical characteristics of the badminton player's single-leg landing.Moreover,by using male athletes as a control,mechanical mechanism of the higher injuries rate of female was further explored,providing guidelines for female badminton player to develop targeted training plans to prevent injuries.Method:Recruiting 16(eight males and eight females)badminton athletes of Shanghai University of Sport reaching national second level or higher were recruited as the subjects,collecting the single-leg landing of the badminton Overhead stroke.The Vicon 3D infrared motion capture system(sampling frequency:200Hz),Kistler 3D force measuring platform(sampling frequency:1000Hz)and Delsys wireless electromyography acquisition system(sampling frequency: 2000Hz)were used to synchronously collect Marker point trajectory,ground reaction,and lower extremity muscle activity.An independent-sample t-test was performed to examine the male and female athletes during the single-leg landing,the lower extermity hip,knee,and ankle on the kinematic parameters(joint angle,joint angular velocity,center-of-gravity displacement),kinetics parameters(ground reaction force,joint moment),stiffness,energy and muscle activity parameters(pre-activation,post-activation,and co-activation)difference.The significant levels of all parameters were at 0.05.Result: 1.General characteristics of single-leg landing of the overhead ball: 1)In the single-leg landing after overhead stroking,the same joint angle changes were shown for both male and female athletes.During the entire cushioning stage from the ground contact to the maximum knee flexion angle,the hip flexion angle were increased,the abduction angle were decreased constantly,and external rotation gradually transferred to internal rotation immediately after contacting the ground;the knee flexion angle were increased constantly,and valgus and external rotation of knee were shown;the angle between the foot and the ground was the largest while touching the ground,and the dorsiflexion of the foot begins at the same time,accompanied by foot varus and tibial rotation or external rotation.2)Knee and ankle worked negatively,which were energy absorption.Among them,the main energy absorptions were done by ankle joint,followed by the knee joint,and the hip joint had the weakest energy absorption capacity.3)There was no difference in the co-activation ratio between female and male knee joints in the pre-activation stage and post-activation stage.both being less than 1.2.Gender difference of single-leg landing motion of overhead ball: 1)At the peak of the ground reaction force,the abduction angle of female hip joints was significantly greater than that of men(p = 0.043),and the maximum abduction angular velocity at the buffer stage was significantly greater than that of men(p = 0.027);2)At the time of peak ground reaction force,the knee flexion angle(p = 0.034)and valgus angle(p = 0.017)of women are greater than men,while the peak knee extension torque(p = 0.046)was smaller than men;3)For female,the ground angle between the foot and the ground(p = 0.044),foot varus angle(p = 0.042),varus angle velocity(p = 0.028),internal and external rotation(p = 0.044),at touching stage,and ankle flexion and extension activity at the cushioning stage(p = 0.038)were are greater than men.In the cushioning stage,the peak flexion moment of female ankle joints(p = 0.035)was significantly smaller than that of men;4)The stiffness of female lower limbs was significantly higher than that of men(p = 0.047),while the stiffness of knee joints was smaller than that of men(p= 0.036);5)Electromyography activity: In the pre-activation stage,the RMS of the tibialis anterior muscle of women was 42% higher than that of men(p = 0.011),and the ratio of co-activation of the ankle tibialis anterior muscle and the gastrocnemius muscle was significantly higher than that of men(p = 0.042);In the post-activation stage,the activation of the quadriceps femoris(p = 0.028)and hamstring muscle(p = 0.040)was significantly higher in women than in men.Conclusions:(1)In the single-leg landing action of the overhead stroke,the athletes use the energy absorption strategy with the plantar flexor muscle group as the main and the extensor knee muscle group as the supplement to resist the impact load.(2)In the single-leg landing action of the overhead stroke,muscle activation pattern dominated by the quadriceps was showed.A mismatch in the ratio of co-activation between the quadriceps and hamstring muscles may cause the quadriceps to contract excessively,causing the tibia to move forward,thereby increasing the potential risk of injury.(3)Female athletes had greater knee valgus angles and moments than men,as well as a greater angle between the foot and the ground at the time of the touch,with foot varus and tibial rotation.These characteristics reduce joint stability and increase the joint load when the athlete lands.At the same time,higher stiffness of the lower extremity was shown among female athletes,which increased the impact load to a certain extent and reduced the cushioning and energy absorption.The smaller stiffness of the knee joint also inhibits the protective effect on the knee joint.As a result,female athletes have suffered more lower extremity injury,especially the risk of ACL injury.(4)It was recommended that during the landing process,athletes could land by increasing the range of joint motion,reducing the angle between the foot and the ground,or rotating the joint to increase the effective absorption of energy by the joints.This strategy reduces the impact of the landing and reduce the occurrence of injuries;Muscle strength training need to be aimed at the large joint muscle groups of the lower extremity and the coordination of the quadriceps and hamstring muscles.At the same time,the strength training of the corresponding small muscle groups around the ankle joint could not be ignored,since the fuction of improving the joint stability. |
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