| Objective: Badminton is a typical net separated non-contact confrontation project.During a game,it involves countless hitting rounds and requires repeated turning,jumping and landing and different hitting actions.These unique action skills increase the risk of injury to badminton players.It has been reported that the proportion of ACL injury is the main in non-contact injuries.The backcourt header of one foot landing is a high incidence of badminton ACL injury.At the same time,the injury risk of female athletes is higher than that of men.If the landing method is unreasonable in the process of sports,it may increase the risk of ACL and lower limb injury.Sports fatigue will have an impact on the movement mode of human body.Badminton is considered to be the project with the highest degree of fatigue in sports racket.Sports fatigue will reduce the whole body muscle strength and affect proprioceptive function and action strategy.Therefore,this paper aims to study the biomechanical changes of lower limbs of badminton college athletes before and after fatigue and different genders,and to explore the impact of fatigue on the risk factors related to anterior cruciate ligament injury.Methods: In this study,20 badminton special athletes(10 men and 10 women)with more than four years of sports experience were recruited,and their badminton special fatigue was induced.The infrared light spot three-dimensional motion capture system(Nokov)and three-dimensional force measuring platform(Betec)are used for synchronous acquisition,Obtain the kinematics and dynamics data of the head top ball Single-leg landing before and after fatigue,Determine the biomechanical indexes such as joint three-dimensional angle,three-dimensional moment and ground reaction force at different characteristic times.2 ×2two-way ANOVA of mixed design was used to test the effects of fatigue and gender on the changes of lower limb sports biomechanical characteristics,in which the class I error probability of significance standard was defined as less than 0.05.Results: There is no interaction between fatigue and gender in the lower limb kinematics and dynamics data of one foot landing.In the kinematic data results,regardless of gender,compared with before fatigue,the landing time after fatigue showed a larger hip rotation angle(p=0.001),a smaller knee flexion angle(p=0.026)and a larger knee valgus angle(p=0.031).Compared with before fatigue,the peak time of ground reaction after fatigue showed a smaller trunk rake angle(p=0.001)and knee flexion angle(p=0.019)significantly decreased.Regardless of fatigue,compared with male athletes,female athletes showed smaller hip flexion angle(p<0.001),hip valgus angle(p=0.014),larger hip internal rotation angle(p<0.001),knee valgus angle(p=0.048),knee flexion angle(p=0.015)and knee internal rotation angle(p=0.036)at the time of landing.Compared with male athletes,The peak time of ground reaction force of female athletes shows that the smaller hip valgus angle(p=0.009)and the larger hip internal rotation angle(p=0.027).In the dynamic data,regardless of gender,compared with before fatigue,the landing time after fatigue showed smaller knee flexion torque(p<0.001),peak knee flexion and extension torque(p=0.025),larger knee valgus torque(p<0.001)and larger knee external rotation torque(p<0.001).Regardless of fatigue,compared with male athletes,female athletes showed less knee flexion torque(p=0.02)and greater knee valgus torque.Conclusion:(1)Fatigue can affect the changes of lower limb biomechanics of head and head ball single-leg landing.Badminton players show a small knee flexion angle at the time of landing after fatigue and the peak time of the first reaction force on the ground,and their lower limbs tend to land in a more upright way.At the time of landing after fatigue,the knee valgus torque and external rotation torque increase significantly,and there is a small trunk forward inclination at the first peak time of the ground reaction force.These factors will increase the risk of knee ACL injury.In addition,there is no significant difference in the peak value of ground reaction force.At the first peak of ground reaction force,the internal rotation angle of hip joint increases significantly.Hip joint is the main stability mechanism during dynamic landing.Athletes may cushion the ground impact force by hip joint rotation during landing.(2)When female athletes landed on the head and head with one foot,regardless of the fatigue landing time,they showed a small knee flexion angle and knee pronation angle,the knee valgus angle related to female ACL injury factors increased significantly at the landing time,and the hip valgus angle decreased at the first peak of ground reaction force.These factors show that women have a greater risk of ACL damage in badminton landing on one foot. |
