The Effects Of Lunge Distance And Foot Condition On The Knee Under Left-forward Lunges In Badminton Players

Objective:The left-forward lunge is commonly used in badminton.Athletes perform left-forward lunge quickly to hit the ball with the backhand in a short time.During the fast lunge,the knee of athletes bear a strong impact,and excessive load acting on the knee may lead to sports injury;when in repeated lunge,long-term severe loads may lead to overuse of the knee,then induce chronic knee injuries.While the lunge distance and foot position are important factors affecting the load of knee in lunge movements.It is necessary to understand the sports characteristics of the knee when player lunging at different distances and different foot position,which is helpful to understand the knee injury in lunge task and strengthen the prevention of the injury.Therefore,the purpose of this study is to analyze the knee movement characteristics of badminton players under the 1.5 times leg length lunge,the maximum lunge and the maximum lunge with foot external rotation;and to quantify and compare the differences of knee motion characteristics in two different distance lunges and two different foot position lunges;then to explore the effects of lunge distances and foot position on the knee of 6 degrees of freedom kinematics,kinetics,and muscle activation.Finally try to understand the risk factors of knee injury under different conditions,and to provide theoretical reference for badminton players’ special training and injury prevention.Methods:Ten university female badminton athletes were recruited in this study.Participants had no history of injuries or surgeries in the lower limbs,and the right leg must be their dominant leg.The subjects’ knee Magnetic resonance imaging(MRI)data were collected before lunging testing to screen knee injuries,and to construct threedimensional knee models of femur and tibial.The High-Speed Dual-plane Fluoroscopic Imaging System(DFIS)at a rate of 100 Hz,the Qualisys motion capture system at a rate of 200 Hz,the Kistler three-dimensional force capture system at a rate of 1000 Hz and the Delsys wireless surface Electromyography recording system at a rate of 2000 Hz were used in the study.The data collection involved acquiring fluoroscopic images,three dimensional motion,the ground reaction force and Electromyography signals simultaneously during three left-forward lunge trials.Left-forward lunge tasks include the lunge distance of 1.5 times leg length(1.5*(leg length)),individual’s maximum distance(MAX),and the maximum distance with external rotation of the right foot(MAX+ER)while the foot deflection angle increases by 20°compared to the MAX lunge,including two lunging distances and two foot position.Then analyzing and comparing the 6 degrees of freedom motion of knee,kinematic characteristics and the Electromyography muscles activation in characteristic points,braking and return phases during three lunges.Paired sample T test was used to compare the differences of knee in the left-forward lunges under different lunge distances and different foot condition.Results:1.Compared with the 1.5*(leg length)lunge,the varus rotation of tibiofemoral joint increased by 1.40°(P = 0.048)during the braking phase in the MAX lunge,and the flexion and varus rotation of tibiofemoral joint increased significantly in the recovery phases respectively during the MAX lunge.Between two distance lunges,compared with the 1.5*(leg length)lunge,the flexion of the tibiofemoral joint increased significantly at the initial contact and at the first peak of the ground reaction force in the MAX lunge.Between two foot position lunges,the posterior translation of tibiofemoral joint at the characteristic time like 0.02 s before the maximum knee flexion was significantly larger than that in the MAX+ER lunge.2.The ground reaction force of anterior-posterior direction and vertical direction in the MAX lunge was significantly larger than that of the 1.5*(leg length)lunge.And the ground reaction force of anterior-posterior direction and vertical direction in the MAX+ER lunge was significantly larger than that of the MAX lunge.When the lunge distance and foot deviation angle increased,the knee varus moment increased significantly,and the distance and foot position had no significant effect on the knee extension moment and the knee joint power in anterior-posterior,medial-lateral and vertical three directions.3.Under two lunging distance movements,compared with the 1.5*(leg length)lunge,the post-activation of rectus femoris muscle was significantly higher during the MAX lunge,and the thigh muscle corporate activation of 1.5 times leg length was higher than that of maximum at both pre-activation and post-activation stages.Under two foot position movements,compared with the MAX lunge,the pre-activation of the vastus lateralis,tibialis anterior and medial and lateral gastrocnemius increased respectively during the MAX+ER lunge.When lunging at the two foot position,the corporate activation of calf muscles of pre-activation and post-activation in the MAX were higher than that in the MAX+ER lunge.Conclusions:1.Between two distance lunges,compared with the 1.5*(leg length)lunge,both the flexion and varus rotaiton of tibiofemoral joint increased significantly in the MAX lunge,particularly the flexion,varus rotation and posterior translation in some characteristic points,which may apply anterior tibial force and varus torque to the knee;the vertical ground reaction increased significantly during the MAX lunge and this would produce higher knee loading;the activation of quadriceps and hamstrings were in higher level during the MAX lunge,and this may cause a higher risk of knee injury.Therefore,compared with 1.5 times leg length,the risk of knee injury may be higher at the maximum distance.2.Between two foot position lunges,compared with the MAX lunge,the posterior translation of tibiofemoral joint decreased significantly in some points during the MAX+ER lunge,thus the posterior translation increased greatly and the higher posterior tibial force may be transmitted directly to the knee;the hamstrings and the calf muscles showed a higher activity level in the MAX+ER lunge,and excessive muscle forces may produce a potential knee injury.Therefore,the potential risk of knee joint injury may be higher with the increase of foot deviation angle at the maximum lunge distance.