The Influence Of Two Types Of Squat On Biomechanical Characteristics During Deep Squat And Jump Landing

Objective:This study investigated the effects of two types of squat(restricted squat: knees are not allowed beyond toes; unrestricted squat:knees beyond toes) on biomechanical characteristics of lower limbs and trunk during deep squat、 countermovement jump with swing arms and drop landing.To explore the possible mechanisms of injury prevention and performance improving by comparing this two types of squat under different movement modes providing the theoretical basis and the scientific support for athletes and coaches to choose training methods.Methods:Subjects were 15 male players,with a history of weight training for at lest two years,caming from Beijing Sports University.High-speed infrared motion capture system and force platform were used to collect Kinematic and kinetic data during deep squat、countermovement jump with swing arms and drop landing while using different types of squat.Results:When deep squat,useing the restricted squat,the maximum moments in the knee were 8% lower than unrestricted squat,but in hip were 12% higher restricted squat also caused more anterior lean of trunk. Two types of squat had no significant differences on the vertical jump height.During drop landing, restricted squat had smaller knee flexion angle and larger vertical ground reaction force.Unrestricted squat had bigger knee flexion angle and same knee extention monment,Vertical peak force time,What’s more unrestricted squat had bigger knee flexion angle and knee extention moment.Conclusions:1、Although restricting forward movement of knees may minimize stress on knees,it is likely that forces are inappropriately tranferred to the hips and low-back region.2、Restricted deep squat can increase hip extention torque.reduce knee extention torque.3、Two types of squat had no significant effect on sports performance during vertical jump.restricted jump can be more fully mobilize hip musle 4、 Restricted squat can provide cushion landing approach which will reduce the probability of injury.such as fatigue damage at the end of the patella, but it will increase the rate of anterior cruciate ligament injury; Because of the larger Angle of knee flexion and knee extension torque restricted squat type way of cushion to the ground may easily cause overfatigue around patella damage (such as the end of the patellar tendon disease).