Effect Of Knee Brace On The Lower Limb Biomechanical Characteristics Of Male College Students During Drop Jump

Research purpose:By analyzing the influence of knee brace on the lower limb biomechanical characteristics of male college students during drop jump and the difference of training factors on the influence,the influence of knee brace on sports injury and sports performance was explored.Research methods:Ten male college athletes and 10 healthy male college students with no sports experience completed the deep jump motion test under the condition of wearing three types of knee brace respectively.Qualisys three-dimensional motion capture system,Kistler three-dimensional force measuring table and Delsys surface electromyography system were used to collect the impact force,kinematics,dynamics and electromyography data of lower limbs in the process of wearing different knee protectors.Research results:(1)Ground impact parameters: the vertical ground reaction force peak(GRF-Z),ground lateral force peak(GRF-X),horizontal backward force peak(GRF-Y),maximum load rate and impact impulse suffered by wearing each knee brace at the landing stage were significantly lower than those suffered by the non-brace group(P< 0.05).(2)Kinematic parameters of lower limbs: the landing Angle,Angle change and joint angular velocity of knee,hip and ankle joints were significantly lower than those of the group without the knee brace(P<0.05);The changes of knee flexion Angle,knee abduction Angle,hip adduction Angle,hip internal rotation Angle,maximum knee flexion Angle,maximum knee abduction Angle,maximum hip adduction Angle,maximum hip internal rotation Angle and joint Angle at touchdown time of wearing brace C were significantly smaller than those of brace A and brace B(P<0.05);The jump height and center of mass velocity in the take-off and flight stage of the knee joint wearing group were significantly higher than those of the group without the knee joint wearing group(P<0.05).(3)Lower limb dynamics parameters: the peak power of knee,hip and ankle in the landing stage with all knee protectors was significantly lower than that in the no-protectors group(P< 0.05);The peak power of subjects’ knee and hip joints wearing brace C was significantly lower than that of brace A and brace B(P<0.05).(4)Lower limb neuromuscular control parameters: there were no significant differences in the integrated electromyography value of muscle surface and root mean square amplitude value of muscle surface electromyography with each knee brace compared with the no-brace group and among brace groups(P> 0.05).(5)The influence of training factors: the vertical ground reaction force peak(GRF-Z),ground lateral force peak(GRF-X),horizontal backward force peak(GRF-Y),maximum load rate and impact impulse,hip Angle change,knee Angle and Angle change were significantly lower in the experimental group than in the control group(P<0.05);Hip Angle,jump height and centroid velocity in the experimental group were significantly higher than those in the control group(P<0.05).Research conclusion:(1)Three types of knee protectors,including bidirectional patella band knee protector,patella open-hole binding knee protector and double-pressure high-strength sleeve knee protector,can effectively slow the ground impact force on the lower limb joints of the subjects,improve the stability of lower limb,reduce the change Angle of lower limb joint,improve the peak power of lower limb joint.(2)Dual-pressure high-strength sleeve knee pads have significantly better effects on kinematic parameters of lower limbs than bidirectional patella band knee pads and patella open-hole binding knee pads,and have no significant differences with the other two knee pads in ground impact force and dynamic parameters.(3)The ability of subjects with exercise basis to relieve ground reaction forces and improve kinematic and dynamic parameters was significantly better than that of subjects without exercise basis.However,the protective effect of knee brace was not significantly affected by exercise basis or not.