不同程度疲劳对排球运动员急停起跳动作的下肢生物力学影响

Effects of different degrees of fatigue on the biomechanics of lower limbs of volleyball players during sudden take-off

目的:对比不同程度疲劳状态下排球运动员完成急停起跳动作的下肢生物力学变化,探讨疲劳所引起的前交叉韧带损伤机制和运动表现变化。方法:9名男性排球运动员通过连续的变向跑和原地纵跳来获得下肢神经肌肉疲劳,通过纵跳衰减量将疲劳划分为无疲劳(NF)、中度疲劳(MF)、重度疲劳(SF)三个等级,在每个等级下分别采集受试者急停起跳动作的运动学、动力学数据,将采集到的数据根据既有标准划分为急停、起跳、腾空三个阶段并进行统计学分析。结果:(1)随着疲劳程度的加深,受试者完成急停和起跳阶段的时间逐渐延长,MF状态和SF状态与NF状态相比均有显著性差异(P<0.05),MF与SF状态相比也具有显著性差异(P<0.05)。(2)与NF状态相比,急停阶段达到MF等级时,膝关节屈伸角度范围显著减小(P<0.05),膝关节伸角峰值和踝关节内旋角度范围明显增大(P<0.05),伸膝力矩峰值显著增大(P<0.05);达到SF时,膝关节屈伸角度范围显著减小(P<0.05);起跳阶段达到NF等级时,髋、膝、踝三个关节屈伸角度范围均显著减小(P<0.05),膝伸角速度峰值、膝伸角峰值明显减小(P<0.05),伸膝力矩显著减小(P<0.05);达到SF时,髋、膝、踝三个关节屈伸范围显著减小(P<0.05),膝伸角峰值、膝伸角速度峰值、伸膝力矩显著减小(P<0.05)。结论:疲劳对排球运动员急停起跳过程中下肢运动生物力学参数产生了较大影响,总的动作完成时间增加将会减少动作完成的高效性,急停阶段膝关节屈角的减小可能会增加前交叉韧带损伤的风险,起跳阶段关节屈伸范围减小造成腾空高度的降低。

Objective:the biomechanical changes of lower limbs of volleyball players who complete emergency stop and take-off under different degrees of fatigue were compared,and the mechanism of anterior cruciate ligament injury caused by fatigue and the changes of sports performance were discussed.Methods:nine male volleyball players obtained lower limb neuromuscular fatigue through continuous changing direction running and in-situ vertical jump.Through the attenuation of vertical jump,the fatigue was divided into three levels:no fatigue(NF),moderate fatigue(MF)and severe fatigue(SF).Under each level,the kinematic and dynamic data of subjects'emergency stop and take-off were collected,According to the existing standards,the collected data are divided into three stages:emergency stop,take-off and flight,and statistical analysis is carried out.Results:(1)with the deepening of fatigue,the time for subjects to complete the emergency stop and take-off phase gradually prolonged.Compared with NF state,MF state and SF State had significant differences(P<0.05),MF state also had significant differences compared with SF State(P<0.05).(2)Compared with NF state,when the emergency stop stage reaches MF level,the range of knee flexion and extension angle decreases significantly(P<0.05),the peak range of knee extension angle,the range of ankle internal rotation angle increases significantly(P<0.05),the peak value of knee extension torque increases significantly(P<0.05),and when it reaches SF,the range of knee joint decreases significantly(P<0.05);When the take-off stage reaches NF level,the flexion and extension range of hip,knee and ankle decreases significantly(P<0.05),the peak value of knee extension angle velocity,the peak value of knee extension angle,and the knee extension torque decreases significantly(P<0.05).When reaching SF,the flexion and extension range of hip,knee and ankle decreases significantly(P<0.05),the peak value of knee extension angle,knee extension speed and the knee extension torque decreased significantly(P<0.05).Conclusion:fatigue has a great impact on the biomechanical parameters of lower limbs in the process of emergency stop and take-off,the increase of total action completion time will reduce the efficiency of action completion;the reduction of knee flexion angle in the emergency stop stage may increase the risk of anterior cruciate ligament injury;the reduction of joint flexion and extension range in the take-off stage,Resulting in a reduction in the height of the flight.