疲劳诱发如何影响跃起着地动作时下肢关节负荷及平衡能力?

How fatigue affects loads and balance ability of lower extremity joints from leaping to ground?

背景:人体处于疲劳状态下,其控制肌肉的能力便会下降,但目前对疲劳后跃起着地下肢关节负荷及平衡能力的改变情况尚不明确。目的:探讨疲劳诱发对运动员着地下肢关节运动学、动力学及动、静态平衡的影响,从而为预防运动损伤提供重要参考依据。方法:采用闭锁式动力链动作对16名优秀男子排球选手先诱发肌肉疲劳,再利用Vicon红外线运动图像采集系统及三维力测力台同步收集受试者跃起着地动作的运动学、动力学及足底压力中心参数。结果与结论:(1)疲劳后着地所测得的髋关节最大屈曲角度、活动范围和膝关节的活动范围显著小于疲劳前(P<0.05);(2)疲劳后着地膝关节达到最大屈曲角度的时间显著下降,而地面反作用力最大值呈显著增加(P<0.05);(3)疲劳后着地,动、静态平衡在足底压力中心的偏移半径、移动速度及移动所复盖面积呈显著增加(P<0.05);(4)结果提示,疲劳后跃起着地受试者往往采取较为僵硬的着地动作,以尽快维持姿势稳定;疲劳后着地受试者身体平衡能力显著下降,造成着地后的冲击力无法有效地减少,从而增加了运动伤害发生的风险。

BACKGROUND： Ability of muscle control will be decreased when human body is in fatigue. However, the loads and balance ability of lower extremity joints from leaping to ground after fatigue are unclear. OBJECTIVE： To investigate the effect of fatigue on the kinematics, dynamics and dynamic and static balance of the lower extremity joints in athletes, so as to provide an important reference for preventing sports injuries. METHODS： Sixteen elite male volleyball players were induced to suffer from muscle fatigue using the closed kinetic chain action. Corresponding motion parameters of leaping dynamics, kinematics and plantar pressure center measured by Vicon infrared image acquisition system and three-dimensional force were collected.RESULTS AND CONCLUSION：（1） The maximal hip flexion angle, the movement range and the range of motion of knee joint after fatigue were significantly lower than those before fatigue（P 0.05）.（2） The time to maximum knee flexion was decreased significantly after fatigue than that before fatigue, and the maximum ground reaction force was significantly increased after fatigue（P 0.05）.（3） The dynamic and static balance in the center of pressure offset radius, velocity and the cover area were significantly increased after fatigue（P 0.05）.（4） These results indicate that the subjects tend to take a relatively stiff action for leaping after fatigue, in order to maintain a stable posture as soon as possible. The balance ability is significantly reduced after fatigue. As a result, the impact force from leaping to ground cannot be effectively reduced, thereby increasing the risk of sports injuries.