士兵负重单脚落地时膝关节生物力学特征以及与等速肌力的关系

Biomechanical Characteristics of the Knee Joint During Single-Leg Landing of Soldiers and its Relationship with Isokinetic Muscle Strength

目的分析士兵负重单脚落地对膝关节产生的影响,并探讨与肌力的关系,为日常负重训练提供依据。方法采用Vicon动作捕捉系统和AMTI测力台分别采集12名士兵学员不负重和负重15 kg从30 cm高度单脚落地时膝关节的运动学和动力学数据,同步采集大腿前后侧肌群表面肌电(surface electromyography,sEMG),并进行膝关节屈伸等速肌力测试。结果与无负重相比,负重15 kg落地时膝关节屈曲角度和胫骨反作用力显著增加(P<0.05),股直肌、股内外侧肌和股二头肌sEMG最大值均显著增加(P<0.05),其余指标负重前后无显著差异(P>0.05)。伸膝峰值力矩与无负重单脚落地垂直地面反作用力呈显著负相关(P<0.05),其余指标无显著相关关系(P>0.05)。结论负重15 kg单脚落地增加了膝关节屈曲角度和胫骨反作用力,大腿前后侧肌群的激活可缓解落地时的地面反作用力,肌力对于预防落地损伤具有一定作用。

Objective To analyze the impact of soldiers’single-leg landing with load carriage on knee joint,and investigate its relationship with muscle strength,so as to provide references for daily load carriage training.Methods A total of 12 soldiers were required to perform single-leg landing from the 30 cm height without load carriage and with 15 kg load carriage,respectively.The kinematic and kinetic parameters were collected using Vicon motion capture system and AMTI force platform.The surface electromyography(sEMG)of anterior and posterior thigh muscles were also collected simultaneously,and the isokinetic strength during knee flexion and extension was tested.Results Compared with landing without load carriage,knee flexion angle and joint reaction force significantly increased during landing with 15 kg load carriage(P<0.05).The maximum sEMG of rectus femoris,lateral and medial femoral,biceps femoris increased significantly(P<0.05),but there were no significant differences in other indexes without and with load carriage(P>0.05).There was a significant negative correlation between peak moment of knee extension and vertical ground reaction force during single-leg landing without load carriage(P<0.05),while other indexes had no significant correlations(P>0.05).Conclusions Knee flexion angle and joint reaction force significantly increase during single-leg landing with 15 kg load carriage,the activation of anterior and posterior thigh muscles can relieved the ground reaction force during landing,and muscle strength plays some role in preventing landing injury.