Dynamic knee valgus at peak vGRF.

Dynamic knee valgus (DKV) occurs during landing after a fatigue task involving the lower extremity. However, the manner in which different peripheral fatigue tasks affect DKV remains unknown. In this study, we investigated the DKV via electromyography during single-leg landing considering the hip-joint fatigue task (HFT) and knee-joint fatigue task (KFT) performed by healthy men. We recruited 16 healthy male participants who performed a single-leg jump-landing motion from a height of 20 cm before and after an isokinetic hip abduction/adduction task (HFT) and knee extension/flexion task (KFT). Three-dimensional motion analysis systems were attached to the left gluteus medius and quadriceps, and surface electromyography was used to analyze the lower limb kinematics, kinetics, and muscle activity. The primary effects and interactions of the task and fatigue were identified based on the two-way repeated-measures analysis of variance. The results of the average angle during landing indicated that DKV occurs in KFT, whereas HFT applies external forces that adduct and internally rotate the knee at peak vertical ground reaction force (vGRF). Furthermore, both KFT and HFT exhibited an increase in muscle activity in the quadriceps. The analysis revealed that the occurrence of DKV varies depending on the peripheral fatigue task, and the effects on average DKV during landing and DKV at peak vGRF vary depending on the peripheral fatigue task.

动态膝内翻（Dynamic knee valgus, DKV）指下肢疲劳任务后落地过程中出现的异常膝部姿态，但目前尚未明确不同外周疲劳任务对DKV的具体影响机制。本研究针对健康男性受试者，设置髋关节疲劳任务（Hip-joint fatigue task, HFT）与膝关节疲劳任务（Knee-joint fatigue task, KFT）两种干预方式，通过肌电图（electromyography）分析单腿落地过程中的DKV变化。本研究招募16名健康男性受试者，让其分别在等速髋外展/内收任务（即HFT）以及等速膝关节伸/屈任务（即KFT）干预前后，完成从20cm高度起跳的单腿跳落动作。研究将三维运动分析系统的采集节点附着于受试者左侧臀中肌与股四头肌部位，并采用表面肌电图（surface electromyography）采集并分析下肢运动学、动力学指标与肌电活动数据。采用双因素重复测量方差分析，明确任务类型与疲劳状态的主效应及交互作用。落地阶段平均角度分析结果显示，KFT干预后会出现DKV；而在峰值垂直地面反作用力（vGRF）时刻，HFT会对膝关节施加使其内收并内旋的外力。此外，KFT与HFT干预后，股四头肌的肌电活动均出现显著升高。本研究结果证实，DKV的发生情况会随外周疲劳任务类型的不同而改变，且不同外周疲劳任务对落地过程中平均DKV以及峰值vGRF时刻的DKV的影响也存在显著差异。