Zhang Qiang, Ruan Mianfang, Singh Navrag B, Huang Lingyan, Zhang Xin, Wu Xie
Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
College of Physical Education, Wenzhou University, Wenzhou, China.
J Hum Kinet. 2021 Jan 29;76:161-173. doi: 10.2478/hukin-2021-0052. eCollection 2021 Jan.
Few studies have focused on the effect of fatigue severity on landing strategy. This study aimed to investigate the effect of fatigue progression on ground reaction force during landing. Eighteen participants performed a fatigue exercise protocol. Then participants performed drop landings at three levels of fatigue: no fatigue, medium fatigue, and severe fatigue. Multiple linear regression was conducted to identify the predictors of the peak vertical ground reaction force at each level of fatigue. Two-way ANOVAs were conducted to test the effect of fatigue on the vertical ground reaction force and the predictors. For the vertical ground reaction force, the knee joint stiffness and the knee angle at initial contact were the main predictors at no fatigue. The peak knee flexion angle and knee power were the main predictors at medium fatigue. However, the peak ankle plantarflexion moments became the main predictor at severe fatigue. The vertical ground reaction force decreased from no to medium fatigue (p = 0.001), and then increased from medium to severe fatigue (p = 0.034). The knee joint stiffness decreased from no to medium fatigue (p = 0.049), and then remained unchanged from medium to severe fatigue. The peak knee flexion angle increased from no to medium fatigue (p = 0.001), and then slightly decreased from medium to severe fatigue (p = 0.051). The results indicate that fatigue progression causes a transition from stiff to soft landing, and then to stiff landing. Participants used ankle joints more to control the landing intensity at severe fatigue.
很少有研究关注疲劳严重程度对着陆策略的影响。本研究旨在调查疲劳进展对着陆过程中地面反作用力的影响。18名参与者执行了一项疲劳运动方案。然后，参与者在三个疲劳水平下进行了下落着陆：无疲劳、中度疲劳和重度疲劳。进行多元线性回归以确定每个疲劳水平下垂直地面反作用力峰值的预测因素。进行双向方差分析以测试疲劳对垂直地面反作用力和预测因素的影响。对于垂直地面反作用力，初始接触时的膝关节刚度和膝关节角度是无疲劳时的主要预测因素。在中度疲劳时，膝关节屈曲峰值角度和膝关节功率是主要预测因素。然而，在重度疲劳时，踝关节跖屈峰值力矩成为主要预测因素。垂直地面反作用力从无疲劳到中度疲劳时下降（p = 0.001），然后从中度疲劳到重度疲劳时增加（p = 0.034）。膝关节刚度从无疲劳到中度疲劳时下降（p = 0.049），然后从中度疲劳到重度疲劳时保持不变。膝关节屈曲峰值角度从无疲劳到中度疲劳时增加（p = 0.001），然后从中度疲劳到重度疲劳时略有下降（p = 0.051）。结果表明，疲劳进展导致从僵硬着陆过渡到柔软着陆，然后再到僵硬着陆。参与者在重度疲劳时更多地使用踝关节来控制着陆强度。
