Muscle fatigue negatively affects gait, and the changes in gait pattern due to muscle fatigue is influenced by which muscles are fatigued and pre-existing physical activity levels. However, how these factors alter gait stability and variability, measures related to risk of fall, remains unclear. To explore how muscular fatigue affects linear and nonlinear gait features in young adults, the effects of triceps surae fatigue and weight training level on gait variability and local stability, as well as a 12-min recovery time of post-fatigue period, were evaluated in young adults (trained and untrained groups). Some features were estimated, i.e., (i) step length (SL) and step frequency (SF), (ii) average standard deviation of trunk acceleration along strides (VAR), and (iii) local dynamic stability (LDS; maximum Lyapunov exponent). LDS presented a significant increase in the anterior-posterior direction with recovery to trained group. SL and SF changed immediately post-fatigue and recovered for both groups, while VAR increased significantly in all directions, with a recovery in the vertical direction for both groups and in the medial-lateral direction for trained group. Localized fatigue affected the analyzed gait variables independent of the participant’s training condition, and an interval of 12 min does not seem to be enough for a complete recovery, suggesting a longer recovery period after tasks involving localized triceps surae fatigue to guarantee basal levels of gait variability and local stability.

Flow chart of the experimental protocol. A) Pre-fatigue: 4 min walking at PWS. B) Post-fatigue: first 4 min walking after fatigue protocol. C) Post-fatigue: second 4 min walking after fatigue protocol. D) Post-fatigue: third 4 min walking after fatigue protocol (PWS, preferred walking speed; AP, anterior-posterior; V, vertical; ML, medial-lateral).

肌肉疲劳会对步态产生负面影响，并且由于肌肉疲劳而导致的步态变化会受到肌肉疲劳程度和预先存在的身体活动水平的影响。但是，这些因素如何改变步态的稳定性和可变性以及与跌倒风险相关的措施，目前尚不清楚。为了探讨肌肉疲劳如何影响年轻人的线性和非线性步态特征，我们评估了肱三头肌肱三头肌疲劳和体重训练水平对步态变异性和局部稳定性以及疲劳期后12分钟恢复时间的影响。年轻人（训练有素和未经训练的群体）。估计了一些特征，即（i）步长（SL）和步频（SF），（ii）躯干加速度沿步幅的平均标准偏差（VAR），以及（iii）局部动态稳定性（LDS；最大Lyapunov指数） ）。随着训练组的恢复，LDS在前后方向上显着增加。疲劳后SL和SF随即改变，两组均恢复，而VAR在各个方向均显着增加，两组均在垂直方向上恢复，而训练组在内侧-外侧方向上恢复。局部疲劳会影响分析的步态变量，而与参与者的训练条件无关，间隔12分钟似乎不足以使患者完全康复，这表明在涉及局部肱三头肌腓肠肌疲劳的任务之后，恢复更长的恢复期以确保基础步态变异和局部稳定。而VAR在所有方向上均显着增加，两组在垂直方向上都有恢复，而训练有素的组在内侧-外侧方向上都有恢复。局部疲劳会影响分析的步态变量，而与参与者的训练条件无关，间隔12分钟似乎不足以使患者完全康复，这表明在涉及局部肱三头肌腓肠肌疲劳的任务之后，恢复更长的恢复期才能确保基础步态变异水平和局部稳定。而VAR在所有方向上均显着增加，两组在垂直方向上都有恢复，而训练有素的组在内侧-外侧方向上都有恢复。局部疲劳会影响分析的步态变量，而与参与者的训练条件无关，间隔12分钟似乎不足以使患者完全康复，这表明在涉及局部肱三头肌腓肠肌疲劳的任务之后，恢复更长的恢复期以确保基础步态变异和局部稳定。

实验方案的流程图。A）疲劳前：在PWS步行4分钟。B）疲劳后：疲劳协议后的前4分钟步行。C）疲劳后：疲劳方案后第二秒步行4分钟。D）疲劳后：疲劳协议后第3分钟步行（PWS，首选步行速度； AP，前后； V，垂直； ML，内侧）。