Renda Erika, Yang Chen, Côté Julie N
Department of Kinesiology and Physical Education, McGill University, 475 Pine Avenue West, Montreal, Quebec H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, Quebec H7V 1R2, Canada.
Department of Kinesiology and Physical Education, McGill University, 475 Pine Avenue West, Montreal, Quebec H2W 1S4, Canada; Occupational Biomechanics and Ergonomics Laboratory, Michael Feil and Ted Oberfeld/CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, Quebec H7V 1R2, Canada.
J Electromyogr Kinesiol. 2022 Dec;67:102717. doi: 10.1016/j.jelekin.2022.102717. Epub 2022 Oct 22.
We have previously demonstrated that fatigue at different locations impacts joint angles, angular variability, and coordination variability differently. However, the neuromuscular control aspects underlying these kinematic changes have never been demonstrated. Seventeen young adults (8 males) were recruited. Electromyographic electrodes were placed on: upper trapezius, pectoralis major, anterior and middle deltoid, biceps and triceps brachii, and left and right erector spinae. Subjects performed the repetitive pointing task (RPT) at 1 Hz for 30 s before and after localized fatigue tasks, which consisted of one shoulder, one elbow and one lower back isometric fatiguing protocols until exhaustion in randomized order. Electromyographic amplitude (RMS), variability (SD) and mean power frequency (MnPF) were calculated for each of the pre-fatigue and post-fatigue RPT trials. There were sex × fatigue location interaction effects on upper trapezius RMS (p = 0.038) with males' values increasing the most after shoulder fatigue. Females' triceps brachii RMS was greater compared to males after shoulder, elbow, and trunk fatigue (p = 0.003, p = 0.001 and p = 0.007 respectively). There were sex × fatigue location effects on left erector spinae MnPF (p = 0.011) with males and females' values decreasing the most after trunk fatigue, but more so in males. Results demonstrate that males and females compensate differently during a repetitive pointing task when their elbows, shoulders and trunks are locally fatigued, which could have implications on sex-specific workplace injury risks. See Table 1 for acronyms.
我们之前已经证明，不同部位的疲劳对关节角度、角度变异性和协调性变异性的影响各不相同。然而，这些运动学变化背后的神经肌肉控制方面从未得到证实。招募了17名年轻人（8名男性）。将肌电图电极放置在：斜方肌上部、胸大肌、三角肌前束和中束、肱二头肌和肱三头肌，以及左右竖脊肌。受试者在局部疲劳任务前后以1Hz的频率进行30秒的重复指向任务（RPT），局部疲劳任务包括一个肩部、一个肘部和一个下背部的等长疲劳方案，直至疲劳耗尽，顺序随机。计算每次疲劳前和疲劳后RPT试验的肌电图振幅（RMS）、变异性（SD）和平均功率频率（MnPF）。在斜方肌上部RMS上存在性别×疲劳部位的交互作用（p = 0.038），男性的值在肩部疲劳后增加最多。在肩部、肘部和躯干疲劳后，女性肱三头肌的RMS比男性更大（分别为p = 0.003、p = 0.001和p = 0.007）。在左侧竖脊肌MnPF上存在性别×疲劳部位的效应（p = 0.011），男性和女性的值在躯干疲劳后下降最多，但男性下降得更多。结果表明，当男性和女性的肘部、肩部和躯干局部疲劳时，他们在重复指向任务中的补偿方式不同，这可能对特定性别的工作场所受伤风险有影响。首字母缩略词见表1。
