School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, Canada; Aging and Movement Laboratory, Bruyère Research Institute, Élisabeth Bruyère Hospital, Canada.
School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, Canada; Aging and Movement Laboratory, Bruyère Research Institute, Élisabeth Bruyère Hospital, Canada.
J Electromyogr Kinesiol. 2022 Aug;65:102676. doi: 10.1016/j.jelekin.2022.102676. Epub 2022 Jun 6.
The main aim of this study was to determine sex differences in central and peripheral fatigue produced by a sustained isometric exercise of ankle plantar flexors in healthy young adults. Ten males and fourteen females performed a sustained isometric ankle exercise until task failure. Maximal voluntary isometric contraction (MVIC) torque (plantarflexion), voluntary activation level (using the twitch interpolation technique), and resting twitch contractile properties [twitch peak torque (ST), twitch half relaxation time, and low frequency fatigue (LFF) ratio] were measured before, immediately after, and throughout a recovery period (1, 2, 5, and 10 min) following the exercise protocol in order to characterize neuromuscular fatigue. Fatigue had effects (p≤ 0.05) on all dependent variables (reduction in MVIC, VA and twitch torque and slowing of relaxation time). However, no significant differences in performance fatigability markers (MVIC torque decline and time to fatigue) and only minor differences in the variables reflecting central and peripheral fatigue mechanisms were found between males and females. A regression analysis did suggest a somewhat greater role of central fatigue in males compared with females. Females also showed a slightly greater and more prolonged decline in ST and LFF after exercise compared with males. The presence of only minor differences in central and peripheral fatigue mechanisms between males and females in the present study could be explained by the lack of important sex differences in performance fatigability, which could be due to lesser sex differences in the relative area of type I muscle fibers and in contractile function (muscle strength) of ankle plantar flexors as compared with other muscle groups.
本研究的主要目的是确定健康年轻成年人进行持续等长踝关节跖屈运动时中枢和外周疲劳的性别差异。10 名男性和 14 名女性进行持续等长踝关节运动，直至任务失败。在运动方案之前、之后立即以及在运动后恢复期间（1、2、5 和 10 分钟）测量最大自主等长收缩（MVIC）扭矩（跖屈）、自愿激活水平（使用抽搐插值技术）和休息抽搐收缩特性[抽搐峰值扭矩（ST）、抽搐半松弛时间和低频疲劳（LFF）比]，以表征神经肌肉疲劳。疲劳对所有依赖变量（MVIC、VA 和抽搐扭矩降低以及松弛时间减慢）都有影响（p≤0.05）。然而，在表现疲劳标志物（MVIC 扭矩下降和疲劳时间）方面，男性和女性之间没有发现显著差异，而反映中枢和外周疲劳机制的变量只有微小差异。回归分析表明，男性的中枢疲劳作用略大于女性。与男性相比，女性在运动后 ST 和 LFF 的下降幅度更大，持续时间更长。本研究中男性和女性之间中枢和外周疲劳机制只有微小差异的原因可能是由于在性能疲劳方面没有重要的性别差异，这可能是由于与其他肌肉群相比，I 型肌纤维的相对面积和踝关节跖屈肌的收缩功能（肌肉力量）的性别差异较小。
