Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA.
Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA, USA.
J Musculoskelet Neuronal Interact. 2022 Dec 1;22(4):504-513.
Females tend to fatigue less than males after isometric exercise, but less is clear for isotonic exercise. Further, there have been relatively few sex comparisons for fatigability of the plantar flexors (PFs). We sought to investigate potential sex differences in contractile properties after a sustained maximal voluntary isometric contraction (MVIC) and isotonic contractions.
Twenty-seven physically active males (n=14; 22±2 yrs) and females (n=13; 21±2 yrs) randomly performed a 2 min MVIC and 120 concentric isotonic (30% MVIC) contractions for the PFs on separate visits. Before and after each fatiguing task, muscle activation was obtained from brief MVICs, which was followed (~2 sec) by tibial nerve stimulation at rest. Contractile properties including peak twitch, absolute and normalized time to peak twitch, and half relaxation time were calculated.
No sex differences existed for fatigue-induced changes in muscle activation (p=0.09-0.41; =0.33-0.69) or contractile properties (p=0.19-0.96; =0.06-0.94).
Peripheral fatigue, as indicated by contractile parameters, did not differ between sexes after isometric or isotonic exercise. The PFs similar fiber type proportions between sexes or greater fiber type heterogeneity may explain why sex differences in fatigability, though common in other muscle groups (e.g., knee extensors), were not expressed in this muscle group.
女性在进行等长运动后比男性疲劳程度低，但等张运动则不太清楚。此外，对于跖屈肌（PFs）的疲劳性，进行性别的比较相对较少。我们试图研究在持续最大自主等长收缩（MVIC）和等张收缩后收缩性能的潜在性别差异。
27 名身体活跃的男性（n=14；22±2 岁）和女性（n=13；21±2 岁）分别在不同的访问中随机进行 2 分钟的 MVIC 和 120 次同心等张（30%MVIC）的 PFs 收缩。在每次疲劳任务之前和之后，从短暂的 MVIC 中获得肌肉激活，然后在休息时（~2 秒）进行胫神经刺激。计算包括峰值抽搐、绝对和归一化峰值抽搐时间以及半松弛时间在内的收缩性能。
性别之间在肌肉激活（p=0.09-0.41； =0.33-0.69）或收缩性能（p=0.19-0.96； =0.06-0.94）的疲劳诱导变化方面没有差异。
等长或等张运动后，收缩参数表明外周疲劳在性别之间没有差异。PFs 中相似的纤维类型比例或更大的纤维类型异质性可能解释了为什么在其他肌肉群（例如膝伸肌）中常见的疲劳性性别差异在这个肌肉群中没有表现出来。
