College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan.
Graduate School of Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan.
Sci Rep. 2019 Nov 13;9(1):16718. doi: 10.1038/s41598-019-53375-z.
This study investigated whether the sex difference in fatigability of the knee extensors (KE) is explained by the sex difference in fatigue-induced changes in the shear modulus of one or more muscles of KE in 18 young men and 23 young women. The shear moduli of the resting rectus femoris and medial and lateral vastus muscles (VL) were measured before and after a sustained contraction at 20% peak torque during a maximal voluntary isometric contraction of KE until the endurance limit, in addition to evoked torque and voluntary activation (VA%). The fatigue-induced decrease in maximal muscle strength was more prominent in men than in women. Only the VL shear modulus for men increased after the fatiguing task, and a sex difference was observed in the percentage change in the VL shear modulus before and after the fatiguing task. The fatigue-induced decreased ratio was greater for men than for women in evoked torque, but not in VA%. These results suggest that although peripheral and central fatigue both influenced the fatigue-induced decrease in maximal muscle strength regardless of sex, the sex difference in KE fatigability is explained by that in peripheral fatigue, particularly the degree of peripheral VL fatigue.
本研究旨在探讨在 18 名年轻男性和 23 名年轻女性中，股四头肌（KE）的疲劳性性别差异是否可以用 KE 中一种或多种肌肉的剪切模量在疲劳诱导下的变化来解释。在 KE 的最大自主等长收缩期间，以 20%的峰值扭矩进行持续收缩，直到耐力极限，除了诱发扭矩和自愿激活（VA%）之外，还测量了休息状态下股直肌和内侧及外侧股四头肌（VL）的剪切模量。与女性相比，男性在最大肌肉力量的疲劳诱导下降更为明显。只有男性的 VL 剪切模量在疲劳任务后增加，并且在疲劳任务前后，VL 剪切模量的变化百分比存在性别差异。在诱发扭矩中，男性的疲劳诱导降低比率大于女性，但在 VA%中则不然。这些结果表明，尽管无论性别如何，外周和中枢疲劳都会影响最大肌肉力量的疲劳诱导下降，但 KE 疲劳性的性别差异可以用外周疲劳来解释，特别是外周 VL 疲劳的程度。
