Neuromuscular Research Lab, Faculdade de Motricidade Humana, Universidade de Lisboa, Estrada da Costa, 1499-002, Cruz Quebrada, Dafundo, Portugal.
CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Estrada da Costa, 1499-002, Cruz Quebrada, Dafundo, Portugal.
Sci Rep. 2021 Apr 14;11(1):8141. doi: 10.1038/s41598-021-87443-0.
Muscle fatigue is a limiting factor of human performance. It is unclear whether sex-based differences in fatigability exist during dynamic exercise of varying velocities of contraction. We aimed at exploring sex differences in muscle fatigue elicited by maximal isokinetic muscle contractions performed at different angular velocities. Twenty-six healthy participants (13 men: 23.2 ± 1.5; 13 women: 21.9 ± 3.0 years) were tested for concentric knee-extension at slow, moderate and fast angular isokinetic velocity (60, 180 and 300º.s, respectively), on non-consecutive days. The impact of sex on fatigue resistance and consecutive recovery for each isokinetic condition was explored by calculating the percent change in maximal voluntary isometric contraction (MVIC) and in rate of torque development (RTD), from pre- to post-isokinetic exercise (30 repetitions). The isokinetic fatigue index was also determined. No sex differences were obtained in response to isokinetic contractions completed at 60º.s. After performing muscle contractions at 300º.s, women had a significantly greater loss in MVIC than men (- 18.4 ± 5.5 vs. - 12.9 ± 3.8%; p = 0.009) and larger decreases in work output during isokinetic exercise (- 34.2 ± 8.9 vs - 27.5 ± 10.6%; p = 0.017). Recovery of initial MVIC strength was greater for women post-exercise at 180º.s (15.6 ± 4.1% vs. 6.7 ± 9.5; p = 0.003). No differences were found between sexes in any condition for RTD from pre- to post-fatigue. These results suggest the presence of a sexually dimorphic fatigability in response to dynamic (isokinetic) contractions favouring men at higher absolute velocities of contraction.
肌肉疲劳是人体表现的限制因素。目前尚不清楚在不同收缩速度的动态运动中是否存在疲劳性的性别差异。我们旨在探讨在不同角速度下进行最大等速肌肉收缩时肌肉疲劳引起的性别差异。26 名健康参与者（男性 13 名：23.2±1.5 岁；女性 13 名：21.9±3.0 岁）分别在非连续的几天内进行慢、中、快角速度（分别为 60、180 和 300°·s）的向心膝关节伸展测试。通过计算从等速运动前到后的最大随意等长收缩（MVIC）和扭矩发展率（RTD）的百分比变化，来探索性对每种等速条件的抗疲劳能力和连续恢复。还确定了等速疲劳指数。在完成 60°·s 的等速收缩时，没有观察到性别差异。在完成 300°·s 的肌肉收缩后，女性的 MVIC 损失明显大于男性（-18.4±5.5%比-12.9±3.8%；p=0.009），在等速运动期间的工作输出减少更大（-34.2±8.9%比-27.5±10.6%；p=0.017）。在 180°·s 运动后，女性的初始 MVIC 强度恢复更大（15.6±4.1%比 6.7±9.5%；p=0.003）。在疲劳前后，RTD 没有在任何条件下存在性别差异。这些结果表明，在对动态（等速）收缩的反应中存在性别二态性的疲劳性，有利于更高绝对收缩速度的男性。
