Ischemic preconditioning (IPC) is suggested to decrease fatigability in some individuals but not others. Sex differences in response to IPC may account for this variability and few studies systematically investigated the effects of IPC in men and women. The goal of this study was to determine if time to task failure, perception of pain, and neuromuscular mechanisms of fatigability were altered by IPC in men and women. Ten women (29 ± 5 years old) and 10 men (28 ± 6 years old) performed isometric contractions with the plantar flexor muscles of the dominant leg at 20% of maximal voluntary contraction until task failure. We used a repeated measures design where each individual performed 3 randomized and counterbalanced test sessions: (A) IPC session, cuff inflation and deflation (5 min each repeated 3 times) performed before the exercise by inflating cuffs to the non-dominant leg and arm; (B) sham session, cuffs were inflated for a short period (1 min); and (C) control session, no cuffs were involved. Compared with control, IPC increased time to task failure in men (mean difference, 5 min; confidence interval (CI) of mean difference, 2.2; 7.8 min; P = 0.01) but not women (mean difference, − 0.6 min; CI of mean difference, − 3.5; 2.4 min; P = 0.51). In men, but not women, the IPC-induced increase in time to task failure was associated with lower response to pressure pain (r = − 0.79). IPC further exposed sex differences in arterial pressure during fatiguing contractions (session × sex: P < 0.05). Voluntary activation, estimated with the twitch interpolation technique, and presynaptic inhibition of leg Ia afferents were not altered after IPC for men and women. The tested variables were not altered with sham. The ergogenic effect of IPC on time to task failure was observed only in men and it was associated with reductions in the perception of pain. This pilot data suggest the previously reported inter-individual variability in exercise-induced fatigability after IPC could be a consequence of the sex and individual response to pain.

中文翻译：

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非运动肢体缺血预处理后易疲劳性的性别差异

建议缺血预处理 (IPC) 可降低某些人的易疲劳性，但不能降低其他人的易疲劳性。对 IPC 反应的性别差异可能是这种可变性的原因，很少有研究系统地调查 IPC 对男性和女性的影响。本研究的目的是确定 IPC 是否会改变男性和女性的任务失败时间、疼痛感知和易疲劳的神经肌肉机制。10 名女性（29 ± 5 岁）和 10 名男性（28 ± 6 岁）以最大自主收缩的 20% 对优势腿的跖屈肌进行等长收缩，直到任务失败。我们使用了重复测量设计，其中每个人都进行了 3 个随机和平衡的测试阶段：(A) IPC 阶段，运动前通过将袖带充气至非优势腿和手臂进行袖带充气和放气（每次 5 分钟，重复 3 次）；(B) 假手术，袖口充气一小段时间（1 分钟）；(C) 控制会话，不涉及袖口。与对照组相比，IPC 增加了男性的任务失败时间（平均差异，5 分钟；平均差异的置信区间 (CI)，2.2；7.8 分钟；P = 0.01），但女性没有（平均差异，- 0.6 分钟；CI 为平均差异，- 3.5；2.4 分钟；P = 0.51）。在男性而非女性中，IPC 诱导的任务失败时间增加与对压痛的反应降低有关 (r = − 0.79)。IPC 进一步暴露了疲劳收缩期间动脉压的性别差异（会话×性别：P < 0.05）。用抽搐插值技术估计的自愿激活，男性和女性在 IPC 后腿部 Ia 传入的突触前抑制没有改变。测试变量没有被假手术改变。仅在男性中观察到 IPC 对执行任务失败时间的人体工程学影响，并且它与疼痛感知的减少有关。该试验数据表明，先前报告的 IPC 后运动引起的疲劳的个体间差异可能是性别和个体对疼痛反应的结果。