INTRODUCTION Cerebral blood flow and thermal perception during physical exercise under hyperthermia conditions in females are poorly understood. Because sex differences exist for blood pressure control, resting middle cerebral artery velocity (MCAVmean), and pain, we tested the hypothesis that females would have greater reductions in MCAvmean and increased thermal perceptual strain during exercise hyperthermia compared to males. METHODS Twenty-two healthy active males and females completed 60 min of matched exercise metabolic heat production in a 1) control cool (24.0 ± 0.0 °C; 14.4 ± 3.4% Rh) and 2) hot (42.3 ± 0.3 °C; 28.4 ± 5.2% Rh) conditions in random order, separated by at least 3 days while MCAvmean, thermal comfort, and preference was obtained during the exercise. RESULTS Compared to 36 °C mean body temperature (Mbt), as hyperthermia increased to 39 °C Mbt, females had a greater reduction in absolute (MCAvmean), and relative change (%Δ MCAvmean) and conductance (%Δ MCAvmean conductance) in MCAVmean compared to males (Interaction: Temperature x Sex, P ≤ 0.002). During exercise in cool conditions, absolute and conductance MCAvmean was maintained from rest through exercise; however, females had greater MCAVmean compared to males (Main effect: Sex, P < 0.0008). We also found disparities in females' perceptual thermal comfort and thermal preference. These differences may be associated with a greater reduction in partial pressure of end-tidal CO2, and different cardiovascular and blood pressure control to exercise under hyperthermia. CONCLUSIONS In summary, females exercise cerebral blood flow velocity is reduced to a greater extent (25% vs 15%) and the initial reduction occurs at lower hyperthermia mean body temperatures (~38 °C vs ~39 °C) and are under greater thermal perceptual strain compared to males.

中文翻译：

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运动热疗期间脑血流速度的性别差异

介绍 女性在高热条件下进行体育锻炼时的脑血流量和热感知知之甚少。由于在血压控制、静息大脑中动脉速度 (MCAVmean) 和疼痛方面存在性别差异，我们测试了以下假设：与男性相比，女性在运动热疗期间 MCAvmean 的降低幅度更大，热感知应变增加。方法 22 名健康活跃的男性和女性在 1) 控制冷 (24.0 ± 0.0 °C; 14.4 ± 3.4% Rh) 和 2) 热 (42.3 ± 0.3 °C; 28.4 ± 5.2% Rh) 条件以随机顺序相隔至少 3 天，而 MCAvmean、热舒适度和偏好是在锻炼期间获得的。结果 与 36 °C 平均体温 (Mbt) 相比，随着体温升高至 39 °C Mbt，与男性相比，女性的绝对值 (MCAvmean)、相对变化 (%Δ MCAvmean) 和电导 (%Δ MCAvmean 电导) 的降低幅度更大（相互作用：温度 x 性别，P ≤ 0.002）。在凉爽条件下运动期间，绝对和电导 MCAvmean 从休息到运动保持；然而，与男性相比，女性具有更高的 MCAVmean（主效应：性别，P < 0.0008）。我们还发现女性在感知热舒适度和热偏好方面存在差异。这些差异可能与呼气末 CO2 分压的更大降低以及不同的心血管和血压控制与高热下运动有关。结论 总之，