Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
J Appl Physiol (1985). 2012 Sep 1;113(5):746-57. doi: 10.1152/japplphysiol.00637.2012. Epub 2012 Jul 12.
To assess potential mechanisms responsible for the lower sudomotor thermosensitivity in women during exercise, we examined sex differences in sudomotor function and skin blood flow (SkBF) during exercise performed at progressive increases in the requirement for heat loss. Eight men and eight women cycled at rates of metabolic heat production of 200, 250, and 300 W/m(2) of body surface area, with each rate being performed sequentially for 30 min. The protocol was performed in a direct calorimeter to measure evaporative heat loss (EHL) and in a thermal chamber to measure local sweat rate (LSR) (ventilated capsule), SkBF (laser-Doppler), sweat gland activation (modified iodine-paper technique), and sweat gland output (SGO) on the back, chest, and forearm. Despite a similar requirement for heat loss between the sexes, significantly lower increases in EHL and LSR were observed in women (P ≤ 0.001). Sex differences in EHL and LSR were not consistently observed during the first and second exercise periods, whereas EHL (348 ± 13 vs. 307 ± 9 W/m(2)) and LSR on the back (1.61 ± 0.07 vs. 1.20 ± 0.09 mg · min(-1) · cm(-2)), chest (1.33 ± 0.06 vs. 1.08 ± 0.09 mg · min(-1) · cm(-2)), and forearm (1.53 ± 0.07 vs. 1.20 ± 0.06 mg · min(-1) · cm(-2), men vs. women) became significantly greater in men during the last exercise period (P < 0.05). At each site, differences in LSR were solely due to a greater SGO in men, as opposed to differences in sweat gland activation. In contrast, no sex differences in SkBF were observed throughout the exercise period. The present study demonstrates that sex differences in sudomotor function are only evidenced beyond a certain requirement for heat loss, solely through differences in SGO. In contrast, the lower EHL and LSR in women are not paralleled by a lower SkBF response.
为了评估女性在运动期间出汗减少的潜在机制，我们在递增的热耗散需求下，检查了运动期间的出汗功能和皮肤血流（SkBF）的性别差异。8 名男性和 8 名女性以 200、250 和 300 W/m(2)的体表面积代谢产热率进行骑行，每个速率连续进行 30 分钟。方案在直接量热计中进行，以测量蒸发热损失（EHL），并在热室中进行，以测量局部出汗率（LSR）（通风胶囊）、SkBF（激光多普勒）、汗腺激活（改良碘纸技术）和背部、胸部和前臂的汗量输出（SGO）。尽管男女之间对热耗散的需求相似，但女性的 EHL 和 LSR 增加明显较低（P ≤ 0.001）。在第一和第二运动期间，EHL 和 LSR 的性别差异并不一致，而 EHL（348 ± 13 与 307 ± 9 W/m(2))和背部的 LSR（1.61 ± 0.07 与 1.20 ± 0.09 mg · min(-1) · cm(-2))、胸部（1.33 ± 0.06 与 1.08 ± 0.09 mg · min(-1) · cm(-2))和前臂（1.53 ± 0.07 与 1.20 ± 0.06 mg · min(-1) · cm(-2)，男性与女性）在最后一个运动期间明显增加（P < 0.05）。在每个部位，LSR 的差异仅归因于男性的 SGO 更大，而不是汗腺激活的差异。相比之下，整个运动期间没有观察到 SkBF 的性别差异。本研究表明，出汗功能的性别差异仅在一定的热耗散需求下表现出来，仅通过 SGO 的差异。相比之下，女性的 EHL 和 LSR 较低并不伴随着 SkBF 反应较低。
