Fortney S M, Senay L C
J Appl Physiol Respir Environ Exerc Physiol. 1979 Nov;47(5):978-84. doi: 10.1152/jappl.1979.47.5.978.
In an attempt to explain why females experience greater strain than males during exercise in the heat, we studied the responses of nine females to moderate exercise (40% VO2 max) on a cycle ergometer in a cool (16--20 degrees C, 30% rh) and a hot (45 degrees C, 30% rh) environment. Venous blood was sampled during rest, at the 40th min of exercise, and 25 min after exercise. Test runs were then performed during a 4-wk training program (phase 2) and during heat acclimation (phase 3). Except for K+, changes in plasma constituents during exercise were not altered by training or acclimation. A greater mean decrease in plasma volume occurred during exercise in a hot (11.9%) than in a cool (3.9%) environment. Plasma osmolality and protein concentration increased due to the loss of plasma water. The most striking response to training was a significant expansion of resting plasma volume (9.7%) and total protein content (11.6%). During acclimation, sweat rates increased and mean skin temperatures significantly decreased. Hemodilution reported in heat-acclimated men was not seen. The factor primarily responsible for improved cardiovascular fitness in these women during acclimation may have been the maintenance of a larger central blood volume.
为了解释为何女性在热环境中运动时比男性承受更大的压力，我们研究了9名女性在凉爽（16 - 20摄氏度，相对湿度30%）和炎热（45摄氏度，相对湿度30%）环境下，在自行车测力计上进行中等强度运动（最大摄氧量的40%）时的反应。在休息时、运动第40分钟以及运动后25分钟采集静脉血样。然后在为期4周的训练计划（第2阶段）和热适应期间（第3阶段）进行测试。除钾离子外，运动期间血浆成分的变化不受训练或热适应的影响。与凉爽环境（3.9%）相比，在炎热环境中运动时血浆量的平均减少幅度更大（11.9%）。由于血浆水分流失，血浆渗透压和蛋白质浓度升高。训练最显著的反应是静息血浆量显著增加（9.7%）和总蛋白含量增加（11.6%）。在热适应期间，出汗率增加，平均皮肤温度显著降低。未观察到热适应男性中出现的血液稀释现象。这些女性在热适应期间心血管适应性改善的主要因素可能是维持了更大的中心血容量。
