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ENVIRONMENTAL, EXERCISE AND RESPIRATORY PHYSIOLOGY

Effects of menstrual cycle and physical training on heat loss responses during dynamic exercise at moderate intensity in a temperate environment

¹Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Kobe; and ²Osaka International University, Osaka, Japan

Submitted 11 August 2004 ; accepted in final form 24 January 2005

We evaluated the effects of the menstrual cycle and physical training on heat loss (sweating and cutaneous vasodilation) responses during moderate exercise in a temperate environment. Ten untrained (group U) and seven endurance-trained (group T) women (maximal O₂ uptake of 36.7 ± 1.1 vs. 49.4 ± 1.7 ml·kg^–1·min^–1, respectively; P < 0.05) performed a cycling exercise at 50% maximal O₂ uptake for 30 min during both the midfollicular and midluteal menstrual phase in a temperate environment (ambient temperature of 25°C, relative humidity of 45%). In group U, plasma levels of estrone, estradiol, and progesterone at rest and esophageal temperature (T_es) during exercise were significantly higher during the midluteal than during the midfollicular phase (P < 0.05). Sweating rate and cutaneous blood flow (measured via laser-Doppler flowmetry) on the chest, back, forearm, and thigh were lower during the midluteal than during the midfollicular phase during exercise. T_es threshold for heat loss responses was significantly higher and sensitivity of the heat loss responses was significantly lower in the midluteal than in the midfollicular phase, regardless of body site. These effects of the menstrual cycle in group U were not observed in group T. The sweating rate and cutaneous blood flow were significantly higher in group T than in group U, regardless of menstrual phase or body site. T_es threshold for heat loss responses was significantly lower and sensitivity of heat loss responses was significantly greater in group T than in group U in the midluteal phase; however, sensitivity of the sweating response was significantly greater in the midfollicular phase. These results suggest that heat loss responses in group U were inhibited in the midluteal phase compared with in the midfollicular phase. Menstrual cycle had no remarkable effects in group T. Physical training improved heat loss responses, which was more marked in the midluteal than in the midfollicular phase.

thermoregulation; estradiol; progesterone; long-term endurance training; heat acclimatization

This article has been cited by other articles:

				T. K. Ichinose, Y. Inoue, M. Hirata, A. K. M. Shamsuddin, and N. Kondo Enhanced heat loss responses induced by short-term endurance training in exercising women Exp Physiol, January 1, 2009; 94(1): 90 - 102. [Abstract] [Full Text] [PDF]