To examine the effects of physical training on heat loss responses of young women in relation to menstrual cycles, 11 physically trained (T group) and 13 untrained (U group) women were exposed to passive heating 〔by placing the lower legs and feet in a 42℃ water bath for 60 min while sitting in a warm (30℃, 45%RH) chamber〕 in their midfollicular and mid-luteal phases. Female hormones on the experimental day increased from the mid-follicular to mid-luteal phase in the T and U groups, but the magnitude of increase was significantly lower in the T group. During the passive heating, rectal (Tre) and mean skin temperatures were significantly lower in the T group than in the U group regardless of the menstrual phase. Although Tre and mean body (Tb) temperatures before and during the heating increased from the mid-follicular to the mid-luteal phase in the U groups, the tendency was not observed in the T group. Therefore the group differences of Tre and Tb were more remarkable in the mid-luteal phase. The increase of skin blood flow measured by laser-Doppler flowmetry (%LDF) did not differ between the groups regardless of body site and menstrual phase. Local sweating rate (msw) was significantly greater in the T group than in the U group on chest, back and forearm (but not on forehead and thigh) in the both menstrual phases, but no menstrual phase-related differences were observed in either group. Analysis of the relationship of the frequency of sweat expulsion (Fsw) - Tb, msw - Fsw or %LDF - Tb suggested that in women physical training improves sweating and vasodilation functions, and central and peripheral mechanisms in the sweating function and central rather than peripheral mechanism in the vasodilation function. The improvement of the central mechanism in the both functions by physical training was more marked in the mid-luteal than the mid-follicular phase (due to the marked group difference of the female hormones in the mid-luteal phase). The improvement of peripheral mechanisms was greater in the sweating rather than the vasodilation function, and its magnitude differed with body site.

DESCENTE SPORTS SCIENCE Vol.24/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE