The aim of this study is based on the thermoregulatory mechanism during cycling exercise at the high and low body temperature phases of the menstrual cycle in young women. Two types of the exercise were employed ; submaximal (60% Vo₂max) prolonged exercise and exercise to exhaustion with gradual increase in its intensity at the room temperature of 26 degrees and relative humidity of 60%.
　The results obtained were as follows ;
　1 ) At resting period, rectal and tympanic temperatures at a high body temperature phase was higher than at a low temperature phase, while mean skin temperature at the high temperature phase was low, compared with that at the low phase. And Vo₂ and HR at the high phase was, also, larger than those at the low phase.
　2 ) During exercise, parameters pertainig to temperature changed in similar manner.
　But relative change in the variables at low temperature phase were larger compared with high temperature phase. However, it made no great difference in mean, skin temperature between high and low temperature .phase, but the mean body temperature showed large increment ratio in the low temperature phase. In this study, these results suggested the higher "set-point" temperature and the larger "thermosensitivity" in the high body temperature phase.

DESCENTE SPORTS SCIENCE Vol.16/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE