Sportsmen and women are often exposed to the direct solar radiation in summer. In this condition, it is important to guard against the radiant heat. The present study was carried out to investigate the effect of putting on the headgear during exercise. Four healthy men were loaded by a bicycle ergometer at 450 kpm/min for 20 min. under the vertical heat radiation of 1.2 cal/cm²/min in a room of 30℃ with 60% relative humidity and 0.73 m/sec air flow.
　The results are outlined as follows;
　1) In average, the values of heart rate, oxygen consumption, rectal temperature and mean skin temperature during exercise and recovery in case of putting on the headgear were no different from no headgears, whears total sweat volume of back, rate of body weight loss and skin temperature rise of parietal region in case of putting on the headgear were significantly smaller than those of no headgear respectively.
　2) High correlation was recognized between skin temperature of parietal region and rate of body weight loss. This result indicates that the smaller rise of skin temperature prevents the additional water loss of body during exercise.
　3) There was no difference of response between putting on a baseball cap and a Kimotsuki's coolness hat in this experimental condition.

DESCENTE SPORTS SCIENCE Vol.3/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE