Three men ages of 36, 63 and 67 yrs old exercised for 30 min on a bicycle ergometer at a work rate of 300 kpm/min and recovered for 30 min in a hot (32℃ Ta, RH 46%) and a cool (22℃ Ta, RH 40%) environment, respectively.
　Heart rate at 30 min of exercise in a cool and a hot environment was 86 and 90 bpm for 36 yrs man, 102 and 144 bpm for 63 yrs man, and 109 and 150 bpm for 67 yrs man, respectively.
　Average values of blood pressure during exercise in a cool and a hot environment were 146.3/74.0 (systolic/diastolic) and 150.4/43.5 mmHg for 36 yrs man, 153.9/68.5 and 159.6/71.7 mmHg for 63 yrs man, and 171.0/91.5 and 180.9/89.7 mmHg for 67 yrs man, respectively.
　Increment in rectal temperature at 30 min of exercise in a cool and a hot environment was 0.2 and 0.3℃ for 36 yrs man, 0.1 and 0.7℃ for 63 yrs man, and 0.2 and 0.6℃ for 67 yrs man, respectively. Ventilation at 30 min of exercise in a hot environment was greater than that of a cool environment by 10.1%, 20.4% and 23.4% for 36 yrs, 63 yrs and 67 yrs man, respectively. Oxygen intake during exercise was also greater in a hot environment compared with that of a cool environment by 13.4%, 22.2% and 19.4% for 36 yrs, 63 yrs and 67 yrs man, respectively.
　The peak values of blood lactate in a cool and a hot environment were 0.95 and 2.10 mmole/l for 63 yrs man, and 1.64 and 2.62 mmole/l for 67 yrs man, respectively.
　These results show that the stress of exercise in a hot-humid environment was considerably greater for high aged persons than for younger persons.

DESCENTE SPORTS SCIENCE Vol.14/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE