To determine the optimal cooling area of the body surface to reduce exercise-heat stress, the effects of various body surface areas being cooled by perfusion of a tube-lined suit (PTLS) on thermoregulatory responses was evaluated during exercise in a hot environment. Seven male subjects performed three sessions of 20-min cycle exercise at light intensity (250W/m²) in a room maintained at 30℃. The subjects were dressed in clothing with low moisture permeability (rain coat) over PTLS covering whole body surface except for the face, hands, and feet. Esophageal (Tes), deep thigh (Tcore) and mean skin temperature (T ̅sk), heart rate (HR), skin blood flow (SkBF), thermal sensation (TS), and dehydration (DEH) were measured under six conditions under various body surface cooling conditions ; 1) whole body (WHO), 2) upper body (UP), 3) lower body (LOW), 4) lower body except lower leg (THI), 5) head and neck (HN), and 6) no body cooling (NO). Coolant temperature at the inlet was 20℃ for all conditions. The Tes, Tcore, and HR during exercise were significantly (p<0.01) higher in NO and HN, and SkBF and DEH were significantly (p<0.01) lower in WHO than in other conditions. However, there was a similar tendency in Tes between WHO, UP, THI, and LOW, and Tcore in UP was significantly (p<0.01) higher than that in WHO, THI, and LOW. In comparison with resting level, T ̅sk and TS significantly (p<0.01) rose in NO and HN, and fell in UP and WHO, but remained constant in THI and LOW during exercise. These results suggest that upper body surface cooling is able to maintain high Tcore while Tes, Tsk, and TS are as low as those with whole body cooling during exercise in a hot environment.

DESCENTE SPORTS SCIENCE Vol.25/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE