To examine the significance for physical fitness and sports medicine of cutaneous arteriovenous anastomoses (AVA) in human extremities from a viewpoint of thermal physiology, 15 healthy women were participated as a subject. The effects of local heating by the leg-immersion in water bath on finger skin blood flow (mainly AVA flow) was studied at the ambient temperatures (Ta) of 25℃ (warm environment) and 28℃ (hot environment). In the warm environment, the temperature of the water bath (Tw) was steadily raised from 28℃ to 41℃ in 37 min, and then kept at constant Tw of 41℃ for 33min. In the hot environment, Tw was steadily raised from 35℃ to 41℃ in 17 min and then kept at constant Tw of 41℃ for 43min. Simultaneous blood flow (BF) recordings from the finger and the forearm skin were made continuously using laser-Doppler flowmeter.
　As Tw was raised in the warm environment, finger BF decreased for approximately 15 min (leg skin temperature of 34.5℃ to 40.0℃) and then increased until end of the experiment. However, there was no decrease of finger BF in the hot envionment. Heat-induced vasoconstriction (HIVC) was not observed in the forearm skin in both environments.
　These results suggest that HIVC in the finger caused by local leg heating in the warm environment is controlled via the reflexive control mechanism and may be limited to AVA vessels in the finger skin.

DESCENTE SPORTS SCIENCE Vol.19/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE