Heat-induced vasoconstriction in the fingers between swimmers and runners

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To analyze the Heat-induced vasoconstriction during thermal stress in swimmers and runners, the present study compares swimmers trained in water with runners who trained on land.The subjects for this study were eight college male swimmers (S group) and 8 college male athletes who trained on land (R group). There were no significant differences in body height, body weight, %body fat between S group and R group. They trained regularly for 1.5 - 2 hours a day, 5-7 times in a week. All subjects were informed of the aims, risks, and benefits of this investigation both verbally and in writing prior to signing an informed consent.The finger blood flow was measured in water of 35℃ to 43℃ every 10 minutes by laser Doppler flowmetry (LDF). And finger, upperarm, oral temperature were measured.During immersion at 35℃ to 43℃, the finger temperature continuously raised, and were smaller in the R group.In the R group, BF% was significantly lower than that of the S group. The initial HIVC was observed four minutes after the immersion in both groups and the second HIVC at 16 minutes in the R group.These results suggested that arteriovenous anastomosis (AVA) in the fingers are more quantitatively and/or functionally superior in the R group and the differences in the local heat tolerance are might be caused by the heat transfer characteristics (evaporation/conduction) of the training environments.