太陽放射を伴った暑熱環境下における衣服の色の
温熱生理反応および運動持久能力に与える影響

Effects of Clothing Colour on Thermophysiological
Responses and Endurance to Handgrip Exercise
under Warm Conditions with Sun Radiation

by

Masako Kato, Hiromi Tokura
Department Environmental Health, Nara Women's University

ABSTRACT

The aims of our study were to examine some effects of clothing colours on thermophysiological responses and endurance of handgrip exercise under the warm conditions with the artificial and natural sun radiation. Black and white garments made of cotton were consisted of T-shirts with long sleeves and long trousers.
In the first experiment, 7 subjects volunteered and kept sitting for 1 hour in the chamber at 32℃ with the artificial sun radiation. The main results were as follows; though rectal temperature was kept constant revel between black and white garment during the experiment, skin temperature on foot, local sweat rates from forearms and mass loss were higher in the white garment. Clothing surface temperature was significantly higher level in the black.
In the second experiment, 1 subject sat for 1 hour under the outdoor conditions in summer in Nara. After then, handgrip exercise was performed until volitional exhaustion and the number of contractions was counted. Major finding were that clothing surface temperature in the black increased higher than that in the first experiment and the number of contractions was greater in the black garment after 1 hour sitting in the sun.
This study presented that thermoregulatory effectors were activated more and the endurance to handgrip exercise was smaller in the white garment under the summer sum radiation.

　要　旨

　太陽放射を伴った暑熱環境において、衣服の色がヒトの温熱生理反応や局所的な運動持久力にどのような影響を与えるのかを検討した。実験では、同じ素材から成る白色と黒色の長袖・長ズボンを比較した。
　実験１では人工太陽を伴って、環境温３２℃に設定した人工気候室で、７名の被験者が１時間椅座安静を保った。温熱生理反応の測定の結果、深部体温である直腸温では２種類の衣服の間に有意な差は見られなかったものの、足背部皮膚温、体重減少量、局所発汗速度で白色の衣服が高いレベルを示した。逆に衣服表面温度では、黒色の衣服で高いレベルを示した。
　実験２では実際の夏期屋外において、１名の被験者が１時間椅座安静を保った後、ハンドエルゴメータによる局所的な運動持久力を測定した。その結果、衣服表面温は実際の屋外環境の方がより黒色で高いレベルであること、運動持久力も黒色で高い数値を表わした。
　以上の結果、衣服表面温度屋布の色の日射に対する物理的性質などが起因して、夏期屋外での衣服の色がヒトの温熱生理反応屋運動持久力に影響することがわかった。