Heat Reaction of Heat Acclimatized Tropical Resident in Serial Exposures to Hot Sauna : A Comparative Study

暑熱順化・熱帯地非スポーツマン(1名)と日本人スポーツマン(2名)を60℃の高温低湿サウナに週2回(1回:30分),3週間反復負荷させて対暑反応を比較検討した.対暑反応指標として発汗量(体重減少比),口腔温,脈圧,心拍数等をサウナ負荷前後で測定し次の結果を得た.(1)対暑反応の順化発現時間が日本人スポーツマンで延長を認める以外熱帯地人との間に有意の差を認めなかった.(2)すなわち,熱帯地人はサウナ負荷第1回目から対暑反応に順化が獲得されたが,日本人スポーツマンでは5回の負荷を要した.(3)両者間に核温(口腔温)の上昇率や心拍,脈圧に軽度温度適応変化を認めたが,この結果は運動トレーニングが生体反応の季節変動の調整や暑熱順化の形成過程に大きな役割を果たしていることを示す。以上の結果から熱帯地人の寒冷地在住後の脱順化についても検討を加えた.The effects of cold season on heat acclimatized tropical resident were studied from his reactions to six consecutive heat exposures in hot dry sauna (temp. 60℃) over a period of 3 weeks during summer in Japan. Two young Japanese sportsmen were subjected to similar heat exposures and their reactions were compared with those of the tropical resident. Pulse rate (PR) oral temperature (To), body weight (BW) and pulse pressure (PP) of the 3 subjects were recorded before and at the end of 30 minutes sauna exposures. Functional individuality of responses was apparent. While the tropical resident's post-exposure increase (mean±SE) were lower (PR 16±2.3; BW loss % 0.84±0.12; To 1.42±0.11℃), the Japanese sportsmen had proportionally higher increases. There was no statistically significant difference between the 3 subjects in pulse pressure change percentage. In the time course, the tropical resident had a decline in post-exposure increases of PR, To, Bw loss and PP from the 2nd experiment to the 6 th experiment. One of the Japanese sugjects had a decline in the post-exposure increases markedly from 5th heat exposure. The other sportsman had a decline in the increases of To and PR from the 3rd heat exposure, while his PR and BW losses remained almost constant (r:0.082 and r:0.045 respectively). The results indicate that deacclimatization to heat does not take place after cold exposure to winter or spring. Further the heat acclimation procedure was capable of inducing heat acclimation to the sportsmen. It is thought that regular physical training can contribute to heat adaptation procedures