| Keywords |
Passive heat load ; Sweat volume ; Activated sweat gland density ; Sodium ; aldosterone ; Fluid balance |
| Abstract |
The purpose of this study is to confirm the sudomotor sensitivity through quantitative assesment on the whole body sweat loss volume (WBSLV) and the mean activated sweat gland density (M-ASGD) based on maximal O2 uptake capacity (VO2max) upon passive heat load (PHL), and to examine its impact on fluid balance system. Thus, analyses about serum [Na+] and [Ald] were performed. In order to achieve the goal, people at late 30 s are divided into two groups such as a general group of sedentary life (Utr = 7) and a physical trained group (Tr = 8) (age, 37.3 ± 3.5 vs. 38.6 ± 5.4 yrs; O2max, 31.8 ± 0.9 vs. 38.31 ± 4.9 ml · kg?1· min?1; BSA, 1.08 ± 0.0 vs. 1.11 ± 0.0 m2). PHL (half bath in hot water, 41oC for 30 min, room temperature of 23 ± 0.5oC with 60 ± 3% relative humidity) was applied. The results showed that WBSLV and M-ASGD were significantly higher in the Tr than the Utr after PHL (**p < 0.01). It was also shown that serum [Na+] and [Ald] also were significantly higher in Tr after PHL (#p < 0.05) and Tr still tended to be high after the recovery period of 60 min. Consequently, if the performance of VO2max is improved, the sudomotor sensitivity would be improved. It causes to increase both WBSLV and M-ASGD. On the other hand, it is confirmed that compensatory system for body fluid balance worked more efficiently. It is expected that the tolerance against thermal stress will be improved since body heat is easily removed through this physiological adaptation. |