Human thermoregulation during prolonged exposure to warm and extremely humid environments expected to occur in disabled submarine scenarios.

Human thermoregulation during prolonged exposure to warm and extremely humid environments expected to occur in disabled submarine scenarios. Am J Physiol Regul Integr Comp Physiol. 2020 Apr 01;: Authors: Schlader ZJ, Johnson BD, Pryor RR, Stooks J, Clemency BM, Hostler D Abstract Military and civilian emergency situations often involve prolonged exposures to warm and very humid environments. We tested the hypothesis that increases in core temperature and body fluid losses during prolonged exposure to warm and very humid environments are dependent on dry bulb temperature. On three occasions, fifteen healthy males (23±3 y) sat in 32.1±0.1°C, 33.1±0.2°C or 35.0±0.1°C, and 95±2% relative humidity normobaric environments for 8 h. Core temperature (telemetry pill) and percent change in body weight, an index of changes in total body water occurring secondary to sweat loss, were measured every hour. Linear regression models were fit to core temperature (over the final 4 h) and percent changes in body weight (over the entire 8 h) for each subject. These equations were used to predict core temperature and percent changes in body weight for up to 24 h. At the end of the 8 h exposure, core temperature was higher in 35°C (38.2±0.4°C, P<0.01) compared to 32°C (37.2±0.2°C) and 33°C (37.5±0.2°C). At this time, percent changes in body weight were greater in 35°C (-1.9±0.5%) compared to 32°C (-1.4±0.3%, P<0.01) but not 33°C...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - Category: Physiology Authors: Tags: Am J Physiol Regul Integr Comp Physiol Source Type: research