Effects of heat acclimation states on thermoregulatory response during agricultural work in the heat

To examine the effects of heat acclimation states on thermoregulatory responses in agricultural workers, this study investigated the differences in core temperature, hydration states, working times, and working intensity between workers native to subtropical and temperate region who were acclimatized or not acclimated to hot environment during agricultural work in summer. The study was conducted on fine days from August to June in 2005 and 2004 on Miyako Island, Japan. Subjects were 18 male residents of Tokyo (a temperate region) who had newly arrived on Miyako Island for less than 1 week (group N: non-heat-acclimated), 5 male residents of Tokyo who had been working on Miyako Island for more than 2 weeks (group S: short-term heat-acclimated), and 11 male residents of Miyako Island (group L: long-term heat-acclimated). The total sweat rates of group S and group L were significantly higher than those of group N. Fluid intake of group L was significantly higher than that of group N and S. Degrees of rehydration (fluid intake/total sweat rate, %) was lower (p