Variability in Intake and Dehydration in Young Men during a Simulated Desert Walk

摘要

Voluntary dehydration was examined in young unacclimatized men walking under simulated desert conditions. Thirty-three subjects (20-33 yrs) walked on a treadmill for 30 min.h(-1) for 6 h in a hot environment (40 C db/ 26 C wb, 4.02 km.h(-1) windspeed). Cool (15 C) water was provided ad libitum in canteens. Two subpopulations of individuals were identified: those drinkers (D) (n=20) who maintained body weight loss at less than 2% and those who were reluctant to drink (reluctant drinkers, RD) (n=13) and lost more than 2% body weight (BW) despite continual availability of cool water. RD consumed 31% less water than D and this resulted in a significantly greater BW loss in RD than D. However, the only statistically significant differences in plasma indices of hypohydration were the higher final plasma Na+ and protein levels in RD. Rectal temperature was higher in the RD, whereas final heart rates were unaffected. Our results indicate that about 40% of young adult males may be reluctant to drink, thus will voluntarily dehydrate even when cool water ad libitum during intermittent exercise in the heat. The reduced intake of reluctant drinkers may be critical in predisposing them to increased risk of dehydration and heat injury.