Fig. 5.
(A) Athletes had higher water turnover (WT) than non-athletes, even after adjusting for physiological and environmental variables (P < 0.001). (B) Hunter-gatherers (HG), mixed farmer and hunter-gatherer (HGF), and subsistence agriculturalists (SA) had higher water turnover than other people (C), even after adjusting for physiological and environmental variables (P < 0.001). Note that there are no males in the database who fell into the SA category. (C) People who lived in countries with a low Human Development Index (HDI) had higher WT than people who lived in countries with high or middle HDI, even after adjusting for physiological and environmental variables (P < 0.001). (D-F) Relationship between water turnover and outdoor air temperature, physical activity level (PAL), or fat-free mass. The countries were categorized as high (red), middle (green), and low (blue) HDI. (D) A significant interaction (P < 0.001) was observed between outdoor air temperature and HDI in water turnover. The association between outdoor air temperature and water turnover is weak in high HDI countries (r = 0.086, P < 0.001) but strong in men in low HDI countries (r = 0.604, P < 0.001). (E, F) A significant interaction (P < 0.001) was observed between HDI and PAL or FFM in water turnover. Correlation coefficients were significantly higher (P < 0.001) in low HDI countries (r = 0.484 to 0.670, P < 0.001) than in high HDI countries (r = 0.367 to 0,510, P < 0.001).