Hydration profile and influence of beverage contents on fluid intake by women during outdoor recreational walking

Abstract

This study examined hydration status, sweat losses, and the effects of flavoring and electrolytes on fluid intake for women (n=27, age=24±4years) walking at a self-selected pace for ~1h on a 1km outdoor path during summer mornings or evenings. Over five consecutive days, participants consumed ad libitum one non-caloric beverage containing: (1) water (W), (2) acidified water (AW), (3) acidified water with electrolytes (AWE), (4) acidified water with flavor (AWF), and (5) acidified water with flavor and electrolytes (AWFE) in a counter-balanced order during walks and a 1-h recovery period. Walk Wet bulb globe temperature (26.2±1.8°C) and pace (6.0±0.5km/h) did not differ among beverages (P>0.05). Thirty-four percent of pre-walk urine specific gravity samples exceeded 1.020. Flavoring (AWF 700±393mL; AWFE 719±405mL) did not result in greater consumption (P>0.05) over W (560±315mL), with all three beverages exceeding grand mean sweat losses (528±208mL). Addition of electrolytes did not influence (P>0.05) the intake between AW versus AWE or AWF versus AWFE. The results of this study indicate that the majority of women will consume fluids in excess of their sweat losses within 1h post-walk. Over half of consumption took place during walks, highlighting the importance of fluid availability during exercise. Great among-subjects variability in sweat losses and fluid intake support the need for promoting individualized hydration strategies based on the changes in body mass for athletic populations.