Effects of an electrolyte additive on hydration and drinking behavior during wildfire suppression

Objective. - The purpose of this study was to compare the effects of a water + electrolyte solution versus plain water on changes in drinking behaviors, hydration status, and body temperatures during wildfire suppression. Methods. - Eight participants consumed plain water, and eight participants consumed water plus an electrolyte additive during 15 hours of wildfire suppression. Participants wore a specially outfitted backpack hydration system equipped with a digital flow meter system affixed inline to measure drinking characteristics (drinking frequency and volume). Body weight and urine-specific gravity were collected pre- and postshift. Ambient, core, and skin temperatures were measured continuously using a wireless system. Work output was monitored using accelerometry. Results. - There were no differences between groups for body weight, drinking frequency, temperature data, activity, or urine-specific gravity (1.019 ± 0.007 to 1.023 ± 0.010 vs. 1.019 ± 0.005 to 1.024 ± 0.009 for water and water + electrolyte groups pre- and postshift, respectively; P < .05). There was a main effect for time for body weight, demonstrating an overall decrease (78.1 ± 13.3 and 77.3 ± 13.3 kg pre- and postshift, respectively; P < .05) across the work shift. The water group consumed more total fluid (main effect for treatment) than the water ± electrolyte group (504 ± 472 vs. 285 ± 279 mL·h^-1 for the water and water + electrolyte groups, respectively; P < .05). Conclusion. - The addition of an electrolyte mixture to plain water decreased the overall fluid consumption of the water + electrolyte group by 220 mL·h^-1 (3.3 L·d^-1). Supplementing water with electrolytes can reduce the amount of fluid necessary to consume and transport during extended activity. This can minimize carrying excessive weight, possibly reducing fatigue during extended exercise.