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±13.3kg 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±279mLh⁻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 220mLh⁻¹ (3.3Ld⁻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.

Key words: firefighting, ultraendurance, water, electrolyte solution, hydration