Wilderness and Environmental Medicine, 19, 172 180 (2008)


Effects of an Electrolyte Additive on Hydration and Drinking Behavior During Wildfire Suppression

John S. Cuddy, MS; Julie A. Ham, MS; Stephanie G. Harger, MS; Dustin R. Slivka, PhD; Brent C. Ruby, PhD

From the Human Performance Laboratory, University of Montana, Missoula, MT.

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

View the entire study in PDF

Paul S. Auerbach, founder and past-president of the Wilderness Medical Society, provided independent commentary of the study in his article:

Electrolyte Additives for Hydration by Paul S. Auerbach, MD, MS, FACEP, FAWM

Hydration Essentials

Everything you ever wanted to know about electrolytes and how to maintain optimal hydration during intense activity or competition. (Most articles are in Adobe Acrobat Reader format. If you don't have Acrobat you can “Get Acrobat Reader” here.)

Water + Electrolytes: How They Prevent Dehydration
Hyponatremia: Maintaining the Balance Between Electrolytes & Fluids
Balancing Act (What Are Electrolytes?), by Matthew Tim Anderson, B.I.S.
Dehydration, An Imbalance of Water & Minerals, by Chris D. Meletis, ND
elete™, Electrolytes and Human Health

Important Electrolytes

Want to learn more about the single electrolytes in elete and what science has to say about their role in health? Click on the headlines below.

Chloride: The Forgotten Essential Mineral, by Chris D. Meletis, N.D.
Chlorine, Chloride: What's the Difference? by Alexander G. Schauss, Ph.D.
Magnesium and Health, by Chris D. Meletis, N.D.
Human Needs for Magnesium, by Mildred S. Seelig, M.D., Master of Public Health, Master of the American College of Nutrition

Electrolytes, Etc.

Additional information pertaining to electrolytes and health as well as information about other important minerals.

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Recommendations for Electrolyte Usage Under Arduous Conditions by Brent C. Ruby, Ph.D., FACSM