Effect of Heat Acclimation on Sweat Minerals
Abstract
Purpose: This study examined the impact of 10 days of exercise-heat acclimation on sweat mineral concentrations. Methods: Eight male subjects walked on a treadmill at 3.5 mph, 4% grade for 100 continuous minutes or until rectal temperature reached 39.5 C on 10 consecutive days in an environmental chamber set at 45 C, 20% relative humidity. Arm sweat samples were collected during the first 30 min of exercise-heat stress on days 1 and 10 using a polyethylene arm glove. Results: Final core temperature and HR values were significantly lower (P < 0.05) on day 10 versus day 1. Whole-body sweating rates increased by approximately 6% (P = 0.12). Sweat sodium concentration on day 10 (36.22 + or - 7.22 mM) was significantly lower than day 1 (54.49 + or - 16.18 mM) (P < 0.05). Sweat mineral concentrations of calcium (~29%), copper (~50%), and magnesium (~43%) were also significantly lower on day 10 versus day 1 of heat acclimation (P < 0.05). A trend for lower sweat iron (~75%; P = 0.07) and zinc (~23%; P = 0.10) concentrations were observed from day 1 to day 10. The estimated hourly sweat mineral losses (arm concentration x whole-body sweat rate) were reduced for calcium (~27%), copper (~46%), and magnesium (~42%) (P < 0.05), but not iron (75%) or zinc (~16%) (P > 0.05), from day 1 to day 10. Conclusion: Exercise-heat acclimation conserves arm sweat mineral concentrations and possibly whole-body sweat losses of calcium, copper, and magnesium, and may reduce sweat iron and zinc concentrations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2007
- Accession Number
- ADA480325
Entities
People
- Henry C. Lukaski
- Michael N. Sawka
- Robert W. Kenefick
- Samuel N. Cheuvront
- Troy D. Chinevere
Organizations
- United States Army Research Institute of Environmental Medicine