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Acute effects of dehydration on sweat composition in men during prolonged exercise in the heat.
Acta Physiol Scand. 2004 Sep; 182(1):37-43.AP

Abstract

AIM

To determine whether acute exercise-heat-induced dehydration affects sweat composition, eight males cycled for 2 h at 39.5 +/- 1.6% VO2peak on two separate occasions in a hot-humid environment (38.0 +/- 0.0 degrees C, 60.0 +/- 0.1% relative humidity).

METHODS

During exercise, subjects ingested either no fluid (dehydration) or a 20 mmol L(-1) sodium chloride solution (euhydration). The volume of solution, calculated from whole-body sweat loss and determined in a familiarization trial, was ingested at 0 min and every 15 min thereafter. Venous blood was collected at 0, 60 and 120 min of exercise and sweat was aspirated from a patch located on the dominant forearm at 120 min.

RESULTS

Following the 2-h cycling exercise, sweat [Na+] and [Cl-] was greater (P < 0.05) in the dehydration trial (Na+ 91.1 +/- 6.8 mmol L(-1); Cl- 73.3 +/- 3.5 mmol L(-1)) compared with the euhydration trial (Na+ 81.1 +/- 5.9 mmol L(-1); Cl- 68.5 +/- 3.3 mmol L(-1)). In addition, dehydration invoked a greater serum [Na+] (142.2 +/- 0.7 mmol L(-1); P < 0.05), [Cl-] (105.8 +/- 0.6 mmol L(-1); P < 0.05) and [K+] (5.27 +/- 0.2 mmol L(-1); P < 0.05) over the euhydration values for [Na+], [Cl-] and [K+], respectively (138.9 +/- 0.6, 102.9 +/- 0.5 and 4.88 +/- 0.1 mmol L(-1)). Plasma aldosterone was also significantly higher during exercise in the dehydration trial compared with the euhydration trial (53.8 +/- 3.8 vs. 40.0 +/- 4.3 ng dL(-1); P < 0.05).

CONCLUSIONS

Acute exercise-heat stress without fluid replacement resulted in a greater sweat [Na+] and [Cl-] which was potentially related to greater extracellular fluid [Na+], plasma aldosterone or sympathetic nervous activity.

Authors+Show Affiliations

Strathclyde Institute for Biomedical Sciences, University of Strathclyde, Glasgow, UK.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15329055

Citation

Morgan, R M., et al. "Acute Effects of Dehydration On Sweat Composition in Men During Prolonged Exercise in the Heat." Acta Physiologica Scandinavica, vol. 182, no. 1, 2004, pp. 37-43.
Morgan RM, Patterson MJ, Nimmo MA. Acute effects of dehydration on sweat composition in men during prolonged exercise in the heat. Acta Physiol Scand. 2004;182(1):37-43.
Morgan, R. M., Patterson, M. J., & Nimmo, M. A. (2004). Acute effects of dehydration on sweat composition in men during prolonged exercise in the heat. Acta Physiologica Scandinavica, 182(1), 37-43.
Morgan RM, Patterson MJ, Nimmo MA. Acute Effects of Dehydration On Sweat Composition in Men During Prolonged Exercise in the Heat. Acta Physiol Scand. 2004;182(1):37-43. PubMed PMID: 15329055.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Acute effects of dehydration on sweat composition in men during prolonged exercise in the heat. AU - Morgan,R M, AU - Patterson,M J, AU - Nimmo,M A, PY - 2004/8/27/pubmed PY - 2004/12/21/medline PY - 2004/8/27/entrez SP - 37 EP - 43 JF - Acta physiologica Scandinavica JO - Acta Physiol Scand VL - 182 IS - 1 N2 - AIM: To determine whether acute exercise-heat-induced dehydration affects sweat composition, eight males cycled for 2 h at 39.5 +/- 1.6% VO2peak on two separate occasions in a hot-humid environment (38.0 +/- 0.0 degrees C, 60.0 +/- 0.1% relative humidity). METHODS: During exercise, subjects ingested either no fluid (dehydration) or a 20 mmol L(-1) sodium chloride solution (euhydration). The volume of solution, calculated from whole-body sweat loss and determined in a familiarization trial, was ingested at 0 min and every 15 min thereafter. Venous blood was collected at 0, 60 and 120 min of exercise and sweat was aspirated from a patch located on the dominant forearm at 120 min. RESULTS: Following the 2-h cycling exercise, sweat [Na+] and [Cl-] was greater (P < 0.05) in the dehydration trial (Na+ 91.1 +/- 6.8 mmol L(-1); Cl- 73.3 +/- 3.5 mmol L(-1)) compared with the euhydration trial (Na+ 81.1 +/- 5.9 mmol L(-1); Cl- 68.5 +/- 3.3 mmol L(-1)). In addition, dehydration invoked a greater serum [Na+] (142.2 +/- 0.7 mmol L(-1); P < 0.05), [Cl-] (105.8 +/- 0.6 mmol L(-1); P < 0.05) and [K+] (5.27 +/- 0.2 mmol L(-1); P < 0.05) over the euhydration values for [Na+], [Cl-] and [K+], respectively (138.9 +/- 0.6, 102.9 +/- 0.5 and 4.88 +/- 0.1 mmol L(-1)). Plasma aldosterone was also significantly higher during exercise in the dehydration trial compared with the euhydration trial (53.8 +/- 3.8 vs. 40.0 +/- 4.3 ng dL(-1); P < 0.05). CONCLUSIONS: Acute exercise-heat stress without fluid replacement resulted in a greater sweat [Na+] and [Cl-] which was potentially related to greater extracellular fluid [Na+], plasma aldosterone or sympathetic nervous activity. SN - 0001-6772 UR - https://www.unboundmedicine.com/medline/citation/15329055/Acute_effects_of_dehydration_on_sweat_composition_in_men_during_prolonged_exercise_in_the_heat_ L2 - https://doi.org/10.1111/j.1365-201X.2004.01305.x DB - PRIME DP - Unbound Medicine ER -