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Changes in body water and electrolytes during heat acclimation: effects of dietary sodium.
Aviat Space Environ Med. 1987 Feb; 58(2):143-8.AS

Abstract

In an effort to describe the influence of both high (HNA) and low (LNA) dietary sodium (399 vs. 98 mEq Na+ X d-1) on body fluids during heat acclimation (HA), nine untrained males underwent 8 d of HA twice (90 min treadmill walking, 5.6 km X h-1, 6% grade) in an environmental chamber (40.1 degrees C, 23.5% RH). Mean wholebody Na+ balance calculations indicated that HNA resulted in an increase of Na+ of $916 mEq per 8 days per subject, whereas LNA resulted in a relative Na+ deficiency of -230 mEq per 8 days per subject. Subjects exhibited typical HA adaptations of decreased heart rate (HR), decreased rectal temperature (Tre) during exercise, and an increase in resting plasma volume (PV) during both diets. Significant HNA vs. LNA differences (p less than 0.05) were observed in HR (days 3-5), Tre (days 3-6), PV (day 4), plasma osmolality (day 4), plasma Na+ (day 4), urine Na+ (days 2-8), and sweat Na+ (days 4 and 8). The between-diet differences in HR, Tre and PV were not detectable by the end of each dietary-exercise regimen. Needle biopsy samples (20-50 mg, lateral aspect of the gastrocnemius) indicated that muscle Na+ and muscle water were similar on all days, except day 9 when intracellular fluid expansion during LNA was noted. Change in body weight was not strongly correlated with delta PV (R2 = 0.47, 0.10) and neither osmotic forces nor plasma protein movements explained all PV shifts adequately.(

ABSTRACT

TRUNCATED AT 250 WORDS)

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Authors

Armstrong LE
No affiliation info available
Costill DL
No affiliation info available
Fink WJ
No affiliation info available

MeSH

AcclimatizationAdultBlood ProteinsBody TemperatureBody WaterDiet, Sodium-RestrictedHeart RateHot TemperatureHumansMaleMusclesOsmolar ConcentrationPlasma VolumeSodiumSweatingWater-Electrolyte Balance

Pub Type(s)

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

Language

eng

PubMed ID

3827790

Citation

Armstrong, L E., et al. "Changes in Body Water and Electrolytes During Heat Acclimation: Effects of Dietary Sodium." Aviation, Space, and Environmental Medicine, vol. 58, no. 2, 1987, pp. 143-8.
Armstrong LE, Costill DL, Fink WJ. Changes in body water and electrolytes during heat acclimation: effects of dietary sodium. Aviat Space Environ Med. 1987;58(2):143-8.
Armstrong, L. E., Costill, D. L., & Fink, W. J. (1987). Changes in body water and electrolytes during heat acclimation: effects of dietary sodium. Aviation, Space, and Environmental Medicine, 58(2), 143-8.
Armstrong LE, Costill DL, Fink WJ. Changes in Body Water and Electrolytes During Heat Acclimation: Effects of Dietary Sodium. Aviat Space Environ Med. 1987;58(2):143-8. PubMed PMID: 3827790.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Changes in body water and electrolytes during heat acclimation: effects of dietary sodium. AU - Armstrong,L E, AU - Costill,D L, AU - Fink,W J, PY - 1987/2/1/pubmed PY - 1987/2/1/medline PY - 1987/2/1/entrez SP - 143 EP - 8 JF - Aviation, space, and environmental medicine JO - Aviat Space Environ Med VL - 58 IS - 2 N2 - In an effort to describe the influence of both high (HNA) and low (LNA) dietary sodium (399 vs. 98 mEq Na+ X d-1) on body fluids during heat acclimation (HA), nine untrained males underwent 8 d of HA twice (90 min treadmill walking, 5.6 km X h-1, 6% grade) in an environmental chamber (40.1 degrees C, 23.5% RH). Mean wholebody Na+ balance calculations indicated that HNA resulted in an increase of Na+ of $916 mEq per 8 days per subject, whereas LNA resulted in a relative Na+ deficiency of -230 mEq per 8 days per subject. Subjects exhibited typical HA adaptations of decreased heart rate (HR), decreased rectal temperature (Tre) during exercise, and an increase in resting plasma volume (PV) during both diets. Significant HNA vs. LNA differences (p less than 0.05) were observed in HR (days 3-5), Tre (days 3-6), PV (day 4), plasma osmolality (day 4), plasma Na+ (day 4), urine Na+ (days 2-8), and sweat Na+ (days 4 and 8). The between-diet differences in HR, Tre and PV were not detectable by the end of each dietary-exercise regimen. Needle biopsy samples (20-50 mg, lateral aspect of the gastrocnemius) indicated that muscle Na+ and muscle water were similar on all days, except day 9 when intracellular fluid expansion during LNA was noted. Change in body weight was not strongly correlated with delta PV (R2 = 0.47, 0.10) and neither osmotic forces nor plasma protein movements explained all PV shifts adequately.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0095-6562 UR - https://www.unboundmedicine.com/medline/citation/3827790/Changes_in_body_water_and_electrolytes_during_heat_acclimation:_effects_of_dietary_sodium_ L2 - https://antibodies.cancer.gov/detail/CPTC-RRM2-2 DB - PRIME DP - Unbound Medicine ER -