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Fluid replacement during prolonged exercise: effects of water, saline, or no fluid.
Med Sci Sports Exerc. 1991 Jul; 23(7):811-7.MS

Abstract

This study assessed the need to replace sodium in endurance exercise less than or equal to 6 h in duration by comparing responses to fluid replacement with water, saline (25 mmol.l-1), or no fluid. Eight subjects (five male, three female) participated in three 6-h exercise trials on an electrically braked cycle ergometer at 55% VO2max, at 30 degrees C and 50% r.h. In the water (W) and saline (S) trials, sufficient fluid was ingested to balance sweat and urinary fluid losses, while in the third trial, no fluid (NF) was ingested. Plasma sodium less than or equal to 130 mmol.l-1 was a criterion for trial termination. In the NF trial, heart rate, rectal temperature, plasma sodium, plasma aldosterone, and rating of perceived exertion were all significantly higher (P less than 0.001) than during W and S, whereas plasma volume was lower (P less than 0.001). On average, subjects terminated this trial 1.5 h prior to its scheduled completion, having lost 6.4% body weight. In contrast, no significant differences between fluid replacement with W or S were detected, although the effect of time on all aforementioned variables was highly significant (P less than 0.001). Saline intake was not associated with significantly higher plasma sodium during exercise than was water intake: plasma sodium decreased significantly during both W (to 135.5 +/- 0.5 mmol.l-1) and S (to 137.3 +/- 0.7 mmol.l-1). No subject had to terminate a trial based on plasma sodium less than or equal to 130 mmol.l-1.(

ABSTRACT

TRUNCATED AT 250 WORDS)

Authors+Show Affiliations

Human Performance Laboratory, Ball State University, Muncie, IN 47306.No affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

1921673

Citation

Barr, S I., et al. "Fluid Replacement During Prolonged Exercise: Effects of Water, Saline, or No Fluid." Medicine and Science in Sports and Exercise, vol. 23, no. 7, 1991, pp. 811-7.
Barr SI, Costill DL, Fink WJ. Fluid replacement during prolonged exercise: effects of water, saline, or no fluid. Med Sci Sports Exerc. 1991;23(7):811-7.
Barr, S. I., Costill, D. L., & Fink, W. J. (1991). Fluid replacement during prolonged exercise: effects of water, saline, or no fluid. Medicine and Science in Sports and Exercise, 23(7), 811-7.
Barr SI, Costill DL, Fink WJ. Fluid Replacement During Prolonged Exercise: Effects of Water, Saline, or No Fluid. Med Sci Sports Exerc. 1991;23(7):811-7. PubMed PMID: 1921673.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fluid replacement during prolonged exercise: effects of water, saline, or no fluid. AU - Barr,S I, AU - Costill,D L, AU - Fink,W J, PY - 1991/7/1/pubmed PY - 1991/7/1/medline PY - 1991/7/1/entrez SP - 811 EP - 7 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 23 IS - 7 N2 - This study assessed the need to replace sodium in endurance exercise less than or equal to 6 h in duration by comparing responses to fluid replacement with water, saline (25 mmol.l-1), or no fluid. Eight subjects (five male, three female) participated in three 6-h exercise trials on an electrically braked cycle ergometer at 55% VO2max, at 30 degrees C and 50% r.h. In the water (W) and saline (S) trials, sufficient fluid was ingested to balance sweat and urinary fluid losses, while in the third trial, no fluid (NF) was ingested. Plasma sodium less than or equal to 130 mmol.l-1 was a criterion for trial termination. In the NF trial, heart rate, rectal temperature, plasma sodium, plasma aldosterone, and rating of perceived exertion were all significantly higher (P less than 0.001) than during W and S, whereas plasma volume was lower (P less than 0.001). On average, subjects terminated this trial 1.5 h prior to its scheduled completion, having lost 6.4% body weight. In contrast, no significant differences between fluid replacement with W or S were detected, although the effect of time on all aforementioned variables was highly significant (P less than 0.001). Saline intake was not associated with significantly higher plasma sodium during exercise than was water intake: plasma sodium decreased significantly during both W (to 135.5 +/- 0.5 mmol.l-1) and S (to 137.3 +/- 0.7 mmol.l-1). No subject had to terminate a trial based on plasma sodium less than or equal to 130 mmol.l-1.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/1921673/Fluid_replacement_during_prolonged_exercise:_effects_of_water_saline_or_no_fluid_ DB - PRIME DP - Unbound Medicine ER -