Effect of glycerol-induced hyperhydration on thermoregulatory and cardiovascular functions and endurance performance during prolonged cycling in a 25 °C environment

Goulet, E.D.B., Robergs, R.A., Labrecque, S., Royer, D., & Dionne, I.J. (2006) Effect of glycerol-induced hyperhydration on thermoregulatory and cardiovascular functions and endurance performance during prolonged cycling in a 25 °C environment. Applied Physiology, Nutrition, and Metabolism, 31(2), pp. 101-109.

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We compared the effect of glycerol-induced hyperhydration (GIH) to that of water-induced hyperhydration (WIH) on cardiovascular and thermoregulatory functions and endurance performance (EP) during prolonged cycling in a temperate climate in subjects consuming fluid during exercise. At weekly intervals, 6 trained male subjects ingested, in a randomized, double-blind, counterbalanced fashion, either a glycerol (1.2 g glycerol/kg bodyweight (BW) with 26 mL/kg BW of water - aspartame-flavored fluid) or placebo solution (water - aspartame-flavored fluid only) over a 2 h period. Subjects then performed 2 h of cycling at 66% of the maximal oxygen consumption (VO2 max) and 25 °C while drinking 500 mL/h of sports drink, which was followed by a step-incremented cycling test to exhaustion. Levels of hyperhydration did not differ significantly between treatments before exercise. During exercise, GIH significantly reduced urine production by 246 mL. GIH did not increase sweat rate nor did it decrease heart rate, rectal temperature, or perceived exertion during exercise as compared with WIH. EP was not significantly different between treatments. Neither treatment induced undesirable side effects. It is concluded that, compared with WIH, GIH decreases urine production, but does not improve cardiovascular or thermoregulatory functions, nor does it improve EP during 2 h of cycling in a 25 °C environment in trained athletes consuming 500 mL/h of fluid during exercise.Key words: prolonged exercise, fluid balance, heart rate, rectal temperature, exercise capacity.

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ID Code: 96841
Item Type: Journal Article
Refereed: Yes
Additional Information: cited By 21
Keywords: glycerol, adult; article; bicycle; body fluid; cardiovascular system; clinical trial; controlled clinical trial; controlled study; crossover procedure; double blind procedure; drug effect; endurance; exercise test; heart rate; human; male; metabolism; oxygen consum, Adult; Bicycling; Body Fluids; Body Temperature Regulation; Cardiovascular System; Cross-Over Studies; Double-Blind Method; Exercise Test; Glycerol; Heart Rate; Humans; Male; Oxygen Consumption; Physical Endurance
DOI: 10.1139/h05-006
ISSN: 1715-5320
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Schools > School of Exercise & Nutrition Sciences
Copyright Owner: Copyright 2006 NRC Research Press
Deposited On: 28 Jul 2016 05:03
Last Modified: 02 Aug 2016 03:58

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