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Effects of oral and intravenous rehydration on ratings of perceived exertion and thirst

RIEBE, DEBORAH; MARESH, CARL M.; ARMSTRONG, LAWRENCE E.; KENEFICK, ROBERT W.; CASTELLANI, JOHN W.; ECHEGARAY, MARCOS E.; CLARK, BERNARD A.; CAMAIONE, DAVID N.

Medicine & Science in Sports & Exercise: January 1997 - Volume 29 - Issue 1 - pp 117-124
Applied Sciences: Psychobiology and Social Sciences

The purpose of this investigation was to compare the effects of oral and intravenous saline rehydration on differentiated ratings of perceived exertion(RPE) and thirst. Eight men underwent three randomly assigned rehydration treatments following a 2- to 4-h exercise-induced dehydration bout to reduce body weight by 4%. Treatments included 0.45% saline infusion (IV), 0.45% saline oral ingestion (ORAL), and no fluid (NF). Following rehydration and rest (2 h total), subjects walked at 50% ˙VO2max for 90 min at 36°C (EX). Central RPE during ORAL was lower (P < 0.05) than IV and NF throughout EX. Local RPE during NF was higher (P < 0.05) than IV and ORAL at minutes 20 and 40 of EX and overall RPE during NF was higher (P < 0.05) than ORAL at minutes 20 and 40 of EX. Significant correlations were found between overall RPE and mean skin temperature for IV (r = 0.72) and NF (r = 0.75), and between overall RPE and thirst ratings for IV (r = 0.70). Thirst ratings were not different among trials at postdehydration. Following rehydration, thirst was higher(P < 0.05) during NF than IV and ORAL and lower (P < 0.05) during ORAL than IV at all subsequent time points. Results suggest that oral rehydration is likely to elicit lower RPE and thirst ratings compared with intravenous rehydration.

Human Performance Laboratory, Department of Sport, Leisure and Exercise Science, and Department of Physiology and Neurobiology, The University of Connecticut, Storrs CT 06269-1110

Submitted for publication April 1996.

Accepted for publication September 1996.

The authors thank Douglas Casa, Mike Whittlesey, Nicole Johnson, Marie Kenefick, Dean Aresco, Stavros Kavouras, and Dane McFarland for their technical support. We also thank our subjects for their participation.

This work was supported in part by grants from the Proctor and Gamble Company and the University of Connecticut Research Foundation.

Current addresses: Robert W. Kenefick, University of New Hampshire, Durham, NH; John W. Castellani, U.S. Army Research Institute of Environmental Medicine, Natick, MA; Marcos E. Echegaray, University of Puerto Rico.

Address for correspondence: Deborah Riebe, Department of Physical Education, University of Rhode Island, 10 Tootell Road, Suite 2, Kingston Rl 02881.

©1997The American College of Sports Medicine