EFFECTS OF ORAL AND INTRAVENOUS REHYDRATION ON RATINGS OF PERCEIVED EXERTION AND THIRST

The purpose of this investigation was to compare the effects of oral a nd intravenous saline rehydration on differentiated ratings of perceiv ed exertion (RPE) and thirst. Eight men underwent three randomly assig ned rehydration treatments following a 2- to 4-h exercise-induced dehy dration bout to reduce body weight by 4%. Treatments included 0.45% sa line 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 degrees 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 ove rall RPE during NF was higher (P < 0.05) than ORAL at minutes 20 and 4 0 of EX. Significant correlations were found between overall RPE and m ean 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 sugg est that oral rehydration is likely to elicit lower RPE and thirst rat ings compared with intravenous rehydration.