Awareness of water losses does not impact thirst during exercise in the heat: a double-blind study

Abstract

The purpose of this study was to identify if awareness of water loss could impact thirst perception during exercise in the heat. Eleven males participated in two sessions in random order, receiving true or false information of their water losses every 30 minutes. Thirst perception (TP), actual dehydration, stomach fullness, and heat stress were measured every 30 minutes during intermittent exercise until dehydrated by ~4% body mass (BM). Post exercise they ingested water ad libitum for 30 minutes. Preexercise BM, TP, and hydration status were not different between sessions (p>0.05). As dehydration progressed during exercise TP increased significantly (p= 0.001), but it was the same for both sessions (p=0.447). Post-exercise water ingestion was almost identical (p=0.949) between sessions. In this study, thirst was a good indicator of fluid needs during exercise in the heat when no fluid was ingested, regardless of receiving true or false water loss information.