Influence of Fluid Ingestion on Sweat Rate Status While Exercising in the Heat

The purpose of this study was to determine the effects of differing volumes and temperatures of ingested water on sweat rate while exercising in the heat. Participants exercised for 3 hours in a hot room at WBGT 35.5 and 50% relative humidity. The subjects walked on an electric treadmill at 40% VO2 max, rested for 5 minutes, then completed a 1 mile time trial at peak exertion on a non-motorized treadmill (Woodway Curve), with the remainder of the hour spent resting. Subjects ingested 1 ml/kg body weight of water at ambient temperature or 0.5 ml/kg body weight ice every 10 minutes throughout the 3-hour trial. Pre and post body weight were measured to calculate bodyweight loss and sweat rate. Previous studies have not compared differing volumes of fluid of varying temperature, making this experiment novel. Sweat rate is important because it helps determine how much fluid is being utilized to aid in thermoregulation by evaporative cooling. The results of this study suggest that thermoregulation may be more influenced by the temperature of the fluid rather than the volume