Can heart rate be used to predict sweat rate in submaximal cycling?

Fluid intake during exercise is essential for athletic performance and health. Some athletes overcompensate by drinking in excess, resulting in hyponatremia. ACSM guidelines have identified that sweat rate is individual, influenced by several factors, and that the goal of fluid intake should be to limit sweat loss to less than 2% change in body weight. Developing a simple mathematical equation that uses heart rate to predict sweat rate could prove valuable in improving athletic performance and preventing heat related illness. 11 male and 6 female trained cyclists volunteered to perform 2x30 minute cycling trials at 55 and 75% heart rate reserve intensity. Body mass was recorded before and after each trial to determine sweat losses. Pearson coefficient determined no significant correlations between heart rate and body mass loss at 55 or 75% HR intensities (p >0.05). Significant difference was found in body mass change between 55 and 75% intensities (p < 0.05).