C-32 Free Communication/Poster - Fluid and Electrolyte Balance: JUNE 2, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
Holly Emmanuel, Lawrence E. Armstrong FACSM, Jennifer F. Klau, Paula Y.S. Poh, Jenna M. Apicella, Douglas J. Casa FACSM, Carl M. Maresh FACSM. University of Connecticut, Storrs CT
Ad libitum drinking behavior is influenced by multiple factors including oropharyngeal sensations, thirst, plasma hyperosmolality, hypovolemia, and stomach distention. These factors modify central neuroendocrine responses which preserve fluid-electrolyte homeostasis. Fluid characteristics and palatability (i.e., sweetness and saltiness) are especially important.
PURPOSE: To identify changes in the preferred level of sweetness and saltiness in a rehydration fluid, during the course of exercise-heat acclimation (10 d) and subsequent sleep deprivation (28 h).
METHODS: Eleven subjects (age, 20 ± 1 y; height 183.7 ± 8.4 cm; mass, 81.7 ± 12.2 kg; body fat, 10.1 ± 2.9 %; VO2max, 53.2 ± 8.8 ml·kg-1·min-1) were heat acclimated (33°C, 30-50% relative humidity) via motorized treadmill walking at 5.6 km·h-1, 5% incline. Subjects evaluated the saltiness, sweetness, and overall palatability (three visual analog scales) of 10 different fluids (ranging from water to very sweet and very salty); they also rated thirst and thermal sensations. Repeated measures ANOVA, Pearson-product correlations, and multiple regression analyses were used to examine heat acclimation, sleep loss effects (day 9 vs 11), and overall palatability.
RESULTS: There was no change in sweetness, saltiness, and overall palatability ratings due to heat acclimation (10 d) (p=0.83,p=0.95, p=0.95) or sleep loss (28 h) (p=0.94, p=0.89, p=0.90), nor was there a change in thirst, and thermal ratings.
CONCLUSION: The main finding of this study was that the perceptions of sweetness and saltiness (i.e., carbohydrate and sodium chloride content) in a rehydration fluid after exercise are major determinants of overall palatability. The highest ratings tended (i.e., statistical trend) to be given to the fluids with highest carbohydrate content, and lowest ratings to the fluids with the lowest osmolality and the highest salt content. Interestingly, the fluids with the highest palatability ratings did not correspond to fluid mixtures that optimize fluid absorption.