Hunger and thirst: issues in measurement and prediction of eating and drinking.
- Richard D Mattes
- Physiology & behavior
We measured the dose-response effects of drink sodium content (treatments: 0 mmol/l, 18 mmol/l, 30 mmol/l, 40 mmol/l, and 60 mmol/l) on sensory perception and palatability in athletes at four time points: in a sedentary laboratory setting (non-exercise context), pre-exercise, and after 60 min and 120 min of aerobic-circuit exercise. Fifty-five triathletes and runners (30 males, 39.7 (8.0 S.D.) years; 25 females, 37.2 (9.2 S.D.) years) sip-tested chilled 6% carbohydrate drinks varying in sodium content during sedentary and pre-exercise conditions and had ad lib access to drinks during exercise conditions. There was a significant intensity discrimination among all sodium levels (p<or=0.001) except 0 mmol/l vs. 18 mmol/l, and 30 mmol/l vs. 40 mmol/l. There were no significant differences among time points for perceived salt intensity. However, overall drink acceptability and liking of saltiness of the 60 mmol/l drink was greater pre-exercise, after 60 min and after 120 min of exercise than during the sedentary condition. The environmental cues of the exercise context may be associated with an increase in palatability of the drink containing 60 mmol/l of sodium over the sedentary condition. Sensory measures provided better differentiation (were more sensitive to treatment effects) among salt concentrations than was fluid intake. Neither thirst nor sweat loss were related to drink palatability or liking of saltiness. Liking of saltiness but not thirst was related to fluid intake. There was a significant negative correlation between sodium ingested (mg/kg) and percent body mass loss.