INFLUENCE OF SODIUM ON GLUCOSE BIOAVAILABILITY DURING EXERCISE

To examine the influence of beverage sodium content on glucose bioavai lability during exercise, six trained men were studied during 30 min o f cycle ergometer exercise at 65% VO2max. Immediately prior to exercis e, subjects ingested 400 ml of a 10% glucose solution containing 100 m u Ci of D-(3-H-3]-glucose, with a sodium concentration of either 0, 25 , or 50 mmol.l(-1). Trials were conducted in the morning after an over night fast and in randomized order at least 1 wk apart. Blood samples were obtained from a forearm vein before and during exercise and subse quently analyzed for plasma glucose and H-3-glucose activity and blood lactate. No differences in oxygen uptake, heart rate, or brood lactat e were observed between trials. Resting plasma glucose levels were not different between trials. The increases in plasma glucose and the pla sma accumulation of H-3-glucose were similar in the three trials. Thes e results indicate that alterations in beverage sodium content, from 0 -50 mmol.l(-1), have no effect on glucose bioavailability, as measured by increases in plasma glucose and H-3-glucose activity during modera te intensity exercise.