The purpose of this study was to determine if lowering carbohydrate (CHO) concentration in a sport drink influences gastric emptying, intestinal absorption, or performance during cycle ergometry (85 min, 60% VO2peak). Five subjects (25 ± 1 y, 61.5 ± 2.1 mL · kg−1 · min−1 VO2peak) ingested a 3% CHO, 6% CHO, or a water placebo (WP) beverage during exercise. Gastric emptying was determined by repeated double sampling and intestinal absorption by segmental perfusion. Total solute absorption and plasma glucose was greater for 6% CHO; however, neither gastric emptying, intestinal water absorption, or 3-mi time trial performance (7:58 ± 0:33 min, 8:13 ± 0:25 min, and 8:25 ± 0:29 min, respectively, for 6% CHO, 3% CHO, and WP) differed among solutions. These results indicate lowering the CHO concentration of a sport drink from 6% CHO does not enhance gastric emptying, intestinal water absorption, or time trial performance, but reduces CHO and total solute absorption.
Rogers is with the Dept of Exercise Science, the University of Iowa, Iowa City, IA 52242. Summers is with the Dept of Internal Medicine, the University of Iowa Hospitals and Clinics, Iowa City, IA 52242. Lambert is with the Dept of Exercise Science and Athletic Training, Creighton University, Omaha, NE 68178.