HARGREAVES, M., D.L. COSTILL, A. COGGAN, W.J. FINK, and I. NISHIBATA. Effect of carbohydrate feedings on muscle glycogen utilization and exercise performance. Med. Sci. Sports Exerc., Vol. 16, No. 3, pp. 219–222, 1984. Ten men were studied during 4 h of cycling to determine the effect of solid carbohydrate (CHO) feedings on muscle glycogen utilization and exercise performance. In the experimental trial (E) the subjects ingested 43 g of sucrose in solid form along with 400 ml of water at 0, 1, 2 and 3 h of exercise. During the control trial (C) they received 400 ml of an artificially sweetened drink without solid CHO. No differences in JOURNAL/mespex/04.02/00005768-198406000-00017/ENTITY_OV0312/v/2017-07-20T222108Z/r/image-pngO2, heart rate, or total energy expenditure were observed between trials; however, respiratory exchange ratios were significantly (P<0.05) higher during E. Blood glucose was significantly (P<0.05) elevated 20 min post-feeding in E; however, by 50 min no differences were observed between trials until 230 min (E = 4.5 ± 0.2 mmol·1-1 vs C = 3.9 ± 0.2, JOURNAL/mespex/04.02/00005768-198406000-00020/ENTITY_OV0398/v/2017-07-20T222108Z/r/image-png ± SE; P<0.05). Muscle glycogen utilization was significantly (P<0.05) lower during E (100.7 ± 10.2 mmol·kg-1 w.w.) than C (126.2 ± 5.5). During a sprint (100% JOURNAL/mespex/04.02/00005768-198406000-00017/ENTITY_OV0312/v/2017-07-20T222108Z/r/image-pngO2max) ride to exhaustion at the end of each trial, subjects performed 45% longer when fed CHO (E = 126.8 ± 24.7 s vs C = 87.2 ± 17.5; P<0.05). It was concluded that repeated solid CHO feedings maintain blood glucose levels, reduce muscle glycogen depletion during prolonged exercise, and enhance sprint performance at the end of such activity.
©1984The American College of Sports Medicine