Abstract

This study examined the effect of three exercise-diet regimens on muscle glycogen supercompensation and subsequent performance during a 20.9-km run. A diet containing 15 carbohydrate (CHO,L), 50 CHO (M), or 70 CHO (H) was arranged in three trials as follows trial A = 3 days L, 3 days H trial B = 3days M, 3 days H trial C = 6 days M. For each trial a 5-day depletion-taper exercise sequence was conducted on the treadmill at 73 V02max. A day of restpreceded the 20.9-km performance run. Muscle biopsies were obtained from the gastrocnemius on days 4 and 7. Trials A, B, and C elevated muscle glycogen to 207, 203, and 159 mmol glucosyl unitskg wet tissue (mmG), respectively. The performance run in both trials A and B utilized significantly more glycogen than in trial C. There were, however, no differences in either performancerun times or post-performance run glycogen levels between the trials. These data demonstrate that (1) muscle glycogen can be elevated to high levels with a moderate exercise-diet regimen (2) initial muscle glycogen levels influencethe amount subsequently utilized during exercise (3) carbohydrate loading is of no benefit to performance for trained runners during a 20.9-run run. Verf.-Referat