PERSISTENCE OF SUPERCOMPENSATED MUSCLE GLYCOGEN IN TRAINED SUBJECTS AFTER CARBOHYDRATE LOADING

Several carbohydrate (CHO)-loading protocols have been used to achieve muscle glycogen supercompensation and prolong endurance performance. This study assessed the persistence of muscle glycogen supercompensati on over the 3 days after the supercompensation protocol. Trained male athletes completed a B-day CHO-loading protocol that included cycle er gometer exercise and dietary manipulations. The 3-day depletion phase began with 115 min of cycling at 75% peak oxygen uptake followed by 3 X 60-s sprints and included the subjects consuming a low-CHO/high-prot ein/high-fat (10:41:49%) diet. Subjects cycled 40 min at the same inte nsity for the next 2 days. During the 3-day repletion phase, subjects rested and consumed a high-CHO/low-protein/low-fat (85:08:07%) diet, i ncluding a glucose-polymer beverage. A 3-day postloading phase followe d, which involved a moderately high CHO diet (60%) and no exercise. Gl ycogen values for vastus lateralis biopsies at baseline and postloadin g days 1-3 were 408 +/- 168 (SD), 729 +/- 222, 648 +/- 186, and 714 +/ - 196 mmol/kg dry wt, respectively. The CHO-loading protocol increased muscle glycogen by 1.79 times baseline, and muscle glycogen remained near this level during the 3-day postloading period. Results indicate that supercompensated muscle glycogen levels can be maintained for at least 3 days in a resting athlete when a moderate-CHO diet is consumed .