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 supercompensation over the 3 days after the supercompensation protocol. Trained male athletes completed a 6-day CHO-loading protocol that included cycle ergometer 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-protein/high-fat (10:41:49%) diet. Subjects cycled 40 min at the same intensity 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, including a glucose-polymer beverage. A 3-day postloading phase followed, which involved a moderately high CHO diet (60%) and no exercise. Glycogen values for vastus lateralis biopsies at baseline and postloading 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.
Goforth
H W
HW
Human Performance Department, Naval Health Research Center, San Diego, California 92186-5122, USA.
Arnall
D A
DA
Bennett
B L
BL
Law
P G
PG
D000328:Adult; D004040:Dietary Carbohydrates / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*
D004040:Dietary Carbohydrates; D006003:Glycogen