Dietary carbohydrate, muscle glycogen, and exercise performance during 7 d of training.
The effects of moderate- or high-carbohydrate diets on muscle glycogen and performance in runners and cyclists over 7 consecutive days of training were determined. Muscle biopsies were performed on 4 separate days before exercise for 1 h at 75% peak oxygen consumption (VO2) followed by five, 1-min sprints. After the training session on day 7, subjects ran or cycled to exhaustion at 80% peak VO2. Muscle glycogen for cyclists and runners was maintained with the high-carbohydrate diet but was reduced 30-36% (P < 0.05) with the moderate-carbohydrate diet. All subjects completed all training sessions, and there were no differences in times to exhaustion on day 7. For cyclists and runners, consuming a moderate-carbohydrate diet over 7 d of intense training reduces muscle glycogen but has no apparent deleterious effect on training capability or high-intensity exercise performance. A high-carbohydrate diet maintains muscle glycogen, but this has no apparent benefit on training capability or high-intensity exercise performance.
Sherman
W M
WM
Exercise Physiology Laboratory, School of Health, Physical Education, and Recreation, Ohio State University, Columbus 43210.
Doyle
J A
JA
Lamb
D R
DR
Strauss
R H
RH
D000328:Adult; D001642:Bicycling; D001706:Biopsy; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D015444:Exercise / Q000502:physiology*; D006003:Glycogen / Q000032:analysis*; D006339:Heart Rate; D006801:Humans; D008297:Male; D009132:Muscles / Q000737:chemistry*; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*; D012420:Running
D004040:Dietary Carbohydrates; D006003:Glycogen