title: The effects of carbohydrate loading on muscle glycogen content and cycling performance.
abstract: This study compared the effects of supplementing the normal diets of 8 endurance-trained cyclists with additional carbohydrate (CHO), in the form of potato starch, for 3 days on muscle glycogen utilization and performance during a 3-hr cycle ride. On two occasions prior to the trial, the subjects ingested in random order either their normal CHO intake of 6.15 +/- 0.23 g/kg body mass/day or a high-CHO diet of 10.52 +/- 0.57 g/kg body mass/day. The trial consisted of 2 hr of cycling at approximately 75% of VO2peak with five 60-s sprints at 100% VO2peak at 20-min intervals, followed by a 60-min performance ride. Increasing CHO intake by 72 +/- 9% for 3 days prior to the trial elevated preexercise muscle glycogen contents, improved power output, and extended the distance covered in 1 hr. Muscle glycogen contents were similar at the end of the 3-hr trial, indicating a greater utilization of glycogen when subjects were CHO loaded, which may have been responsible for their improved cycling performance.
authors.affiliation: Bioenergetics of Exercise Research Unit, Medical Research Council, Observatory, South Africa.
authors.forename: L H
authors.initials: LH
authors.lastname: Rauch
authors.forename: I
authors.initials: I
authors.lastname: Rodger
authors.forename: G R
authors.initials: GR
authors.lastname: Wilson
authors.forename: J D
authors.initials: JD
authors.lastname: Belonje
authors.forename: S C
authors.initials: SC
authors.lastname: Dennis
authors.forename: T D
authors.initials: TD
authors.lastname: Noakes
authors.forename: J A
authors.initials: JA
authors.lastname: Hawley
mesh_terms: D000328:Adult; D001642:Bicycling; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D011198:Solanum tuberosum; D013213:Starch / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007773:Lactates; D013213:Starch; D006003:Glycogen