HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J Appl Physiol 102: 183-188, 2007. First published September 28, 2006; doi:10.1152/japplphysiol.00799.2006
8750-7587/07 $8.00

This Article Free upon publication Full Text Free Full Text (PDF) Free All Versions of this Article: 102/1/183    most recent 00799.2006v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by De Bock, K. Articles by Hespel, P. Search for Related Content PubMed PubMed Citation Articles by De Bock, K. Articles by Hespel, P.

Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise

Research Center for Exercise and Health, Faculty of Kinesiology and Rehabilitation Sciences, Katholieke Universiteit Leuven, Leuven, Belgium; and Copenhagen Muscle Research Centre, Institute of Exercise and Sports Sciences, University of Copenhagen, Copenhagen, Denmark

Submitted 20 July 2006 ; accepted in final form 25 September 2006

The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers (n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise (75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before (150 g) and during (1 g·kg body weight^–1·h^–1) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 ± 1 x 10^–2 optical density (OD)/µm²] than in type I fibers (8.0 ± 1 x 10^–2 OD/µm²; P < 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 ± 1 x 10^–2 OD/µm² to 4.5 ± 1 x 10^–2 OD/µm² (P = 0.001), but it did not significantly change during CHO (P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.

insulin; human muscle; glycogen breakdown

This article has been cited by other articles:

				K. De Bock, W. Derave, B. O. Eijnde, M. K. Hesselink, E. Koninckx, A. J. Rose, P. Schrauwen, A. Bonen, E. A. Richter, and P. Hespel Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake J Appl Physiol, April 1, 2008; 104(4): 1045 - 1055. [Abstract] [Full Text] [PDF]