Rapid carbohydrate loading after a short bout of near maximal-intensity exercise

FAIRCHILD, T. J., S. FLETCHER, P. STEELE, C. GOODMAN, B. DAWSON, and P. A. FOURNIER. Rapid carbohydrate loading after a short bout of near maximal-intensity exercise. Med. Sci. Sports Exerc., Vol. 34. No. 6, pp. 980-986. 2002. Purpose: One limitation shared by all Published carbohydrate-loading regimens is that 2-6 d are required for the attainment of supranormal muscle glyco-en levels. Because high rates of glycogen resynthesis are reported during recovery from exercise of near-maximal intensity and that these rates could in theory allow muscle to attain suptanormal glycogen levels in less than 24 h. the purpose of this study was to examine whether a combination of a short bout of high-intensity exercise with I d of a high-carbohydrate intake offers the basis for an improved carbohydrate-loading regimen. Methods: Seven endurance-trained athletes cycled for 150 s at 130% VO2peak followed by 30 s of all-out cycling. During the following 24 h, each subject was asked to ingest 12 g.kg(-1) of lean body mass (the equivalent of 10.3 g.kg(-1) body mass) of high-carbohydrate foods with a high glycemic index. Results: Muscle glycogen increased from preloading levels (+/- SE) of 109.1 +/- 8.2 to 198.2 +/- 13.1 mmol.kg(-1) wet weight within only 24 h, these levels being comparable to or higher than those reported by others over a 2- to 6-d regimen. Densitometric analysis Of muscle sections stained with periodic acid-Schiff not only corroborated these findings but also indicated that after 24 h of high-carbohydrate intake. glycogen stores reached similar levels in Type I, IIa. and IIb muscle fibers. Conclusion: This study shows that a combination of a short-term bout of high-carbohydrate intake enables athletes to attain supranormal muscle high-intensity exercise followed by a high-carbohydrate intake enables athletes to attain supranormal muscle glycogen levels within only 24 h.