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Maximizing postexercise muscle glycogen synthesis: carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures

2000; Elsevier BV; Volume: 72; Issue: 1 Linguagem: Inglês

10.1093/ajcn/72.1.106

1938-3207

Luc J. C. van Loon, Wim H. M. Saris, Margriet Kruijshoop, Anton J. M. Wagenmakers,

Exercise and Physiological Responses

Background: Postexercise muscle glycogen synthesis is an important factor in determining the time needed to recover from prolonged exercise. Objective: This study investigated whether an increase in carbohydrate intake, ingestion of a mixture of protein hydrolysate and amino acids in combination with carbohydrate, or both results in higher postexercise muscle glycogen synthesis rates than does ingestion of 0.8 g•kg−1•h−1 carbohydrate, provided at 30-min intervals. Design: Eight trained cyclists visited the laboratory 3 times, during which a control beverage and 2 other beverages were tested. After the subjects participated in a strict glycogen-depletion protocol, muscle biopsy samples were collected. The subjects received a beverage every 30 min to ensure ingestion of 0.8 g carbohydrate•kg−1•h−1 (Carb trial), 0.8 g carbohydrate•kg−1•h−1 plus 0.4 g wheat protein hydrolysate plus free leucine and phenylalanine•kg−1•h−1 (proven to be highly insulinotropic; Carb + Pro trial), or 1.2 g carbohydrate•kg−1•h−1 (Carb + Carb trial). After 5 h, a second biopsy was taken. Results: Plasma insulin responses in the Carb + Pro and Carb + Carb trials were higher than those in the Carb trial (88 ± 17% and 46 ± 18%; P < 0.05). Muscle glycogen synthesis was higher in both trials than in the Carb trial (35. 4 ± 5.1 and 44.8 ± 6.8 compared with 16.6 ± 7.8 μmol glycosol units•g dry wt−1•h−1, respectively; P < 0.05). Conclusions: Addition of a mixture of protein hydrolysate and amino acids to a carbohydrate-containing solution (at an intake of 0.8 g carbohydrate•kg−1•h−1) can stimulate glycogen synthesis. However, glycogen synthesis can also be accelerated by increasing carbohydrate intake (0.4 g•kg−1•h−1) when supplements are provided at 30-min intervals.