Journal Title (Medline/Pubmed accepted abbreviation): Int J Sport Nutr Exerc Metab
Page numbers: 515-532
doi (if applicable): N/A
Article type: Review
Summary of article:
This review summarized the clinical evidence for postexercise carbohydrate, protein, and caffeine intake to stimulate muscle glycogen synthesis and protein/amino acid intake for muscle protein synthesis, as well as the effects of these nutrients on subsequent performance. Future research directions and practical guidelines are also summarized. Overall, stimulating muscle glycogen synthesis with carbohydrates may be best achieved by an intake of 1.2 g/kg/hr at 15- to 30-minute intervals, although the evidence for influence by amount, timing, and frequency is somewhat conflicting. Coingestion with protein has no further effects, and coingestion with amino acids/protein only increases synthesis when carbohydrate intake is lowered to ≤ 1.0 g/kg/hr. Not enough evidence exists to determine if caffeine coingestion has a positive effect on postexercise muscle glycogen synthesis. Stimulating muscle protein synthesis with carbohydrate intake has no effects; however, coingestion with protein/amino acids further stimulates synthesis compared with protein/amino acids alone. Protein/amino acid intake postexercise does increase muscle protein synthesis, although this process is affected by the type, amount, and timing of ingestion. Further research is necessary to establish an optimal regimen. Subsequent exercise performance may be improved by postexercise intake of the optimal carbohydrate regimen described above, and there are increased benefits with protein/amino acids coingestion; however, the relationship between increased muscle glycogen synthesis and performance is yet to be confirmed. Results of several studies suggest that postexercise caffeine intake enhances muscle glycogen synthesis only when coingested with carbohydrates. Caffeine intake during exercise can increase intestinal absorption of carbohydrates; however, the effects of caffeine intake on glucose absorption in the recovery setting have not been adequately defined. Future research should aim to establish an optimal postexercise nutritional regimen that is practical in sport-specific settings.
Interpretation of findings/Key practice applications:
Although the clinical evidence suggests that the ideal postexercise carbohydrate intake is 1.2 g/kg/hr, this large amount of carbohydrate ingestion is not always practical. The intake of a lesser carbohydrate amount with protein (0.8 g/kg/hr and 0.2-0.4 g/kg/hr, respectively) may achieve similar results with a palatable volume for ingestion. Moreover, all types of athletes can benefit from this postexercise nutritional regimen, even though the current focus of postexercise nutritional content is different for endurance (carbohydrates) versus resistance (protein) athletes.