HIGHLIGHTED TOPIC Regulation of Protein Metabolism in Exercise and Recovery Essential amino acid and carbohydrate ingestion before resistance exercise does not enhance postexercise muscle protein synthesis

Fujita S, Dreyer HC, Drummond MJ, Glynn EL, Volpi E, Rasmussen BB. Essential amino acid and carbohydrate ingestion before resistance exercise does not enhance postexercise muscle protein synthesis. J Appl Physiol 106: 1730–1739, 2009. First published June 5, 2008; doi:10.1152/japplphysiol.90395.2008.—Ingestion of an essential amino acid-carbohydrate (EAA CHO) solution following resistance exercise enhances muscle protein synthesis during postexercise recovery. It is unclear whether EAA CHO ingestion before resistance exercise can improve direct measures of postexercise muscle protein synthesis (fractional synthetic rate; FSR). We hypothesized that EAA CHO ingestion before a bout of resistance exercise would prevent the exercise-induced decrease in muscle FSR and would result in an enhanced rate of muscle FSR during postexercise recovery. We studied 22 young healthy subjects before, during, and for 2 h following a bout of high-intensity leg resistance exercise. The fasting control group (n 11) did not ingest nutrients, and the EAA CHO group (n 11) ingested a solution of EAA CHO 1 h before beginning the exercise bout. Stable isotopic methods were used in combination with muscle biopsies to determine FSR. Immunoblotting procedures were utilized to assess cell signaling proteins associated with the regulation of FSR. We found that muscle FSR increased in the EAA CHO group immediately following EAA CHO ingestion (P 0.05), returned to basal values during exercise, and remained unchanged at 1 h postexercise. Muscle FSR decreased in the fasting group during exercise and increased at 1 h postexercise (P 0.05). However, the 2 h postexercise FSR increased by 50% in both groups with no differences between groups (P 0.05). Eukaryotic elongation factor 2 phosphorylation was reduced in both groups at 2 h postexercise (EAA CHO: 39 7%; fasting: 47 9%; P 0.05). We conclude that EAA CHO ingestion before resistance exercise does not enhance postexercise FSR compared with exercise without nutrients.