Essential amino acid and carbohydrate ingestion prior to resistance exercise does not enhance post-exercise muscle protein synthesis.
Fujita S, Dreyer HC, Drummond MJ, Glynn EL, Volpi E, Rasmussen BB.
University of Tokyo.
Ingestion of an essential amino acid-carbohydrate (EAA+CHO) solution following resistance exercise enhances muscle protein synthesis during post-exercise recovery. It is unclear whether EAA+CHO ingestion prior to resistance exercise can improve direct measures of post-exercise muscle protein synthesis (FSR; fractional synthetic rate). We hypothesized that EAA+CHO ingestion prior to 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 post-exercise recovery. We studied 22 young healthy subjects before, during, and for 2 hr 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 hr prior to 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 hr post-exercise. Muscle FSR decreased in the Fasting group during exercise and increased at 1 hr post-exercise (P<0.05). However, the 2 hr post-exercise 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 hr post-exercise (EAA+CHO: 39+/-7%; Fasting: 47+/-9%; P<0.05). We conclude that EAA+CHO ingestion prior to resistance exercise does not enhance post-exercise FSR as compared to exercise without nutrients. Key words: essential amino acids, resistance exercise, muscle protein synthesis, protein metabolism, leucine.
PMID: 18535123 [PubMed - as supplied by publisher]