Muscle protein breakdown has a minor role in the protein anabolic response to essential amino acid and carbohydrate intake following resistance exercise

• DOI: 10.1152/ajpregu.00077.2010
• Publication Date: 2010-06-03T01:59:29Z
• Authors: Erin L. Glynn; Christopher S. Fry; Micah J. Drummond; Hans C. Dreyer; Shaheen Dhanani; Elena Volpi; Blake B. Rasmussen
• Keywords: Muscle Atrophy

Muscle protein breakdown (MPB) is increased following resistance exercise, but ingestion of carbohydrate during postexercise recovery can decrease MPB with no effect on muscle synthesis (MPS). We sought to determine whether a combination essential amino acids (EAA) low or high could effectively reduce exercise and improve net balance (NB). hypothesized that higher levels resulting increases in circulating insulin would inhibit associated signaling, augmented NB. Thirteen male subjects were assigned one two groups receiving equivalent amounts EAA (approximately 20 g) differing (low = 30, 90 g). Groups ingested nutrients 1 h after an acute bout leg exercise. Leg phenylalanine kinetics (e.g., MPB, MPS, NB), signaling proteins, mRNA expression assessed successive biopsies using stable isotopic techniques, immunoblotting, real-time quantitative PCR, respectively. tended (P < 0.1) MPS 0.05) similarly both nutrient ingestion. No group differences observed, ring finger (MuRF1) content MuRF1 remained elevated ingestion, while autophagy marker (light-chain 3B-II) decreased 0.05). Forkhead box-O3a phosphorylation, total atrophy F-box (MAFbx) protein, MAFbx caspase-3 unchanged. conclude the enhanced anabolic response detected when EAA+carbohydrate are postresistance primarily due increase minor changes regardless dose level.