Regulation of muscle protein by amino acids

What regulates muscle protein synthesis? Exercise, nutrition, both?

This study concludes that "plasma concentrations of EAA regulate muscle protein metabolism in human subjects. The magnitude and duration of response is dependent on the magnitude of the change in concentrations, the timing of increases in concentration in relation to exercise and the concurrent insulin response resulting from any carbohydrate ingested with EAA."

Read the full text here:

Wolfe RR. Regulation of muscle protein by amino acids. J Nutr. 2002 Oct;132(10):3219S-24S. doi: 10.1093/jn/131.10.3219S. PMID: 12368421.