Essential amino acids and muscle protein recovery from resistance exercise

Do increased levels of EAAs alone stimulate muscle protein synthesis (MPS)?

Are carbohydrates required at the same time?

Is insulin responsible for the increased MPS response to EAAs?

ANSWERS: YES. NO. NO.

In this study, researchers set out to determine the independent effect of ingestion of EAAs on net muscle protein synthesis after resistance exercise.  The results demonstrated that "ingestion of a relatively small amount (6 g) of EAA effectively stimulated net muscle protein balance after resistance exercise." They also found that "there is a dose response to the amount of EAAs given" as "the response of net balance was about twice the previous published response to 6 g of mixed amino acids."

And regarding additional carbohydrates or the role of insulin in stimulating MPS? The authors further concluded that "additional carbohydrate provided no advantage to EAAs alone" nor did insulin concentrations change over time. 

Read the full-text here: https://doi.org/10.1152/ajpendo.00466.2001

American Journal of Physiology-Endocrinology and Metabolism 2002 283:4, E648-E657