The optimal dose of protein to increase muscle protein synthesis after resistance exercise has been determined to be about 20 grams of high quality protein which contains approximately 10 grams of essential amino acids.
Endurance exercise is a much different stimulus than resistance exercise and whether the same holds true for optimal levels of protein remain unclear.
appears to be the key to engaging protein synthesis, and during endurance exercise the body burns some of the leucine as fuel which may diminish its anabolic potential. To test whether endurance exercise could benefit from greater leucine researchers tested the effects of a 10 gram essential amino acid drink to a similar one that was enriched with leucine. The leucine-enriched drink contained 3.5 grams leucine compared to 1.87 in the control essential amino acid drink. The drinks were consumed during 60 min of cycling exercise. Muscle protein synthesis was 33% greater after the leucine-enriched drink. The results suggest that increasing the availability of leucine during endurance exercise is important to promote recovery of muscle proteins after exercise.
Pasiakos SM, McClung HL, McClung JP, Margolis LM, Andersen NE, Cloutier G Pikosky MA, Rood JC, Fielding RA, Young AJ. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. Am J Clin Nutr. 2011 Jul 20.