2009 Studies & Research Blog

Stimulating protein synthesis- Just Leucine or all the Essential Amino-Acids?

This question comes up a lot, should I be taking just leucine or a bcaa supplement or the full spectrum of essential amino acids(EAA’s) when trying to maximize protein synthesis and build muscle.  Just to be clear our bodies need all the EAA to build muscle, but protein synthesis can be stimulated simply by leucine alone.  Regardless, without the other EAA present, muscle cannot be built, suggesting taking leucine or just the bcaa’s alone is a poor choice unless the other EAA’s are available in the body from a previous meal or supplement.  Now, while many body builders are eating every few hours, the availability of the other EAA’s may not be too much of issue, but there is another interesting advantage of taking all the EAA’s over  leucine or bcaa supplements and that is the DURATION that protein synthesis will last. A study compared the rate of muscle protein synthesis(MPS), infusing leucine alone VS a full EAA mixture over four hours. What the researchers found was, that leucine alone stimulated MPS for 15-30 minutes but then declined rapidly. But when full EAA mixture was infused, MPS was simulated for the full four hours. Based off the research, it appears that a full EAA mixture(leucine is an EAA) will increase MPS for atleast 4 hours, while leucine alone falls short after just 30 minutes.  This information, while useful for any exercise enthusiast who trains for lean body mass, it is especially useful for individuals who train in the morning prior to eating protein.

Kobayashi H, Kato H, Hirabayashi Y, Murakami H, Suzuki H.Modulations of muscle protein metabolism by branched-chain amino acids in normal and muscle-atrophying rats.
J Nutr. 2006 Jan;136(1 Suppl):234S-6S.

BY: Athletic Edge Nutrition, The Nutrient Timing Specialists.