L-Leucine has been getting a lot of press recently, as it’s been linked to greater levels of protein synthesis and mTOR activation. The latest study was a real eye-opener: Supplementation with leucine resulted in more muscle mass even in the absence of training. Researchers at Leeds Beckett University in England will publish an article on this soon in the European Journal of Clinical Nutrition. The researchers divided 25 subjects, all healthy and aged between 65 and 75, into three groups. The first group took a placebo every day – the control group. The other two groups took capsules every day that contained a mixture of essential amino acids.

Wait a minute – so it wasn’t JUST Leucine: They were getting EAA’s in addition to Leucine.

The lesson for us all: You need to read the whole study. One of the supplementation groups took a mix that contained 20 percent leucine. A subject who weighed 80 kg consumed approximately 3.5 g leucine in the form of the supplement every day. The members of the other supplementation group took a mix that consisted of 40 percent leucine, so they consumed about 7 g leucine each day. Interestingly, this does use for muscle building effects is much higher than the 3 g recommended generally by supplement experts.


Before and after the supplementation period, the researchers tested the subjects’ physical functioning. They tested the subjects’ handgrip strength, counted how many times the subjects could stand up and sit down again [30 seconds chair test] and measured how many meters the subjects could walk in 6 minutes [6 minutes walk test].

These functions improved in the subjects who had taken the supplement, in both the 20 and 40 percent leucine mixtures.


BCAA’s stimulate protein synthesis, while Essential Amino Acids (EAA’s) complete the process and build new muscle.

Big difference…

The ideal then, is to consume EAA’s and not stand alone Leucine or even BCAA’s. Both the American Journal of Physiology (Endocrinology and metabolism) and the Journal of Sports Sciences have shown that human subjects given 6 grams of a specific essential amino acid blend taken pre-workout increased their muscle protein synthesis by almost 600%(1)(2).

So there it is A practical, inexpensive strategy that gives you an incredible edge. In subsequent articles, I’ll be showing you how to construct the ideal intra and post-workout protocol to max out your gains.


  1. Borsheim, E. et al. American Journal Physiology Endocrinology Metabolism 2002; 283:E648– E657. Essential amino acids and muscle protein recovery from resistance exercise.
  2. Tipton, Kevin. Wolfe, Robert. Journal of Sports Sciences. 2004. 22, 65-79. Protein and amino acids for athletes.