Hamilton, ON, Canada and Natick, MA — The American Journal of Clinical Nutrition recently printed two separate articles that cover the mechanisms through which amino acids affect protein synthesis. Athletes often consume protein drinks to support muscle growth.
In the first study, Daniel W.D. West from McMaster University and colleagues gave eight health men either 25 grams of whey pulse at one time, or 10 protein shots (2.5-g drinks). The digestion of these pulsed drinks were intended to mimic how milk casein is digested. The group analyzed how the protein was synthesized during rest and after resistance exercise. They found that the large dose was more effective that the pulse doses at increasing muscle protein synthesis. At the same time, the whey protein taken in one dose elevated essential amino acid concentrations more than the shots (162% versus 53% increase) after exercise.
The second group, led by Stefan M Pasiakos of the U.S. Army Research Institute of Environmental Medicine, give eight individuals leucine-enriched drinks (3.5 g or 1.87 g) during two rounds of cycling. Both drinks also contained 10 grams of protein as essential amino acids. Muscle protein synthesis and whole-body protein turner were analyzed. It turned out that muscle protein synthesis was 33% greater after drinking the beverage with 3.5 grams of leucine than drinking the lesser quantity of leucine. Also, the high-leucine drink caused less whole-body protein breakdown.
Published in WholeFoods Magazine, October 2011 (online 8/22/11)