Protein quality matters when it comes to building muscle

Attention Crossfit®, HIIT, Orange Theory® and absolutely anyone who cares about maintaining muscle mass - Tier 1 Canada Research Chair in Skeletal Muscle Health, Dr. Stuart M. Phillips of MacMaster University, reasons that the quality of protein you consume for muscle building with resistance training may be more important than you realize. In a recent article in Nutrition and Metabolism, Dr. Phillips reviewed the current science to examine the effects of the quality of supplemental protein on changes in muscle mass, strength and body composition when combined with strength training. His comprehensive inquiry suggests that based on the new proposed method to evaluate protein quality using its indispensable (or essential) amino acid composition and its digestibility, protein sources that provide leucine (an essential amino acid) - such as whey protein - are the strongest determinant of muscle protein synthesis and likely muscle growth.

"My assessment of the data on protein supplementation and resistance exercise reveals that the amount of leucine in a protein supplement has the greatest impact on muscle protein synthesis," said, Dr. Phillips. "Leucine is not only a building block for protein, but a trigger for working muscles to synthesize more protein. In essence, it turns on muscle protein synthesis like a light switch so that over time, there could be greater gains in lean body mass and strength, and subsequently, body composition improvements."

Proteins with the greatest content of leucine include whey protein isolate or concentrate. Whey protein is a milk protein that is considered high-quality due to its amino acid profile and high score for digestibility. Based on the culmination of data inspecting protein types and muscle protein synthesis, whey protein rated higher than other protein sources such as soy, pea or rice.

"The outcome of this review isn't just applicable to strength trainers," Dr. Phillips notes. "As we age, muscle loss becomes prevalent if we don't thwart the decline. Leucine-rich whey protein supplementation, combined with resistance exercise, may be one way to help preserve muscle mass throughout the lifespan."

While more research is warranted to further characterize proteins based on their quality, digestibility and amino acid profile, as well as to identify their impact on the aging population - at this point, consumers should reach for a leucine-containing protein supplement, like whey, to maximize gains from hard workouts.

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To read the complete review: http://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-016-0124-8