Sports physiologists know that maximizing muscle building requires adequate amounts of high-quality dietary protein—rich in branched-chain amino acids such as leucine—and a resistance training regimen such as weight lifting. Less known are the precise cellular and molecular signals that explain how these factors promote muscle growth.
A new study from New Zealand and Australian scientists reports that leucine-rich whey protein combined with resistance exercise stimulates muscle growth in young and older men by way of increasing the activation of molecular modification (mTOR signaling) of muscle proteins. Interestingly, while the combination of exercise and whey protein increased activation of some muscle proteins to a similar degree in young and old before training, the diet/exercise combination was distinctly blunted in the older subjects.
According to the authors of the study, just published in the journal Applied Physiology, Nutrition and Metabolism, while exercise and whey protein combined to effectively activate muscle proteins in young men, deficiencies in this signaling pathway were evident in muscles from older individuals.
“Strategies to improve muscle growth in the elderly should not dismiss the use of protein, particularly whole proteins high in leucine [such as whey protein], in conjunction with a resistance exercise program,” the researchers wrote.
The researchers compared the impact of whey protein supplementation (27 grams consumed after each of 36 resistance training sessions over 12 weeks) or a placebo on cell signaling protein activation. They also addressed the effects of aging on these specialized proteins by examining muscle from young (ages 18 to 25) and older (ages 60 to 75) males before and after the 12-week training program. The importance of understanding muscle growth and maintenance in aged individuals is particularly important considering the prevalence of sarcopenia (age-related muscle loss) in elderly populations.
With this in mind, the IsaLean Shake containing 23 grams of protein per serving made up of primarily whey and IsaPro providing18 grams of whey protein per serving can be used advantageously by young and elderly for maximizing the signaling needed for maintaining or stimulating muscle growth when consumed along with a resistance training program.
Reference: Farnfield MM et al. Activation of mTOR signalling in young and old human skeletal muscle in response to combined resistance exercise and whey protein ingestion. Appl Physiol Nutr Metab 2011 Dec 13. doi: 10.1139/h11-132