In 2006, Robert R. Wolfe published a commentary in The American Journal of Clinical Nutrition, noting, “the importance of maintaining muscle mass and physical and metabolic functions in the elderly is well-recognized. Less appreciated are the diverse roles of muscle throughout life and the importance of muscle in preventing some of the most common and increasingly prevalent clinical conditions, such as obesity and diabetes.” In his conclusion, Dr. Wolfe called for more research to help us better understand how nutrition, combined with physical activity, influences muscle development and maintenance.
Since then, the American Society for Nutrition (ASN) has published a range of research studies and scientific reviews that shed new light on the role nutrition and physical activity can play in developing and maintaining muscle mass throughout the lifespan. Below are representative samples from each of ASN’s four peer-reviewed journals.
Enhancements of resistance training-induced skeletal muscle mass and function could reasonably be achieved by supplementation with protein and creatine.
Beginning in the fifth decade of life, we tend to start losing muscle mass and strength. This process, known as sarcopenia, can lead to an increased risk of disability and a lower quality of life among older adults. There are no pharmaceutical treatments for sarcopenia; however, evidence shows resistance training can help us maintain muscle mass and strength as we age. In addition, it is possible that the muscle mass and strength gains realized by resistance training can be enhanced by certain nutritional supplements. ASN member Stuart M. Phillips therefore sought to review the current evidence to determine whether it was strong enough to recommend the use of any particular nutritional supplements to enhance the effects of resistance training among older adults.
According to the author’s findings, “data reviewed here show that enhancements of resistance training-induced skeletal muscle mass and function could reasonably be achieved by supplementation with protein and creatine.” The review also notes that emerging data “are suggestive that the omega–3 class of polyunsaturated fatty acids may render skeletal muscle more sensitive to the anabolic effects of resistance exercise.”
Muscle protein synthesis was optimized with the 20-gram dose of whey protein.
Research has shown that whey protein is an effective protein source in helping individuals build and maintain muscle mass; however, the ideal amount of whey protein that is needed to stimulate muscle protein synthesis has not been fully researched, in particular among young men. In response, Oliver C. Witard et al. designed and implemented a study to determine the optimal dose of whey protein for the stimulation of muscle protein synthesis, working with a group of 48 young men aged 19 to 25.
Study participants were divided into four groups. Each group was given a standardized breakfast. Three hours later all participants were asked to perform an intense leg resistance exercise routine. Immediately after performing the exercise, participants ingested a drink containing 0, 10, 20, or 40 grams of whey protein, depending on their assigned group. The researchers discovered that myofibrillar muscle protein synthesis was optimized with the 20-gram dose of whey protein. Interestingly, “the ingestion of a dose of whey protein greater than 20 grams results in a diminished return in terms of stimulating myofibrillar muscle protein synthesis and, instead, stimulates amino acid oxidation and ureagenesis.”
The authors found no difference in the muscle protein synthesis rates among subjects who had consumed milk protein, corn protein, or a mixture of the two.
While it is agreed that protein consumption is essential for the development and maintenance of muscle mass, there is still debate over whether some sources of protein may be more effective muscle builders than others. In particular, much research has focused on the differential effects of animal-based protein versus plant-based protein on muscle synthesis. To help address this question, ASN member Philippe J. M. Pinckaers et al. conducted a study that compared the muscle protein synthesis rates of healthy young men between the ages of 22 and 30 following the ingestion of 30 grams of milk protein, 30 grams of corn protein, or a blend of 15 grams of milk protein and 15 grams of corn protein. In this randomized, double blind, parallel-group design study, the authors found no difference in the muscle protein synthesis rates among subjects, regardless of whether they had consumed milk protein, corn protein, or a mixture of the two.
The group that had consumed the nightly protein supplement had made greater gains in both strength and muscle mass.
In addition to studying how different types and amounts of protein affect the development and maintenance of muscle mass, researchers have also investigated how the timing of protein ingestion may also play a role in muscle synthesis. ASN member Tim Snijders et al., for example, designed an experiment to assess the impact of dietary protein supplementation before sleep on muscle mass and strength gains during a course of resistance exercise training. Forty-four young men between the ages of 21 and 23 were assigned to a progressive 12-week resistance exercise training program. One group consumed a supplement containing 27.5 grams of casein protein every night before sleep; the other group received a noncaloric placebo.
Following the 12-week exercise course, the authors discovered that the group that had consumed the nightly protein supplement had made greater gains in both strength and muscle mass. The authors therefore concluded that “protein ingestion before sleep represents an effective dietary strategy to augment skeletal muscle mass and strength gains during prolonged resistance-type exercise training in healthy, young men.”
Searching ASN journals, you’ll find many more articles exploring the complex links between nutrition, physical activity, and muscle development and maintenance. In addition, if you are conducting research in this area, please consider submitting your findings for publication in an ASN journal to ensure that your important findings have global impact.