Editorial: Nutritional Strategies to Promote Muscle Mass and Function Across the Health Span

Abstract

Skeletal muscle is a highly plastic tissue, able to remodel in response to its physical demands. This includes growth (i.e., hypertrophy) in response to the application of external forces (e.g., exercise) and loss (i.e., atrophy) in response to the withdrawal of these forces (e.g., detraining, immobilization). Given its central role in converting chemical energy to mechanical work, skeletal muscle is unquestionably important for individuals wishing to excel in athletic competition, effectively navigate rehabilitation settings (e.g., return to play, remobilization after injury), and perform activities of daily living (e.g., maintain functional independence with age). However, this tissue is a major contributor to the basal metabolic rate and is the preferred storage depot for dietary sugars and fats, which positions it as a vital tissue for the maintenance of metabolic health. Thus, maintaining an adequate quantity and quality of skeletal muscle is important for optimal health and performance throughout the lifespan. This recent special issue on "Nutritional strategies to promote muscle mass and function across the health span" represents a collection of 21 articles, including 12 original research articles, from 130 of the world leaders in the fields of muscle physiology, nutrition, and exercise physiology. A common theme throughout the special issue is the interactive effects of muscle contraction and dietary nutrients, in which exercise can "make nutrition better" and nutrition can improve muscle mass and function. For example, Oikawa et al. highlighted the importance of maintaining muscle activity to help stave off the deleterious effects of "anabolic resistance, " which is the impaired ability to utilize dietary amino acids to support muscle protein synthesis and tissue remodeling that ultimately leads to decrements in muscle mass and function. Importantly, the authors highlight that reduced daily step counts, which could be interpreted as "benign" inactivity in comparison to more severe immobility such as cast, bedrest, and spaceflight, is actually far more common in today's society and recapitulates the muscle deconditioning that is evident from these more extreme models of muscle disuse. This is an important health message given the recent (as of publication) shelter-at-home practices of ongoing pandemics (1). However, some potential nutritional strategies to minimize the loss of muscle mass and function could include greater protein intake (as suggested by Oikawa et al.), increased polyunstaturated fatty acids (PUFA's, as suggested by McGlory et al.), and/or creatine supplementation (as highlighted by Candow et al.), all of which may have greater efficacy in populations already at risk for low muscle mass and/or function such as the elderly and/or pre/post-operative patients. This discussion was also extended by Beaudry and Devries who highlighted the potential benefit of dietary protein (and potentially that which is dairy-based) and exercise (especially resistance exercise) in countering the metabolic

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