Dietary protein, exercise and skeletal muscle: is there a synergistic effect in older adults and the elderly?

Progressive resistance training (PRT) and dietary protein are both regarded as key factors for the maintenance of muscle health and function during ageing. Short-term acute studies have consistently shown that combining PRT with an adequate dose of high quality, rapidly digested, leucine rich protein sources can produce additive or synergistic benefits on skeletal muscle protein synthesis in older adults compared to PRT or dietary protein alone. However, there are mixed findings from the available randomized controlled trials (RCTs) conducted over ≥12 weeks with muscle mass, strength and/or function as the outcome. Of the 18 RCTs conducted in adults aged ≥60 years that we identified, only three reported a significant protein-exercise interactive effect on muscle mass and/or strength; none observed an additive benefit on muscle function. This chapter provides a brief overview on some of the reasons as to why there are inconsistent findings, with a focus on the type, dose, spread and/or change in protein intake, timing of consumption, pattern or distribution of intake and the potential influence of co-ingestion with other nutrients.