The additive effects of exercise and essential amino acid on muscle mass and strength in community-dwelling older Japanese women with muscle mass decline, but not weakness and slowness: a randomized controlled and placebo trial

Background Exercise and essential amino acid supplementation have been separately shown to improve muscle mass in elderly people, however, the combined, added effects of both interventions have yielded inconsistent results on muscle mass, strength, and physical function improvement. Aims To investigate the additive effects of exercise and essential amino acid supplementation on muscle mass, strength, and walking ability in older Japanese women with muscle mass decline, but not weakness and slowness. Methods One hundred thirty women over 65 years of age were defined as having muscle decline and randomly assigned into two groups; exercise and amino acid supplementation ( n = 65) or exercise and placebo supplementation ( n = 65). The exercise group attended a 60-min comprehensive training program once a week and were encouraged to perform a home-based exercise program. The amino acid or placebo group ingested a 3 g supplement daily for 3-month. Body composition was determined by bioelectrical impedance analysis. Interview data and functional fitness measurements, such as muscle strength and walking ability were collected at baseline and after the 3-month intervention. Results There were no significant group × time interactions in primary outcomes such as muscle mass and strength. However, interactions were observed in the degree of low back discomfort ( P = 0.014). Percent change of low back discomfort was significantly greater in exercise + amino acid group compared with exercise + placebo group. Conclusions The combination of exercise and amino acid supplementation had a beneficial effect on low back discomfort. However, additional effects were not observed in primary outcomes including muscle mass and strength in this population.