Effect of whey protein supplementation after resistance exercise on the muscle mass and physical function of healthy older women: A randomized controlled trial

AIM: To evaluate the effectiveness of a 24-week program of nutritional supplementation using whey protein, ingested after resistance exercise, in increasing muscle mass and physical function among community-dwelling healthy older Japanese women. METHODS: We carried out a randomized controlled trial, with 81 healthy women, aged 65-80 years, allocated to three groups of 27 participants each: the exercise and protein supplementation group, the exercise only group, and the protein supplementation only group. A 24-week program of resistance exercise, carried out twice per week, was combined with whey protein supplementation, containing 22.3 g of protein. The total protein intake for participants in all three experimental groups was adjusted to a level of at least 1.2 g/kg bodyweight/day, and more during the intervention period. Between-group differences in the pre- to post-intervention change in skeletal muscle mass and physical function were evaluated using an analysis of variance. RESULTS: The pre- to post-intervention increase in the skeletal muscle mass index was significantly higher for the exercise only group than for the protein supplementation only group (P =0.008), and significantly higher for the exercise and protein supplementation group than for either the exercise only (P =0.007) or protein supplementation only (P <0.001) groups. Similarly, the increase in grip strength and gait speed was significantly greater for the exercise and protein supplementation group than for the protein supplementation only group (grip strength P =0.014, gait speed P =0.026). CONCLUSIONS: Whey protein supplementation, ingested after resistance exercise, could be effective for the prevention of sarcopenia among healthy community-dwelling older Japanese women. Geriatr Gerontol Int 2018; 18: 1398-1404.