Differences in muscle adaptation to a 12-week mixed power training in elderly men, depending on usual protein intake

Introduction: Normal aging is often associated with a decline of muscle mass (MM), strength (MS) and quality (MQ: MS/MM), leading to functional incapacities. This aging-related deterioration of muscles may involve a decreased protein intake. Mixed power training has been recently shown to induce positive effects on MM, MS and MQ. However, to our knowledge, no study has examined if muscle adaptations following mixed power training could be influenced by the daily amount of protein ingested in elderly men.

Methods: Twenty-one men completed the intervention and were divided into 2 groups based on their usual protein intake: PROT 1.1- (<1.1 g·kg^-1·d^-1 [n = 10; 73 ± 3 years]) and PROT 1.2+ (>1.2 g·kg^-1·d^-1 [n = 11; 73 ± 3 years]). Body composition (DXA: lean and fat masses), MS (1-maximal repetition on leg-press and handgrip strength), MQ (MS/body mass and MS/lower limb lean mass), functional capacities (Short Physical Performance Battery/Senior Fitness Test), dietary intake (3-day food record) and energy expenditure (accelerometer; 7 days) were measured. Mixed power training intervention consisted in power and functional exercises (12 weeks; 3 times/week; 1 h/session).

Results: Lower limb MS increase in the PROT 1.2+ group was greater from that of the PROT 1.1- group when normalized to lower limbs lean mass (p = 0.036). In addition, a trend for greater gain in lower limb MS normalized to body mass (p = 0.053) was observed in the PROT 1.2+.

Conclusion: To optimize mixed power training effects on muscle function, healthy older men should ingest daily at least 1.2 g·kg^-1·d^-1 of protein. These beneficial effects of a higher usual protein intake were observed especially for MQ, which is one of the best predictors of functional capacities in older adults.