Effects of high-protein diet combined with exercise to counteract frailty in pre-frail and frail community-dwelling older adults: study protocol for a three-arm randomized controlled trial.

Background: The proportion of older citizens is increasing worldwide. A well-known syndrome in old age is physical frailty which is associated with a greater risk of disabilities in activities of daily living, greater reliance on in-home services, hospitalization, institutionalization, and premature mortality. The purpose of this study is to determine the effects of an intervention with high-protein diet alone or in combination with power training in pre-frail and frail old adults.

Methods: The study is a community-based assessor-blinded parallel randomized controlled trial (RCT), consisting of two phases. Phase 1 is a 1-month stabilization phase, where self-reliant community-dwelling adults + 80 years old will receive individual guidance regarding protein intake, to prevent the risk of negative protein balance prior to phase 2 and to only include participants who have reached the minimum recommended level of protein intake (1.0 g/kg/day) in the randomized controlled trial. Phase 2 is a 4-month RCT where 150 participants will be randomized into the following three arms: protein-only where participants will be provided with dairy products to increase their protein intake to 1.5 g/kg/day, protein + exercise where participants will be provided with the protein intervention in combination with power training two times a week, and recommendation group where participants will continue as in phase 1. Primary outcome is lower leg muscle power. Secondary outcomes include physical function and mobility, frailty status, muscle mechanical function, body composition, nutritional status, and health-related quality of life. The statistical analysis will include an intention-to-treat analysis of all randomized participant and per-protocol analysis of all compliant participants. The study hypothesis will be tested with mixed linear models to assess changes in the main outcomes over time and between study arms.

Discussion: The finding of this study may add to the knowledge about the beneficial effects of high-protein diet from dairy products combined with power training to counteract frailty in community-dwelling older adults. This may ultimately have an impact on the ability to live well and independent for longer.

Trial Registration: ClinicalTrials.gov NCT03842579 . Registered on 15 February 2019, version 1.