High-intensity progressive resistance training to prevent falls in community-dwelling adults aged 80 years and older with reduced muscle strength: protocol for the ReFit randomised controlled trial

IntroductionFalls are a major cause of injury-related morbidity, mortality, and healthcare utilisation among older adults, with the greatest burden occurring in those aged [≥]80 years. Multicomponent exercise programmes that include balance and resistance exercises reduce falls, whereas the effect of resistance training delivered as a standalone fall-prevention intervention remains uncertain. Existing resistance-training trials have generally been small, underpowered for fall outcomes, and have produced inconsistent findings, despite reduced muscle strength being an important modifiable risk factor in the oldest old. The resistance training prescription used in these studies has not always aligned with recommendations for optimal strength adaptations in terms of intensity or progressive overload, which may explain this uncertain efficacy. Therefore, this study aims to determine whether 12 months of high-intensity progressive resistance training reduces fall rates in community-dwelling adults aged [≥]80 years with reduced muscle strength. Methods and analysisThis single-centre, randomised controlled trial conducted in Trondheim, Norway, includes 241 community-dwelling adults aged [≥]80 years with reduced muscle strength. Participants are randomly assigned (1:1) to either standard care with written physical activity guidance or a twice-weekly high-intensity progressive resistance training intervention for 12 months. The primary outcome is the rate of falls over 12 months. Secondary outcomes include time to first fall, fall-related injuries, muscular function, physical performance, balance, body composition, cardiometabolic health, cognition, and participant-reported outcomes. Cost-effectiveness is assessed from a healthcare perspective over the 12-month intervention period using costs and quality-adjusted life years. Analyses follow the intention-to-treat principle, using negative binomial regression for the primary outcome. The first participant was included on 30 March 2023, and the last participant was included on 29 September 2025. The 12-month intervention period is expected to be completed by September 2026. Ethics and disseminationThe study has received approval from the Regional Committee for Medical and Health Research Ethics in Norway (REK; reference number 462261). All participants provided written informed consent before participating. Findings will be shared via peer-reviewed publications, conference presentations, and communication with stakeholders and the public. Trial registration numberClinicalTrials.gov (NCT05691166), registered 11 January 2023. Available at: https://clinicaltrials.gov/study/NCT05691166