Effectiveness of a Physical Exercise Prescription Program in Primary Care to Improve Physical Fitness and Quality of Life in Adults Aged 65 Years and Older in a Rural Basic Health Area—Study Protocol for a Randomized Controlled Trial (PREFIS-AP)

Physical inactivity contributes substantially to morbidity, disability, functional decline, and premature mortality in older adults. General physical activity counselling in primary care does not necessarily translate into structured, individualized exercise prescription. PREFIS-AP evaluates a standardized Exercise Prescription Program embedded in routine rural primary care for community-dwelling adults aged 65 years and older. PREFIS-AP is a single-center, pragmatic, parallel-group randomized controlled trial with 210 planned participants allocated 1:1 to a 12-week individualized multicomponent Exercise Prescription Program or usual primary care. The intervention combines clinical and functional assessment, an electronic health record decision-support module, and multicomponent exercise. The primary outcome is the 12-week Six-Minute Walk Test (6MWT) distance adjusted for baseline distance. Secondary outcomes include physical activity, health-related quality of life, strength, lower-limb function, anthropometry, medication burden, and safety; rectus femoris morphology assessed by point-of-care ultrasound is exploratory. The primary analysis will follow the intention-to-treat principle and compare 12-week 6MWT distance between groups adjusted for baseline distance. PREFIS-AP will evaluate the clinical effectiveness and feasibility of integrating structured exercise prescription into routine rural primary care. Limitations include the single-center setting, inability to blind participants and intervention providers, additional exercise-professional support, and 12-week follow-up. Secondary and exploratory analyses are not independently powered.