Effects of a Community-based Multicomponent Physical Exercise Program on Physical Function, Frailty, and Sarcopenia in Older Adults From the Municipality of Santoña: a Quasi-experimental Study.

Most of the existing evidence on the benefits of multicomponent exercise for reversing frailty and sarcopenia in older adults comes from lab-based clinical trials conducted in highly controlled hospital or laboratory settings. While these studies have strong internal validity, they often lack ecological validity, meaning they do not reflect the real-world conditions, barriers, and adherence dynamics of community-based programs. There is therefore a public health need to evaluate whether the efficacy demonstrated in controlled settings translates into real, sustainable effectiveness when delivered through existing municipal, real-world programs.

This study evaluates a pre-existing, independently run community exercise program organized by the Santoña Town Council (Cantabria, Spain) for older adults referred through local health centers. The program has been running for several years and will continue to be delivered by the Town Council regardless of this study's outcome. The scope of this research is limited to the scientific evaluation of participants' physical and functional status before and after their participation in the program; the research team has no role in designing, modifying, or delivering the exercise intervention itself.

Design: This is a quasi-experimental, single-group, repeated-measures (pre-post) study. A passive control group was not included, as the community health-promotion nature of the program makes it inappropriate to withhold access to exercise and its benefits from eligible older residents. Each participant serves as their own control, comparing baseline and post-intervention measures.

Intervention being evaluated: The municipal exercise program follows a 36-week multicomponent format addressing strength, balance, endurance, and flexibility, structured according to the FITT-VP principles of the Vivifrail model (Izquierdo, 2019). Sessions are supervised by qualified exercise professionals who individualize training loads. The research team is not modifying this program in any way; researchers are solely adding an assessment protocol before and after each 36-week cycle.

Recruitment and timeframe: Recruitment will take place annually over four consecutive academic years (2026/2027 to 2029/2030), with an estimated 60 participants recruited per cohort, for a cumulative total of approximately 240 participants across the study period.

Outcome assessment: At baseline (week 0) and at the end of each 36-week cycle (week 36), participants will undergo: basic anthropometric measurements (weight, height, waist circumference); a self-perceived fitness questionnaire (IFIS); the Short Physical Performance Battery (SPPB), assessing balance, 4-meter gait speed, and 5-times chair-stand performance; handgrip strength via isometric dynamometry; the 30-Second Chair Stand Test as an additional measure of lower-limb strength; and the 6-Minute Walk Test to assess cardiorespiratory capacity. No blood draws, biopsies, or other biological samples are collected at any point.

Safety considerations: Because participants are community-dwelling older adults rather than clinical patients, the assessment protocol does not interfere with any necessary medical treatment, and no placebo is used. Expected adverse effects are mild and transient (e.g., delayed-onset muscle soreness, general fatigue, occasional mild joint discomfort), with a low inherent risk of musculoskeletal injury or falls associated with physical exertion. All sessions are supervised by qualified exercise professionals, loads are individualized, and an adverse event monitoring and reporting protocol is in place. Participants are covered by the Santoña Town Council's civil liability insurance for municipal activities and facilities.

Setting: Data collection and the exercise program take place at municipal sports facilities and community centers made available by the Santoña Town Council under an institutional collaboration agreement. Scientific direction, statistical analysis, and custody of anonymized data are centrally managed by the research team at the University of Granada (UGR).

• Handgrip strength [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]
• 30-Second Chair Stand Test [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]
• 6-Minute Walk Test (6MWT) distance [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]
• Body weight and Body Mass Index (BMI) [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]
• Waist circumference [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]
• Self-perceived fitness (International Fitness Scale, IFIS) [Time frame: Baseline (week 0) and post-intervention (week 36), for each of the four annual cohorts (2026-2030)]