The TRACKFRAILTY project aims to answer the following main research questions:

i) What is the prevalence of physical frailty in individuals living in residential care facilities (RCF) from Portugal's Cova da Beira subregion (Interior Center Region)? ii) What factors best predict frailty status? iii) Is strength training effective in reversing physical frailty in RCF residents? iv) In the long term, what dose of strength training volume is needed to promote the most significant health benefits in frail RCF residents? Based on these research questions, the TRACKFRAILTY project aims to quantify the prevalence of frailty in Portuguese RCF residents from the Cova da Beira subregion and analyze the effects of long-term strength training with different volumes on reversing physical frailty.

The TRACKFRAILTY project will consist of two primary research activities. Activity one will be a cross-sectional study to quantify the prevalence of physical frailty in residential care facility (RCF) residents from Portugal's Cova da Beira subregion (Interior Center Region). Activity two will be a randomized controlled trial to compare different strength training volumes for reversing frailty in RCF residents.

The prevalence study will include a representative sample of RCF residents from Portugal's Cova da Beira subregion. The investigators will use a comprehensive recruitment strategy, including contacts and meetings with the technical directors of several RCFs from the Cova da Beira subregion. Participants must comply with the inclusion criteria to make part of the study, namely men or women aged 50 and above residing in RCFs in Cova da Beira, capable of collaborating with the research team members, and giving written or oral informed consent. Exclusion criteria will comprise individuals with severe dementia (inability to speak or communicate with permanent care and assistance) and hospitalized and bedridden individuals.

After recruitment, the investigators will implement an evaluation protocol in two parts. The first part will include the collection of i) sociodemographic data, ii) diseases, iii) medications, iv) smoking status and alcohol consumption, v) self-perceived health-related quality of life, vi) self-reported unintentional weight loss, vii) falls history (last 12 months); viii) disability level, ix) self-reported exhaustion, x) physical activity level, xi) cognitive function, xii) emotional state, and xiii) relational/social aspects. The second part will include the collection of i) hemodynamic data, ii) anthropometric data, iii) lower extremity function data, and iv) upper extremity function data. The investigators will assess frailty using Fried's criteria (self-reported unintentional weight, self-reported exhaustion, low physical activity, muscle weakness, and slowness). Individuals with 3-5 criteria will be considered frail, 1-2 pre-frail, and 0 non-frail. Frail and pre-frail individuals will be invited to participate in the randomized controlled trial.

Research activity two will be a randomized, single-blind, three-arm (two experimental groups and one control group), parallel-group study of 30 weeks. The investigators will randomly assign the participants into three groups: less-volume (LV), more-volume (MV), and control (CG). The CG will perform stretching exercises supervised by two exercise physiologists during the intervention (two sessions per week). The LV and MV groups will undergo three 10-week strength training cycles, each with two weekly sessions. In the first cycle, LV will perform around 1500 total repetitions, while MV will perform around 2000. In the second and third cycles, the volume will increase by 20% with reference to the previous cycles in both experimental groups. Training frequency, exercises, and intensities will be the same in both groups. In brief, participants will perform 1-3 sets per exercise of 4-7 repetitions (LV) or 6-10 repetitions (MV) with intensities ranging from 5% to 10% of body weight and 1-10 kg. Strength exercises will include chair squats, seated medicine ball throws, seated knee extensions, seated shoulder presses, standing calf raises, standing biceps curls, seated lateral raises, and chair stand + 4-meter walk.

The investigators will administer the evaluation protocol described in research activity one before the first 10-week training cycle and after the first, second, and third 10-week training cycles. The primary outcome measure will be the frailty phenotype (Fried's criteria). The secondary outcome measures will include physical tests, cognitive function, emotional state, relational aspects, health-related quality of life, falls, feasibility, and safety. A statistician will analyze the data following an intention-to-treat and per-protocol analysis.

Inclusion Criteria:

• Men or women residing in residential care facilities (RFC) from the Cova da Beira subregion of Portugal
• Non-frail, pre-frail, and frail individuals (prevalence study)
• Pre-frail and frail individuals (randomized controlled trial)
• Capable of collaborating with the research team members
• Capable of giving written or oral informed consent

Exclusion Criteria:

• Severe dementia (inability to speak or communicate with permanent care and assistance)
• Hospitalized and bedridden individuals

A statistician blinded to group allocation and the identity of the participants will analyze the data.