Chronic Respiratory Diseases (CRDs) are associated with substantial morbidity and mortality, ranking as the third leading cause of death worldwide. Pulmonary rehabilitation (PR) is a fundamental evidence-based intervention for the management of a variety of CRDs, such as Chronic Obstructive Pulmonary Disease (COPD) and Interstitial Lung Diseases (ILDs). However, the benefits of PR tend to decline over time and there is currently no strong evidence that patients translate those benefits into a more active lifestyle. There is an urgent need for evidence-based interventions to promote physical activity (PA) participation, whilst maintaining PR positive effects in the long-term. Community-based PA interventions adjusted to the local context, as well as patients' needs and preferences, might be a key strategy to meet this target. CENTR(AR) will be a sustainable response to support healthy lifestyles and enhance long-term PR benefits, by providing access to PR within Primary Healthcare Centres (PHC), followed by the inclusion in a community-based PA program, which embraces urban facilities and available resources.

The Global Burden Disease Study 2017 estimated that 544.9 million people worldwide had a chronic respiratory disease (CRD). Globally, it is estimated that 3.914.196 deaths were due to CRDs in 2017, accounting for 7% of total all-cause deaths, ranking CRDs as the third leading cause of death worldwide. Pulmonary rehabilitation (PR) is a well-established, cost-effective intervention for the management of CRDs (e.g., COPD, ILD), which has been found to improve exercise capacity, dyspnoea and quality of life. Unfortunately, PR remains an underutilized resource in the community. Despite substantial improvement following PR, benefits tend to decline over time (approximately, within a 12-month period) and there is currently no strong evidence that patients translate those benefits into a more active lifestyle. This is of utmost importance since physical activity (PA) levels predict important outcomes in COPD, for example, with low PA levels being associated with a higher risk of exacerbation-related hospitalization and mortality. That said, it is still unknown how best to maintain long-term effects of PR, whilst promoting patients' adherence to a physically active lifestyle. Most studies reporting on interventions to improve PA among patients with CRDs (e.g., COPD) focus exclusively on patients' individual factors, disregarding interpersonal/social and environmental factors associated with PA. Community-based PA interventions adjusted to the local context, which leverage existing social support and community (infra)structures, may be key elements for success. Indeed, the community offers a variety of physical activity modalities (e.g., urban trails, physical activity/exercise classes at the municipality level), which can be explored and further personalized to meet patients' needs and preferences. By targeting the community, as opposed to the "individual per se", the possibility of promoting a behavioral change towards a more physically active lifestyle becomes more likely. Building on existing knowledge, CENTR(AR) primary aim is to implement and assess the effectiveness of a personalised community-based PA program to increase PA levels, as well as prevent/stop the decline and consolidate PR benefits (in several health-related domains) in people with CRDs, following PR.

Additionally, CENTR(AR) will also aim at:

1) Improving access to and delivery of community-based PR for people with CRDs in Primary Healthcare Centres (PHC) within the Centre Region of Portugal; 2) Identifying barriers and facilitators, as well as preferences and motivations of adherence to PA; 3) Educating/Empowering/Capacitating non-health professionals delivering municipal physical activity/exercise classes, to ensure patients' safety and quality care; 4) Designing and validating urban walking and/or cycling trails by a) measuring the physiological response and energy expenditure associated with the use of those trails; b) assessing the environmental/physical features of the urban trails; 5) Validating the available municipal physical activity/exercise classes (as described in 3); 6) Promoting intersectoral collaboration at the municipality level, leveraging partnerships between PHC and existing community physical activities, thereby filling in the gaps in the continuity of care after PR; 7) Increasing health literacy amongst municipal professionals in regard to CRDs, as well as health promotion and community empowerment.

Randomized Controlled Trial (RCT)

Aims & Outcomes Primary aim: Assess the effectiveness of a community-based PA program, tailored to patient's needs and preferences, to increase PA levels in people with CRDs.

Secondary aim(s): Determine the short-, mid- and long-term effects of CENTR(AR) on exercise capacity, functional status, HRQoL, symptoms, AECOPD and healthcare utilisation, peripheral muscle strength, motivation for exercise, and emotional status; Establish the influence of patients' motivations and preferences in adhering to the CENTRAR program and engaging in a physically active lifestyle.

At each time-point, the following data will be collected: Socio-demographic and anthropometric data; Lung function; Healthcare utilization; Health-related quality of life (HRQoL); Impact of disease; Fatigue; Dyspnoea; Cough and sputum; Social support and social network; Anxiety and depression; Motivation to exercise; Perception of change; Exercise capacity; Peripheral muscle strength; Functional status; Balance; Physical activity levels; Adverse events; Adherence; Qualitative data (individual and focus groups interviews)

Study Design & Intervention

After completion of PR, participants will be randomised to an experimental group (EG) or a control group (CG). The EG will enrol in a 6-month personalised community-based PA program, which will/should be attended twice-weekly, minimum. During the first month the physiotherapist will guide patients through all available physical activities; afterwards, patients will be asked to choose one or two activities, according to their preferences, which they will attend for five more months. Physiotherapists' support will gradually decrease over time. The CG will receive a leaflet with PA recommendations.

Sample Size Estimation

The sample size was estimated using G*Power 3.1.9.6, with an effect size specification "as in G*Power 3.0", for the within-between interaction of a repeated measures ANOVA with two groups (control and experimental) and 3 measurements (immediately after, and 6 to 12 months post-PR) of the defined primary outcome (MVPA). The investigators considered an α of 0.05, a power of 0.80, a repeated measures correlation of 0.5, a nonsphericity correction of 1 and an expected effect size f of 0.30. The effect size f was derived from the partial η2 of 0.21 (f=0.516) obtained from a study which aimed to assess the impact of a PA-focused behavioural intervention during and after PR on PA levels in patients with COPD. A smaller f value of 0.30 was chosen to account for a longer follow-up period (up to 12 months) and differences in selected time-points. The calculated sample size was 20 (i.e., 10 in each group) COPD patients and considering a possible 50% dropout rate, the final sample size was determined to be 40. Since no significant differences are expected in the primary outcome between COPD and ILD patients, a sample size of 40 was also determined for the latter. In summary, a total sample size of 80 was found to be required to detect significant within-between group differences in MVPA.

Inclusion Criteria:

• Clinical diagnosis of a chronic respiratory disease;
• Stable clinical condition (defined as no acute exacerbation or hospitalization in the previous month).

Exclusion Criteria:

• Signs of cognitive impairment;
• Neoplasic/Immunologic disease or an unstable/significant cardiac (e.g., exertional angina, valvular heart disease, congestive heart failure, etc.), musculoskeletal/orthopaedic, neuromuscular or psychiatric condition limiting ability to exercise or co-operate.