FITME Study: Formulating Individualised Exercise Prescription in Chronic Obstructive Pulmonary Disease

Overview

This randomised controlled trial aims to: i) compare the power output at the first metabolic threshold (WMT1) between the MT1 and the six-minute walking test (6MWT)-based cardiorespiratory exercise prescriptions in chronic obstructive pulmonary disease (COPD); ii) compare exercise adherence, peripheral muscle strength, health-related quality of life, dyspnoea, fatigue, disease impact and emotional status between MT1 and 6MWT-based exercise prescriptions. Patients will be recruited via the pulmonology services from Unidade Local de Saúde do Baixo Mondego and Unidade Local de Saúde de Aveiro.

Chronic obstructive pulmonary disease (COPD) is a progressive and impactful disease characterised by chronic ariflow. Beyond its primary respiratory symptoms (i.e. dyspnoea, sputum production, cough, and frequent exacerbations), COPD is often accompanied by systemic, extrapulmonary manifestations such as skeletal muscle dysfunction. Exercise is a structured, purposeful subset of physical activity designed to improve or maintain one or more components of physical fitness and health benefits. Within the management of COPD, conventionally delivered through pulmonary rehabilitation programme, exercise training triggers crucial extrapulmonary adaptations. By improving peripheral muscle function and cardiovascular efficiency, it reduces the overall load on the pulmonary system, ultimately improving symptoms, preventing hospitalizations, and halting clinical deterioration. To achieve these adaptations, a minimum threshold of external load (typically moderate-intensity exercise) should be implemented. International guidelines and expert consensus recommend healthcare professionals to prescribe cardiorespiratory exercise based on field tests (i.e. 6MWT). However, as a submaximal assessment, the 6MWT typically elicits submaximal functional responses, which distinctively differ from the peak physiological demands captured during a cardiopulmonary exercise test (CPET). Recent evidence highlights the first metabolic threshold (MT1) as an optimal benchmark for prescribing cardiorespiratory exercise. This physiological marker establishes the transition from light to moderate exercise intensity and can be accurately determined via a CPET. Sticking to traditional exercise prescription models can cause imprecise monitoring and dosing, which may compromise patient safety, increase frustration, and lower adherence. This ongoing uncertainty in prescribing cardiorespiratory exercise for people with COPD can impair pulmonary rehabilitation outcomes and potentially lead to flawed healthcare policy decisions. Therefore, the primary aim of this study is to compare exercise prescription based on MT1 and on the 6MWT for improving power output at MT1 in people with COPD. Secondary aim is to compare exercise adherence, peripheral muscle strength, health-related quality of life, dyspnoea, fatigue, disease impact, and emotional status between MT1 and 6MWT-based prescriptions. This study will be conducted at Unidade Local de Saúde do Baixo Mondego, Figueira da Foz, Unidade Local de Saúde da Região de Aveiro, and at the Laboratory of Research and Respiratory Rehabilitation of the School of Health Sciences of the University of Aveiro (LAB3R-ESSUA). Patients with a formal diagnose of stable COPD and a maximal CPET with MT1 determination will be included. Individuals who have unstable or severe comorbidities (e.g., musculoskeletal, neurological, cardiovascular, neoplastic, or immunological) that prevent participation in pulmonary rehabilitation, as well as those who have completed or attended a pulmonary rehabilitation program within the past 12 months will be excluded. Sociodemographic and general clinical data will be collected. Instruments assessing health-related quality of life, dyspnoea, fatigue, disease impact, emotional status, and cough will be applied. Sample size calculation was performed using G\*Power version 3.1 (Heinrich Heine University Düsseldorf, Germany). A sample size calculation was computed using G\*Power3.1.9.6 for the within-between interaction of a mixed ANOVA with two groups and 2 assessments (baseline and post pulmonary rehabilitation) of the primary outcome. The sample size was estimated considering an alpha=0.05, power=0.80, repeated measures correlation=0.5, nonsphericity correction=1, and a moderate effect, partial eta squared (η2) of 0.06, the required sample size was 34 participants. As the anticipated dropout rate was 25% a final anticipated sample size was 46 participants (23/group).