• Exercise
• COPD ÀÜ Mechanisms

Physical activity is defined as any body movement made by skeletal muscles that results in energy expenditure, including leisure time, domestic and work-related activities. Patients with COPD are less physically active when compared with people without COPD, including age-matched controls1 and individuals with other chronic illnesses such as heart disease, diabetes and arthritis.2 In fact, physical activity drops off 10 years earlier in patients with COPD than in sedentary healthy people, and before the onset of breathlessness.3 This lack of physical activity is associated with worse health outcomes. Patients with COPD with the lowest levels of physical activity are at increased risk of hospitalisation due to exacerbations4 and of death due to any cause.5 Increasing physical activity therefore has potential to improve health and prolong survival in people with COPD. Furthermore, patients say that an increase in activity is an important goal for them,6 more important than prolonging survival.7

Increasing physical activity however is surprisingly difficult. Pulmonary rehabilitation—a physical and behavioural intervention—improves exercise performance in patients with COPD, but is not always accompanied by increased physical activity in daily life.8 Beyond pulmonary rehabilitation, alternative therapeutic strategies to improve physical activity include counselling, nutritional supplementation, respiratory support and bronchodilators. Recent systematic reviews of such interventions in COPD found that evidence in this field was often low quality and heterogeneous.9 ,10 While interventions targeted at specific patient subgroups appear successful, such as dietary supplementation in cachectic patients and nocturnal non-invasive ventilation with exercise training in hypercapnic patients, …