The interviews were semi-structured; a framework of themes related to physical activity guided the interviewer. The framework of themes this website was based on potential topics identified in the literature and finalised after discussion with medical experts and two pilot interviews with people with COPD. The topic list of the interviews is presented in Box 1. Interview questions in this framework guided the interviewer but unanticipated themes were allowed.

The interviewer made notes during the interview and wrote them up fully directly after. History of physical activity What kind of physical activities have you undertaken in the past? Motivation to be physically active What are the reasons for you to be physically active? Motivation to be physically inactive What are the reasons for you to be physically inactive? Experiences with physical activity How does it feel for you

to be physically active? Cognitions about physical activity Do you feel that you benefit from being physically active? Self-efficacy for physical activity Do you feel confident in your ability to perform the physical activities you intend to do? Opportunities and barriers to become physically active Do you experience specific opportunities in becoming physically active? Do you experience Selleck OSI744 specific barriers in becoming physically active? Social support for physical activity Do you experience support for physical activity? For example, support from family, friends, physician or physical therapist? Preferred type of activity Do you prefer performing a certain type of physical also activity? Physical activity: Physical activity was measured with a triaxial accelerometera. Participants were instructed to wear the small device around their waist continuously for one week, except during showering and swimming. The device is able to detect types of activity (lying, sitting, standing, shuffling, and locomotion) and to measure steps and energy expenditure. It has been shown to be an accurate instrument to measure postures and gait in older adults and people with COPD (Dijkstra et al

2010, Langer et al 2009). Other measurements: Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were measured by trained lung function technicians with a spirometerb according to European Respiratory Society/American Thoracic Society guidelines ( Miller et al 2005). Dyspnoea severity was determined by the modified Medical Research Council dyspnoea index ( Bestall et al 1999). Exercise capacity was measured with the 6-minute walk test ( ATS 2002). Two 6-minute walk tests with at least one hour in between were performed to account for a training effect and the higher score was used in the analyses. All measurements were performed over three study visits. At Visit 1, participants were interviewed at home. During Visit 2 at the hospital, lung function was measured and the accelerometer was explained.