Physical activity patterns in patients in different stages of chronic obstructive pulmonary disease

It has previously been suggested that exercise capacity is decreased in COPD and that it is associated with degree of disease. The reduced exercise capacity may plausibly be due to low levels of physical activity in this patient group. The aim of the present study was to assess exercise capacity and physical activity in different stages of COPD and to examine the associations between exercise capacity, pulmonary function and degree of physical activity. A total of 44 COPD patients and 17 healthy subjects participated in the study. Exercise capacity was assessed using the 6-minute walking test and physical activity was assessed using an accelerometer worn all waking hours during 7 days. Mean exercise capacity was significantly lower in COPD patients compared with healthy subjects. Mean physical activity level and time spent at least moderately active were significantly lower in patients with moderate and severe COPD compared with healthy subjects while no differences in time spent sedentary were observed between the study groups. Pulmonary function, mean physical activity level and time spent at least moderately physically active were significantly associated with exercise capacity in the patients. We conclude that patients with moderate and severe COPD are less physically active compared with healthy subjects. Furthermore, mean physical activity level and physical activity of at least moderate intensity are positively associated with exercise capacity in COPD, while time spent sedentary is not, which stresses an important role of physical activity on exercise capacity in these patients.