Daily physical activity after bronchoscopic lung volume reduction: a pilot study.

Daily physical activity is an important outcome variable in patients with chronic obstructive pulmonary disease (COPD) and has shown to be mainly associated with dynamic lung hyperinflation [1]. Physical inactivity is known to cause muscle deconditioning, which increases the ventilatory requirements during exercise, and in turn increases lung hyperinflation and worsens dyspnoea, thus contributing to a downward spiral [2]. This is especially true in patients with emphysema, in which destruction of alveolar tissue can result in progressive static and dynamic lung hyperinflation. Moreover, physical inactivity is a strong predictor of mortality in COPD patients [3]. Notwithstanding the beneficial effects of regular physical activity, physical activity levels in COPD patients are low, especially in those with severe COPD [4].