Physical activity (PA) and exercise are interrelated but separate concepts. PA refers to bodily movement

produced by skeletal muscles that results in energy expenditure. Exercise is a subset of PA, in which

generally higher levels of muscular activity are performed for a purpose, such as achieving physical fitness

or winning a sporting contest. Higher exercise capacity is considered to be permissive of greater PA in

the home and community settings. Individuals with chronic obstructive pulmonary disease (COPD) are

physically inactive when compared with healthy age‑matched control subjects. Furthermore, physical

inactivity is independently associated with adverse outcome in patients with COPD, including more rapid

disease progression, impaired health status, and increased health care utilization and mortality risk. While

there are several methods to objectively measure PA, recent scientific studies have commonly utilized

questionnaires and activity monitors. The latter include simple pedometers and complex accelerometers,

which can measure and record movement in up to 3 planes. In COPD, multiple patient characteristics and

disease severity markers are related to activity level, including pulmonary physiological abnormalities

such as airway obstruction and hyperinflation; exercise capacity such as the 6‑minute walking distance;

exacerbations of respiratory disease; and comorbid conditions. Clinical trials of bronchodilators, supplemental

oxygen therapy, exercise training or pulmonary rehabilitation, or PA counseling have provided

inconsistent results in demonstrating increased PA from the interaction. This is probably because the

phenomenon of physical inactivity is complex, resulting not only from physiological impairments, but

symptoms, cultural, motivational, and environmental factors.