Exercise Limitation in Chronic Obstructive Pulmonary Disease

The inability to engage in the usual activities of daily living is one of the most distressing experiences of people afflicted with chronic obstructive pulmonary disease (COPD). Exercise intolerance progresses relentlessly as the disease advances, contributing to reduced quality of life. It has become clear that in COPD, exercise intolerance ultimately reflects complex integrated abnormalities of the ventilatory, cardiovascular, peripheral muscle and neurosensory systems that vary in degree from patient to patient. Ventilatory limitation and perceived respiratory difficulty are often the dominant contributors to exercise curtailment in more advanced disease, but not necessarily the only ones. Recently, there has been great interest in the role of cardiovascular and peripheral muscle dysfunction (and their interaction) in exercise limitation in COPD. In this review, we examine in some detail the pathophysiological derangements that are evident during exercise in COPD with the hope of identifying specific mechanisms that are amenable to therapeutic manipulation. Keywords: COPD, exercise, ventilatory mechanics, dyspnea, dynamic hyperinflation, muscle dysfunction, energy metabolism