Reasons for Exercise Intolerance in Patients with Chronic Obstructive Pulmonary Disease

Abstract

Exercise hyperpnoea is the consequence of the interaction of chemical, neural, muscular, haemodynamic and mechanical processes. The exact nature of the symptoms limiting exercise in chronic obstructive pulmonary disease (COPD) patients is not fully understood. Exercise limitation in COPD patients is generally attributed to a combination of abnormalities of ventilatory mechanics, respiratory muscle function, alveolar gas exchange, and cardiac function. COPD patients demonstrate widely variable exercise capacities, even among patients with similar levels of disease severity and it is likely that different factors are responsible for exercise limitation in different patients. The poor relationship between measurements of pulmonary function and exercise tolerance in COPD patients suggest the importance of non-cardiopulmonary factors in limiting exercise tolerance. The exact cause of exercise limitation in COPD patients is not fully understood and the attribution of limitation should be made with caution.