Exercise in chronic obstructive pulmonary disease

Abstract

Dyspnoea and exercise limitation are among the most common symptoms experienced by patients with chronic obstructive pulmonary disease (COPD) and are linked to poor perceived health status and increased mortality. Cardiopulmonary exercise testing (CPET) provides a unique opportunity to objectively evaluate the ability of the respiratory system to respond to measured physiological stress across the spectrum of disease severity. In symptomatic mild COPD, the combined abnormalities of increased wasted ventilation leading to increased ventilatory demand and critical erosion of the dynamic inspiratory reserve volume lead to intolerable respiratory discomfort and early exercise limitation. In moderate-to-severe COPD, these major physiological abnormalities that culminate in pronounced demand-capacity imbalance of the respiratory system and dyspnoea become further amplified and are evident at relatively low exercise intensities. In this group, exercise intolerance is often further compounded by the effects of generalized skeletal muscle deconditioning and worsening cardio-circulatory dysfunction. Last but not least, significant dynamic lung hyperinflation on exertion has recently been demonstrated in asymptomatic subjects with mild airway obstruction. It goes without saying that identification of specific physiological derangements exposed by CPET facilitates an individualized approach to management in COPD.