Commentary on: Inspiratory Muscle Training, with or without Pulmonary Rehabilitation, for COPD: A Critical Appraisal of a Cochrane Review

Abstract

Approximately 300 million people worldwide have COPD (1) with a global prevalence of between approximately 10-12.2% (2-4). COPD is a highly prevalent respiratory disease in the United Kingdom, ranking as the second most common lung disease, with approximately 1.2 million people diagnosed (5).

In COPD, oxidative stress and sarcomere injury lead to proteolysis and subsequent atrophy of the diaphragm, the main inspiratory muscle (6). The reduction in capacity of the respiratory muscles lead to a reduction in the body’s capacity to generate inspiratory pressures, thus reducing lung capacity and is thought to contribute to dyspnoea in adults with advanced COPD (7).

Respiratory muscle weakness is a modifiable weakness and can be targeted with interventions including variations in frequency and duration of Inspiratory Muscle Training (IMT) (8). Inspiratory muscle training uses resistance to challenge inhalation, stimulating respiratory muscles and potentially enhancing contractile force through hypertrophy (9). A previous Cochrane review examined the effectiveness of IMT, both with and without pulmonary rehabilitation, in increasing inspiratory muscle strength in individuals with COPD (10).