Uncertainty persists regarding the usefulness of incorporating inspiratory muscle training (IMT) in pulmonary rehabilitation programs for patients with chronic obstructive pulmonary disease. In this study the investigators investigate whether IMT associated with exercise training would be better than exercise training alone, with regard to exercise capacity, inspiratory muscle strength and dyspnea.

Study design: A double-blind parallel controlled trial Setting: outpatient clinic Inclusion criteria: Subjects between 40 and 75 years of age referred by a physician to the Pulmonary Rehabilitation Program, with a clinical and spirometric diagnosis of moderate to severe COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD).

Outcome measurements: Inspiratory muscle strength (using maximal inspiratory pressure, MIP), exercise capacity (using six-minute walk test) and dyspnea were measured.

Inclusion Criteria:

• Subjects with a clinical and spirometric diagnosis of moderate to severe COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD)
• In a stable condition (without exacerbations or infections for at least a month)
• Had to be former smokers (> 6 months without smoking)
• subjects referred by a physician to the Pulmonary Rehabilitation Program

Exclusion Criteria:

• Subjects with a known history of asthma, or severe and/or unstable heart disease or any other pathological condition that could impair their physical activities