The purpose of this study is to examine whether breathing helium-hyperoxia during exercise in a pulmonary rehabilitation program can improve the exercise tolerance and health related quality of life of patients with Chronic Obstructive Pulmonary Disease (COPD).

It is well accepted that the exercise training as part of a comprehensive pulmonary rehabilitation program can improve exercise tolerance, functional status and quality of life in patients with COPD. It is feasible that if patients were able to perform a greater volume or intensity of exercise during rehabilitation then the outcomes of the program would be improved. Recent research has demonstrated that breathing a helium-hyperoxic gas mixture can significantly reduce dynamic hyperinflation and dyspnea during exercise in patients with COPD and can increase exercise tolerance to a greater extent than breathing room air or a nitrogen-based hyperoxic gas. If patients with COPD were to breathe a helium-hyperoxic gas during exercise they should be able to tolerate a greater intensity of exercise while maintaining similar levels of exertional symptoms to those observed at lower exercise intensities breathing room air. As a result patients randomized to the helium-hyperoxia condition should obtain greater improvements in exercise tolerance than those receiving usual care (i.e. breathing room air)

Comparisons: Standard pulmonary rehabilitation of patients with COPD receiving either usual care (air breathing) or helium-hyperoxia (40% O2, 60% Helium).

Inclusion Criteria:

• FEV1/FVC<70% predicted;
• FEV1<70% predicted;
• RV>140% predicted.

Exclusion Criteria:

• Cardiovascular contraindications to exercise;
• Musculoskeletal abnormalities that limit exercise tolerance;
• SpO2<85% during a constant work rate test;
• On supplemental oxygen.
• Exacerbation within the last month