The purpose of this study was to compare the effect of exercise treatment combined with breathing retraining (a computerized feedback program), with exercise treatment combined with heliox (a helium and oxygen combination), with exercise only in patients with moderate to severe chronic obstructive pulmonary disease. This was an 8-week intervention study.

Dynamic hyperinflation limits exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Recently, several innovative approaches have been developed to reduce the burden of dynamic hyperinflation. Two such innovations, ventilation-feedback training and Heliox supplementation during exercise show great promise and posit a reduction in dynamic hyperinflation as a key to their effectiveness. In our recently completed trial, when age, FEV1 and RV/TLC were controlled, exercise plus VF (E+VF) was superior to E training alone (E only) or VF training alone in improving exercise tolerance. The mechanism responsible for this difference was, in part, a reduction in exercise-induced dynamic hyperinflation secondary to a change in breathing pattern. In additional preliminary studies, we determined that exercise tolerance can be increased when patients exercise while inhaling Heliox. Similar to VF, the mechanism for exercise improvement with Heliox was a reduction in exercise-induced dynamic hyperinflation. Although both interventions are promising, there are no definitive data to support use of either intervention as a standard of care for pulmonary rehabilitation.

Hypothesis/Research Questions Overview: The two primary hypotheses are that patients with moderate-severe COPD who successfully complete eight weeks of (a) E+VF training will achieve longer exercise duration than patients randomly assigned to E only and (b) E+heliox training will achieve longer exercise duration than patients randomly assigned to E only.

Methods: This study was a randomized controlled clinical trial. After baseline testing is completed, 103 subjects with moderate-severe COPD were randomized into one of three groups: E+VF, E+Heliox and E training only. Follow-up testing was completed at 8 weeks. testing, activity monitoring, and dyspnea measurements. After baseline testing was completed, randomized subjects trained in the Physical Performance Laboratory three times weekly. Exercise prescriptions were standardized and based on data from the exercise stress test.

Inclusion Criteria:

• 40 years of age
• FEV1 70%
• FEV1/FVC <70%
• RV/TLC > 120%

Exclusion Criteria:

• Respiratory infection/exacerbation within last 4 weeks
• Exercise limiting heart disease
• Primary asthma
• Congestive heart failure New York Heart Association (NYHA) Class III-IV
• Exercise limiting peripheral arterial disease or arthritis
• Inability to walk on a treadmill

Adverse events were collected during the time period that the patient was enrolled in the study. When the patient completed the study (after 14 week testing was completed), we stopped collecting adverse event information.