The Impact of Pulmonary Rehabilitation on Dyspnea in Chronic Obstructive Pulmonary Disease

Mechanisms of Dyspnea Relief Following Exercise Training in COPD

Dyspnea (respiratory discomfort) and activity limitation are the most common symptoms of chronic obstructive pulmonary disease (COPD) and contribute importantly to a perceived poor quality of life. Recent international guidelines have stressed the importance of dyspnea alleviation and improvement exercise tolerance as a means of enhancing quality of life and other long term outcomes in this population. Modern pharmacotherapy is the first step in symptom management but the overall impact of bronchodilator therapy is relatively small. Exercise training remains the most effective treatment for ameliorating dyspnea and improving exercise endurance and was the main focus of this study.

The main objectives of the study were:

1. To conduct and compare detailed studies of respiratory mechanics during cycle exercise before and after exercise training (EXT) compared with an untrained control group. By multiple regression analysis, the investigators will establish the main contributors to dyspnea relief after EXT.
2. To compare the magnitude of change in endurance during constant work rate cycle exercise with those measured during walk tests and the endurance shuttle walk test after EXT relative to control. To evaluate which test (constant work rate cycle, six-minute walk test, or endurance shuttle walk test) is the most sensitive test for measuring changes in endurance after EXT versus control.
3. To compare the change in standardized dyspnea ratings (Borg Scale) during constant-load cycling with a variety of other activity-related dyspnea questionnaires. To evaluate which of these measurements is the most sensitive for examining changes in perceived discomfort during exercise.
4. To evaluate the contribution of psychological factors (anxiety, fear, respiratory panic, self-efficacy) to the perceived improvement of symptoms following EXT. The investigators will use multiple regression analysis to examine associations between changes in perceived dyspnea and changes in anxiety and self-efficacy measured by validated questionnaires and Borg intensity ratings?

Inclusion Criteria:

• diagnosis of COPD
• clinically stable
• presence of activity-related dyspnea (Baseline Dyspnea Index < 9)
• 40-80 years of age

Exclusion Criteria:

• other significant disorders or diseases that could interfere with conduct of the intervention or tests
• body mass index < 18 or > 40 kg/m2