Time of Exercise Re-training With Chronic Obstructive Pulmonary Disease (COPD)

This study is comparing the effects of exercising in the morning versus the evening as part of a pulmonary rehabilitation program for people with COPD (chronic obstructive pulmonary disease, a condition that makes breathing difficult). **You may be eligible if...** - You are 18 or older - You have been diagnosed with COPD - You are enrolled in a respiratory rehabilitation program with at least 18 sessions over 4 weeks - You are covered by social security **You may NOT be eligible if...** - You have heart conditions that make exercise unsafe - You have other health conditions that prevent participation in a rehabilitation program - You are unable to provide written informed consent Talk to your doctor to see if this trial is right for you.