Chronic obstructive pulmonary disease (COPD) is a common smoking-related lung disease. Patients with COPD are at increased risk of developing cardiovascular disease such as heart attacks and strokes. A simple measurement called arterial stiffness is a good assessment of how likely people are to have cardiovascular disease, both in healthy populations and those with COPD. Aortic Pulse wave velocity (aPWV) measures arterial stiffness,

Pulmonary Rehabilitation (PR) - a 6 week supervised group exercise and education class - is an effective intervention in COPD to reduce symptoms, improve exercise performance and prevent exacerbations. However, the effect of PR on cardiovascular risk in COPD is controversial as two small positive studies suggested benefit and one larger study did not.

Investigators have recently shown that cardiovascular risk is higher in those COPD patients who get the most infections (exacerbations). PR is an effective intervention for preventing COPD exacerbations. Logically, the exercise component would be expected to reduce cardiovascular risk too.

Investigators want to identify which patients with COPD get cardiovascular benefit from a PR programme and why others do not. Investigators propose to measure aPWV before and after PR. Investigators will then classify participants as responders or non-responders defined as the presence or absence of a significant improvement in aPWV. Investigators will be collecting demographic and clinical information including daily physical activity level and how effective the PR has been to enable the investigators to identify the characteristics of patients who do, and do not achieve cardiovascular risk reduction in response to PR in COPD. This will inform on better design of PR programmes for people living with COPD.

Inclusion Criteria:

• Patient diagnosed with COPD. The patient must be referred to PR from his/her physician with spirometry results confirming that he/she has chronic obstructive pulmonary disease (defined as post-bronchodilator FEV1/VC <0.70 and a compatible exposure history).
• Ability to exercise.

Exclusion Criteria:

• Neuromuscular diagnosis.
• Patient involved in any ongoing drug intervention study.