This study seeks to examine genome-wide DNA methylation patterns associated with physical activity and exercise capacity from peripheral blood collected from participants with chronic obstructive pulmonary disease (COPD) before and after participation in a structured 9-week outpatient pulmonary rehabilitation program.

Individuals who are referred to pulmonary rehabilitation IN THE COURSE OF THEIR USUAL CLINICAL CARE will be invited to participate in this observational study. Participants who enroll in the study will undergo two in-person visits, once before initiating pulmonary rehabilitation classes and once at the conclusion of pulmonary rehabilitation classes. Participation in this study will not alter the course of the participants' usual clinical care.

Inclusion Criteria:

• Age >40 years
• Diagnosis of COPD (defined as an FEV1/FVC<0.7 or evidence of emphysema on radiologist's read of a chest CT obtained in the course of patient's usual care)
• Referral to and participation in the VA Boston Pulmonary Rehabilitation program

Exclusion Criteria:

• Active or unstable cardiac disease
• Inability to ambulate > 1 block
• Recent acute exacerbation of COPD (defined as new or increased dose of systemic steroids and/or antibiotics for pulmonary indications)

This study will recruit from Veterans referred to the VA Boston Pulmonary Rehabilitation Program who have a confirmed diagnosis of COPD.

Individual level data will be entered into an approved research repository behind the VA firewall. Data will be shared with qualified researchers (see below)

3 years

Prospective researchers must complete VA-required trainings in HIPAA, information security, and CITI training.