Inclusion Criteria:

• COPD (determined by ratio of forced expiratory volume in 1 second to forced vital capacity [FEV1/FVC] <0.7) • Age >= 40 years

Exclusion Criteria:

• Exacerbation of COPD or use of systemic corticosteroids in the 3 months prior to enrollment
• Change in COPD therapy in the 3 weeks prior to enrollment
• Requirement of >6 LPM supplemental oxygen at rest
• Requirement of >10 LPM supplemental oxygen with exertion
• Active/uncontrolled cardiovascular disease (e.g. hypertension with blood pressure >150/100 despite antihypertensives; coronary artery disease with angina; left ventricular ejection fraction ≤40%; arrhythmia; pulmonic, mitral or aortic valvular abnormality greater than mildin severity; tricuspid regurgitation greater than moderate in severity; diabetes with HbA1c >8.5%)
• Volume overload (jugular vascular distension or greater than trace peripheral edema)
• World Health Organization Functional Class IV
• Known pulmonary hypertension with mean pulmonary artery pressure >45 mmHg
• Interstitial lung disease thought to be primary etiology of pulmonary hypertension
• Untreated severe obstructive sleep apnea or obesity hypoventilation syndrome
• Active malignancy (other than skin)
• Medical conditions that limit exercise on an upright stationary bicycle (e.g. osteoarthritis, imbalance/gait instability, etc.)
• Pregnancy
• Body mass index <18 or >35
• Hematocrit <25% or >55%
• For invasive CPET, chronic anticoagulation that is unable to be held for the study visit
• For invasive CPET or Part 2 exercise training, forced expiratory volume in 1 second of <20%
• For Part 2 exercise training, already engaged in routine exercise training (>30 minutes at >3 METs 3 times/week or more)
• For Part 2 exercise training, unwillingness/inability to complete initial in-person exercise training sessions for approximately 35 minutes 3x/week for 3 weeks (followed by exercise training sessions with an option for hybrid remote/in-person participation)
• For Part 2 exercise training with an option for hybrid remote exercise training, any medical conditions which threaten the safety of remote exercise training (e.g. imbalance/gait instability, etc.)