COPD heart puzzle: study aims to uncover hidden strain

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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 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%; uncontrolled arrhythmia; pulmonic, mitral or aortic valvular abnormality greater than mild in severity; tricuspid regurgitation greater than moderate in severity) * 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 * Untreated severe obstructive sleep apnea and/or obesity hypoventilation syndrome * Active malignancy (other than skin) * Medical conditions that limit exercise on an upright stationary bicycle (e.g. severe osteoarthritis, imbalance/gait instability, etc.) * Pregnancy * Body mass index \<18 or \>35 * Hematocrit \<25% or \>55% * For subset undergoing right heart catheterization, chronic anticoagulation that is unable to be held for the study visit * For subset undergoing right heart catheterization or exercise training, forced expiratory volume in 1 second of \<20% * For exercise training, already engaged in routine exercise training (\>30 minutes at \>3 METs 3 times/week or more) * For exercise training, 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 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.).