Continuous Versus High Intensity Interval Exercise in Chronic Obstructive Pulmonary Disease

Inclusion Criteria: * Clinical diagnosis of COPD based on smoking history (pack/years) or exposure to other risk factors and post bronchodilation forced expiratory volume (FEV1) to forced vital capacity (FVC) ratio \<0.7 * Resting arterial oxygen partial pressure at room air \>60 mmHg, according to recent (within a week) arterial blood gases assessment * Disease being stable and treated optimal, based on current GOLD guidelines. * Provision of informed written signed consent prior to study entry Exclusion Criteria: * Recent respiratory infection or exacerbation (as indicated by deterioration of respiratory symptoms, hospital admission and/or change in medication within the previous month), within the past 3 months * Changes in COPD medication with the past month * History of asthma and/or reversible airway obstruction (post bronchodilation FEV1/ FVC \>0.7) * Pulmonary hypertension * Congestive heart failure (Left Ventricle Ejection Fraction \<50% in recent echocardiography) * Severe peripheral artery disease * Chronic Kidney disease with eGFR \< 30 ml/min (KDIGO stages 3b, 4 ,5) * Active acute or chronic infectious diseases * Active malignant disease or hematologic disorder under treatment * History of neuromuscular disorder * History of severe intellectual disability or mental disorder * Any contradiction to moderate-high intensity exercise or cardiopulmonary exercise testing according to ATS/ACCP guidelines, such as: myocardial infarction within the past 6 months, unstable angina, syncope, symptomatic severe aortic stenosis, uncontrolled arrhythmias causing symptoms or hemodynamic compromise, acute pulmonary embolus or pulmonary infarction, thrombosis of lower extremities, suspected dissecting aneurysm, pulmonary edema, severe untreated arterial hypertension at rest (\> 200 mm Hg systolic, \> 120 mm Hg diastolic blood pressure), orthopedic impairment that compromises exercise performance.