Inclusion Criteria:  Between the ages of 18-60 Contracted COVID-19 between February - July 2020 Has been clinician-diagnosed with COVID-19 based on PCR/antigen testing, antibody testing, or clinical symptoms Is currently experiencing one or more of the following symptoms, which began only after contracting COVID-19 : dyspnea, cough, chest pain, tachycardia or other arrhythmias, hypertension, hypotension, blood pressure lability, oxygen desaturation, exercise/activity intolerance, fatigue, or dizziness. Has been cleared by a physician for exercise and supplemental oxygen. Has the capacity to provide written, informed consent Able to complete questionnaires in English  Exclusion Criteria:  History of any of the following per the American College of Sports Medicine exercise testing guidelines (American College of Sports Medicine et al., 2018) to be determined during a screening consultation:  Acute myocardial infarction within the past two days Ongoing unstable angina Uncontrolled cardiac arrhythmias Active endocarditis Symptomatic severe aortic stenosis Decompensated heart failure Active pulmonary embolism, pulmonary infarction, or deep venous thrombosis Active myocarditis or pericarditis Acute aortic dissection Physical disability that precludes safe and adequate testing Participants who demonstrate orthostatic intolerance or oxygen desaturation (<90%) during the exercise tolerance test will no longer be eligible for the study because it is not safe for them to exercise on a treadmill.