REmotely Monitored, Mobile Health-Supported High Intensity Interval Training after COVID-19 critical illness (REMM-HIIT-COVID-19)

REmotely Monitored, Mhealth (REMM) supported High Intensity Interval Training (HIIT to improve recovery after Intensive Care Unit (ICU) discharge in patients with COVID-19 (REMM-HIIT-ICU-COVID) will evaluate the feasibility of clinical-, physiological- and patient-centered outcomes associated with a remotely monitored, Mhealth-supported high intensity interval rehabilitation exercise training to improve the functional recovery of survivors who have experienced critical illness with COVID-19 and have been discharged home from the hospital.

Inclusion Criteria:

1. Age >= 18 years
2. ICU admission and subsequent discharge for primary diagnosis of COVID-19 respiratory failure or infection requiring intubation and mechanical ventilation for > 48 hours with an ICU length of stay of ≥ 4 days.
3. Ability to ambulate with or without a gait aid prior to hospital discharge
4. Expected hospital discharge directly back to patient's residence (not to a skilled nursing facility, inpatient rehabilitation center, or long-term acute care hospital)

Exclusion Criteria:

1. Not ambulating independently prior to COVID-19 illness (use of a gait aid permitted)

2. Functional impairment resulting in inability to exercise at hospital discharge (including need for home oxygen requirement)

3. Unable or unwilling to follow coaching via mobile-health iPhone interaction

4. Any absolute contraindications to exercise (as outlined in the American Thoracic Society Guidelines for Cardiopulmonary Exercise Testing), including but not limited to:

   1. Recent (< 5 days) acute primary cardiac event
   2. Unstable Angina
   3. Uncontrolled dysrhythmias causing symptoms or hemodynamic compromise
   4. Symptomatic aortic stenosis
   5. Uncontrolled symptomatic heart failure
   6. Acute myocarditis or pericarditis
   7. Suspected or known dissecting aneurysm