rehabilitation(7) COVID-19(7) IMPROVE(6) Effect(6) reported(5) Patient(5) rehabilitation.(4) electrical(4) maintain(4) neurological(4) Electrical Stimulation(4) Treatment(4) activities(4) Symptom(4) investigated(4) Prevent(4) Evidence(4) Neuromuscular(4) median(3) fatigue(3) affecting(3) dysfunction(3) Intervention(3) survivor(3) observation period(2) Volume(2) applied(2) enrolled(2) syndrome(2) blood flow(2)