Inclusion Criteria:  Participants recovered from mild to moderated signs and symptoms of COVID- 19 after one month. Ability to perform pulmonary function tests correctly. COVID-19 was diagnosed by positive polymerase chain reaction (PCR) testing on nasopharyngeal swab, oxygen saturation was ranged between 92-96% during illness period. CT chest shows ground glass opacity. Their D-dimer was less than 0.5 μg/ml. Two successive negative PCR were before included in study. Participants were in home isolation during illness period.  Exclusion Criteria:  Chronic respiratory disease. Chronic heart disease. Diabetes mellitus. Smoking. Centralized isolation. Severe COVID-19.