Study aim: The effect of pulmonary rehabilitation with progressive muscle relaxation exercise on patient suffering from COVID-19 after hospital discharge Design: Clinical trial with control group, two parallel groups, double blind, randomized, phase three, among 52 participants, permuted block randomization method will be used for random allocation. (trial phase dose not apply for this study) Settings and conduct: Study place: Internal ward of Shahid Beheshti Hospital in Qom. Blinding: double blind (participants and assessor blindness), Evaluator and patients in the study will be blinded during the entire process. The evaluator will be unaware of the study objectives and the randomized distribution of patients to study groups and will not have access to the randomization sequence. Participants/Inclusion and exclusion criteria: Inclusion criteria: COVID-19 confirmed with PCR test and discharged from hospital (at least six days after the onset of symptoms); patients who have the ability read and write in Persian and access to the Internet and video call service. Exclusion criteria: Severe heart condition such as uncontrolled arrhythmias, Chronic pulmonary and kidney condition, severe neurological condition, uncontrolled diabetes or hypertension; Smoker; Athlete; pregnant women Intervention groups: In the intervention group, pulmonary telerehabilitation will be recived with progressive muscle relaxation exercises. Pulmonary rehabilitation includes breathing exercises, aerobic and resistance exercises. The relaxation exercise is based on Jacobsen's summarized method. The active control group receives only pulmonary telerehabilitation. The duration of the intervention in each group is six weeks and the exercises are supervised by the physiotherapist through video call twice a week. Main outcome variables: Exercise capacity