Abstract: Middle East J Rehabil Health Stud. 2021 October; 8(4):e114607. doi: 10.5812/mejrh.114607. Published online 2021 September 22. Research Article Evaluation of the Relationship Between Daily Physical Activity Level and Laboratory Factors and the Length of Hospitalization in Patients with COVID-19 Fatemeh Ehsani 1 1 , Sara Reshadat 2 , Noushin Masoudian 2 and Rasool Bagheri 1, * Neuromuscular Rehabilitation Research Center, Semnan University of Medical Sciences, Semnan, Iran Neurology Ward, Department of Internal Medicine, Kosar Hospital, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran 2 * Corresponding author: Neuromuscular Rehabilitation Research Center, Semnan University of Medical Sciences, Semnan, Iran. Email: rasool.bagheri@ymail.com Received 2021 March 14; Revised 2021 August 14; Accepted 2021 August 21. Abstract Background: Different degrees of disorders are reported in the respiratory, physical, and psychological functions of patients with corona virus disease 2019 (COVID-19). With the experience of improved and discharged COVID-19 patients, physical activity and sports are considered as one of the factors in controlling chronic mental and physical illnesses. Objectives: This study was aimed at investigating the impact of the level of physical activity on some important clinical parameters and convalescence. Methods: Overall, 71 patients with COVID-19 under the age of 65 years admitted to the hospital with positive PCR were included in the study. Based on Beck’s questionnaire, patients were divided into two groups of (1) low and (2) moderate to high physical activity. The duration of hospitalization and some important clinical tests were examined at the time of hospitalization and discharge. The patients were then monitored until discharge. Results: Statistical analyses showed that people with moderate to high physical activity were discharged earlier than the group with low physical activity (P < 0.01). Moreover, patients with moderate to high physical activity had lower erythrocyte sedimentation rate than the group with low physical activity at discharge (P = 0.01). Conclusions: Moderate to high physical activity can significantly reduce the length of hospitalization by improving the immune system to fight COVID-19. However, the factors that can be examined in expressing the reason for this finding need further studies. Keywords: COVID-19, Convalescence, Physical Activity 1. Background More than 55 million confirmed cases of corona virus disease 2019 (COVID-19) have been reported so far. COVID19 as a novel coronavirus infection can cause flu-like symptoms, such as fever (89%), cough (68%), fatigue (38%), sputum production (34%), dyspnea (19%), and pneumonia (15). Severe acute respiratory syndrome (SARS) following COVID-19 is an emerged respiratory disease that exacerbates the rate of mortality (2). Overall, the rate of mortality in this disease is reported 3 - 5%, which is severely higher than the rate of mortality of flu disease (0.1%). Therefore, the identification of preventive factors for decreasing the respiratory symptoms and the rate of mortality following COVID-19 is critical. There is evidence that having regular physical activity and daily exercise is one of the main factors of control- ling chronic diseases (6-8). Doing regular exercise can improve the cardiovascular system, respiratory capacity, and immune system (2, 6, 9). In addition, some studies reported that the rate of..