© 2021 A. CARBONE Editore. All rights reserved.Introduction: To evaluate PCR-positive COVID-19 patients' aerobic capacities during the active disease period and in the 3rd month after treatment and determine the demographic and disease characteristics associated with it. Materials and methods: The study is a prospective, cross-sectional analysis conducted on 123 PCR positive inpatients. The study involved a total of 99 patients who completed follow up. Patients' demographic and disease characteristics, Nord -Trøndelag Health Study Physical Activity Level for Work (HUNT), were compared in terms of aerobic capacity (6-minute walking test) at treatment onset and third month and the change between these two measurements. In addition, demographic and disease characteristics of patients were grouped according to age (18-29, 30-59, 60-64 and >65 years), gender, BMI (<18.5%, 18.5%-24.9% and overweight ≥25%), comorbidities, smoking, level of work physical activity (sedentary, mild, moderate and severe) duration of hospital treatment, presence of pneumonia and oxygen requirement, and compared in terms of aerobic capacity at treatment onset and third month and the change between these two measurements. Results: Older age (r:-0.573, p=0.001 and r:-0.488, p=0.001, respectively), the presence (r:-0.322, p=0.001 and r:-0.238, p=0.017, respectively) and number of comorbidities (r:-0.367, p=0.001 and r:-0.257, p=0.010, respectively), oxygen requirement (r:-0.510, p=0.001 and r:-0.439, p=0.001, respectively), and pneumonia presence (r:-0.693, p=0.001 and r:-0.607, p=0.001, respectively) were negatively correlated with aerobic capacity at treatment onset and third month, and positively correlated with smoking (r:0.385, p=0.001 and r:0.416, p=0.001, respectively) and physical activity level (r:0.698, p=0.001 and r:0.624, p=0.001, respectively). The patients with heavy physical activity had significantly higher aerobic capacity than other levels. Conclusion: The higher aerobic capacity and aerobic capacity change may be correlated with the higher work activity level before the illness. Continuing physical activity, even at home, will promote recovery after the illness.