Comparison of cardiopulmonary fitness level with normal values after COVİD-19 and evaluation of factors affecting physical capacity

Aim: SARS-CoV-2 is a new type of coronavirus detected in late 2019, and the disease caused by the virus is named COVID-19. Since it affects many organs and systems, especially the lungs, it is important to elucidate the long-term effects of COVID-19. The primary aim of the study was to reveal if any change occured in exercise capacity in individuals with a history of COVID-19 and to clarify its relationship with age, gender, physical activity level, disease severity, and comorbidities. The secondary aim of the study was to determine the causes of changes in exercise capacity and to define the objectives of rehabilitation programs. Materials and Methods: The demographic information, symptoms, medical conditions, and disease severity of the participants were recorded. The participants were assessed by the 6-minute walk test, pulmonary function tests, and cardiopulmonary exercise test, and physical capacity was determined by maximum oxygen consumption (VO2max). The participants were also assessed by the International Physical Activity Questionnaire (IPAQ). Results: 53, 44, 26, and 9 participants with mild, moderate, severe, and critical disease severity, respectively, were included. Fatigue, myalgia, and headaches were the most reported symptoms. Obesity, hypertension, and smoking were the most common medical comorbidities. IPAQ results showed that the physical activity levels of the individuals decreased after COVID-19. There was no significant difference regarding disease severity in terms of VO2max levels. There was no significant difference between the VO2max levels of the groups with different physical activity levels of subjects prior to COVID-19. Only in the mild disease severity group the VO2max levels of males were found to be significantly lower than those of females. There were no significant difference in predicted VO2max levels between the groups with and without obesity, hypertension, smoking, diabetes, or atherosclerotic heart disease and between the patients in different age groups. Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in first second (FEV1), and maximal voluntary ventilation (MVV) were found to be lower in the group with decreased exercise capacity. The group with decreased exercise capacity reached the anaerobic threshold earlier during the exercise test. A strong correlation was found between 6-Minute Walk Test walking distance and VO2max levels in COVID-19 patients. Conclusions: It was concluded that the reason for the decrease in exercise capacity of individuals with COVID-19 is primarily decreased physical activity and respiratory limitations. It has been shown that advanced age, low physical activity level and comorbidities, which have negative effects on the course of the disease, do not affect the predicted exercise capacity. It was concluded that rehabilitation programs for individuals with COVID-19 should be designed to prioritize improving functional lung capacities, respiratory muscle strength, and endurance. Key Words: 6-minute walk test, COVID-19, exercise tolerance, cardiopulmonary exercise test, respiratory function tests