Comparison of the exercise capacity, respiratory muscle strength, pulmonary function, muscle oxygenation, and dyspnea in patients with post-COVID-19 syndrome with mild and moderate functional limitations

BACKGROUND AND AIM: Hypoxia, dyspnea, and respiratory function abnormalities take place in patients following coronavirus disease 2019 (COVID-19) due to pulmonary involvement. Moreover, abnormalities in skeletal and respiratory muscles negatively affect exercise capacity. In this study, exercise capacity, respiratory and peripheral muscle strength, pulmonary function, muscle oxygenation, and dyspnea were compared in patients with mild and moderate functional limitations who had post-COVID-19 syndrome. METHODS: In this study, patients with moderate functional limitations with post-COVID-19 syndrome were included on the basis of the Post-COVID-19 Functional Status Scale (PCFS) score 2 mild (n=15) and PCFS score 3 (n=20). Respiratory muscle strength (mouth pressure device), exercise capacity (6min walk test [6-MWT)], pulmonary function (spirometry), peripheral muscle strength (dynamometer) and muscle oxygenation (Moxy (R) device), dyspnea during daily living activity [London Chest Activity of Daily Living Scale [LCADL)] were evaluated. RESULTS: Patients with moderate functional limitations with post-COVID-19 syndrome had statistically lower maximal inspiratory and expiratory pressures, 6-MWT distance, and pulmonary function parameters (peak expiratory flow, forced expiratory flow 25%-75%) when compared to those with mild functional limitations (p<0.05). Muscle oxygen saturation, quadriceps femoris muscle strength, LCADL total, and all sub -parameters scores were similar in both groups (p>0.05). CONCLUSIONS: Patients with post-COVID-19 syndrome with moderate functional limitations have less respiratory muscle strength, exercise capacity, and more exertional dyspnea and airway obstruction than those with mild functional limitations. The effects on muscle oxygenation, lower extremity muscle strength, and dyspnea during activities of daily living are similar. Decreased exercise capacity and dyspnea in patients with moderate functional limitations may be associated with decreased respiratory muscle strength. Patients with post-COVID-19 syndrome should be evaluated according to their functional status, and exercise should be planned according to their limitations.