Assessment of Exercise Capacity of Individuals with Long COVID: A Cross-sectional Study

Background: Clinical investigations of long-term effects of coronavirus disease 2019 (COVID-19) are rarely translated to objective findings. Objectives: To assess the functional capacity of individuals reported on deconditioning that hampered their return to their pre-COVID routine. Methods: Assessment included the 6-minute walk test (6MWT) and the 30-second sit-to-stand test (30-STST). We compared the expected and observed scores using the Wilcoxon signed-rank test. Predictors of test scores were identified using linear regression models. Results: We included 49 individuals, of whom 38 (77.6%) were recovering from mild COVID-19. Twenty-seven (55.1%) individuals had a 6MWT score lower than 80% of expected. The average 6MWT scores were 129.5 ±121.2 meters and 12.2 ± 5.0 repeats lower than expected scores, respectively (P< 0.001 for both). The 6MWT score was 107.3 meters lower for individuals with severe COVID-19 (P = 0.013) and rose by 2.7 meters per each 1% increase in the diffusing capacity of carbon monoxide (P = 0.007). The 30-STST score was 3.0 repeats lower for individuals who reported moderate to severe myalgia (P = 0.038). Conclusions: Individuals with long COVID who report on deconditioning exhibit significantly decreased physical capacity, even following mild acute illness. Risk factors include severe COVID-19 and impaired diffusing capacity or myalgia during recovery.