Test-Retest Reliability and Minimal Detectable Change in Chester Step Test and 1-Minute Sit-to-Stand Test in Long COVID Patients

The COVID-19 is a multiorgan disease that appeared in December 2019 in the Chinese province of Wuhan. It produces various clinical manifestations, although it mainly affects the respiratory system. Given these potentially detrimental long-term consequences of COVID-19, an appropriate assessment must be carried out to plan early rehabilitation interventions. To assess the persistent symptoms it produces, as well as exercise tolerance for a given exertion, stress testing is a feasible and cost-effective option. Therefore, the objective of this study was to provide test-retest reliability for the Chester Step Test and 1 minute Sit to Stand tests and to establish the minimum detectable change in Long-COVID patients. Method: This observational, descriptive, cross-sectional study was conducted following the STROBE guidelines. A total of 42 patients carried out, twice per partici-pant, the Chester Step and 1-Minute Sit-to-Stand (1min-STST) tests on two different days, with a five-day time lag between the initial measurement and the second measurement. Results: The Test-retest reliability for the Chester Step was excellent within session ICC (95% CI) 0.96 (0.93 to 0.98), being even better for the 1-STST, ICC (95% CI) 0.98 (0.96 to 0.99). Establishing a change of at least 16.96 steps (MDC90) or 20.15 steps (MDC95) and 1.89 stands (MDC90) or 2.71 stands (MDC95), respectively. Conclusions: The Chester Step and 1min-STST tests are reproducible and reliable tools to measure exercise tolerance in long COVID patients. The minimum detectable changes observed in the values recorded by the participants can be very useful for the evaluation of the effectiveness of interventions applied to these patients.