Intra-Rater Reliability of 30 s Sit-To-Stand and Timed-Up-and-Go Tests in Older Adults with Post-COVID-19 Syndrome: A Pilot Study

Background: Post-COVID-19 syndrome (PCS) is associated with impairments in mobility, balance, and physical function, which may reduce quality of life. The 30 s Sit-to-Stand (30STS) and Timed Up and Go (TUG) tests are widely used clinical measures; however, their intra-rater reliability in older adults with PCS has not been established. Reliable outcome measures are essential for clinical assessment and rehabilitation planning. Methods: In this single-center pilot study, nineteen older adults with PCS were recruited as a convenience sample. Participants completed three trials of the 30STS and TUG tests on day one, with the protocol repeated after three days. The 30STS evaluates lower-limb strength and functional performance, while the TUG assesses balance, gait, and fall risk. Intra-class correlation coefficient (ICC), standard error of measurement (SEM), and minimum detectable change (MDC) were calculated. Results: The TUG showed an ICC of 0.995 (95% CI: 0.991–0.998), SEM of 0.48 s, and MDC of 1.33 s. The 30STS showed an ICC of 0.986 (95% CI: 0.973–0.994), SEM of 0.26 repetitions, and MDC of 0.72 repetitions. Conclusions: The TUG and 30STS demonstrate excellent intra-rater reliability and appear to be feasible clinical tools for assessing functional performance in older adults with PCS. However, findings should be interpreted cautiously due to the small, single-center pilot design and single evaluator. Further research is needed to confirm generalizability across broader PCS populations and clinical settings.