Intra-rater reliability, inter-rater reliability and minimal detectable change of the posterior shoulder endurance test in elite athletes

Objective: Investigate intra-rater and inter-rater reliability of the posterior shoulder endurance test (PSET) and calculate minimal detectable change (MDC) to establish measurement properties and inform use of the PSET in practice. Study design: Test-retest reliability. Setting: British Canoe Slalom National Training Centre. Participants: Twelve participants (7 male, 5 female; 22.5 +/- 4.48 years; 73.4 +/- 6.36 kg) were investigated by two physiotherapists with > 10 years' experience. Main outcome measure: Intraclass correlation coefficients (ICC) were calculated for intra-rater reliability (ICC 3,1) and inter-rater reliability (ICC 2,1) and used to calculate MDC. Results: Intra-rater reliability scores were 0.84 and 0.85 for rater A and B, respectively, with 95% confi-dence interval (CI) crossing moderate to excellent reliability for both raters (0.5-0.75 and > 0.9). Inter rater reliability scores were 0.74 and 0.63 at baseline and follow-up, respectively, with 95% CI crossing poor to good reliability in both time points (< 0.5 and > 0.75). MDC95% for intra-rater scores was 6 repetitions, MDC95% for inter-rater scores was 8 repetitions at baseline and 9 repetitions at follow-up. Conclusion: The PSET has acceptable intra-rater reliability but further work is needed to narrow the CI to an appropriate level for inter-rater reliability. The MDC calculated helps clinicians interpret changes in tests scores. (c) 2021 Elsevier Ltd. All rights reserved.