Reproducibility and discriminant validity of the Posterior Shoulder Endurance Test in healthy and painful populations

Objective: This investigation measured the reproducibility and discriminant validity of the Posterior Shoulder Endurance Test (PSET) on painful and non-painful populations. Design: Reliability and validity study. Setting: Laboratory setting. Participants: Thirty subjects (male = 11; female = 19). Main outcome measures: Time to failure (TTF) was the primary outcome measure to determine reliability of the PSET. Discriminant validity identified with receiver operator characteristic (ROC) curves utilized TTF separately in men and women since they used different loads. Results: There were 25/30 subjects (painful = 12; non-painful = 13) tested a second time. ICC, SEM, and MDC90 ranged respectively from 0.77, 13.1 s, 30.6 s in the painful group to 0.85, 7.3 s, 17 s in the non-painful group. The male ROC curve AUC was 0.833 with 47 s resulting in the best combination of sensitivity = 0.833, and specificity = 0.80. The female ROC curve AUC was 0.633 with 46 s resulting in the best combination of sensitivity = 0.600 and specificity = 0.889 at 46 s. Conclusion: The PSET is a reliable way to measure shoulder girdle muscular endurance. These data suggest that the PSET discriminates painful and non-painful individuals better in men compared to women.