Inter-rater reliability of baseline push-pull dynamometer for shoulder and scapular muscle strength testing among healthy individuals

Inter -rater reliability of push‒pull dynamometers (PPDs) are essential to ensure consistent and accurate measurements in laboratory and clinical settings. The objective of this study is to evaluate the inter-rater reliability of the Baseline® PPD in testing shoulder and scapular muscle strength among healthy individuals. This study included 35 healthy individuals who underwent standardized independent shoulder and scapular muscle strength testing by two raters using Baseline® PPD. Inter-rater reliability for muscle strength measurements ranged from moderate to good (ICC = 0.53–0.90). The SEMs for the push and pull muscle strength tests ranged from 2.2 to 5.8 N and 3.1 to 4.9 N, respectively. The MDC (95% CI) ranged from 6.09 to 15.06 for the push strength tests and 8.58 to 13.57 for the pull strength tests. Bland‒Altman plots revealed no systematic bias for most PPD tests, except for the push muscle strength of the serratus anterior, upper trapezius, and external rotators. The Baseline® PPD demonstrated acceptable inter-rater reliability and agreement for assessing shoulder and scapular muscle strength among healthy individuals. Further studies are warranted to evaluate its reliability in athletes and individuals with shoulder disorders to expand its clinical and research applications. Clinical Trial Registry of India number :(CTRI/2023/07/055409)