Reliability of measures of scapular protraction strength in the supine and seated positions.

[Purpose] The purpose of this study was to investigate the intra-rater reliability of measures of scapular protraction strength using a novel method. [Subjects] Forty-nine healthy subjects participated in this study. [Methods] Subjects performed maximal isometric scapular protraction on the left and right sides in the supine and seated positions. During scapular protraction, resistance was applied to the olecranon, and the strength of scapular protraction was measured using a load cell. Intra-rater reliability was calculated as the intra-class correlation coefficient (ICC3,1). [Results] High intra-rater reliability scores (0.97-0.98) for scapular protraction strength were observed in the supine and seated positions. [Conclusion] These findings demonstrate that the method described herein may provide a more reliable and convenient method to measure scapular protraction strength than common current practice does.