Establishing normative data on scapulothoracic musculature using handheld dynamometry

Context: Scapular strength deficits have been linked to shoulder dysfunction. Objective: To establish normative data on the scapulothoracic musculature in normal subjects using a handheld dynamometer. Design: Descriptive normative data study. Setting: Field research. Subjects: 172 subjects with varying levels of overhead activity. Methods: A handheld dynamometer was used to test the upper, middle, and lower trapezius; rhomboids; and serratus anterior. Main Outcome Measures: A 2-factor ANOVA was performed for each of the muscles by activity level and unilateral ratio by activity-level analyses. Post hoc analysis included multiple pairwise comparisons, using the Dunn-Bonferroni correction method. Results: Activity level did not significantly affect the unilateral ratios: Elevation:depression was 2.5:1, upward:downward rotation was 1.5:1, and protraction:retraction was 1.25:1. A rank order from strongest to weakest was established through significant comparisons. Conclusion: The unilateral ratios along with the rank order should be considered when discussing scapular rehabilitation protocols.