The Posterior Athletic Shoulder Test: A Valid, Reliable Tool for Evaluating Posterior Shoulder Performance

The Athletic Shoulder (ASH) test is a valid and reliable isometric assessment of long-lever anterior shoulder strength across multiple arm positions. Overhead activities such as throwing and swimming place significant demands on the shoulder’s posterior stabilizers (rotator cuff and scapular stabilizers), identifying a need for a Posterior ASH (PASH) test to assess strength and fatigue of these muscles. PURPOSE: To determine the validity and reliability of the PASH test for evaluating posterior shoulder strength. METHODS: The PASH test was performed with identical abduction positions to the ASH test – T (90°), Y (135°), and I (~180°) – in a standing position while pushing posteriorly. Subject position was standardized; participants stood in a neutral posture with their heels, back, and head resting against the wall. Forty-two active adults (19M, 23F; 22 ± 2.5 yrs) performed two maximal effort repetitions in each position against a wall-mounted force plate. Peak body weight-normalized force and peak normalized sEMG amplitudes (posterior deltoid, superior & inferior trapezius, infraspinatus) were recorded. sEMG data were normalized to the T-position. A three-way ANOVA examined force variation between test positions, sexes, and dominant vs non-dominant arms. Reliability was evaluated using a two-way mixed-effects, covariate-adjusted intra-class correlation coefficient (ICC). sEMG results were compared between positions using pairwise Wilcoxon signed rank tests with Bonferroni correction. RESULTS: PASH showed good-to-excellent within-session reliability (ICC>0.75). There were significant force differences between males and females for all positions (p