The Outstretched Arm Test: comparison of arm dominance and intersession reliability for a new shoulder endurance test

Background/Aims Stability at the shoulder is critical for functional use of the upper extremity. Shoulder pain is highly prevalent, and many daily and occupational tasks require sustained arm elevation where the glenohumeral joint is less stable and more vulnerable. Previous tests have explored shoulder endurance dynamically, isometrically, and isokinetically; however, there appears to be a need for a more focused test of sustained endurance at an elevated position. This study aims to explore a test, the Outstretched Arm Test, created by the author, to measure shoulder endurance at an elevated position using a simple protocol, examine if a difference exists between dominant and non-dominant side performance, and determine intersession reliability. Methods Testing compared dominant to non-dominant sides, and intersession reliability was determined. Hold times were measured with the arm at 90° of shoulder elevation in 35 healthy adult participants (20 women, 15 men; age 20–76 years old, mean ± standard deviation 45.7 ± 16.8 years). A subset of 14 participants (seven women, seven men) were retested for intersession reliability. Results Hold times for the dominant to non-dominant side in women were not statistically different ( t (19)=1.94, P =0.07, d =0.43; mean difference: 5.7 seconds, 95% confidence interval [−0.4, 11.8]). The percent value of hold time for the non-dominant shoulder compared to the dominant shoulder in men was 85.4% and was significantly different ( t (14)=4.23, P =0.001, d =1.09; mean difference: 12.4 seconds, 95% confidence interval [6.1, 18.7]). Intersession reliability for the Outstretched Arm Test on both sides was good to excellent (intraclass correlation coefficient 95% confidence interval ranging 0.73–0.98). Conclusions The Outstretched Arm Test has a simple protocol, satisfactory intersession reliability, and men had longer hold times on their dominant side, whereas no side-to-side difference was observed in women. Implications for practice The Outstretched Arm Test is a practical measure of shoulder endurance at shoulder height. It can aid allied health professionals by providing expected baseline hold times, with the understanding that men may have longer hold times on their dominant side than their non-dominant side, whereas women tend to perform symmetrically. Clinically, the unaffected side may offer a preliminary reference for the affected side, with men expected to have increased hold time on their dominant side and near-symmetrical performance anticipated in women. A side-to-side difference beyond measurement error in women may flag a meaningful endurance impairment.