Total Arc of Motion in the Sidelying Position: Evidence for a New Method to Assess Glenohumeral Internal Rotation Deficit in Overhead Athletes

Authors: Cieminski CJ, Klaers H, Kelly SM, Stelzmiller MR, Nawrocki TJ, Indrelie AJ

Total arc of motion (TA) measured in a supine position has been utilized as a method to detect the presence of glenohumeral internal rotation deficit (GIRD) in overhead athletes. A component of supine TA is supine internal rotation (IR) range of motion (ROM), which has many variables including the amount and location of manual stabilization. A sidelying position for gathering IR ROM has recently been proposed and, when combined with supine external rotation (ER) ROM, constitutes a new method of quantifying TA. This new sidelying TA method, however, has no normative values for overhead athletes.  The purposes of this study were to develop normative values for sidelying TA in overhead athletes, determine any ROM difference between supine and sidelying TA, and examine side-to-side differences within the two TA methods. A secondary purpose of the study was to examine for any effect of gender or level of competition on the two TA methods.  Passive supine IR ROM, supine ER ROM, and sidelying IR ROM were gathered on bilateral shoulders of 176 collegiate and recreational overhead athletes (122 male [21.4±4.7 years, 71.7±2.7 inches, 25.3±2.7 BMI] and 54 female [21.4±5.4 years, 67.6±3.0 inches, 22.5±2.37 BMI]).  The results showed that sidelying TA mean for the dominant shoulder was 159.6°±15.0°; the non-dominant shoulder was 163.3°±15.3°.  Sidelying TA for both shoulders (p < 0.0001) was 14° less than supine TA.  Both TA methods exhibited a 4° dominant-shoulder deficit (p < 0.0001). For the dominant and non-dominant shoulder, respectively, there was no gender (p = 0.38, 0.54) or level of competition (p = 0.23, 0.39) effect on sidelying TA.  The authors concluded that in overhead athletes, sidelying TA is a viable alternative to supine TA when examining for the presence of GIRD. Gender and level of competition does not significantly affect sidelying TA, so the mean of 160° on the dominant shoulder and 163° on the non-dominant shoulder can be used by clinicians.

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