Amitabh Dashottar1, Oren Costantini2, John Borstad3. 1. Simmons College, Boston, MA, USA. 2. Hospital for Special Surgery, New York, NY, USA. 3. The Ohio State University, Columbus, OH, USA.
Abstract
BACKGROUND: Several glenohumeral joint (GHJ) positions have been recommended for assessing and correcting posterior shoulder tightness (PST) however, there is no agreement on which position is better for differentiating posterior muscle tightness from posterior capsular tightness. The purpose of this study was to compare the range of motion change before and after an external humeral rotator muscle fatigue protocol in order to identify a position that shows maximum range of motion change. METHODS: ROM changes across four PST measurements were compared before, immediately after, at 24 hours after, and 48 hours after an external rotator fatigue protocol. Muscle stiffness of the infraspinatus and the teres minor (using a myotonometer) and external rotation force production (using hand-held dynamometry) were measured to verify muscle fatigue. RESULTS: There was a statistically significant interaction between measurement and condition (F = 2.47, p = 0.02). The planned one factor repeated measure ANOVA for each condition revealed that ROM change was statistically significant between PST measurements for all conditions. Post hoc comparisons indicated statistically significant greater overall ROM changes in a measurement combining GHJ extension and internal rotation compared to other tested measurements. There was also a main effect of time on infraspinatus muscle stiffness (F = 10.5, p < 0.0001). Post hoc comparison indicated a statistically significant increase in infraspinatus stiffness immediately after the fatigue protocol (p < 0.05). CONCLUSION: Immediate ROM reduction was observed across all the measurements except horizontal adduction (HAD). Maximum ROM reduction after an external rotation fatigue protocol was measured in a position of GHJ extension. CLINICAL RELEVANCE: Posterior muscle tightness may influence the internal rotation range of motion to a greater extent when measured in glenohumeral joint extension. LEVELS OF EVIDENCE: II-B.
BACKGROUND: Several glenohumeral joint (GHJ) positions have been recommended for assessing and correcting posterior shoulder tightness (PST) however, there is no agreement on which position is better for differentiating posterior muscle tightness from posterior capsular tightness. The purpose of this study was to compare the range of motion change before and after an external humeral rotator muscle fatigue protocol in order to identify a position that shows maximum range of motion change. METHODS: ROM changes across four PST measurements were compared before, immediately after, at 24 hours after, and 48 hours after an external rotator fatigue protocol. Muscle stiffness of the infraspinatus and the teres minor (using a myotonometer) and external rotation force production (using hand-held dynamometry) were measured to verify muscle fatigue. RESULTS: There was a statistically significant interaction between measurement and condition (F = 2.47, p = 0.02). The planned one factor repeated measure ANOVA for each condition revealed that ROM change was statistically significant between PST measurements for all conditions. Post hoc comparisons indicated statistically significant greater overall ROM changes in a measurement combining GHJ extension and internal rotation compared to other tested measurements. There was also a main effect of time on infraspinatus muscle stiffness (F = 10.5, p < 0.0001). Post hoc comparison indicated a statistically significant increase in infraspinatus stiffness immediately after the fatigue protocol (p < 0.05). CONCLUSION: Immediate ROM reduction was observed across all the measurements except horizontal adduction (HAD). Maximum ROM reduction after an external rotation fatigue protocol was measured in a position of GHJ extension. CLINICAL RELEVANCE: Posterior muscle tightness may influence the internal rotation range of motion to a greater extent when measured in glenohumeral joint extension. LEVELS OF EVIDENCE: II-B.
Authors: Joseph B Myers; Sakiko Oyama; Craig A Wassinger; Robert D Ricci; John P Abt; Kevin M Conley; Scott M Lephart Journal: Am J Sports Med Date: 2007-07-03 Impact factor: 6.202