title: A comparison of range of motion change across four posterior shoulder tightness measurements after external rotator fatigue.
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).
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  Posterior muscle tightness may influence the internal rotation range of motion to a greater extent when measured in glenohumeral joint extension.
  
  
  METHODS
  II-B.
authors.affiliation: Simmons College, Boston, MA, USA.
authors.forename: Amitabh
authors.initials: A
authors.lastname: Dashottar
authors.affiliation: Hospital for Special Surgery, New York, NY, USA.
authors.forename: Oren
authors.initials: O
authors.lastname: Costantini
authors.affiliation: The Ohio State University, Columbus, OH, USA.
authors.forename: John
authors.initials: J
authors.lastname: Borstad
keywords: Glenohumeral joint; clinical measurement; horizontal adduction; internal rotation; muscle stiffness