title: Glenohumeral joint laxity and stiffness in the functional throwing position of high school baseball pitchers.
abstract: BACKGROUND
  Repetitive overhead throwing has been theorized to result in chronic adaptations to the capsuloligamentous restraints of the glenohumeral joint.
  
  
  OBJECTIVE
  To compare glenohumeral joint laxity and stiffness between the throwing and nonthrowing shoulders of high school baseball pitchers.
  
  
  METHODS
  Repeated measures.
  
  
  METHODS
  High school athletic training facilities.
  
  
  METHODS
  Twenty-two asymptomatic high school baseball pitchers (age = 16.50 +/- 0.74 years, height = 178.51 +/- 7.66 cm, mass = 75.43 +/- 13.24 kg) from a sample of convenience.
  
  
  METHODS
  We used computerized stress arthrometry to measure glenohumeral joint laxity and stiffness. Anterior glenohumeral joint laxity and stiffness measures were obtained with the shoulder in 90 degrees of abduction and both neutral rotation and 90 degrees of external rotation. Posterior laxity and stiffness measures were obtained with the shoulder in 90 degrees of abduction and neutral rotation.
  
  
  RESULTS
  No clinically significant differences were found for glenohumeral laxity or stiffness between sides. However, a statistically significant main effect for position was present for both laxity and stiffness. Anterior glenohumeral joint laxity in the 90 degrees external rotation position was significantly decreased and stiffness was increased in this position compared with the anterior at neutral and posterior at neutral positions.
  
  
  CONCLUSIONS
  Glenohumeral joint laxity decreases and stiffness increases in the functional throwing position of 90 degrees of abduction and 90 degrees of external rotation. No clinically significant side-to-side differences or directional differences were found in high school baseball pitchers.
authors.affiliation: Arizona School of Health Sciences, A. T. Still University, Mesa, AZ 85206, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Crawford
authors.forename: Eric L
authors.initials: EL
authors.lastname: Sauers