Various theories exist regarding the mechanisms of stiff
shoulder (SS). Potential etiological factors are adhesive
capsulitis [1], decreased capsular volume [2,3], capsular
contractions [4], rotator interval thickening and fibrosis
[5], and subscapularis tendon thickening [5]. Cyriax [6]
proposed that stiffness in a shoulder joint capsule would
restrict motion in a predictable pattern, a capsular pattern
in which external rotation is more limited than
abduction, which in turn is more limited than internal
rotation. Others authors have indicated that posterior
shoulder stiffness is significantly correlated with humeral
internal rotation ROM loss [7-9]. Specifically, several
researchers [10-13] hypothesized that the stiffness of
specific muscles (rotator cuff)