TABLE 2.

Proposed Biomechanical Mechanisms of Clavicular, Scapular or Humeral Kinematic Deviations (adapted from Ludewig and Reynolds 2009).

Mechanism	Associated Effects
Inadequate serratus anterior activation	Lesser scapular upward rotation and posterior tilt
Excess upper trapezius activation	Greater clavicular elevation, reduced scapular posterior tilt
Pectoralis minor tightness	Greater scapular internal rotation and anterior tilt
Posterior capsule tightness	Greater scapular anterior tilt, glenohumeral internal rotation deficit, greater humeral superior or anterior translation
Inadequate rotator cuff activation or partial tearing	Greater humeral superior translation, lesser humeral external rotation
Pectoralis major tightness	Lesser clavicular retraction, greater humeral internal rotation
Thoracic kyphosis or flexed posture	Greater scapular internal rotation and anterior tilt, lesser scapular upward rotation