After 1 minute of rest, participants will perform 6 trials of bilateral, active, weighted arm elevation in the scapular plane and a therapist classifies the scapular motion into specific patterns of scapular dyskinesis. After the evaluation of scapular dyskinesis, the kinematics and surface EMG (sEMG) data will be collected during 5 trials of the same arm movements and 3 selected exercises.

Conscious correction of scapular orientation will be taught to the subjects in the manner described in previous studies. The starting position is determined in each individual by actively positioning the scapula between maximal upward and downward rotation, external and internal rotation, and posterior and anterior tilt. Scapular assistance test (SAT) is also conducted by passively assisting patients' scapula into appropriate position to correct scapula dyskinesis

Conscious control of the scapula is important and can correct neuromuscular coordination as well as strength deficits. The strategy in learning control of scapula into normal orientation can be facilitated by manual guides and/or external cues

Scapular orientation relative to the thorax is described using a Euler angle sequence of rotation about Zs (protraction/retraction), rotation about Y's (downward /upward rotation), and rotation about X"s (posterior/anterior tipping). Scapular elevation is defined as the vertical displacement of the scapular sensor during arm elevation. Humeral orientation relative to the scapula is described using a Euler angle sequence in which the first rotation represents the plane of elevation, the second rotation defines the amount of elevation, and the third rotation describes the amount of axial rotation.

Full bandwidth sEMG data, captured by data acquisition software (AcqKnowledge, Biopac systems Inc., CA, USA)

The measurement of the distance between the posterior border of the acromion and the table