Table 2.

Electrode Placement and MVIC/strength test positions.

EMG collected	Electrode Location	MVIC/Strength test position
Upper Trapezius	A mark was made on the skin at the midpoint on a line joining the C7 spinous process and tip of the posterior lateral angle of the acromion. The electrodes were placed over a point 1/2 distance between this point and the posterior lateral angle of the acromion37	Abduction: The participant abducted his/her arm to 90 ° with thumb pointing up. The hand held dynamometer was applied just proximal to the elbow with the participant sitting upright. The participant abducted his/her arm up against resistance applied through the humerus
Lower Trapezius	The arm was elevated in abduction to 125 ° and the electrodes were placed at the midpoint from the T7 spinous process to the inferior angle of the scapula in line with muscle fibers obliquely superior and laterally38	Prone Elevation: In a prone position, the participant abducted his/her arm to 125 ° with thumb up. Subject was asked to push up against the hand held dynamometer that was placed on distal arm just proximal to the radial styloid.
Serratus Anterior	With the arm elevated to 125 ° the electrodes were places over the 7th intercostal space, just anterior to the fibers of the latissimus dorsi in line with the serratus anterior muscle fibers36	Flexion: With subject seated, resistance was applied with the hand held dynamometer to distal arm proximal to the wrist in a perpendicular direction with the humerus elevated to 125 ° in the sagittal plane