Table 1.

The placement locations of bipolar surface electromyography electrodes on target muscles (i.e., bilateral cervical erector spinae, upper trapezius, and lower trapezius); corresponding procedures for testing maximal voluntary isometric contraction of each muscle.

Testing Order	EMG Electrode Landmarks	MVIC Positioning
1. Cervical Erector Spinae (CES)	2 cm lateral from the C4 spinous process	A participant sat with arms by the side of the body and performed maximal neck extension against manual resistance at the back of the head, applied by an examiner.
2. Upper Trapezius (UT)	Midway between the mastoid process and root of the spine of scapula	A participant sat with arms beside the body, and then performed maximal shrugging of shoulders against an examiners’ downward resistance applied to the acromion.
3. Lower Trapezius (LT)	2 finger-widths medial to the inferior angle of the scapula, at a 45° angle towards the T10 spinous process	A participant in prone lying with arms lifted overhead, in line with lower trapezius muscle fiber orientation. The participant raised the arms towards the ceiling using maximal effort against the examiner’s downward force applied just distal to the humeroulnar joint line.