Table 2 The locations of electrodes and MVIC positions

Upper trapezius

The halfway point between the spinous process of the seventh cervical vertebra and the acromion

In a sitting position with abduction at 90°

Middle trapezius

The halfway point between the scapular medial border and the T3

In a prone position with horizontal abduction at 90° and external rotation

Lower trapezius

At 2/3 on the line from the trigonum spinea to the T8

In a prone position with horizontal abduction in 120° in line with the fibers of the muscle and the thumb pointing upward

Serratus anterior

In the mid-axillary line over the fifth rib

In a sitting position with maximum resistance given to upward rotation of the scapula with the shoulder flexed

Middle deltoid

The halfway point of the acromion and the deltoid tuberosity

In a sitting position with abduction at 90°