Table 1.

Placement of the EMG electrodes.

Muscle	Electrode placement location
Transversus abdominis (TA)	Along either side of the course of the underlying muscle fibers and centered 2 cm cephalic to the pubic bone, just lateral to the midline, and parallel to the superior pubic ramus [15]
Rectus abdominis (RA)	2 cm lateral from the midline of the umbilicus [15]
Multifidus (MF)	A line from caudal tip posterior spinal iliac superior to the interspace between L1 and L2 interspace at the level of L5 spinous process (i.e., about 2-3 cm from the midline) [15]
Erector spinae (ES)	2 cm lateral to the L3 level [31]
Gluteus medius (Gmed)	1/2 on the line from the highest point of the iliac crest to the greater trochanter [28]
Gluteus maximus (Gmax)	1/2 on the line between the sacral vertebrae and the greater trochanter; this position corresponds to the greatest prominence in the middle of the buttocks above the visible bulge of the greater trochanter [14]