Quantitative analysis of surface and percutaneous electromyographic activity in lumbar erector spinae of normal young women.

Bilateral surface and fine-wire electromyographic activity from the erector spinae at the L4-5 interspace was recorded from 10 female subjects during flexion, extension, rotation to right/left, and sidebending to right/left. Fine-wire electrodes demonstrated significant left-right electromyographic differences during terminal flexion. Surface and fine-wire electromyographic recordings demonstrated a symmetric pattern of activity during extension. A symmetric pattern of erector spinae activity was observed during rotation using fine-wire electrodes but not from surface electrodes. Increased electromyographic activity from the contralateral erector spinae was detected by the surface electrodes during sidebending to neutral movements.