Patterns of muscular activity during movement in patients with chronic low-back pain.

Bilateral paraspinal electromyogram (EMG) at levels L1-L2 and L4-L5, and abdominal EMG of a group of 20 low-back pain patients were compared to those of a group of 20 pain-free controls during flexion, extension, lateral bending to right and left, and rotation to right and left. The results showed no significant left-right differences in paraspinal EMG levels between low-back pain patients and pain-free controls during any of the movements. However, patterns of paraspinal and abdominal EMG were found to be different for low-back pain patients compared to pain-free controls during flexion only.