Reliability of lumbar paravertebral EMG assessment in chronic low back pain.

The reliability of lumbar paravertebral EMG assessment was investigated in a sample of 70 patients with chronic low back pain, (CLBP). Dual-site EMG monitoring was employed during both static postures and movements. Flexion and rotation indices were divided to assess the reliability of patterning of paravertebral EMG during movement. Within-session reliabilities computed for the full sample ranged from 0.66 to 0.97, and between-session reliabilities, computed on a subset of 29 patients retested after varying intervals, ranged from 0.26 to 0.92. Average EMG levels, flexion, and rotation indices showed no statistically significant differences between surgical (n = 40) and nonsurgical patients (n = 30), although EMG variability was consistently greater for surgical patients across the postures and movements. These results indicate that lumbar paravertebral EMG can be reliably measured and therefore has potential utility as an assessment and treatment variable in CLBP.