Comparative analysis of paraspinal and frontalis EMG, heart rate and skin conductance in chronic low back pain patients and normals to various postures and stress.

Eleven chronic low back pain (CLBP) patients were compared with eleven age-matched controls to different postures and stress while measuring paraspinal and frontalis EMG activity, heart rate and galvanic skin response. Contrary to current theory, results indicate that the CLBP group exhibited similar or significantly less paraspinal muscle activity than the control group. Frontalis EMG and skin conductance were significantly higher in the CLBP group. It was concluded that the theories are not supported. An alternative explanation of an increased arousal response and altered ability to respond to demanding tasks leading to pain and eventually to decreased paraspinal muscle activity is suggested.