Paralumbar muscle activity in chronic low back pain.

Muscle spasm is often considered to be a prominent feature operating in chronic low back spin syndrome (LBP). The present study compared levels of paralumbar muscle activity, determined by an electromyogram (EMG), for LBP patients and normal subjects during periods of rest and voluntary muscular contraction. The resting state EMG measure did not differ in the 2 groups. However, when attempting to relax the low back while contracting other muscle groups, LBP patients exhibited higher mean levels of low back muscle activity as compared to the non-pain group. These results would suggest that such "cocontraction relaxation" procedures may provide a viable behavioral technique for assessing and possibly treating functional backache thought to be symptomatic of muscle spasm. Previous studies employing feedback and progressive relaxation techniques have trained subjects to reduce muscle tension in the resting state. Results of the present study suggest that the acquisition of "resting level" relaxation may be of little benefit to patients who exhibit excessive muscular tension while performing daily tasks. Rather, to maximize the likelihood of beneficial results, training would be better directed at relaxation of the low back during activity of other muscle groups.