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Thursday, February 11, 2010

Low back pain sufferers and back muscle weakness

Nice research article linking weakness in back muscles with chronic low back pain. Just another reason to stay active and try to stimulate/exercise those muscles.


Less Activity in Multifidus of LBP Sufferers

Smooth and correct torso movements depend on the coordination of some trunk muscles that produce torque combined with the fine-tuned variations from other muscle groups. Studies have shown that the back extensor muscles are not simply a muscle group, but instead have specific functions for strength or control.

The multifidus appears to be a primary contributor to control and stabilization, while the iliocostalis lumborum pars thoracis (ICLT) produces torque forces in the lumbar region.

This study determined back muscle activity in three groups (77 healthy controls, 24 subacute back-pain patients, and 51 chronic back-pain patients) during strength, coordination, and stabilization exercises. Subacute pain was considered back pain of less than one year. Subjects performed 15 exercises involving kneeling/standing, loading, and lifting. Electromyographic (EMG) activity was recorded for the multifidus and the ICLT at maximum voluntary contraction. The results of the study were as follows:

* During coordination exercises, there was a significant decrease in EMG activity of the multifidus in the chronic-pain group compared to the control group, in post-hoc tests.

* Tests revealed significantly lower activity in both muscles in the chronic-pain group during strength exercises.

* Regarding stabilization exercises, muscle activity was similar for all three groups.

In the long run, low-back-pain patients may have more difficulty recruiting the multifidus for neutral lordosis. The authors conclude, "The possible dysfunction of the [multifidus] during coordination exercises and the altered activity of both muscles during strength exercises may be important in the symptom generation, recurrence or maintenance of low back pain."

Danneels LA, Coorevits PL, Cools AM, et al. Differences in electromyographic activity in the multifidus muscle and the iliocostalis lumborum between healthy subjects and patients with sub-acute and chronic low back pain. European Spine Journal 2002:11(1), pp. 13-19.