Centralization or the Centralization Phenomenon

I went on-line to see what I could find about self-care for low back pain. Several sites mention the use of extension exercises for centralization. What is centralization? I'm not familiar with this term.

Centralization or the centralization phenomenon is a term used by physiotherapists and physicians to describe buttock or leg pain that goes away or gets better with extension movements.

With centralization, the painful symptoms move from a place below the spine up to the midline of the low back area. This change occurs when the patient is placed in an extended position or moves the spine into extension.

Lying on your stomach in the prone position is one starting point. The patient uses the arms to press the upper body up off the table. This is a prone extension position or exercise. If the buttock or leg pain moves into the lower back area, centralization has occurred.

Extension can also be done in the standing position with the same results. In fact, both of these test positions are also used in the treatment of LBP when centralization occurs.

David A. Browder, MAJ, PT, DPT, OCS et al. Effectiveness of an Extension-Oriented Treatment Approach in a Subgroup of Subjects with Low Back Pain: A Randomized Clinical Trial. In Physiotherapy. December 2007. Vol. 87. No. 12. Pp. 1608-1618.