Friday, July 3, 2009


There is increase in PA spine stiffness during voluntary contraction of the lumbar extensor muscles. PA dynamic spinal stiffness at rest and during lumbar isotonic extension tasks ware studied by Colloca & colleagues (2004) in patients with low back by a dynamic mechanical impedance study.

About the study:

13 patients with LBP underwent a dynamic spinal stiffness assessment in the prone-resting position and again during lumbar extensor efforts. Same measurements are taken after PA manipulative thrusts (approximately 150 N, <5 milliseconds) over L3 spinous & transverse processes with the patients at rest and again during prone-lying lumbar isotonic extension tasks.

Dynamic spinal stiffness characteristics revealed that

1. A significant increase in the PA dynamic spinal stiffness was noted for thrusts over spinous process during isotonic trunk extension tasks compared with prone resting.

2. But no significant changes were noted for the same measures over the transverse processes.

This study suggest in trunk extension tasks normally the spine stabilization occurs by the paraspinal muscles any PA force to the central spinal area only increase the effort of stabilization by these muscles. Colloca & colleagues concluded that the trunk musculature and spinal posture plays a predominate role in providing spinal stability.


Colloca CJ et al; J Manipulative Physiol Ther. 2004 May;27(4):229-37.

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