Influence of Abdominal Bracing on Spinal Curvature During Sitting

In a recent post I reviewed evidence on the association of prolonged sitting with lumbar disc degeneration (http://digg.com/d31MSNP).

One issue alluded to in this article was the potential influence of abdominal bracing on pressures exerted on the lumbar spine.  

[I can hear my dad at this point commenting that a lot of this information boring and too technical.  Maybe so, but the details I think are potentially very useful.  Besides I am used to being boring.]

A study by Watanabe et al. follows up on this point with a study that demonstrates the “Influence of trunk muscle co-contraction on spinal curvature during sitting reclining against the backrest of a chair.” [Electromyogr. Clinc. Neurophysiol. 2008 (48): 359-365]

Generally when sitting, the pelvis rotates backwards and lumbar lordosis is flattened.  Slouching.  We all do it all too often.  Studies have shown that this posture increases the load on intervertebral discs and the spine (see http://digg.com/d31MSNP). 

Sitting Posture and Low Back Pain

On the other hand, studies have shown that co-contraction of the abdomen and spine stabilizing muscles (or abdominal bracing) enhances the stability of the lumbar spine and sacroiliac joint.  (See http://digg.com/d31LPR7 for a more detailed discussion of the importance of abdominal bracing and review of the literature).

Watanabe et al. took a group of subjects, had them sit in office-type chairs with a backrest and measured muscle activity with EMG and spinal curvature.  What they found was interesting. 

The study showed that “co-contraction of the trunk muscles during sitting while reclining against the backrest of a chair can bring about correct lumbar curvature, effectively stabilize the lumbopelvic region, and decrease focal stress on passive structures.” [Electromyogr. Clinc. Neurophysiol. 2008 (48): 359-365]

Take-home message: You have muscles in the abdomen and stabilizing the spine for a reason.   Use them.  When sitting, engage your core and co-contract the abdomen in an abdominal brace.  You will feel the difference and your spine will be the healthier for it.