Slouching and Back Pain.
Why is it that low back pain can be so much worse when we sit relaxed? Your mother probably always told you not to slouch, and, according to research from the Netherlands, she was right!
A group of researchers (Snijders et al, 2004) set about looking at the stresses and strains on the lowest parts of the spine, the L5 disc, and the iliolumbar ligament (connects the spine to the pelvis) when we sit in an unsupported slouch. In this slouch position the upper back leans against a high back rest and the length of the back is unsupported.
Snijder’s et al. looked at how far the Iliolumbar ligaments were stretched in this position, and how much force was placed on them. They carried out this study on cadavers
Research on Slouching and Lower Back Pain
The research showed that sitting in a slouch with back support at the shoulder level caused the pelvis to roll backwards and the lumbar spine to flatten. The L5 rolled forward on the sacrum, lengthened the iliolumbar ligament and stretching the back of the L5S1 disc. They found the strain put on the iliolumbar ligament was close to failure point. This is significant as studies have found this ligament can be a real source of low back pain.
Loading of the intervertebral discs
When the subjects were studied sitting with a lumbar support and no shoulder support, the load on the ligaments and disc was reduced substantially. The results of this and other studies suggest that we can reduce the strain on the structures at the base of our spine by sitting with lumbar support.
The authors do not recommend sitting with a high back rest, as they have found this reduces the effectiveness of a lumbar support. Instead they recommend sitting with a lumbar support and at least 6cm free shoulder space to reduce the risk of low back pain due to prolonged sitting.
Reference
- The influence of slouching and lumbar support on iliolumbar ligaments, intervertebral discs and sacroiliac joints
Chris J. Snijders, Paul F. G. Hermans, Ruud Niesing, Cornelis W. Spoor and Rob Stoeckart. Clinical Biomechanics. May 2004, Vol 19, Issue 4, pages 323-329.
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