An Interesting Science Study

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This caught my eye as something you all might be interested in.


I’ve been reading Ultimate Back Fitness and Performance by Stuart McGill.  He also wrote Low Back Disorders and has authored well over 20 peer reviewed articles.  If you’d like to read his work I’d recommend Back Mechanic, which was written to be more accessible for those without an anatomy and physiology background.

In his book he referenced a study that he’d done called, “Disc prolapse: evidence of reversal with repeated extension”.  Intriguing isn’t it?


“Disc” is the common name applied to the complex structure that separates one vertebral body from another.  It’s not actually a disc as there is no bouncy cartilaginous coin that could be removed from its surroundings and retain the same nature it has while in place.


The “disc” has a pulpy center and a thick outer layer composed of layered oblique fibers that resist torsional stresses.  The disc can either be round or kidney shaped as part of normal human variations.


A prolapse is a herniation where the pulpy center (the nucleus pulposus) makes it all the way through the fibrous ring (the annulus fibrosus) to the outside of the disc.


McGill mentions that, “Previous research has established that repeated flexion can create disc prolapse…”  which is why we have probably all heard that we should lift with our knees and not with our back, and that we shouldn’t slouch for prolonged periods of time.  Both slouching and rounding the back when we forward bend are examples of repeated lumbar spine flexion.


So, the problem is the repeated use of lumbar spine flexion and the damage it does to spinal discs.  There are other problems with back rounding too, but one thing at a time.


In his science experiment McGill used 18 pig spines, compressed them and then repeatedly flexed them.  I don’t know for exactly how long because this is not a free full text article on PubMed and I didn’t want to pay the $57 to read it.  But the abstract has a pretty good amount of detail.


Of the 18 spines, 11 prolapsed and 2 got end plate fractures (a different kind of spinal injury).  The 11 prolapsed spines were then compressed and repeatedly extended.  Extension is the position your lumbar spine would be in if you laid on your belly and used your arms to push your shoulders away from the ground.


Of the 11 prolapsed spines, 5 reduced (the nucleus went back into the center of the disc) and 6 didn’t after the repeated extension.  That may not sound impressive, but a nearly 50% success rate with what could be a conservative (non-risky or damaging) treatment on an early science study is really exciting.  I’m aware that a lot of people diagnosed with disc herniations are recommended for surgery, but what if you could reduce the herniation just by engaging in a program of deliberate spinal extension?


McGill also mentions that the prolapsed discs that reduced had significantly less height loss, which translates to less potential for aggravating stenosis (narrowing) of the spaces where the spinal nerves exit the spinal cord and go do what they do in the rest of the body.


Here’s the conclusion from the abstract:


“Conclusion: This study showed that with repeated flexion, in porcine cervical spines, disc prolapse was initiated and that the displaced portion of nucleus can be directed back towards the center of the disc in response to particular active and passive movements/positions.”


This study took place in 2009. I’m on tenterhooks to know what’s been done since then.  


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