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Thursday, July 1, 2010

Reader email question

Got this question this week from a reader in Norway, and while it's not the most common, his back problem is more common than people realize:

I have spondylolisthesis grade 3. Bike fitting will be critical as a wrongly fitted bike is very painful.

What are the adjustments I would most likely need on a bike that is basically fitted right for a healthy back?
What are the typical “spondy adjustments”?

I (am) cycling quite a lot today on a hybrid that is 20 inches. I am 172 cm. The bike is maybe too big but it seems my back is better when I am streched forward.
I prefer a lying forward position (racing style) and the large bike size allows the seat to be adjusted forward compared to the pedals. Seat being slightly too low.

But I also want to do off road cycling. Problem is that the off roaders are smaller and more upright. (But there is no point in adjusting the off roader to give me a racing position)

I will be very happy to have some ideas about this from you.

Kind regards


For those unfamiliar, a spondylolisthesis (not to be confused with spondylosis or spondylolysis -- professors in medical and PT schools love to torture first years with the differences between them) is when one vertebral body begins to slip forward relative to the one below it.  This slipping forward closes off the space for the spinal cord (within the spinal column/vertebrae) as well as for the nerve roots as they exit the spinal column.  Occasionally people even have a "step deformity" where if you run your fingers down the spine you can feel a "step" or a larger bump, which is the now more prominent vertebral body below.

These are tricky and early detection routinely is misdiagnosed as some sort of disk injury.  The treatments for disk injury and spondylolisthesis, however, are nearly opposite, so distinguishing is important.

In general, lumbar flexion helps to reduce the slipping vertebra, or puts it in a neutral position -- often clients can feel the bone "click" back into alignment very softly.  Lumbar extension, or back bending has the effect of pushing the bone further forward and causing more pain.

These people often get severe symptoms if they sleep on their stomach or have to stand in one place too long. 

You'll notice that our friend from Norway is more comfortable in a racing or stretched out position, and he's not alone.  My clients with spondylolisthesis often are more comfortable stretched out on their road racing bike, and really can't tolerate their mountain bike due to it's upright position.  The upright mountain bike position, like standing in one place, requires active abdominal stabilization in order to keep some "flexion pressure" on the lumbar spine -- or really just to keep the spine in neutral.  When we stand in place, our trunk muscles get lazy and we begin to "rest" on the static (non-muscular) structures of the spine, like the spinal ligaments, and more often than not our balance point pushes us into lumbar extension.  A very similar thing happens when we are in an upright position on our bike.  The stretched out racing position actually removes the need for active muscular stabilization because it aligns the vertebrae in flexion.

So what to do?

The obvious correction would be to set up a mountain bike in close to the same aggressive position that you find on a road bike, but few people want to have this position on their mountain bike because in the wrong terrain it can make it much more likely that you will catapult over the handlebars. 

The better fix is a careful positioning of the seat.  The tilt of the seat, is the biggest issue.  You actually want to err on the side of having the seat level or even tilted slightly up.  In order to keep pressure off the perineum (your softer bits) this forces you to rotate your pelvis posteriorly slightly which in turn creates some lumbar flexion, or at least a neutral lumbar spine.  The overall reach of the bike should be such that a bit of lumbar flexion can be created without getting too far forward with your position (resulting in the aforementioned trip over the bars), and shouldn't cause your shoulder blades to protract significantly in order to reach the handlebars (you don't want a rounded upper back posture).

This seat positioning is the most important factor, however a very good way to ensure that you have less trouble with your spondylolisthesis is aggressive strengthening of the abdominal muscles.  The abdominals are responsible for keeping the spine in a neutral position and preventing that lumbar extension.

So, thank you, for the great question, and please don't hesitate with more.

Stay tuned, as I am fortunate to have gotten my hands on a set of Zipp full carbon 404 clinchers.  I will post about them in the next few days.

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