Spinal Fusion and Mountain Biking

Question:

I have a 40 year old female client who is a pro mountain biker and cyclist. She had a spinal fusion in L4 and L5, but she is otherwise healthy and has no other medical problems. I have been training her twice a week for the last year, doing mainly weights and functional training. Can you please give me some training and rehab ideas for her?

Answer:

What we should always keep in mind with a spinal fusion is the motion lost at the fused segments must be found somewhere else. If L4-L5 segments aren’t moving, than there is going to be increased motion in all three planes at L5-S1 and L3-L4. Although the motion increase in these other segments might not be excessive, it will be greater than normal. And the increased motion will be cumulative with every movement, every day, on or off the bike.

The other information important for a client with this kind of history is to understand what preceded the surgery. It is helpful for you to know if the surgery was the result of damage from a traumatic incident (such as a fall on the mountain bike) or if it was caused by long term mechanical stress to that area of the body.

If it was the latter, your training and post rehab exercise design should also address factors related to her global mechanics. Her global mechanics are part of the complete picture of why the back was injured in the first place. Consider biomechanical assessments such as posture, single standing and squatting and gait.

A spinal fusion is often performed to keep two segments from moving on one another to mitigate pain and stabilize that area of the spine. A fusion is rarely the first intervention for a back injury, unless it was traumatic and there is a risk of further damage or paralysis.

Much of what your client does on a mountain bike involves lumbar and lower thoracic flexion with a posterior pelvic rotation. Weight transfer from leg to leg with pedaling while in this position will add frontal and transverse plane motion to the pelvis and lumbar spine.

Consider viewing mountain biking as a single leg force production activity as any ground based activity as it relates to the lumbo-pelvic region. We tend to look at biking as a simultaneous leg drive activity because both legs are in motion. But there is a weight shift to the limb going through the power phase, especially when the rider is “out of the saddle.”

The temptation might be to do some sport specific training with her. However, I believe that it is in the best interest to your client’s long term health and function to first challenge her body off of the bike. Getting her on the ground and off the bike might help you better assess during activity if there are any functional differences in strength, balance or ROM between the two limbs that might be able to “hide” on the bike.

If her fusion was not the result of trauma, the bike mechanics are likely a major factor in the cumulative stress on her lumbar segments. And if the fusion has been the only intervention, it is possible she will experience a similar problem at the segments above or below the fusion.

Prolonged flexion of the spine causes physiological creep (lengthening) of the spinal ligaments and slows the response time of the spinal extensors to pull the body out of the flexion. Both of these predispose the vertebral column to increased shear in the sagittal plane. This is not good for the desk jockey or the cyclist.

Issues such as pelvic obliquity, asymmetrical innominate rotations, functional scoliosis, etc. are all areas that can affect long term lumbar spine health and function.

Depending on how long ago her surgery was and how comprehensive her rehabilitation was, you may need to take her through some preliminary stabilization work. Consider reviewing one of Dr. Stuart McGill’s books.

There is currently some debate of bracing with the abdominal region during activity because it would seem to inhibit normal motion of the trunk on the pelvis. I personally agree with this view AFTER the client/athlete has progressed through various motor learning stages and demonstrated proficiency through these stages.

But mountain biking could be an exception to that view as it relates to advanced function. First, because the hands are fixed to the handlebars at all times, we have limited need for trunk rotation on the pelvis. Second, because the upper body is also transferring force through the trunk in a top down manner and not just a bottom up manner as most ground based exercises.

After your client demonstrates she is ready to progress, try having her work the lower extremities unilaterally while standing with her hands out in front, fixing the upper body and trunk. For example, have her doing single leg squats while the free leg reaches in all three planes. The fixed upper body will aid in balance, but it will also produce a different reaction at the thoracic and lumbar spine and the hip than it if the hands were free. These reactions will be closer to the events on a bike than if the upper body follows the hip motion.

Best of luck.