One of the most troubling conditions, for my lower back pain patients, is when they experience symptoms down their leg (commonly known as sciatic). One of the reasons for this is a result of irritation to the nerve root at the spine. A possible reason for this is due to a herniated disc bulging out against the nerve root.

Most disc injuries are a result of flexion (forward bending) and rotation. Herniated discs typically are found on the back of the disc and tending to be on one side over the other. I liken the disc of the spine as a jelly filled doughnut. The outer layers are tough and fibrous (unlike a doughnut); imagine it like an onion with multiple layers. The inner portion is gelatinous. If you take a jelly filled doughnut and smash it with your fist the jelly squirts out the area of least resistance through the hole where the jelly was injected (that’s why your first bite should be where the hole is so you don’t squirt someone). In the case of a disc herniation the gelatinous portion pushes in the direction where the outer layers have been weakened. This can cause a bulge to the disc. If large enough this herniation can affect the nerve.

It would stand to reason that moving in the opposite direction would help squish the bulge back into the centre and therefore reduce irritation on the nerve root and the symptoms down the leg. This is called centralization. Robin Mckenzie, a therapist from New Zealand, popularized the use of back extension exercises for back pain and has been reported to have success in reducing patients’ symptoms. Though I am not trained in the Mckenzie Method, here are some extension exercises that I give my patients. I have found success with people performing about 10 repetitions, holding for 10 seconds each repetition. This can be done when symptoms occur or periodically throughout the day. I do not recommend these exercises if they increase symptoms.

I recently found a research article which found evidence of a disc bulge being reduced. This research paper used porcine (pig) spine to examine the effects of repeated extensions on disc bulges. Just so you know pig spine (the neck region) is very similar to a human’s lumbar (lower back) spine.

This is what the researchers found:

Repeated pure extension or extension with side flexion (depending on the location of the herniation) after disc prolapse was found to redirect the displaced portions of the nucleus back to the central part in a number of discs.
The frequency of repeated extension was one extension per second (1 Hz)
The number or repetitions were at least 900 repetitions.
The specimens that did not respond to reversal testing had prolapsed to a greater extent (more volume posteriorly and closer to the outer annulus) than those that did respond

Based on this finding we can see that not all people will respond to this treatment. We have to remember that even if we reduce a herniated disc it may not be the reason for the back pain. We already know that there are people sitting reading this post who have a herniated disc but no back pain.

I often suggest these exercises especially for those who are involved in jobs that result in activities with repeated or sustained flexion or rotation. I have even used it as an ounce of prevention.

Dr. Notley

Winnipeg Chiropractor/Athletic Therapist since 2000

P.S. Based on this information I will be changing how I use this exercise. I will be seeing how repeating extensions every 1 second and increasing the number or repetitions will result in improvement in my patient symptoms. I’m always learning and willing to change based on what the research says.

book appointment

Originally posted on May 17, 2022 @ 4:36 pm

Back Care: Mckenzie Extensions