If you’ve been in our office, there is a high possibility that you are familiar with our McKenzie extension exercise. We may have called it something along the lines of extensions, press ups, cobra, upward dog, end-range loading, etc. We use this exercise quite frequently, but why? Well to put it quite simply, because it works! But is that a good enough reason? For some, maybe, and for others, maybe not. So let’s take a little dive into what we understand about what is going on in the joint.
First lets name the joint we’re targeting here. The joint, or joint complex we’re affecting is the IVJ or Inter Vertebral Joint. So lets do a break down. In the lumbar spine we have 5 vertebrae. Each vertebrae has two superior articular facets that connect to the vertebrae above and two inferior articular facets that connect to the vertebrae below. So lets paint a picture and use L4 and L5 vertebrae as reference. The superior articular facets of L5 are going to connect or “articulate” with the inferior articular facets of L4. The two facets join to makes whats called a zygapophyseal, or more simply, a facet joint. Those are two of the important joints. The Third is another important joint that is in-between the vertebral bodies of L4 and L5. Here is what is called the disc, which consists of a soft Gel-like center called the nucleus pulposus, which is surrounded by a network of fibrous tissue weaved together to form a strong capsule for the nucleus. We call this fibrous tissue the Annulus fibrosis. Both the nucleus and the annulus form what is known as the IVD or the Intervertebral disc. So adding up the disc and the facets, we get the Intervertebral joint. So what do these joints surround? Shown in the image below, the small holes between the disc and the facet joints are known as the neural foramina or the intervertebral foramina. It is through this hole that the spinal nerves exit the spinal canal and run to their target tissue. In this case that would be the nerves of the lower extremity.
So what motions do these joints perform? Mostly flexion and extension, which in the low back translates to bending forward(flexion) and bending backward(extension). There is a smaller degree of rotation allowed by these joints but ideally the lumbar spine shouldn’t need to rotate as much in relation to other regions of the body. Here we’re going to focus on flexion and extension.
What we do know is that when we extend the joints to their end range we are stimulating small receptors within the joints known as mechanoreceptors. When we stimulate the receptors they send signals to the brain about that joint position, which overrides the pain signal being sent to the brain and allows for a less painful movement of that joint. By repeating this motion we continuously stimulate the receptors and not only decrease the pain during movement, but can eventually restore function and range of motion within the joint that was previously lost. That’s why we use the phrase “motion is the potion”. So why does the extension exercise tend to work so well compared to others? There isn’t necessarily one answer to that question and it may vary depending on each individual. One theory is that we live in a world where we as a society that is much more sedentary than is ideal. For the first 18 years of life we send children to school where they will be sitting for long hours of the day. Many jobs in today’s society involve sitting at a desk for most of the day. What happens in the spine when we sit is we push our lumbar spine into flexion which puts increased load on the disc and compresses the joint. Which in turn will increase pressure in the foramina and also the nerve. The more time we spend in this position increases the likelihood that we will lose motion and compress the lumbar spine which can result in low back pain. So if seated lumbar flexion increases load on the lumbar spine, that must mean that lumbar extension decreases load on the lumbar spine, right? Right! Our aim with this treatment is to decrease the load on the spine which will take pressure off of the nerves of the lumbar spine.
So now you may ask, is this exercise right for you? Come see one of our excellent providers and find out! For each patient who is experiencing back pain and/or sciatic pain we perform a McKenzie assessment to determine a directional preference to reduce symptoms and improve function. Also it’s possible that extensions are not the answer, in these cases there are multiple other movements that we test. If all else fails, we have a phenomenal referral network to multiple different healthcare professionals and we will get you to where you need to be!