One of the most common causes of low back pain is lumbar disc pain. The disc has an outer layer made up of cartilaginous (annulus fibrosus) layers surrounding a gel-like center (nucleus pulposus). There is one disc between each bony vertebral level in our low back. According to Stuart McGill, PhD, it behaves more as a ball-bearing joint than a “shock absorber” (that is for a later topic). The anatomy allows us to bend our low backs with great flexibility in all directions. The outer third of the disc is innervated by sinu vertebral nerves, meaning that it can transmit pain signals coming from the low back. The annulus fibrosus is thinnest near to where the nerves to our legs are traveling in our spinal canal.
A disc injury is a tearing of the outer layer allowing the inner gel to work its way to the outside of the disc. The tearing and subsequent leakage of disc material causes a lot of inflammation in the spinal canal. This inflammation can cause back pain, muscle spasms and irritate the nerves to the leg, causing leg pain. If the disc material causes pressure and compression of the nerves of the legs, this can lead to weakness.
Stuart McGill PhD showed that the lumbar disc material can herniate through the outer layer (annulus fibrosus) in as little as 20,000 repetitions of forward flexion or twisting through the lumbar spine. It is unlikely to cause a disc herniation if you bend backwards or sideways. Stooping, sitting, and bending at the waist are causes of disc herniation and subsequently back or leg pain.
His research also has shown that humans will bend forward over 1,000 times a day and backwards only 150 times a day. With this in mind, it is easy to see how we can cause a disc herniation just by doing our day-to-day routines. However, we move in ways that are safe for our discs, such as backwards, very rarely. Therefore, WE CAUSE LOW BACK PAIN BY THE WAY WE MOVE!
There is good news. Proper lifting mechanics can decrease your risk of lumbar disc herniations and back pain. For example, professional weightlifters lift extreme amounts of weight in a squatting position and you find that they do not get disc herniations more frequently than the general population. Why is this? They have proper strength and flexibility within their core, pelvis, and in their hips.
Most treatments for low back pain are reactive, meaning that treatment is started after someone is already experiencing back pain. Most treatments do not decrease your risk of future back pain. Research shows that the only thing to decrease your risk of future low back pain is exercise. So again I encourage you to get into that exercise program and if you have pain with exercise, ask for help from a physical therapist and physician.
Valley Sports & Spine Clinic
Giving you Back your Life
Dr. Ethan Colliver