Lifting injuries are among the most frequent causes of low back pain that chiropractors see. These types of injuries can come from lifting something very heavy one time, but are more often from repetitive lifts of moderately sized objects. Now that the winter months are upon us, shoveling can be a common cause of a low back injury. While lifting and/or shoveling may not always be able to be avoided, understanding the structure and the function of the lower back may result in safer lifting technique, and
therefore some injuries may be prevented.
Because lifting heavy objects puts a massive load on the lower back, the most commonly injured tissues due to improper or over-lifting are the intervertebral discs of the lumbar spine. These intervertebral discs are located between each vertebra in your spine, and act like cushions between the bones. The discs have a very unique structure, different from any other type of anatomy in the body. They are kind of formed like jelly donuts, soft material in the middle surrounded by thicker tissue on the outside. This thick tissue is actually made of layers of rings packed tightly on top of each other. The fibers of these rings are oriented at about 45-degree angles, with each ring alternating which direction the fibers are running, creating X-like patterns.
These alternating layers of rings become vital to the health of the discs for a number of reasons. First, the angled orientation of these fibers makes the discs very prone to injury during any motion involving a bend, twist, and lift, like shoveling snow. This is a classic movement that will injure a disc, because when the spine rotates half of the ring layers will become stretched, while the other half become relaxed. This puts the disc tissue itself in a compromised position. Also, when we bend over and lift something relatively heavy, a lot of pressure is put on our spine angled towards the back. Imagine squeezing one end of that jelly donut and pressure shifting the jelly toward the opposite side. That is what happens when we lift something up. So combining the bend, twist, and lift actually increases the likelihood of that interior disc tissue (the jelly) from breaking through the ring layers that are not in their most stable position due to the
rotation. When the inner tissue of the disc starts breaking through those outer rings, you will form a disc bulge. When the inner tissue breaks through the outermost ring layer and leaks past the boundary of the disc, that is now officially, and unfortunately, a disc herniation.
Let’s revisit another important component of the ring layers, which is their nerve supply. The key with the nerve supply to the discs is that only the very outer rings have nerves that run directly to them. This is important because your body cannot feel anything that a nerve doesn’t supply. In the case of a disc injury, this is huge because that inner disc material may have already started breaking through the inner parts of the rings, but your body can’t tell it is happening because there are no nerves to that area. It isn’t until the jelly breaks to the outside of the rings before the brain knows
there is a problem, and at that point it is often too late.
Preventing disc injuries completely can be difficult, especially if your job or daily routine entails lifting and carrying heavy objects. However, with proper lifting mechanics and keeping the spine functioning, everyone stands a fighting chance at avoiding injury.
Yours in Health, Dr. Alex