Lower back pain is notoriously difficult to diagnose. Modern medicine looks for tangible problems, such as those that show up on an X-ray or MRI, in the diagnosis of back pain. But a majority of people with recurrent and chronic back pain don’t have visible spinal injuries. This has led to the reasonable assumption that many cases of back pain involve the musculature.
Muscular dysfunction comes in many forms. The muscles of your core may simply be too weak to hold the upper body and support the spine, meaning they’re fatigued and strained by improper posture. When one muscle doesn’t do its job, another compensates; this leads to overuse of some muscles, which can in turn lead to the development of knots called trigger points which lock in chronic tension. Both overused and underused muscles fail to receive proper nutrition from blood flow and are prone to painful spasms.
There are a number of muscles throughout the lower back and pelvis that are responsible for keeping the pelvis and spine neutral, supporting proper posture and body mechanics. A problem with one muscle can cause a chain reaction by kick-starting the compensation cycle. Recently, researchers sought to assess whether people with lower back pain exhibit differences in the use of three key muscles: the quadratus lumborum, the psoas major and the lumbar erector spinae muscles.
This study was small, consisting of only 19 participants, 10 of whom had recurrent lower back pain, with the remaining 9 serving as the control group. Researchers first measured engagement of the lumbar erector spinae muscles in each participant; these muscles stretch from the sacrum at the base of the spine to the 5 lumbar vertebrae and the 6 lowest ribs on each side of the body. The erector spinae is responsible for extending the back, or bending backward.
All participants were tested for engagement of the quadratus lumborum (QL) and psoas major when sitting in 3 different positions: flatback, slouching and with a slight inward lumbar arch (lordosis). The QL stretches from the hip bone to the lowest rib, with offshoots to the lumbar vertebrae. The psoas stretches from the top of the thigh bone to the lumbar vertebrae.
Researchers found no difference in general between the group with back pain and the control group with no back pain in terms of QL and psoas engagement; however, when they took into account those with high and low erector spinae activation, differences emerged.
Lower back pain participants who had high erector spinae (ES) activation levels had lower psoas engagement levels in the slight lordosis posture than the lower back pain participants with low ES activation levels. This latter group exhibited higher levels of QL and psoas activation in flatback posture and greater QL activation in slight lordosis posture than the control group did.
To learn more about this study, see www.jospt.org.
So, what does all that mean? First, it illustrates that people with back pain have different patterns of muscle usage, meaning there isn’t a one-size-fits-all muscular dysfunction we can count on. Second, it demonstrates that, in people with back pain, muscle imbalance may well be a factor in pain. The fact that low activation of ES corresponds to higher use of the QL and psoas can mean either that these latter muscles are compensating for a weak ES muscle, or that chronic tension in them inhibits the activation of the ES, indicating a potential treatment track for individuals with this pattern.
Perhaps one of the most important points to take away from this study, and others like it, is that muscular back pain requires an individualized approach to diagnosis and treatment. Seeing a physical therapist and a myofascial release expert trained to detect patterns of muscle compensation, tension and weakness can help you identify and correct complex muscular back pain causes.