Have you ever felt stiffness in your lower back? Have you ever thought about what it could be? It feels like bone on bone, tearing, ripping, and compressing structures. It feels like there is a vice around your back, right? It’s doesn’t let you bend over, or touch your toes, or put on your shoes. What if I told you that this feeling could be a sensation, a protective response, that it may not correlate with any actual biomechanical stiffness?
Many conditions such as arthritis, neck pain, and low back pain treatments are targeted around joint stiffness. Stiffness is a significant predictor of disability. The most prevalent condition treated of these three is low back pain, accounted in about 10% of individuals worldwide. As healthcare costs rise, our ability to treat this area does not improve, something is wrong here…
The following explains the findings of a 2016 study by Stanton et al, whom experimented to explain the argument against a correlation of actual structural stiffness and the perception of feeling stiff. They looked at structural stiffness, perception of force applied to the spine, and the effect of adding an auditory stimulus to applied pressure to the spine. They compared individuals with chronic back pain and the perception of stiffness to healthy individuals without low back pain.
First, stiffness in the lower back was shown to be poorly correlated with actual objective stiffness in the structures of this area. Instead, it can be more accurately viewed as a “perceptual inference that may serve to reduce movement and re-injury.” (1) Stiffness can be viewed as a possible learned behavior that severed to protect a once acutely injured area. Our bodies are extremely smart and they try and protect us from injury, however, once the injury has healed, if we do not retrain that area to move once again, it will remain guarded, “stiff” if you will.
Second, people with the perception of stiffness in their lower back overestimated the amount of force applied to the spine and were better at detecting a change in this force applied. Being hypersensitive in an area of the body can be correlated with a change in the brain’s perception of how it views, controls, and perceives that area. The connection is a bit blurry. With a blurry connection, the brain can get protective and hence can create this learned “stiffness”
Lastly, adding a sound in conjunction with the applied force altered the sensation of the degree of force applied to the area of the spine. This means when force was applied to the spine with a sound that is perceived as light, soft, airy, it changed how much force the person reported feeling.
This article concluded that the feeling of stiffness in the spine is multimodal and is derived from both sensory and perceptual inputs, NOT necessarily actual spine stiffness. This is a very interesting finding and can significantly alter how we as clinicians treat low back pain. As a person with low back pain, this can change how you view your symptom. It does not mean that it is not there, it is truly there! You feel the stiffness, but what this article debunks is the feeling that there is actual, structural stiffness that needs to be broken up, stretched, or cut. Next time you feel that symptom, try and think about what is NOT happening vs what you may think is happening.
Stanton et al. Feeling stiffness in the back: a protective perceptual inference in chronic low back pain. Scientific Reports August 29, 2017.