How Does the Chiropractic Adjustment Work?
Our last blog post discussed the philosophy employed by Queen City Chiro. Unsurprisingly, the chiropractic adjustment was highlighted as a key component of our treatment philosophy. While a widely used technique across osteopaths, physical therapists, and chiropractors of course, few truly understand the mechanism and benefits of a chiropractic adjustment. I promised we would deconstruct each technique used in our office, so lets dive in...
As aforementioned, a few medical practitioners are trained in the art of the chiropractic adjusting. Osteopaths and physical therapists spend a few weeks learning the skill at some point during their education. However, chiropractors spend years learning, refining, and mastering the technique. With thousands of hours of experience learning the technique and understanding its effects, no one is more qualified to discuss this manual therapy than a chiropractor.
Let us begin with an investigation of technique. Before we can understand how the chiropractic adjustment works, we must explore what it is! An adjustment is a manual technique applied to the junction between two bones (a joint!). A joint, in conjunction with your muscles and ligaments, is designed to allow for movement across specific directions. For example, the joints in your cervical spine (there are 20 in total!) are oriented to allow you to rotate, flex, extend, and bend your neck. Commonly, our everyday activities, such as texting or writing emails, cause dysfunction within our joints, as muscles and ligaments grow tight due to repetitive motion. A chiropractor is trained to restore the normal physiological movement in joints by moving them through their normal ranges of motion. It is a common misconception that restricted motion is required for benefit. As we will see, the chiropractic adjustment delivers an array of benefits, even in healthy joints. But I digress; lets get back to the basics.
The chiropractic doctor employs a high velocity, low amplitude thrust when performing a chiropractic adjustment. Using their hands, the chiropractic table, or a chiropractic adjusting tool (such as the Activator), chiropractors quickly and carefully move the joint through its normal ranges of motion. This element of the technique is crucial, as we will soon learn. High velocity adjustments are fast, occurring in milliseconds. Moreover, the low amplitude ensures the joints are moved within their normal, physiologic ranges of motion, ensuring the joint is healed and not compromised. The rapid and precise adjustment delivers roughly 3000 newtons of force in a fraction of a second 1. This precise force conveys several benefits.
As discussed, joints are constrained by their muscles and ligaments. Everyday activities cause these muscles and ligaments to grow hypertonic, or tight, restricting the joints motion. Restricted motion is a powerful pain generator. Thankfully, the chiropractic adjustment corrects restricted movement. Ligaments contain Golgi tendon organs, which maintain a constant state of tension in the tissue. Likewise, muscles contain spindle receptors, maintaining a constant state of tension within muscles. When stretched rapidly, as observed during a high velocity, low amplitude chiropractic adjustment, these Golgi tendon organs and muscle spindle receptors are reset, relaxing ligaments and musculature, and restoring the joint to its normal physiological state 2. Speed is essential in obtaining this benefit, which is just one of the many reasons why adjustments must be performed by trained chiropractors to achieve optimal results (another discussion for another time!). However, chiropractors are nueromusculoskeletal specialists. The chiropractic adjustment addresses more than the musculoskeletal system.
The chiropractic adjustment is extremely effective at restoring normal function within the musculoskeletal system. However, the benefits do not end here. The chiropractic adjustment is exceptionally effective at treating the neurologic system as well. Joints possess specialized neurons called mechanoreceptors. These mechanoreceptors detect movement and send signals to the brain, allowing the mind to know where the body is in space. This sense of self-awareness, or proprioception, is essential for navigation through the physical world. However, these signals have a secondary benefit as well. These signals share a common pathway to the brain with pain signals. When mechanoreceptors are activated, they actually overwhelm the common nerve pathway, never allowing them to reach the brain 3! Here, chiropractic can actually benefit the function of your organs, but as you will see is a common theme, this is a blog post for another time!
So far, we have addressed why chiropractic adjustments must be fast, powerful and controlled. Moreover, we have discussed how these skilled adjustments affect muscles, joints, and the nervous system. I saved the final talking point for last, as it is least important, despite presenting as one of the most common questions for chiropractors. Let us discuss the CRACK! Many of us are crack addicts (don’t worry, were not discussing addiction here). We love the sound produced from a great chiropractic adjustment. However, it is a relatively meaningless event. The crack or pop heard during a chiropractic adjustment is known as a cavitation. When the chiropractic adjustment causes the two bones of a joint to move and separate, a negative pressure is created inside the joint space. The negative pressure causes small gasses to draw out from the joint surface and into the joint space, creating an audible noise! The noise, or lack thereof, does not dictate whether an adjustment was successful, but rather an insignificant byproduct of the treatment itself. The crack heard during a chiropractic adjustment is no different than that observed when cracking your own knuckles. I hope our discussion today gave you a little insight into the interworkings and mechanics of a chiropractic adjustment. Check back in for more posts like these, and feel free to leave a message if you would like a particular topic discussed!
-Take care & we hope to see you soon!
References:
1. Owens, E. F., Jr, Hosek, R. S., Sullivan, S. G., Russell, B. S., Mullin, L. E., & Dever, L. L. (2016). Establishing force and speed training targets for lumbar spine high-velocity, low-amplitude chiropractic adjustments. The Journal of chiropractic education, 30(1), 7–13. https://doi.org/10.7899/JCE-15-5
2. Pickar, J. G. (2002). Neurophysiological effects of spinal manipulation. The spine journal, 2(5), 357-371.
3. Pickar, J. G., & Bolton, P. S. (2012). Spinal manipulative therapy and somatosensory activation. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, 22(5), 785–794. https://doi.org/10.1016/j.jelekin.2012.01.015
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