When a high velocity low amplitude (HVLA) thrust is applied to a joint by a trained physician such as a chiropractor, naturopathic physicians, or some doctors of osteopathic medicine, several things happen.
First of all, bubbles may form around the joint creating a cavitation resulting in an audible “pop” sound. A common misconception among chiropractors and patients alike is that if a “popping” sound isn’t heard, then the bone didn’t move. This is simply not true as bones can move all the time without having popcorn popping in our joints. A simple demonstration of this, that is visible to the eye, is by waving your hand under water and seeing the bubbles appear. This is also a cavitation.
When an HVLA thrust is administered properly feel-good hormones, or endorphins such as serotonin and endogenous cannabinoids are secreted. This decreases pain!
(Bishop, M. D., Torres-Cueco, R., Gay, C. W., Lluch-Girbés, E., Beneciuk, J. M., & Bialosky, J. E. (2015). What effect can manual therapy have on a patient’s pain experience?. Pain management, 5(6), 455–464. https://doi.org/10.2217/pmt.15.39)
Inflammation is decreased as the stress from the misalignment of the joint is alleviated.
Restorative range of motion occurs when the joint is adjusted.
Nerve function and vascular function associated with the area being treated is revived.
The quick stretch of the muscle from the adjustment causes the golgi tendon organ of the muscle to be stimulated causing the muscle to relax. When a muscle relaxes it ceases to pull on the bone it is attached to.
With this realization, we can conclude that chiropractors use the bones as long levers to adjust the muscles! For truly it is often the muscles pulling on the bone that causes the bone/joint to be restricted.