It is probably the most common question we get asked: “What is that cracking sound?”
Whether you have been getting adjusted for years or you are thinking about booking your first appointment, it is natural to wonder what is actually going on when a chiropractor adjusts your spine. So let’s break it down.
The sound: what causes the “crack”?
That popping or cracking sound you hear during an adjustment is called cavitation. It has nothing to do with bones cracking or grinding together.
Your joints are surrounded by a capsule filled with fluid called synovial fluid. This fluid lubricates the joint and helps it move smoothly. When a chiropractor applies a quick, controlled thrust to a joint, the pressure inside the capsule drops briefly. This pressure change causes dissolved gases (mostly carbon dioxide and nitrogen) to form a small bubble, which collapses almost instantly. That collapse is what creates the sound.
It is the same thing that happens when you crack your knuckles. The sound might be satisfying or a little unsettling depending on your personality, but it is completely harmless. Research published in PLOS ONE (2015) confirmed this mechanism using real-time MRI imaging of joints during cavitation.
And worth noting: the sound is not the point of the adjustment. Sometimes there is no pop at all, and the adjustment is just as effective.
What is actually happening to the joint
The real purpose of an adjustment is to restore normal movement to a joint that has become stiff or restricted.
When a joint is not moving properly, it affects everything around it. The muscles that cross that joint start to tighten up as a protective response. The joints above and below it start to compensate by moving more than they should. Over time, this creates a chain reaction of stiffness, tension, and pain that can spread well beyond the original problem.
A chiropractic adjustment applies a specific, controlled force to that restricted joint. This does a few things:
- Restores range of motion. The joint starts moving through its normal range again, which takes pressure off the surrounding structures.
- Relaxes the surrounding muscles. When the joint moves properly, the muscles guarding it can release their protective tension. This is why many people feel an immediate sense of relief after an adjustment.
- Breaks the compensation cycle. Once the restricted joint is moving again, the joints above and below it no longer need to overwork.
The nervous system connection
This is where it gets interesting. A chiropractic adjustment does more than just move a joint. It has a measurable effect on your nervous system.
Your spine houses your spinal cord, and between each pair of vertebrae, nerves branch out to every part of your body. When a spinal joint is not moving well, it can affect the way those nerves send and receive signals.
Research by Haavik and Murphy (2012) showed that spinal adjustments can change the way the brain processes information from the body. After an adjustment, the brain receives more accurate feedback about where the body is in space and how it is moving. This improved communication can lead to better coordination, reduced muscle tension, and changes in pain perception.
This is also why a chiropractic adjustment can sometimes help with symptoms that seem unrelated to the spine. Headaches, jaw tension, and even shoulder stiffness can all be influenced by how well your spine is functioning.
Does it hurt?
Most people find adjustments comfortable, and many feel immediate relief. You might feel some pressure during the adjustment itself, and occasionally some mild soreness afterwards, similar to what you might feel after a good workout. This usually settles within 24 hours.
If you have a particularly acute or inflamed area, your chiropractor will modify the technique. There are many different adjustment methods available, from traditional manual adjustments to gentler, low-force techniques. The approach is always tailored to you.
Is it safe?
Chiropractic adjustments are widely recognised as one of the safest forms of treatment for musculoskeletal pain. Serious complications are extremely rare.
A large study published in Spine (2007) involving over 19,000 chiropractic treatments found that the risk of a serious adverse event was less than 1 in 10,000. For context, the risk of a serious complication from common over-the-counter anti-inflammatory drugs is significantly higher.
Your chiropractor will always perform a thorough assessment before any treatment to make sure an adjustment is appropriate for you. If it is not the right approach for your situation, they will let you know and suggest an alternative.
What conditions respond well to adjustments?
Chiropractic adjustments can help with a wide range of conditions, particularly those involving the spine and musculoskeletal system:
- Low back pain and stiffness
- Neck pain and restricted movement
- Headaches and migraines
- Thoracic and rib pain
- Sciatica and radiating leg pain
- Joint stiffness and reduced mobility
- Postural problems from desk work or daily habits
If you are not sure whether chiropractic care is right for your situation, the best first step is a proper assessment. We can talk through what is going on, examine you, and give you an honest answer about whether we can help.
The bottom line
A chiropractic adjustment is a safe, controlled movement applied to a joint that is not functioning properly. It restores motion, relaxes tight muscles, and has measurable effects on your nervous system. The cracking sound is just a gas bubble releasing, not bones moving out of place.
If you have been putting off getting checked because you were not sure what to expect, now you know. Book an appointment or get in touch and we will take it from there.
References
- Kawchuk GN, Fryer J, Jaremko JL, Zeng H, Rowe L, Thompson R. Real-Time Visualization of Joint Cavitation. PLOS ONE. 2015;10(4):e0119470.
- Haavik H, Murphy B. The Role of Spinal Manipulation in Addressing Disordered Sensorimotor Integration and Altered Motor Control. Journal of Electromyography and Kinesiology. 2012;22(5):768-776.
- Thiel HW, Bolton JE, Docherty S, Portlock JC. Safety of Chiropractic Manipulation of the Cervical Spine: A Prospective National Survey. Spine. 2007;32(21):2375-2378.
- Pickar JG. Neurophysiological Effects of Spinal Manipulation. The Spine Journal. 2002;2(5):357-371.