You’re no stranger to the popping, snapping, or joint cracking sounds your body makes during movement. These sounds can be surprising or even unsettling, but rest assured, they are generally normal and not a sign of damage. Understanding why your body makes these noises can help you move with confidence and ease, without fear holding you back.

💥 What Creates Joint Cracking Sounds?

Joint cracking sounds come mainly from two scientific phenomena: cavitation and tissue sliding.

1. Cavitation: Gas Bubbles and the “Pop”

When you move a joint, the pressure inside the joint capsule changes quickly, causing gases dissolved in the synovial fluid (mainly nitrogen and carbon dioxide) to form bubbles. These bubbles forming create the classic joint cracking sound. This process is known as tribonucleation and has been visualized through MRI research, including key studies led by Kawchuk and others.

2. Tissue Sliding: The Stick-Slip Phenomenon

Another source of cracking sounds doesn’t come from the joint itself but from the movement of surrounding tissues, like tendons, ligaments, and fascia, sliding over one another. Think of your body as a stack of these tissues, constantly gliding on each other as you move.

And that’s where the perfect summer analogy comes in: the classic Slip ’N Slide. It’s just a long sheet of plastic, sprayed with water (and sometimes soap) to create a slick surface for smooth, effortless sliding. But if the surface isn’t wet? You come to a screeching halt, maybe even walk away with a little tarp burn.

Now, bring that image back to your tissues. When everything’s moving well, the tissues glide smoothly. But when there’s increased friction, from dehydration or lack of movement, things don’t slide so easily. This is where the Stick-Slip phenomenon comes into play. It’s a scientific term describing how materials resist movement due to the static coefficient of friction, then overcome that friction, which creates a popping or cracking sound.

This also explains why joints or tissues can be noisier after you’ve been sitting or resting for a while. Your body’s just working through the friction to get things moving again.

⚠️When Joint Noises Could Indicate Injury

While most joint popping and cracking noises are harmless, it’s important to recognize when they might signal a problem. If joint noises are accompanied by swelling, redness, pain, warmth, or loss of function, this could indicate an injury. If you experience these symptoms along with joint sounds, it’s important to consult a healthcare professional for a proper evaluation and treatment plan.

Remember, joint noises alone are usually benign, but when paired with other symptoms, they warrant further attention.

✅Most Cracking Sounds Are Normal

Before we move on to reassurance, consider this: there is no true silence on Earth. 

“This point was attempted to be proven by John Cage in 1952 when he composed 4’33”, a 4-minute and 33-second-long piece of “silence”. Cage’s motivation behind this piece was likely not ticket sales, rather, it was sparked from time spent in an anechoic chamber at Harvard…This motivated him to show the world that true silence does not exist.” p. 32 Top Selling Hope Not Nope

The other assurance needed is that it is more normal for your body to make noises such as joint cracking sounds, than not.

🔬What Does the Research Say?

You’re definitely not alone in experiencing joint noises, and scientific studies back up that these sounds are mostly harmless:

• McCoy et al. used vibration arthrography and found that 99% of knees produce some type of noise.
• Pazzinatto et al. tracked people over time to see if knee crepitus (joint noise) predicted the need for total knee replacement due to osteoarthritis. The result? No link to higher surgery risk, nor to reduced physical function or quality of life.

But my favorite “study” comes from Donald Unger, who won the Ig Nobel prize for showing that cracking your knuckles over a lifetime does not create arthritis. (Take that, mom!)

😨Although normal, the noise can be scary

De Oliveira et al. studied women with patellofemoral pain and found that while joint cracking sounds from the knee didn’t relate to pain severity or activity level, women with the noise were 4 times more likely to experience pain due to belief systems and fear. 

Robertson et al. explored beliefs about joint cracking sounds and found that fear of these sounds led many to avoid certain activities. Adding to that, negative reactions from family or healthcare providers worsened this fear. 

The takeaway? Your brain works by prediction, constantly evaluating sensory information and previous memories to make sure you are safe. A belief system that joint cracking sounds equal damage can be interpreted as a major red flag to safety. To request said change, the nervous system brings attention to the request via the pain response. The input we receive greatly impacts the output.

💪Empowerment for Athletes: Embrace the Noise, Not the Fear

Joint cracking sounds are mostly normal and not harmful. 

If you do experience discomfort alongside noise, it’s worth checking in with a healthcare professional. Otherwise, focus on how your body feels and functions rather than the sounds it makes.Remember, your perception shapes your reality. When you understand that joint noise is natural and harmless, you can move more freely and confidently.

Author: 

Dr. Dillon Caswell, PT, DPT, SCS

Hope Evangelist | Top-Selling Author & Speaker | Human Performance Expert