What causes the gas build up in joints, that make it able for a person to crack the joints?
In: Biology
To add to what u/CrocodileDog said, the gas is already inside the joint.
All bodily fluids already have gases dissolved in them. In the case of synovial fluid, which is in a sealed capsule, when you stretch that capsule it decreases pressure in the fluid, and the gas comes out of solution. It then slowly reabsorbs over time, which explains why you generally can’t crack the same knuckle twice in rapid succession (refractory period).
Disclaimer, this is the best explanation currently available; it’s not exactly settled science yet.
If I recall, the act of cracking your joint actually causes the air bubble.
So you force your joint apart, which lowers the pressure on the liquid between your joints, which causes a bubble to form, which your body doesn’t like so it collapses again and makes a noise.
This is called cavitation.
Okay, so what does mean when my joints crack when I don’t try to crack them? My ankle cracks almost constantly when I walk.
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