Here’s What Happens When You Crack Your Knuckles

Recognize this sound? If you pop or crack¹ your joints, you probably do. What happens to our joints when we crack them? And is it bad for you? Synovial fluid is this lubricant-like substance that’s found in between your joints. It kind of looks like an egg yolk. So, when you stretch out your joint, you are releasing gas and that gas forms a bubble and it collapses and pops.

In order to crack the same knuckle again, you have to wait about 20 minutes for the gas to return back to that fluid. So how is that different from a pop you hear when you stand up quickly? The sound you’re probably hearing then is the snapping sound tendons make when they slide between muscles or over bones. When a joint moves, the tendon snaps quickly over it and it makes a popping sound. So is a knuckle cracking habit safe? Probably.

Donald Unger was sort of a self-described researcher who chose to pop the joints in one of his hands for 60 years, but not the other one. And he wanted to find out if popping your knuckles would actually give you arthritis. But after 60 years of doing it, he found that he didn’t have any more arthritis in one hand than in the other. Most medical sources agree with his findings, but there is still a chance that it’s not good for you.

One 1990 study did find that cracking your knuckles over a long period of time led to hand swelling and decreased grip strength but there hasn’t been any follow up research on that. So, while cracking your knuckles might not be bad for you, there’s still no guarantee that your popping habit won’t annoy the people around you.