Do you crack your knuckles? Or do you cringe at the sound?
In any case you are probably interested to know what causes that pop.
Well, you will be glad to hear that scientists finally did an MRI scan to see what exactly is happening when your joints crack. The explanation is actually quite simple.
The space between your joints is filled with liquid, the texture of which is similar to that of an egg yolk. It serves as a cushion between bones helping them not to rub against each other. This liquid contains dissolved gas molecules.
When you crack your finger you pull one of the bones away from the other, further away than it would normally go. But as the distance between the two bones increases the amount of liquid stays the same.
When you do that, a low pressure zone is created between the two bones and dissolved gases are pulled out of the fluid (just like when you open a bottle a soda). These gases then form a bubble making a popping sound. But the bubble doesn’t stay there long, it finally dissolves back into the fluid. It takes it about 20 minutes to do that. Which is why you cannot crack the same joint straight away.
There you go, the mystery of knuckles popping is finally explained.
But if popping your knuckles is bad or good has not been agreed upon yet.
Some studies showed that constant knuckle cracking can cause your hands to swell, but another study conducted by Donald L. Unger who cracked the fingers of one of his hands for 50 years, shows that it doesn’t actually cause any problems with the bones. So it seems that for now the biggest concern of knuckle crackers is annoying the people around them 🙂