A lot of people crack their joints. Sometimes it happens involuntarily, some people do it on purpose. But why does it happen? And is it bad for you? This video explains all.
A liquid called synovial fluid lubricates your joints and sometimes a gassy build up can occur within it. The audible crack you hear is the bubbles of this gas popping, and it's actually nothing to do with your bones as some people think.
Fun fact: It takes about 20 minutes for the gas to build up again.
Some cracks, however, can be due to tendons sliding over muscles quickly, it's not all because of the synovial fluid.
Dr. Donald L. Unger was a scientist who decided to be his own human guinea pig, cracking the knuckles in one hand and not the other to see if the act can cause arthritis.
After six years, he found there was no effect. Another study did discover a link between knuckle popping and hand swelling, but there's no real evidence to back it up.
So there you have it! Science says cracking your knuckles won't give you arthritis and doesn't really do any damage (unless there's something science hasn't figured out yet).