The myth that cracking your knuckles is bad for you can be finally put to bed, after a study involving 40 volunteers showed that no short term damage was caused by clicking your fingers.
Researchers from the Radiological Society of North America, used ultrasound to analyse knuckle-cracking in real time. Using the imaging they were able to see exactly what was going on inside the joint at the exact moment of the "pop".
The patients were measured for grip strength, range of motion and laxity, pre- and post-crack, to determine if any short-term damage was caused.
The results? The cracking didn't cause any hand problems . In fact, in some patients, the crack increased the range of motion compared with knuckles that hadn't been cracked.
So what causes a knuckle to "crack" out loud?
"There have been several theories over the years and a fair amount of controversy about what's happening in the joint when it cracks," Dr. Boutin, who conducted the study said.
"We're confident that the cracking sound and bright flash on ultrasound are related to the dynamic changes in pressure associated with a gas bubble in the joint."
Essentially when you crack your fingers, you pull apart two surfaces of the joint, which reduces the pressure. As the pressure drops, so small bubbles of gas are released from the fluid in your joints.
"We think that's why a joint gets more range of motion after you crack it: There's something about lowering the pressure that allows for more laxity," Boutin said.
While one of life's great mysteries may finally be solved, it doesn't stop some people finding the habit a little off-putting.
"We heard from a lot of people, and while some said knuckle-cracking was relieving and helpful, just as many found it disgusting," he said.
"It's just my personal opinion, but I got the feeling that some of these people felt so grossed out by it that they created these myths."
So the myth that cracking your knuckles is bad turns out to just be a little white lie told by parents!