“Doesn’t that hurt?”
“It will give you arthritis!”
“That’s the most bone-chilling sound in the world.”
I’ve heard it all. And I know, my knuckle-cracking habit isn’t exactly flattering. But I can’t help it. I’ve been popping my fingers, back, neck, and other appendages for years. I don’t even remember when I first started. By now, cracking my knuckles is as deeply embedded in my lifestyle as applying lip balm when my pucker feels dry or eating when I’m hungry. Sure, I’ve gone through sober periods where I’ve put my habit on hold. But mostly, cracking my knuckles feels as necessary as scratching a needling, torturous itch.
That said, I don’t want to be that girl who pops her knuckles all day at work. Even I’ll admit that the noise is disturbingly loud for such a small action. Plus, I’m sick of hearing people tell me I’m damaging my joints. Cracking my knuckles isn’t really harming me, right? And while we’re asking questions, what is knuckle cracking, anyway?
To find out once and for all, I spoke to San Diego–based chiropractor Dr. Ryan Curda, D.C., as well as New York City–based physical therapist Dr. Scott Weiss, D.P.T.
For medically supported answers to all the questions you’ve ever had about cracking your knuckles, keep reading!
It’s a simple question, but one most of us have asked ourselves: What’s at work in the body when we hear that popping sound?
“Many believe that cracking knuckles is the bones realigning, which couldn’t be further from the truth,” says Weiss. Actually, the process has to do with your joints.
“Knuckle cracking is the audible sound that occurs when the joints of your fingers are stretched,” says Curda. “These joints are called synovial joints and are surrounded by fluid-filled capsules.” That fluid, called synovial fluid, is there for lubrication and is made up of dissolved gases—mostly nitrogen, Curda says.
When you pull or bend your finger (these are the two most common cracking motions), you stretch that fluid-filled capsule. This decreases pressure inside the gas-packed fluid, causing a small nitrogen bubble to form and then instantly pop. “The collapsing bubble is what causes the audible crack that we hear,” says Curda.
(Here’s a quick video of the whole process, if you want a helpful visual.)
As for why the sound is so loud, science still isn’t totally sure. However, there is a reason why you can’t crack the same joint over and over again. “The gases take about 20 minutes to fully dissolve back into the fluid,” says Curda. That’s the refractory period—the amount of time that needs to pass until you can get cracking again.
“Aside from some degree of compulsion, cracking the knuckles actually releases several pounds of pressure from the joints,” Weiss explains.
As you use your hands throughout the day and the muscles tighten up, the joints end up feeling tight as well. “Cracking the knuckles gives your fingers and joints a stretch to relieve that pressure buildup,” says Curda. In other words, people crack their knuckles for the same reasons they might take a nice, big stretch in the middle of the day: It provides a sigh of relief.
So, what makes certain people love a good knuckle-popping so much? “People that use their hands and fingers regularly during the day without otherwise stretching will feel the need more often,” says Curda. Think writers, coders, surgeons, and artists, to name a few.
But knuckle-cracking dependence goes further than that. Once you get into the habit, you become hooked on that feeling of relief—even the sound itself, says Weiss. “Cracking the knuckles is definitely addicting,” he affirms. It’s not something you can stop on a dime (no matter how much your family members and co-workers complain).
Ah, the million-dollar question. I always wrote off the warnings of arthritis the same way I ignored my grandmother when she told me if I crossed my eyes enough they’d get stuck that way.
Though the phenomenon is somewhat under-studied, science agrees: “There is no evidence that cracking your knuckles has any detrimental effect on your body,” says Curda. Intrinsically, there’s nothing about cracking your knuckles that leads to conditions like arthritis.
However, the worst of us knuckle crackers may not be totally off the hook. Bending the fingers to crack them can wear away the cartilage over time if you do it constantly, says Weiss. He recommends pulling the joint if you feel the need to crack, which is the “safest and most effective way to release the gas in your joints.”
That said, the long-term effects of knuckle cracking are not well known, and more research is needed.
There are things you can do to lessen the urge to crack your knuckles. “Hand, wrist, and forearm stretches performed regularly can help relieve the need to crack your knuckles as often,” says Curda. Every hour or two, try holding your hands in a prayer position in front of your face, then gently pull your hands downward toward your belly button until your elbows spread apart and you feel the stretch. Or, simply clench your hands into a light fist; then spread them wide apart, and repeat.
If you’re committed to leaving your knuckle-popping habit behind you, a certain level of willpower is also necessary, of course. But know that if you still crack a couple times a day, our docs say you’ll be just fine.
Weiss says, “Like all things in life, moderation is key.”
Interested in more fascinating medical knowledge? Check out this story on how coffee affects your skin, according to science.