Short Stuff: Knuckle Cracking

Does knuckle cracking give you arthritis? It doesn't appear to. But that doesn't mean it's harmless. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:04Josh Clark?

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• 1:06Josh Clark?

  Hey, and welcome to the short stuff. Josh, Chuck, Jerry sitting in for Dave. So this is short stuff. Chuck, I have a question for you. Are you cracking your knuckles right now?

• 1:18Speaker 02

  I am. Did you hear that?

• 1:19Josh Clark?

  Yeah. That wasn't like a, like a Foley effect?

• 1:23Speaker 02

  No, I was cracking my knuckles. I'm a knuckle cracker. I don't do it. I did it a lot when I was a kid. But I, I still do it some.

• 1:32Josh Clark?

  This is what my knuckles sound like when I crack them.

• 1:41Josh Clark?

  That's it.

• 1:44Josh Clark?

  The, yeah, I can't do it again because I have to wait 20 to 30 minutes for the air bubbles to come back and cavitate once more.

• 1:51Speaker 02

  Yeah, well, well, tell everybody what's going on here. What, I know there was a lot of, you know, when you're young, everyone was like, it'll give you arthritis and it's your, your bones grinding together. And that's what cracking your knuckles is, and that can't be good for you.

• 2:04Josh Clark?

  Yes. If your bones ground together, you would not be able to think of anything else, but your bones grinding together because you would be in so much pain that you would know your bones are grinding together. That's not what cracking your knuckles is. It turns out instead, it has everything to do with the space and the area around where your bones come together. Your bones don't actually come together.

• 2:27Speaker 02

  That's right. Where there's a joint, that is where two bones meet, but they're separate and they're held together by ligaments and connective tissues and all that stuff. But there's also some, a very other key ingredient in there. It's called synovial fluid. It's a thick, clear liquid that kind of encases that area, right?

• 2:47Josh Clark?

  Yeah. It's, it's thick. It tastes just like orange crush, surprisingly. And when you, when you pop your knuckle, what you're doing is stretching or bending the, the ligaments and connective tissues and the synovial fluid there too, right? So when you do that, that capsule is what it's called, the connective tissue capsule that includes the synovial fluid, it gets stretched, which increases its volume. And then suddenly the pressure inside the capsule in that synovial fluid, it goes down. It decreases in pressure, which means that all these gases that used to just be part of the solution now are part of the problem. I mean, now turn into bubbles.

• 3:28Speaker 02

  That's right. So they become, you know, they form those bubbles. And if you stretch that joint far enough, like, you know, trying to crack your knuckles, the pressure in the capsule goes so low that it just pops those bubbles. And that's the popping sound that we're hearing.

• 3:43Josh Clark?

  There you go. Not your bones rubbing together. Okay. I want you to go to recess and tell your friends, that is not your bones rubbing together.

• 3:52Speaker 02

  Yeah. And then the cavitation you mentioned earlier, I think before we break, we should just clear that up. You said 20 to 30 minutes? That is how long it takes for that gas to re-dissolve into that joint fluid and cavitation is, is possible again.

• 4:09Josh Clark?

  Yeah. Go watch, watch me cavitate my knuckles.

• 4:12Speaker 02

  Yeah, exactly.

• 4:15Josh Clark?

  Oh, I just did one again. Okay. I say we take a little break and come back and talk about how we know that cracking your knuckles doesn't give you arthritis.

• 4:24Speaker 02

  All right. We'll be right back.

• 4:41Speaker 03

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• 4:43Josh Clark?

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• 5:33Josh Clark?

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• 5:46Josh Clark?

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• 6:15Josh Clark?

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• 6:54Josh Clark?

  Chuck, I know we've talked about this guy before, Dr. Donald Unger. I think we did a video about him.

• 6:59Speaker 02

  Yeah.

• 7:00Josh Clark?

  But he, you know what, I'll bet we talked about him in the Ig Nobel Prize episode because he won an Ig Nobel for this.

• 7:08Speaker 02

  I bet you're right.

• 7:09Josh Clark?

  He conducted an experiment for 60 years because he wanted to prove his mother wrong. And he only cracked the knuckles on, I think, his left hand. Never cracked them on his right hand.

• 7:20Speaker 02

  That's crazy.

• 7:20Josh Clark?

  And then after 60 years, he finally said, okay, it's time. And he x-rayed his hands.

• 7:26Speaker 02

  Yeah. If he didn't have the compulsion to crack his knuckles, I could see how this happened. But if you are a knuckle cracker, you're kind of, you feel compelled to do it. So I can't imagine what it would have taken to not crack the knuckles on one hand for that many years. It must've been really tough.

• 7:44Josh Clark?

  Yeah, sure.

• 7:46Speaker 02

  That's my guess. So yeah, he did this over his lifetime. He x-rayed himself on the reg. And eventually decades later, came to the conclusion that he doesn't have any arthritic difference in his hands. Case closed.

• 8:01Josh Clark?

  He had NAD, no arthritic difference.

• 8:04Speaker 02

  That's right.

• 8:05Josh Clark?

  That's not to say though, that even if you don't get arthritis from cracking your knuckles, it's another thing you can tell your friends at recess. Do they even have recess anymore? I guess maybe hour-long screen time?

• 8:17Speaker 02

  No, they have recess.

• 8:19Josh Clark?

  Okay, great. There is damage that you can do from cracking your knuckles habitually. There was a guy named Raymond Broder. And he examined 300 people who cracked their knuckles to look at what their joints looked like. And compared to the control group, no difference with arthritis again. But there was other damage, like soft tissue damage to that, the ligaments and the synovial fluid capsule. And that they had a decrease in grip strength. So if you crack your knuckles a lot, like, don't even think about holding a glass of water with just one hand.

• 8:56Speaker 02

  Yeah, which, you know, as you age, grip strength is important. So it's definitely not a harmless thing. There's some other possible side effects, something called ligament laxity, which is basically looseness. So over time, if you're just doing this a lot,

• 9:12Speaker 02

  that's what leads to the reduced grip strength and sometimes sort of overall hand function.

• 9:16Josh Clark?

  Yeah.

• 9:17Speaker 02

  I think in rare cases, if you're, if you have a really weird method or forceful method, or you're a little too aggressive with it, you can get some soft tissue swelling around the knuckles in the joint.

• 9:30Josh Clark?

  Yeah, you can just straight up injure yourself. If you, you can like dislocate a joint, you can injure your tendons. And even if you don't straight up injure yourself, just habitually cracking your knuckles over time, the stretching of the ligaments can, like you said, the grip strength thing is a, is a big deal, just even without cracking your knuckles. So it also happens in pitchers too, major league pitchers. Imagine minor league pitchers too, but over the years, just throwing over and over and over again, they're stretching those ligaments suddenly violently, basically, which is kind of what you're doing when you crack your knuckles.

• 10:09Josh Clark?

  They're just doing it with different ligaments. But that is why Orel Hershizer's right arm just dangles uselessly at his side. Cause it's been ruined. He ruined it pitching.

• 10:19Speaker 02

  Yeah, I mean, I know you're kind of kidding, but sad but true. Like especially these days, there's been more and more instances of Tommy John surgery being required because pitchers are throwing harder and harder. And if you're not, you know, able to get it near a hundred miles an hour these days, you're not going to have much of a chance. So it's a real problem in baseball.

• 10:42Josh Clark?

  That was a real bring down from my joke.

• 10:44Speaker 02

  Yeah.

• 10:46Speaker 02

  I just love that you love saying Earl Hershizer.

• 10:48Josh Clark?

  Sure.

• 10:49Speaker 02

  What a name.

• 10:52Speaker 02

  Boy, he was great. There was a study in 1990 that confirmed the grip strength thing. I think they studied 74 people who regularly cracked their knuckles and their average grip strength was definitely lower and they had more instances of hand swelling than the 226 people who did not crack. And another interesting thing is they found that in another study, that if you're a habitual knuckle cracker, you are more likely to be a manual laborer, more likely to bite your nails, as I do, smoke cigarettes, which I don't, and drink alcohol, which I do.

• 11:28Josh Clark?

  Yeah. So you're, you know, three for five?

• 11:32Speaker 02

  Yeah, I don't manual labor, so we shouldn't count that one.

• 11:36Josh Clark?

  So there is some benefits to actually cracking your knuckles, though, too. We're not just hating on cracking your knuckles. There's something called the Golgi tendon organs, not the Golgi apparatus. It's a different, different episode altogether. The Golgi tendon organs sense muscle tension. And when you crack your, your knuckles, you're actually relieving some muscle tension. So the, the muscles around the joints, when you crack them, get relaxed. So you can feel like, you know, your, your hands feel pretty mellow after cracking your knuckles. I saw it described as yoga for your knuckles.

• 12:13Speaker 02

  Oh, interesting.

• 12:14Josh Clark?

  Yeah, I thought so, too.

• 12:16Speaker 02

  So like getting your back cracked or something?

• 12:17Josh Clark?

  Basically, yeah, but for your knuckles.

• 12:20Speaker 02

  Yeah, we found one more thing, you know, like I'm at the age where, you know, if I kneel down to get something, you're gonna hear a couple, a snap, crackle and a pop, maybe, coming from some part of my body.

• 12:33Josh Clark?

  Do you make an involuntary sound, too, when you're getting up? I do.

• 12:36Speaker 02

  Oh, oh, yeah, like, oh, God, here we go, or something like that.

• 12:39Josh Clark?

  Like, you can't not do it.

• 12:41Speaker 02

  Yeah, for sure. And when I walk downstairs, my right...

• 12:47Speaker 02

  Ankle, like on every step, just goes pop, pop, pop. So those things happen. I don't think anyone knows exactly where that comes from. There's speculation it could be just like, you know, if it's your knee, it may be your kneecap rubbing on the bones or something like that, or maybe a tendon sliding over a bumpy surface or something like that. So I don't think it's anything to be alarmed about.

• 13:11Josh Clark?

  It is alarming, though, for sure.

• 13:13Speaker 02

  Yeah, because it comes with age. So every new pain and sound is like, huh, that didn't happen a few years ago.

• 13:18Josh Clark?

  Exactly. I should go sit down for a while.

• 13:21Speaker 02

  Right.

• 13:22Josh Clark?

  You got anything else for short stuff, Guy?

• 13:25Speaker 02

  I got nothing else. I can't crack my knuckles. So, oh, wait, there went one. Recavitated.

• 13:31Josh Clark?

  So what does that mean?

• 13:33Speaker 02

  I think that means short stuff is out.

• 13:38Speaker 07

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