Recognize this sound? If you pop or crack your joints, you probably do. What happens to our joints when we crack them? And is it bad for you?
Synovial fluid is this lubricant-like substance that's found in between your joints. It kind of looks like an egg yolk. So when you stretch out your joint, you are releasing gas, and that gas forms a bubble and it collapses and pops. In order to crack the same knuckle again, you have to wait about 20 minutes for the gas to return back to that fluid.
So how is that different from a pop you hear when you stand up quickly? The sound you're probably hearing then is the snapping sound tendons make when they slide between muscles or over bones. When a joint moves, the tendon snaps quickly over it, and it makes a popping sound.
So is the knuckle-cracking habit safe? Probably. Donald Unger was sort of a self-described researcher who chose to pop the joints in one of his hands for 60 years, but not the other one. And he wanted to find out if popping your knuckles would actually give you arthritis. After 60 years of doing it, he found that he didn't have any more arthritis in one hand than in the other. Most medical sources agree with his findings, but there's still a chance it's not good for you.
那麼，拗指節的習慣安全嗎？也許。Donald Unger 是位有點算自稱研究人員的人，他選擇折自己其中一隻手的關節六十年，另一隻手則沒有折。他想要查清楚折指節是否真的會讓你得關節炎。這樣做六十年後，他發現他其中一隻手的關節炎並沒有比另一隻手更嚴重。大多醫學資料和他的發現一致，不過這樣做還是有可能對你不好。
One 1990 study did find that cracking your knuckles over a long period of time led to hand swelling and decreased grip strength, but there hasn't been any follow-up research on that. So while cracking your knuckles might not be bad for you, there's still no guarantee that your popping habit won't annoy the people around you.
一份 1990 年的研究確實發現長期拗指節會導致手腫脹和手握力下降，不過並未有任何那方面的後續研究。所以儘管拗指節可能不會對你有傷害，還是不能保證你那折手指的習慣不會惹惱周圍的人。