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Comment by tapland | Hacker News Reader

I can feel some kind of tension after a short bit of using my hands, and cracking my knuckles relieves it and allows me to continue without any issues. Usually I have to crack them before falling asleep, since the feeling of tension keeps me from sleeping. Doctors never thought this was an issue and I have no joint damage (checked for other reasons).

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I also crack my fingers in the morning, over the day, and before sleeping. I also feel this "tension".

But I am not sure whether it is a real "tension" or something my brain makes up to force me crack my knuckles which gives some perceived relief. Maybe I am just addicted to this relief.

I haven't seen any research on this urge to crack and the possible tension. Is this a physical tension, some psychologically perceived tension due to an addiction, or something else?

Gas buildup, is the best theory I’ve read.

Is it a theory, I thought it was exactly what causes it. The stretching depressurizes the liquidy thing in the joints and that causes dissolved gases to bubble out of solution in nucleation points. It's not really gas build up, but more like opening a can of coke, the pressure drop causes the equilibrium to shift and brings dissolved gases out of solution. At least that's what I thought it was.

But how does this gas or new gas get back into the liquid resulting in new pressure?

My uneducated guess would be that the pressure is the natural state because of the fluid/gas involved, much the same way sediment eventually settles at the bottom of a bottle of orange juice. Over time, the gas will just naturally form inside your joints that way.

Generic life processes? Everything is dissolved you know, including the oxygen and carbon dioxide from respiration. Nitrogen too, though it's not really very useful. The fact that it's all dissolved is how divers get the bends. As the pressure lowers gases drop out of solution and form bubbles, clogging arteries.

I am not doubting the theory of the gas getting out of the liquid.

I was just referring to the "urge" to crack my fingers. I thought, maybe this instant relaxation (with additional auditive feedback) results in an addiction which creates or increases my urge to crack.

Why do you burp? There’s gas pressure - it wants out.

Don’t overthink it! =]

Pretty sure it's not in your head. When I was younger I had growth hormone treatment for a while. I needed to crack more ofthen when on it, and less when I wasn't, and it was apparently a common side effect.

I came here to ask this, as well! Where does that tension come from and the relief one feels after cracking? People keep saying it's built-up gas but that doesn't really explain why we feel so much relief after cracking. (Not just when cracking our knuckles but also, or especially after, cracking our back, neck, etc.)

The article provides some hints at least but I wish there'd be more research on this topic:

> For some people, cracking can provide a sense of relief and a temporary increase in joint mobility, because it stretches the joint, taking it through a wider range of motion. One theory even suggests that cracking stimulates nerve endings around the joint, relaxing surrounding muscles while reducing pain and releasing endorphins – but this hasn't been proven.

Pretty sure it just pushes on nerves there, and there's a ton. And cracking/popping maybe spreads the gas stuff around more.

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