Real-time video: Study reveals secret behind sound of cracking knuckles

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There’s been a misunderstanding for years about what causes the sound when our knuckles crack.

That’s according to new research in the journal PLOS ONE that studied the phenomena on video.

The study says the poppingĀ  sounds have long been attributed to the collapse of an air bubble that forms in the fluids between the joints as they are separated.

But real-time MRIs of a subject cracking his knuckles indicates that theory is backward.

Pressure from pulling, bending or cracking the joint actually causes gases in the fluid between the joints to form the bubble. That formation is what we hear when we hear the pop. The bubble appears as a black spot in the MRI video as the pop sound occurs.

The research also indicates that habitual knuckle cracking has not been shown to increase joint degeneration or damage.

For much more on the study, click here.