Why do knuckles crack?
Two common questions we get are "why do knuckles crack? or why do knees crack?"
When you stretch your fingers, elbows, knees or other joints in your body, you often hear them crack. So, now you wonder why knuckles crack. It is actually not the knuckles that crack, but the fluid surrounding the joints.
The fluid that keeps your joints oiled and lubricated is called synovial fluid. When this fluid is stretched, it creates a bubble. When that bubble pops, you will hear a popping sound - aka knuckle crack.
Since the popped bubble is spread all around your joints, it takes a while before it gets back together to its normal state, which is why you cannot re-crack your knuckles right away.
How often you can re-crack your knuckles varies from person to person. A survey in Research Maniacs office shows that it takes about half an hour to be able to crack your knuckles again. However, for some it takes longer, and others can actually keep cracking. They must have fast moving synovial fluid!
Anyway, now you know why your knuckles crack.