Andriy Popov/Alamy
How can popped knuckles be so exceptionally loud?
Mark Thompson
Tewkesbury, Gloucestershire, UK
The loud noise produced when you crack your knuckles is due to the rapid formation of a gas-filled cavity within the synovial fluid that lubricates your joints.
When you pull or stretch your fingers, it lowers the pressure inside the joint, causing dissolved gases like carbon dioxide to form bubbles. So cracking knuckles, with the sudden formation of these bubbles, creates a popping or cracking sound, similar to opening a bottle of pop, or soda.
However, excessive or forceful knuckle cracking may occasionally lead to minor swelling,…
