PHThe cràcking sound your joints make is the sound of gases being released
Some people love it and some people hate it, but what is it that makes joint cràcking so loud? When joints are stretched, the pockets of gas that get trapped between them are released. When these bubbles of oxygen, nitrogen, and carbon dioxide escape, they might make a popping or cràcking noise. Whether or not intentional joint cràcking is bad for your health has yet to be decided. Some scientists say it harmless, while others say it may lead to osteoarthritis.
(S) bestlifeonline