*pop**pop* The all too familiar sound of someones knuckes cracking is nothing out of the ordinary. Though we have been warned by people (mothers especially) that in doing so, it will cause arthritis. People crack their knuckles for many reasons such as to relieve stress, nervousness, boredom or simply because they can. Personally I cringe at that noise, especially when they are from toes!
But what causes that ‘pop’ sound?
Fiction: Tiny balloons in between the joints and when you apply pressure they pop –kind of like bubble wrap!
Fact: Close! but there is actually a ‘thick, clear liquid’ between the joints called synovial fluid. When you bend your fingers the bones pull apart and the capsule that surround the joint is stretched. This creates more volume and an increase in volume = decrease in pressure (oh how much you learn in chemisty class). This produce a vacuum-like effect which is filled with gases such as oxygen, nitrogen and CO2. As the pressure is reduced the synovial fluid forms bubbles that bursts when its pressure is low enough. Voila!
Ok now the real question about knuckle cracking; does it lead to arthritis?
Fiction:Yes, cracking your knuckles will turn your joints huge and sausage-like and will also cause painful arthritis down the road.
Fact: Total myth! There is no evidence linking arthritis to knuckle cracking. For example, a study published in the ‘Journal of Arthritis’ of Doctor Donald Unger who used himself as a guinea pig to test if there was a connection. Every day for 50 years he would only crack the knuckles on his right hand and not his left. The conclusion? His right hand did not have arthritis and there was no difference between his right and left hand.
Even though it does not lead to arthritis one should not start cracking their knuckles excessively because it may cause stiff or swollen knuckles and loss of grip strength.
Also please be considerate of those around you if you decide to crack your joints because they may not find the popping sound to be as pleasant as you may. 🙂
Images courtesy www.bupipedream.com and www.improbable.com.