What's Cracking?

What Really "Cracks" When You Pop Your Knuckles?

Have you ever wondered...

  • Why do some people crack their knuckles?
  • What is actually "cracking"?
  • Is cracking your knuckles harmful?

How It Works

You may find yourself cracking your knuckles every once in a while or you may be a habitual joint cracker who needs to do it several times a day. Regardless as to the degree of joint cracking, the reasons are pretty across the board. Some people crack their joints on a need to basis. This is, for example, if you have been handwriting a long paper and your joints feel as if they have tightened up and you need to crack them to relieve the tension, or if you have been working out and your hips or shoulders need to be cracked. Others may crack their joints by way of habit or as nervous habit to cope with anxiety.


Your joints are surrounded by a fluid filled membrane. This membrane is what stops your boned from rubbing together and grinding against each other as you move. When you "crack" your joints, you create space between your bones. This allows for a quick influx for the membrane fluid into the negative space. This is what causes the sound and feeling of pain or relief when. Although many people think of cracking joints as something rubbing against something else, producing the sound and feeling, it is actually more of a bubble popping situation.


Many people think that cracking your knuckles is a cause for arthritis. Recent studies have shown that this is not true. However, it can be a sign of arthritis or some other issue. Due to the aching of arthritis, some people are inclined to crack there knuckles for relief. The rule of thumb given by some professionals has been if the cracking of the joints is painless, you should have nothing to worry about, but if there is any pain felt during the act of cracking joints, you may want to go and see a doctor to see what may be causing such discomfort.

Try It Out

Here are a couple of activities for you to try out concerning the cracking of joints

  1. Compare with a friend: Grab a friend who also may be interested in the cracking of knuckles. Each of you try to count how many times you subconsciously crack your joints. Record the reasons that you cracked and if it was beneficial. Record if there was any pain at all and any other observations you may have had. Discuss the results with your friend and compare results.
  2. Compare with yourself: Observe what joints in your body crack and how many times they crack. (For example, I can never seem to crack my neck, my ankles continuously crack, and my knuckles can crack a few times until they can no longer crack. Infer the reasons as to why this may be the case.