Cracking Joints

Category: Health
Last updated on: 10/12/2018
Person holding a cracking joint between their knuckles

Some of us find cracking a joint satisfying, whilst others wince at the thought. But what is actually happening inside your body when a massage therapist twists your back or bends your wrist to the extent that you hear it click or pop?

What is the cracking sound?

Contrary to popular belief, the sound you hear is not your bones realigning back into place. 

Our bodies actually have three different types of joints: those that are permanently fixed in place, semi-fixed ones and those that are moveable. You’ll find the fixed type in between the cranial bones in your skull and the semi-fixed (or cartilaginous joints) in your rib cage. Generally speaking, you should not experience cracking in these types of joints – if you do, you should probably be heading off to A&E as soon as you can! 

It is the third type, moveable or ‘synovial joints’ that you hear click and pop during massage therapy. If you are a habitual joint cracker, you probably already know where many of them are. The knuckles of fingers are the most common personal cracking habit. Massage therapists and chiropractors usually focus on stretching joints around muscles in the back and shoulders which can cause a cracking sound.

907 Synovial Joints

Synovial fluid contained in the joint cavity between your bones acts as a lubricant, aiding movement and flexibility. It contains gases such as carbon dioxide that are produced by the surrounding synovial membrane. When you bend, twist or pull these joints beyond their natural state the cavity stretches causing a change of volume and pressure. Gas bubbles form and then pop. So, the ‘crack’ you hear when you bend your finger at the knuckle is actually just a bubble of gas forming and then bursting. 

It takes 20 – 30 minutes before the synovial fluid is recharged with gases from the membrane, which is why you can’t crack the same joint again immediately. Think of it as infinitely replenishing bubble wrap in between your bones. 


Why does cracking joints feel good? 

Using our muscles continuously during the day causes them to tire and tighten. This can cause the surrounding ligaments and joints to feel tense too. When you crack your fingers you are simply stretching the muscles and joints in that area and relieving built up pressure. Think of it as a knuckle yawn!

A professionally trained Thai massage therapist does the same for your back, twisting the joints to a safe degree to release built up pressure. The resulting cracking sound often feels a little scary but is safe if done properly and very satisfying too. 


Is cracking joints bad for you?

The short answer is probably not. There is no scientific evidence to back up the old wives claim that your knuckles suffer ever-lasting damage if you crack them all day long.  However, like most things in life, we would hazard a guess that too much cracking is probably not good for you. Quite aside from that, hearing other people’s popping toes and clicking fingers, isn’t most people’s idea of dulcet tones so you may suffer some verbal abuse even if not physical.

The occasional cracking of a joint to relieve built up tension is actually deeply satisfying to most and science so far has suggested that it does you no harm. In fact it is so relaxing that it can become addictive – just like massage in general!



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