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Recovery Tip

Did you know that your core muscles, which are the deepest layer of your tummy muscles, should work at all times to brace and protect your back? These muscles switch off due to pain and it takes 50,000 repetitions before they work automatically again to protect your back!

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What happens when you crack your knuckles?

Researchers at the University of Nebraska Medical Centre have gotten together to pull each other’s fingers, and find out what happens when we crack our kncules[i].

These researchers used “cine MRI” which is like an MRI movie, to see inside the joint while it was being cracked and try to figure out what was going on.

The finger of the volunteer was slowly pulled on (distracted), until a ‘crack’ sound that we’re all familiar with was heard. Here’s the video replay:


So what’s happening?


This is consistent with what you see from the outside when you crack your knuckles. The joint surfaces are difficult to pull apart until they crack, at which point they ‘give’ and the joint separates.

Now, there are still a lot of questions about joint cracking. We’re not really sure why joints are easier to move once they’ve cracked, why they stiffen up again, what purpose it serves in terms of joint health or whether it’s beneficial or harmful at all.

Current research suggests that knuckle cracking is not harmful to joint health[ii]. Habitual knuckle cracking is not shown to have any strong links to an increased rate of developing joint problems, no matter how long you’ve been cracking your knuckles for. However, there are only a few studies each with a few hundred people, and the evidence is all self-reported. So we really don’t know enough to make a definitive decision just yet.

In 2011 Dr. Donald Unger was awarded the Medical category Ig Noble Prize for taking the research into his own hands. He published a paper in 1998[iii] that described how he would methodically crack all the knuckles on only his left hand everyday for more than sixty years. He has never had a problem with either of his hands!



So enjoy that satisfying knuckle crack!



[i] Kawchuk, Fryer, Jaremko, Zeng, Rowe & Thompson. 2015. Real-Time Visualization of Joint Cavitation. PLOS ONE. DOI: 10.371/journal.pone.0119470. Retrieved from http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470

 on the 04.11.2015

[ii] de Weber, Olszewski & Ortolano. 2011. Knuckle Cracking and Hand Osteoarthritis. JABFM. DOI: 10.3122/jabfm.2011.02.100156. Retrieved from http://www.jabfm.org/content/24/2/169 on the 04.11.15.

[iii] Unger. 1998. Does Knuckle Cracking Lead to Arthritis of the Fingers? Arthritis and Rheumatism. 41 (5). p949-50