Researchers of a new study have revealed the mechanisms surrounding the loud popping sound that comes from cracking knuckles, a distinct sound that some find annoying while others just can't get enough of. What does the current science say about whether cracking knuckles is good or bad?
Knuckle-Cracking Science
Since 1939, there have been a couple of theories on what actually makes the distinct popping sound that comes with knuckle-cracking, from tightening fibrous capsules to vibrations in the tissue. A new research by a pair from Stanford University in California and the Ecole Polytechnique in France, however, builds on the 1971 theory which states that the sound comes from the collapsing of bubbles within the synovial fluid that encloses and protects the joints.
Using a computer model of the third metacarpophalangeal joint (MPJ) and a mathematical model, researchers found that the sound comes from the partial collapsing of the bubbles in the fluid. In fact, because of the speed of the process and the environment in which the bubbles collapse －surrounded by bones and flesh －researchers found that it is actually possible to produce a crack as loud as 83 decibels.
The study is published in Scientific Reports.
Is Cracking Knuckles Good Or Bad?
Despite the promising results of the study in decoding the mystery of the knuckle-crack, the study did not touch on the other matter of whether knuckle-crackers are harming or helping their joint health. However, there have been previous research which may shed light on the controversial matter, although some of them contradict one another.
In 2015, 17 women and 23 men were subjected to audio and visual examinations of their knuckles as they attempted to crack them and were tested for grip strength, laxity, and range of motion for each MPJ both before and after examinations.
Researchers found no immediate disabilities, swelling, or pain, and no immediate differences in laxity and grip strength among knuckle-crackers and non-knuckle-crackers. In fact, cracked knuckles presented an increased range of motion compared to the knuckles that weren't cracked.
Similarly, several studies have debunked the myth linking knuckle-cracking and increased arthritis risks. In fact, a 2011 study concluded that knuckle-cracking is not linked with arthritis or any other bone disease. However, that still doesn't mean that people can crack their knuckles away because other researchers also document the practice's negative effects.
Contrary to the findings of the 2015 study, some studies found that chronic knuckle-crackers were more likely to experience reduced grip strength, weakened hand bones, and increased likelihood of swollen hands. Further, there have been at least two reports of injuries as a result of trying to crack knuckles.
So is cracking knuckles good or bad? Unfortunately, there is still scientific contention on the matter, but for the time being, perhaps moderation is key in avoiding potential risks while reaping the potential rewards of the practice.
