Some time ago a group of researchers from the University of Utah (United States) conducted a study on the pressure exerted when hitting a punching bag, they analyzed the stiffness generated in the joint of the first finger and the force is transferred up to the thumb.
With the results obtained, they concluded that it is possible that during human evolution the human fist increased the stiffness of the knuckle joint up to four times and doubled the ability of the fingers to transmit force.
This argument supports the theory that when our ancestors came down from the trees and selection for climbing disappeared, manipulation became the dominant selection. A hypothesis that, in some way, would allow us to explain why the arrangement of the knuckles of our hands is different from that of gorillas or chimpanzees.
More than four decades of studies
In 2009, the IgNobel Prize for Biology went to Donald L Unger for a study in which he linked the act of daily knuckle clicking -for five decades- and the appearance of osteoarthritis in the hand.
The truth is that this association had been the subject of analysis and debate for a long time. One of the first to analyze causality was Robert Swezey, in the 1970s. This researcher, after analyzing the joints of almost thirty elderly people who used to crack their knuckles on a regular basis, found no relationship between this act and osteoarthritis.
In any case, at this time the medical community does not recommend this practice, especially during childhood, since it can cause the appearance of some type of musculoskeletal injury.
And it is that repeatedly moving the bone segment of the knuckles with a dry, empty and repetitive crunch, to normalize it later, can cause a decrease in the synovial fluid of the joint.
Microscopic bubble crushing
In general, the joints of our body cause the appearance of an audible sound when they are stretched or manipulated due to the gas that is trapped in the synovial fluid – a viscous fluid that serves as a lubricant for the joint.
Using a mathematical model, researchers from the Polytechnic School of Paris and Stanford University (United States) concluded that the cracking of the knuckles of the hands is due to a partial crushing of microscopic bubbles present in the joint capsules of the hands. the knuckles. According to them, the crushing of a single bubble would be enough to cause the change in pressure and generate the sound.
The truth is that this study contradicts previous approaches, which held that the knuckle crack was the ultimate derivative of the formation of bubbles and not of their crushing.
Regardless of the debate that may arise, what seems to be evident, and all the experts agree, is that the habit of cracking the knuckles is not healthy. Do not do it.