What is the identity of the "cracking" sound that plays a fist or a finger?

byJaysin Trevino

The act of wrapping the held fist with the opposite hand and sounding a creepy sound called "Pokipoki" is done for the purpose of intimidating the opponent in front of the fight etc., and it is said to be called "cracking" or "popping" in English-speaking countries. The cause of the cracking sound is said to be "the sound that the air bubbles in the joint explode", but in a recent study "the sound sounds when air bubbles are formed" is also advocated.

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Researchers have been researching from the beginning of the 20th century about the identity of cracking sounds emitted by the gripping fists. However, despite many researchers challenging the mystery for more than a century, the complete mechanism has not been elucidated.

For many years the theory that "the bubbles formed in joints are crushed and the sound when ruptured is the identity of cracking sounds" was effective, but MRI observed fists at crackingResearch in 2015According to the theory that a sound is heard when a bubble is formed in the joint was newly cast.

I studied at the University of AlbertaGreg Kauchuk"When the joints and joints are rapidly separated, they fill the gaps between the joints,Synovial fluidThe amount of bubbles is lost, and bubbles are formed in the synovial fluid. It is thought that this is the identity of the cracking sound, "he insisted, and gave a great impact to the cracking researchers.

byRobin Inkysloth

Regarding the bubble formation mechanism in the jointCavitation (cavitation)It is known as a physical phenomenon in which air bubbles form when the pressure in the liquid drops. However, as a researcher at Stanford UniversityViness · Chandran · SjaHe questioned this theory and argues that "the sound of cracking is too big for bubbles caused by cavitation."

Mr. Suja et al. 'S research group said that as MRI' s imaging speed is too fast, it was not possible to prove that bubble formation in joints is associated with cracking sounds and instead cracking sounds are mathematically I devised a method to describe it with a model. According to the mathematical model devised by Mr. Suja, the occurrence of cracking sound is caused by a large pressure being applied to the synovial fluid in the joint, and at the same time, the bubbles in the synovial fluid are generated corresponding to the timing of collapse and decrease I understood that.

"The mathematical model we developed is consistent with the theory that cracking sounds" because of the explosion of air bubbles in joints "which has been advocated for cracking sounds so far," said Susa Although it did not actually observe the cracking sound, there is a possibility that further discussion may occur.