Click sounds occur when bubbles burst with synovial fluid that fills the space between joints.
As a child, adults told us scary stories about what can happen if you crunch your fingers from a young age. According to one version, the fingers will tremble like an alcoholic. According to another, in old age it comes back to haunt the arthritis, which the grandmother suffers from. As evidence, grandmother's palm with twisted fingers was presented. True, the old woman herself, as a rule, avoided answering the question: did she crunch her fingers in childhood?
Years have passed, scientists have found that the mechanism of occurrence of tremor and arthritis has nothing to do with the habit of clicking knuckles. However, the nature of the origin of this "music" has long been incomprehensible to physiologists. An attempt to solve this puzzle was undertaken by Vaini Chandran, a chemical engineering specialist at Stanford University (USA) and Abdul Barakat, professor of the hydrodynamics laboratory at the Ecole Polytechnique in Palaise (France). They published the results of their work in Scientific Reports.
Scientists used mathematical modeling to test the hypothesis that knuckle clicks are associated with microbubbles of gas that occur in the thick synovial fluid that fills the space between the joints. In previous experiments, it was found that the same joint cannot click multiple times in a row. It should take about 20 minutes between clicks. This time is necessary for the bubbles to fill with carbon dioxide. Then, when the joint is pulled out of the joint capsule, the pressure on the synovial fluid rapidly increases and the vesicles burst. For the appearance of a characteristic crackle, it is enough for the bubbles to lose 30-40 percent in volume.
It is unclear how useful this information can be for crunching fingers. But in any case, they may not worry that during these exercises they break their joints. It was all about the "magic" bubbles.
YAROSLAV KOROBATOV