The sound of breaking the knuckle is the explosive sound of the air bubble to fill the gap created by the joints.

Video: Explain the sound when breaking the knuckle joint images 1
Breaking the knuckles stimulates the tendons, helps relax muscles.

When breaking the knuckles: The surface of the joints suddenly split off, creating a gap. Synovial fluid is not enough to fill this gap, so air bubbles are formed.

Air bubbles explode in the process of cracking and making a sound. The pressure at the joints is now released.

Breaking the knuckles stimulates the tendons, helps relax muscles. However, it weakens joints.