Users on social media have finally received an answer to a long-standing question: what really happens when you crack your knuckles? Growing up, many were told various myths, such as eating carrots improving night vision or that swallowing fruit seeds could lead to growth inside the body. One prevalent myth suggested that knuckle cracking would lead to arthritis in later life.

However, a video circulating on Reddit, originally from a Vox YouTube short, seems to debunk this myth. The video, shared on the “damnthatsinteresting” board, explained the process using an MRI machine. The narrator clarified that when you crack your knuckles, it creates a pressure change that forms bubbles in the synovial fluid between joints, mostly composed of CO2. The subsequent pop is caused by the partial collapse of these bubbles. The video also mentioned that it takes around 20 minutes for the remaining bubbles to dissolve before you can crack your knuckles again.

The video differentiated this sound from the one produced when standing up quickly, attributing the latter to tendons snapping as they slide over bones. Reassuringly, the video suggested that a habitual knuckle-cracking habit is likely safe, referencing a doctor, Donald Unger, who popped the joints in one hand for 60 years without developing arthritis.

Social media users celebrated this revelation, relieved that their childhood habits were not detrimental. Some users shared their personal experiences and habits, expressing gratitude for the newfound understanding. Despite the generally harmless nature of knuckle cracking, the video cautioned that, like anything, incorrect or excessive cracking could potentially cause damage.