Is ‘Cracking’ your Back or other Joints Harmful?
By Dr Ben Kim
That pop you sometimes hear when you stretch your joints comes from gas leaving the lubricating fluid that surrounds all of your joints. This fluid – called synovial fluid – is a thick liquid that acts as a lubricant
and medium of transport for nutrients and waste products for the bone surfaces, ligaments, and tendons that make up your joints. Your synovial fluid naturally contains dissolved gases – mainly oxygen and carbon dioxide – and when your joints are stretched enough to significantly lower pressure within your synovial fluid, these dissolved gases pop out of your synovial fluid; the bigger the gas bubbles, the louder the pops and cracks.
Can pulling, bending, and twisting your joints to pop them on purpose cause harm? No, not unless you are stretching your joints aggressively enough to cause joint surfaces to rub against one another, which is difficult to do with cartilage lining joint surfaces and acting as shock absorbers. If you’ve lost some of this cartilage due to wear and tear or surgical excision following an injury, then you do want to think twice before regularly cracking such joints.
Most people who stretch their joints to create pops – also called cavitations – do so because it feels good. Stretching your joints alleviates stiffness by stimulating blood flow, which enhances nourishment of joint tissues and removal of waste products from the area.
In fact, in some cases, a joint can become so stiff from inactivity and adhesions that it can become near impossible to stretch the joint enough to create a pop. A good example of this scenario is a frozen shoulder or hip, sometimes called adhesive capsulitis.
For a joint to be optimally functional, the ligamentous capsule that surrounds it needs to be flexible enough to allow for joint play, which is the bit of essential “give” that a joint should have at the limits of normal range of motion; without joint play, joints are not fully functional and are more prone to premature wear and breakdown.
In the case of a frozen shoulder or hip, I often set as a goal to induce enough flexibility into the ligamentous capsule to allow for enough of a stretch to create a pop. When we reach this point, we have confirmation that adhesions are being loosened and joint play is being restored.
The other side of joint stiffness is hypermobility, that is, joints whose capsules are too loose due to genetics, injury, or over-stretching. Yes, it is possible to stretch too much and predispose joints to becoming unstable, which I sometimes see in long-time gymnasts and yoga enthusiasts. But hypermobility is far less common than joints that aren’t flexible enough. So for the average person, there is no need to worry about hearing cracks and pops while stretching.
The take home answer is that if your joints are not unstable and you don’t feel pain while stretching, it’s likely fine to pop or crack your joints if doing so alleviates stiffness and makes you feel better. Just be mindful of not stretching in ways where you compress joint surfaces together, as over time, this may damage the cartilage that lines all of your joint surfaces.