Why Do Joints Pop?

One of my Australian friends in the YTTC-500 course, the one who is casually studying ayurveda, asked why her joints pop and crack. They had progressively been making more noise, and the ayurvedic practitioner she went to see in southern India said it was because her “fire” was high and out of balance. His advice was to fast.

raging fire

Just about all of us in the course had noted an increase in joint popping and cracking over the past couple of weeks, especially about the knees. We were spending at least 3-4 hours in asana practice every day, and most of the other hours were spent cross-legged on the floor for meditation, satsung, lectures, and meals. For me in particular, my right knee was noisy. That’s the one I injured four years ago spending 20 minutes a day in suptavirasana as a part of my meditative practice. (That was too much strain on a medial meniscus, one that was over 40 years old.)

While my friend was considering making an effort to fast for one day each week (and which I encourage for general health promotion), I was surprised that this was ayurveda’s way to “decrease fire” and to quiet her joints. In Yoga (a sister system of ayurveda), fasting is a tapas, a promise to maintain or to refrain from an activity, a promise that requires energy and attention while encouraging spiritual growth. In Sanskrit, the word tapas means “heat.” By going against our general tendencies towards “likes and dislikes” we create friction in the mind and body, generating heat as a byproduct. Fasting is a prototypical form of tapas. When examined through a Yoga lens (not an ayurvedic one), fasting increases fire rather than reduces it. We build heat by going against our love of food and refraining from the constant consumption of it.

“Fire” in the body is eastern medicine terminology. From a Western medical perspective along these same lines, you could say it has more to do with “Air” – another of the five classic elements of creation mentioned in the Upanishads. Most popping noises in normal joints, those without previous damage, are believed to come from the formation and destruction of air bubbles.

diagram of joint showing synovial fluid

What makes joints pop?

There are several theories about what happens when joints make noise, but not a lot of scientific evidence exists. While many of my joints were singing a little more than usual by the end of the course, I believe they were doing so for different reasons.

The popping in my right knee was due to the previous damage. A torn meniscus can have rough ends that rub up against each other. Sometimes when they do, they make a sound – the clicking of one hard surface against another.

Joints pop when their capsules are stretched, and we stretched a lot in our Yoga asana classes. The stretching movements increase the volume of the joint capsule. When the volume of a space is increased, it leads to a decrease in the existent pressure. The lowered pressure within the joint capsule pulls in air bubbles – or makes dissolved gases within the synovial fluid (carbon dioxide and nitrogen) come out of solution. That can make a popping sound as the bubbles get sucked into and appear within the joint space. These tiny air pockets of gas can also make a popping or cracking sound when squeezed back out of a joint space or when they are dissolved into synovial fluid.

Sometimes when we stretch and move, we can pull elastic tendons and ligaments around bones in a way that causes them to “snap” like a rubber band. As we stretch and limber up, there’s more room for movement and an increased tendency to pop the loosened connective tissue around a bony prominence

From a Western medical perspective, the noise our healthy joints and connective tissue makes is harmless. It’s nothing to be concerned about. The worry that it leads to arthritis or knobby joints is unfounded. Instead of looking at it in a negative fashion, consider it a sign of healthy activity – bending and stretching, flexing and extending, moving the body in ways that lead to the best of health and long-term mobility.



    2 Comments to “Why Do Joints Pop?”

    1. Rowen on February 28th, 2013 9:38 am

      Just to clarify, Kathleen, since I was asked this question recently: are there any joints that it is not so good to crack? And, if it becomes a habit, such as knuckle or neck cracking, does it become more of a concern? For example, a friend says he has gotten into the habit of cracking his neck upon waking, and does not feel “right” until he does it. I personally like to get my back cracked on a daily basis. It feels good, and I, as you suggest, consider it a sign of healthy movement. Still, is there any health concern to any particular joint cracking becoming a compulsive habit (other than annoying those around you?)

      A curious topic I have heard many theories about; thank you for addressing it!

    2. Dr. Summers on February 28th, 2013 7:50 pm

      Hi, Rowen. Happy to hear from you! If it makes you happy to crack any of your joints, go ahead. There’s no real data or reliable theory that gives me cause for concern. There’s one decent study about long-term joint cracking of the knuckles that showed no ill effects. When it comes to the neck, the actual popping of the joints is not an issue, but the movements of the neck that cause the joint cracking might be. Anything that puts the head into extension and then rolls it from side to side can shear the vertebral arteries running up through the cervical vertebrae potentially leading to a posterior-circulation stroke. It simply depends on what movements he is doing to get his neck to crack.

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