For generations we’ve been warned that cracking knuckles can cause arthritis.
But while this has been largely discredited, experts have revealed what really happens inside your body when your joints audibly groan, click, scrape and creak – and when it could be a sign of something serious.
When a joint pops or cracks, the sound typically comes from one of three sources: gas bubbles popping within the joint fluid -also known as synovial fluid – tendons or ligaments snapping over bones, or the joints momentarily separating and coming back together.
When you crack your knuckles, for instance, this is caused by a rapid change in pressure within the joint capsule, which creates a vacuum that pulls gases out of the synovial fluid, forming a bubble that makes an audible pop when it bursts.
Consultant rheumatologist and advocate of GOPO Joint Health, Dr Rod Hughes, told the Daily Mail: ‘Joint clicking, or crepitus, is a common phenomenon where joints make popping or cracking sounds during movement.
‘Most of the time, it’s harmless, caused by gas bubbles in the synovial fluid or ligaments and tendons moving over bones.
‘However, clicking can sometimes indicate underlying issues – particularly if it comes with pain, swelling, locking, instability, tingling or reduced mobility.’
With so many potential problems lurking just centimetres under the surface, it’s crucial to understand what’s actually happening beneath the skin, and why certain types of cracking deserve more attention and concern than others.
Experts have revealed what happens inside your body when your joints creak – and when it could be a sign of something serious
Most of the time, it’s just tissue or gas bubbles moving but sometimes it signals early osteoarthritis, meniscus tears or ligament injury.
People who’ve had previous knee injuries, carry extra weight or do high-impact sports are especially prone, and women may notice more discomfort during periods or menopause, when joints can feel looser.
But what people often don’t realise is that joint noises can also reflect muscle control issues rather than structural problems within the joint itself.
A shoulder that pops excessively might be doing so because the shoulder blade – medically known as the scapula – isn’t stabilising properly, forcing the shoulder joint to move unnaturally.
Similarly, hips that click during certain movements might signal that the deep hip stabilisers aren’t working correctly, causing tendons to snap over bony landmarks instead of gliding smoothly.
In these cases, the solution isn’t to worry about the joint itself but to address the underlying muscle weakness or coordination deficit creating the abnormal movement pattern.
Dr Hughes adds that hip and groin clicks are very common, and sometimes it’s just muscle or tendon movement, but it can also indicate labral tears, hip impingement or hernias.
Rotating your hip in a circle or squatting low can reveal if the clicking is accompanied by pain, catching or locking – signs that should be checked.
‘Clicking during exercise or sex isn’t usually dangerous unless pain or weakness appears,’ he says.
Dr Hughes adds that strengthening the muscles around your joints and improving flexibility often reduces clicking and discomfort. Low-impact exercises like swimming, cycling, yoga and targeted strength training are particularly beneficial.
Your sleeping or sitting position can also play into your joint creakiness.
Poor sleep posture can cause misalignment, placing unnecessary stress on joints, ligaments, and tendons.
Sleeping in positions that compress or twist joints can also lead to increased stiffness, pain and creakiness in the morning – and there are biological reasons why you might wake up feeling like stiff and sore, especially during the winter.
Many people complain that their joints get creakier in the damp weather, and this is partly because this type of weather is normally brought about by a low-pressure front, which causes a drop in atmospheric pressure.
The reduction in external pressure allows tissues, including muscles, tendons and joint capsules (the membrane that surrounds the joints) to expand slightly.
Exposure to the cold also changes the nature of muscle tissue, making it less elastic, while the synovial fluid that lubricates joints may thicken and become less fluid.
Meanwhile, blood vessels constrict – reducing blood flow. As a result, you may feel more stiff than normal in the morning.
But not all joint noises happen naturally, with one expert telling he Daily Mail that if you’re in the habit of purposefully cracking your joints you run the risk of becoming addicted to both the sensation and the sound.
Dean Blackstock, Chiropractor & BCA Member, explained: ‘There is a reason why some people are always cracking their knuckles, necks and spines.
‘When you randomly “crack” a joint, it can stimulate receptors that can reduce muscle tension and increase range of motion but only briefly.
The above graphic shows the movement of gas when joints are ‘popped’
‘Once we return back to our activity, such as typing, that wears off pressure builds and the cycle continues.’
The feeling of satisfaction, he says, comes from the neurological response that reduces perceived stiffness and increases joint awareness.
‘We’re essentially told “that felt good” by our brain and humans are hard-wired to avoid pain and seek pleasure typically, so we look for more doing it again and again,’ he says.
Despite the sometimes severe noise, contrary to popular belief, there’s no evidence linking habitual joint cracking to arthritis or long-term joint damage.
One researcher, Dr Donald Unger, cracked the knuckles of his left hand at least twice a day for over 50 years while never cracking those on his right hand.
The results of his personal experiment were surprising. Decades later, he took X-rays of both his hands and found there was no difference between his hands and no signs of arthritis in his left hand.
Dr Unger even won an IgNobel award in 2009 for his research and his contribution to the scientific community. The ‘ignoble’ Nobel Prize is awarded to ‘honour achievements that first make people laugh, and then make them think’.
As for how to relieve stiffness, gentle stretches and staying active can make muscles more flexible and joints more agile.
Experts recommend strengthening the muscles around the joint with slow, controlled resistance work.
Mobility exercises – kept within comfortable ranges – plus working on balance and coordination, can also improve joint control.
