Does running really ruin your knees? Here's what the Science says.

If you've ever started running, you've almost certainly heard this advice: "Be careful... running will ruin your knees." It's probably one of the most common myths surrounding running.

The real question is: is it actually true, or is it simply a belief that's been repeated so often that people accepted it as fact?.

At first glance, it sounds perfectly reasonable. Every time we run, our knees absorb repetitive forces with every stride. The more kilometres we cover, the greater the cumulative load placed on our joints. It's easy to assume that this repeated stress simply wears the knees down over time: But the human body is far more complex than that.

That's exactly why researchers have spent years investigating the question: Does running actually damage the knees, or is something else responsible?

One of the largest systematic reviews and meta-analyses on the topic examined data from more than 114,000 participants. The findings surprised many people. Recreational runners had a lower prevalence of hip and knee osteoarthritis than individuals who didn't run at all. Among competitive athletes exposed to extremely high training volumes, however, this protective effect was no longer as clear, suggesting that the critical factor may not be running itself, but rather the amount of load and how it's managed.

At first, these findings may seem to contradict everything we've been told. If running itself isn't the problem, why has this belief persisted for so long? Perhaps because we often think of our joints as if they were mechanical parts. As though every step gradually wears them down until there's nothing left.

So what's actually happening?

Articular cartilage isn't like the tread on a car tyre that simply wears away with use. It's living tissue that continuously responds to how we use our bodies. Although cartilage has no direct blood supply, movement helps circulate synovial fluid, which plays an essential role in delivering nutrients to the cartilage. When training loads are appropriate, the body adapts, not only do muscles become stronger, but the entire musculoskeletal system gradually adjusts to regular physical activity.

Of course, this doesn't mean runners never get injured. In reality, many running-related injuries aren't caused by running itself, but by doing too much, too soon. This is where a concept known as load management has become central in modern sports science. Although it may sound technical, the idea is actually straightforward: your body needs time to adapt. If you've barely exercised one week and suddenly begin running ten kilometres every day the next, running isn't necessarily the problem. The issue is that your body hasn't had enough time to prepare for that level of stress.

According to experts from the International Olympic Committee (IOC), many overuse injuries don't result from a single incorrect movement. Instead, they develop when the body is exposed to more training stress than it can adapt to over an extended period. That's why gradual progression and adequate recovery are considered just as important as the training itself. 

Interestingly, a more recent systematic review reached a very similar conclusion. Researchers found that regular running, by itself, did not increase the risk of knee osteoarthritis. In fact, knee pain was reported more frequently among non-runners than among people who ran regularly. 

Perhaps it's time to think about running a little differently, not as something that inevitably damages your knees, but as a form of exercise that can remain part of a healthy lifestyle for many years when supported by progressive training, sensible load management and sufficient recovery.

Of course, this doesn't mean you should ignore pain or assume that the same training volume is appropriate for everyone. Listening to your body is always essential, and your training load should reflect your current fitness level, experience and recovery capacity.