Photo Credit: Michael Dawson
“You’re a physio, don’t you know that running is bad for your knees?”.
Whilst we see plenty of knee injuries from clients that run, running isn’t inherently bad for your knees. The most common myth we hear around runners and knee pain is that running is such a high impact sport that it must result in osteoarthritis. Osteoarthritis is where the smooth cartilage that covers our joints degenerates, becoming thinner and rough, and impacting the underlying bone. It’s an easy concept to believe; our bodies are machines with parts that have a fixed lifespan, and if we are hard on the parts then they wear out quicker. This is a concept that needs to be challenged.
The reality is, running is good for cartilage and good for the overall health of the knee. It’s a truth that has been backed up by research too. In one study of almost 75000 runners it was found that frequent running significantly reduced the risk of osteoarthritis. The same study found lower risk of osteoarthritis in runners compared to walkers, with different loads placed through the knee with these two activities. Another study looked at runners who had competed in more than 5 marathons and found that only 9% had developed arthritis, this is significantly lower than the 18% in the matched general populations. Even better news is that it doesn’t matter what age you are when you begin to run. Those who regularly run, starting at any age, are at lower risk of developing osteoarthritis.
The theory behind the lower risk of osteoarthritis is that running helps produce and circulate synovial fluid within a joint. Synovial fluid is beneficial for providing lubrication and decreasing friction for smooth movement. Synovial fluid also provides important nutrients to the cartilage within a joint. As cartilage doesn’t contain blood vessels, it doesn’t get these nutrients without the synovial fluid. This process is improved with loading such as running, where the impact with each step causes an increase in pressure on the cartilage. This forces fluid out of the cartilage and then during unloading the fluid flows back in, like a mechanical pump.
Running also helps build up strength of the muscles involved in the knee joint and helps improve and maintain mobility of the knee. It’s the pounding on the pavement and the constant use that makes this happen.
While it is true that runners are at higher risk of patellofemoral pain syndrome or “runners’ knee”, these issues don’t mean that they will get osteoarthritis. The culprit of knee pain is more likely to be poor running form, carrying too much weight, different leg lengths, muscle imbalances, poor choice in shoes or even clocking up too many K’s in the same shoe. Doing too much before the body is ready can also overload the knee and cause pain. If you are getting knee pain with running, be sure to get it checked out because it’s not just “wear and tear”. So lace up your running shoes, running doesn’t equal worn out knees.
Ryan Smith is a Sports Lab Physiotherapist and running fanatic. He also enjoys pretending he can mountain bike. Ryan is a human movement geek and you can tell that in the way that he treats clinically.