Does running ruin your knees?

By Kate Cross

Running is often branded deadly on the knees. It makes sense – all that pounding the pavement and force can’t be good over time, right? Well, it turns out the opposite may be true. Running may have a protective effect, some science says, but like anything, there are caveats.

Running load and clever cartilage

Running increases the load on the knees – big time! According to Senior Physiotherapist Michael Dermansky*, “the load on the major tendon of the quadriceps muscles … is anything from 4.7 to 6.9 times your bodyweight as you run and the compression forces on the kneecap … can be anywhere from seven to 11.1 times your bodyweight”.

While running does wallop knee cartilage more than walking, interestingly it isn’t linked to greater osteoarthritis and may in fact prime the knees to handle the strain of the exercise, according to research recently published in PeerJ.

“Running,” wrote the authors “places high stresses on cartilage, and in a healthy state these stresses trigger an adaptation response that extends the fatigue-life of cartilage”.

Adds Mr Dermansky: “Although the loads on the tendon and the kneecap are higher in running than in walking, because there is more time spent in the air when running, compared to contact time of the foot to the ground in walking, the total loads on the knee are about the same … depending on … [muscle] control and strength.”

But not all runners are immune

Of course, knee pain doesn’t skip all runners. A meta-analysis of around 115,000 people published in 2017, for example, found that of elite runners, 13.3 per cent had knee osteoarthritis compared to 10.2 per cent of sedentary non-runners. Interestingly, only 3.5 per cent of amateur runners had the condition meaning moderate amounts of running may be the sweet spot.

However, the authors of the Journal of Orthopaedic and Sports Physical Therapy paper concluded that it was impossible to say whether the higher risk among the elite and non-runners was “causative or confounded by other risk factors, such as previous injury”.

Two other factors that Mr Dermansky says can thrash the knees are obesity and poor biomechanics, “especially a lack of strength”.

“The heavier you are, the more the impact forces on the knees, causing friction and abrasion of the lining of the knee joint,” says Mr Dermansky, adding: Poor muscle strength “changes the position and loads on the knee when running, increasing the chance of injury”.

Top running tips

To help aspiring runners care for their knees, Mr Dermansky offers these tips:

• “Start with a well-designed strength program” – Ideally, dedicate six weeks to strengthening before launching your running program. “Building your muscle strength first will give you the biomechanical support to minimize the risk of injuries and improve your running performance in the long-term.”
• Manage your weight – If you’re working on your weight, start your running program with a mix of walking and non-weight bearing exercises (e.g. cycling) to protect the knees and boost your chances of a successful running program long-term.
• “Don’t overdo it” – “Even the best marathon runners do not run marathons … weekly … for their training and neither should you.” Slow and steady wins the race. “The tipping point seems to be 4.5 hours [of running] a week, after which you will go backwards.”

* Interview with Michael Dermansky, Senior Physiotherapist, March 2021