Does Running Really Ruin Your Knees? A Physiotherapist Separates Fact from Fiction

Happy Global Running Day. Whether you are chasing a Personal Best (PB) or just getting out the door for your first kilometre, today is a good day to talk about something that worries almost every runner at some point.

The Question Every Runner Asks

"I love running, but won't it destroy my knees?"

As a physiotherapist, I hear some version of this every single week. A friend warns you. A family member sends you an article. Someone at work tells you they "gave up running to save their joints."

So let's look at what the research actually says.

What the Science Tells Us

A 2023 systematic review published in the Orthopaedic Journal of Sports Medicine analysed 17 studies involving over 14,000 participants. The findings were clear: runners showed no greater signs of knee osteoarthritis than non-runners on X-rays or MRI. In fact, non-runners reported significantly more knee pain and were nearly twice as likely to require a total knee replacement.

Harvard Health, in a 2026 update, summarised the growing body of evidence: recreational runners had an osteoarthritis rate of just 3.5%, compared with 13.3% in competitive runners and 10.2% in sedentary individuals. A separate 2022 analysis of 24 studies found no evidence of cartilage damage on MRI scans taken immediately after running.

And a major 2024 review in the European Journal of Rheumatology concluded that walking, running, and recreational sports are "not related to structural progression of knee osteoarthritis" and can be safely recommended.

The bottom line? Recreational running does not wear out your knees. It may actually help protect them.

So Why Do Runners Get Injured?

If running itself is not the problem, why do so many of us end up hurt?

The answer, overwhelmingly, is load management - or more specifically, doing too much, too soon.

A landmark 2025 study published in the British Journal of Sports Medicine tracked over 5,200 runners across 588,000 running sessions using GPS data. The researchers found that when a single run exceeded the longest run from the previous 30 days by more than 10%, injury risk increased significantly. Doubling the distance in one session more than doubled the risk of an overuse injury.

The traditional "10% rule" (don't increase weekly mileage by more than 10%) is a decent starting point, but this new research suggests that what matters most is what you do in any single session relative to what your body has recently handled.

In short: your body can handle a lot - but it needs time to adapt.

Three Things You Can Do Today

Progress one session at a time. Rather than thinking about weekly totals alone, pay attention to your longest run. If your furthest run in the past month was 8 km, jumping to 12 km in one go is a significant spike. Build up gradually.

Strengthen what supports you. Your knees do not absorb impact alone. Your quadriceps, hamstrings, glutes, and calves all share the load. When these muscles are strong, your joints are better protected. If your glutes are not firing properly, your knee can collapse inward during your stride - a pattern linked to Runner's Knee and Iliotibial  Band (IT Band) issues. A simple strength routine twice a week makes a real difference.

Know when something is not right. Muscle soreness after a hard run is normal and usually fades within 48 hours. Joint pain that lingers, worsens with each run, or wakes you at night is different. That is your body telling you something needs attention - and the earlier you address it, the simpler the fix usually is.

The Real Takeaway

Running is not a destructive activity. It is one of the most effective things you can do for your cardiovascular health, your mental wellbeing, and yes - your joints.

The goal is not to avoid running to protect your knees. The goal is to build your body so your knees can thrive from running.

Happy Global Running Day. Get out there.

If you are dealing with a running-related niggle or want to make sure your body is ready for your next goal, the team at TheraFit can help. Book a consultation and let's get you running stronger.