What about your knees? It’s time to reframe the question
Sophie Raworth’s new book puts our research out in the open.
Our studies have helped challenge the persistent belief that running damages joints. Now the conversation is spreading.
When Sophie Raworth talks about running, people listen. A BBC News presenter, 57, she took up running at 42 and has since completed multiple marathons — including all six World Marathon Majors — as well as ultra-endurance events such as the Marathon des Sables in the Sahara Desert.
In her new book, Running on Air: From BBC Headlines to Life-Changing Finish Lines (Bloomsbury Sport, 2026), she tells that story: from an early London Marathon attempt that ended with her collapsing two miles from the finish, to races across the Alps and the Sahara.
The book also brings Professor Alister Hart’s research into the public conversation through a question many runners are asked sooner or later: “What about your knees?” She encounters it repeatedly — from friends, interviewers and in public debate — often framed as a warning.
The question reflects a belief that the act of running itself is inherently damaging to the joints. According to this view, running creates “wear and tear”, repeated impact damages the knee, and over time, the joint degrades. The logical response, many assume, is to limit exposure — or stop. This belief is intuitive and shapes behaviour: whether people start, continue, or give up running. But it rests on a model of the body that does not reflect how living tissue behaves.
What the research shows
Studies in musculoskeletal health — including work supported by Exercise for Science — point to a different picture. One study followed 81 first-time marathon runners in their forties training for the 2017 London Marathon. MRI scans were taken six months before the race and again afterwards. The results did not show joint deterioration. In some runners, bone marrow and cartilage changes improved, with benefits still visible six months later.
The wider message is clear:
Recreational running is not associated with increased risk of knee osteoarthritis
In some groups, runners show lower rates than non-runners
Joint tissues, including cartilage, adapt in response to load
Injury still occurs. Poor progression, inadequate strength, or insufficient recovery can all contribute. But the underlying assumption — that running itself is harmful — is not supported.
From wear and tear to adaptation
The knee is not a passive structure that wears out: it is a living system that responds to demand. Remove load and capacity declines; apply it well and tissues adapt.
If movement is seen as harmful, people do less of it — and health declines, not just in the joints but across the system. Yet imaging often shows changes that are common, frequently asymptomatic, and a poor guide to what people can safely do.
Changing perceptions
Raworth’s book helps to bridge a gap that has proved difficult to close. By bringing our research evidence into an accessible account grounded in lived experience, she is helping connect it with the decisions people make every day.
Running is not something the knees simply endure: for many, it is part of how they stay healthy. The question about knees and running will keep coming. What matters is that the answer is now grounded in evidence, not assumption.
