Is Running Bad for Your Knees? What a 2026 MRI Study Found

For most everyday runners, the answer is no: a matched MRI study published in August 2026 found no significant difference in knee cartilage structure or knee function between recreational runners and similar non-runners. That matters if the old warning that running wears your knees out has ever put you off, because the factor the researchers did link to knee changes was obesity, not running.

Below, we explain what the study did, what it found, what it cannot tell us, and how to run in a way that keeps your knees happy as a beginner.

What did the 2026 MRI study actually find?

The study was led by researchers at the University of Ostrava in the Czech Republic, working with the University of Oulu in Finland. It was published online on 27 August 2026 in Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine, and drew on a Czech research group of volunteers known as the 4HAIE cohort.

The team looked at 183 adults aged 18 to 65, none of whom had knee symptoms. They were grouped into 61 matched trios: one recreational runner, one non-runner and one adult with obesity (a BMI of 30 or more), with each trio matched for age and sex. Everyone had an MRI scan of the knee, which the researchers used to check cartilage across 12 regions of the main knee joint. Everyone also filled in a standard questionnaire about knee pain, symptoms and how well their knees cope with daily life.

The headline results were:

• Runners vs non-runners: no significant differences in cartilage structure or knee function.
• Adults with obesity: less likely to have normal cartilage in one area of the inner knee (75.4%, compared with 91.8% of runners and 93.4% of non-runners), and up to about four times higher odds of abnormal cartilage findings than the other groups.
• Day-to-day function: questionnaire scores were lowest in the obesity group, especially for everyday activities.

The authors concluded that obesity was associated with more cartilage abnormalities and poorer day-to-day knee function, while recreational running was not linked to structural or functional problems.

Did runners' knees show any differences at all?

Yes, and it is worth being clear about it. As well as checking structure, the researchers measured something called T2, an MRI reading linked to the water content and make-up of cartilage. Runners had higher T2 readings than both other groups in several areas on the outer side of the knee.

In some research, a higher T2 reading is treated as a possible early sign of cartilage change. In this study, though, it did not come with extra structural damage or worse knee function in the runners, and a single scan cannot tell us whether it reflects harm, a normal response to regular loading, or nothing meaningful at all. That is a question for longer studies, so it is best not to read too much into it either way.

What does this study not show?

Good news headlines can make a study sound bigger than it is, so here are the limits worth knowing:

• It is a snapshot. Each person was scanned once, so the study shows links, not cause and effect, and it cannot say how knees change over years of running.
• Everyone was pain-free. The volunteers had no knee symptoms, so the results may not apply to people who already have knee pain or arthritis.
• It is a modest size. 183 people is a solid number for a detailed MRI study, but it is not huge.
• It says little about very high mileage. The published summary compares recreational runners as one group, so it does not tell us much about people running big weekly distances.
• It does not prove weight caused the changes. Obesity was linked to more cartilage changes, but this kind of study cannot show cause.

What do earlier studies say about running and knees?

The new findings fit with earlier research. In 2024, the same research group published a larger study of 1,164 runners and non-runners aged 18 to 65 in the same journal. People running about 6 to 20 km a week (roughly 4 to 12 miles) had healthier-looking cartilage on T2 scans in one area of the inner knee than both non-runners and the runners covering the most distance.

A 2017 review in the Journal of Orthopaedic & Sports Physical Therapy pooled 17 studies covering nearly 115,000 people. Hip and knee arthritis was found in 3.5% of recreational runners, compared with 10.2% of non-runners and 13.3% of competitive runners. The authors were clear that they could not prove cause, and that other factors, such as past injuries, could play a part.

Put together, the picture is fairly consistent. Moderate, recreational running does not appear to wear out healthy knees, while being very inactive, or training at very high volumes, may be linked to more changes.

Why do so many new runners get sore knees, then?

If the research is reassuring, why do knees often ache in the first few weeks? Often it is about how quickly the load goes up rather than running itself. Doing too much too soon, skipping rest days, and legs that are not yet strong enough for the extra work are common culprits. Our guide to why your knees hurt when you start running covers the most common causes and simple fixes.

How can you run in a knee-friendly way?

None of this needs special kit or complicated rules. These simple habits can help most beginners keep their knees comfortable:

If you want a simple routine to begin with, our list of the 5 strength exercises every beginner runner needs is a good place to start, and our beginner's guide to preventing running injuries covers the wider picture.

What if you are carrying extra weight?

The obesity finding is a reason to be kind to your knees, not a reason to stop moving. Walking, run-walk intervals, cycling and strength training are all good ways to build fitness step by step, and you can add more running as you feel ready. If you have a health condition or are not sure where to start, have a chat with your GP first.

When should you see someone about knee pain?

Most mild aches settle with a few days of rest and easier training. NHS guidance suggests seeing a GP if knee pain does not improve within a few weeks, and getting urgent advice from NHS 111 if your knee is very painful, badly swollen, you cannot put weight on it, or it locks or gives way. In many areas you can also refer yourself to NHS physiotherapy services without seeing a GP first.

How does Edge help you run with healthy knees?

Edge builds running and strength into one plan, so the leg work that supports your knees is part of your week rather than an afterthought. Your plan is fully personalised to your current fitness, ready within 24 hours, and you can message a real coach anytime if something feels off. Edge syncs with Strava, Garmin, Apple Health and Coros, so your runs and workouts sit in one place, and you will be training alongside 20,000+ members.

This article is general guidance, not medical advice. If you are new to exercise, returning from injury, or managing a health condition, speak to your GP before starting, and see a physio for any niggle that does not settle.