A person running along a forest dirt trail in daylight

Is Running Bad for Your Knees? What the Evidence Shows

8 min read

Ask most people what running does to their knees and the answer comes back fast. It grinds the joint down, wears out the cartilage, and stores up arthritis for later. The picture is so common that plenty of people avoid running to protect their knees, and plenty of runners quietly worry every time a joint aches.

That belief has now been tested in large studies, including a review of more than a hundred thousand people and years of tracking in adults who already had knee problems. The results point the other way. For most people, recreational running is linked to healthier knees, not worn out ones. Here is what the evidence shows, where the risk is real, and how to run so your joints hold up.

3.5%
Recreational runners with hip or knee osteoarthritis
JOSPT review, 2017, 125,810 adults
10.2%
Sedentary adults with hip or knee osteoarthritis
JOSPT review, 2017
1.7x
More likely knee pain eased in runners who had knee OA
Clinical Rheumatology, 2018, 1,203 adults
2,637
Adults in an OAI study, no higher knee OA risk in runners
Arthritis Care and Research, 2017

Where the worry comes from

The fear rests on a simple idea of the joint as a machine part. Each stride sends a repeated impact through the knee, so more miles should mean more wear, the way a tyre thins with use. It is an easy picture to hold, and it matches the ache many people feel after a hard run.

Cartilage does not behave like a tyre. It is living tissue that responds to load, drawing in fluid and nutrients as the joint moves and adapting to the demand placed on it. Movement is part of how a joint stays healthy, and long spells of sitting still carry their own risk. The wear-and-tear idea captures the short-term ache but misses how cartilage strengthens under regular use over months and years.

What large studies actually found

The clearest picture comes from a 2017 systematic review and meta-analysis in the Journal of Orthopaedic and Sports Physical Therapy. Alentorn-Geli and colleagues reviewed 25 studies covering 125,810 people and compared how often runners and non-runners developed hip or knee osteoarthritis. Recreational runners came out best, at 3.5 percent, against 10.2 percent in sedentary adults. Competitive runners, who train far harder and for far longer, were highest at 13.3 percent.

The pattern held in a community study drawn from the Osteoarthritis Initiative, a large research programme in the United States. Lo and colleagues looked at 2,637 adults, of whom 778 were runners, and found no higher rate of symptomatic knee osteoarthritis, x-ray osteoarthritis, or knee pain among the runners. As the authors put it, "there is no increased risk of symptomatic knee osteoarthritis among self-selected runners compared with non-runners in a cohort recruited from the community. In those without osteoarthritis, running does not appear detrimental to the knees."

Hip or knee osteoarthritis, by activity level0%5%10%15%3.5%10.2%13.3%RecreationalrunnersSedentaryadultsCompetitiverunners

Source: Alentorn-Geli and colleagues, Journal of Orthopaedic and Sports Physical Therapy, 2017. Systematic review of 125,810 people across 25 studies. Recreational runners had the lowest rate of hip or knee osteoarthritis.

The dose matters, not the myth

The competitive runners are the exception worth understanding. These are elite and professional athletes running high volumes at high intensity for many years, often alongside a history of injury, and their rate of 13.3 percent was above sedentary adults. The same review found that running for fewer than 15 years was linked to lower odds of hip or knee osteoarthritis than staying sedentary. The pattern is about dose, not about running itself. Everyday recreational running sits in the protective zone, while very high-mileage training over many years is a far greater demand on the joint, and that is where the extra risk appears.

Recreational running
3.5 percent had hip or knee osteoarthritis, lower than sedentary adults. This is everyday distances at a comfortable effort, a few times a week.
Competitive running
13.3 percent had hip or knee osteoarthritis, above sedentary adults. This is very high mileage and intensity over many years, often with past injuries.

Source: Alentorn-Geli and colleagues, JOSPT, 2017.

What if your knees already hurt?

The bigger surprise is what running does for people who already have knee osteoarthritis. In a 2018 analysis of the Osteoarthritis Initiative, Lo and colleagues tracked 1,203 adults with an average age of 63 for four years. Running was not linked to faster joint damage. The odds of the joint worsening on an x-ray were 0.9, and the odds of new knee pain were also 0.9, where 1.0 means no difference from non-runners.

Running was also linked to better symptoms. People who ran were about 1.7 times as likely to have their knee pain improve over the four years, though that particular estimate sat right at the edge of statistical significance. The authors reported that self-selected running is associated with improved knee pain, and concluded that it "need not be discouraged in people with knee OA." That is a controlled look at a real worry, and it suggests rest is not the automatic answer for people with knee osteoarthritis.

Running with existing knee osteoarthritis1.0 = no differenceStructural worsening0.9New knee pain0.9Knee pain eased1.7x0.51.01.5Odds ratio vs non-runners (below 1.0 = lower risk, above 1.0 = more likely)

Source: Lo and colleagues, Clinical Rheumatology, 2018. 1,203 adults with knee osteoarthritis, followed for four years. Values near 0.9 mean no faster damage, and 1.7 means pain was more likely to ease.

How to run and keep your knees healthy

None of this means every knee tolerates any running plan. The protective pattern in the research comes from sensible, progressive running, not from ignoring pain or piling on mileage. A few habits keep the load in the range the joint adapts to.

Build up slowly
The joint adapts to load over weeks. Add distance and pace in small steps rather than large jumps, so the tissue has time to strengthen and recover between runs.
Strength train your legs
Stronger muscles around the knee share the load and support the joint. Two short sessions a week of squats, lunges and calf work build that support so each stride is easier on the joint.
Manage your body weight
Every extra kilogram adds load to the knee with each stride. The NHS links a healthy weight and regular exercise to better joint health in osteoarthritis.
Respect real pain
A mild ache that settles is normal. Pain that is sharp, swells the joint, or gets worse run after run is a signal to ease off and get it checked.

Who should get advice first

Some people should speak to a physiotherapist or doctor before starting or ramping up running. That includes anyone with a recent knee injury or surgery, advanced osteoarthritis with marked pain and stiffness, or a joint that swells and locks. Getting a plan set for your own knee is sensible, and it is a different thing from avoiding running out of a general fear that it wears the joint out.

Frequently asked questions

Does running cause knee arthritis?
The evidence does not point that way. A 2017 review of 125,810 people found recreational runners had a lower rate of hip or knee osteoarthritis than sedentary adults, 3.5 percent against 10.2 percent. The higher rate was seen in elite, high-mileage competitive runners.
Can I run if I already have knee osteoarthritis?
Often yes, with guidance. A 2018 study of 1,203 adults found running did not speed up joint damage and was linked to better knee pain over four years. Anyone with significant osteoarthritis should get a plan from a physiotherapist first.
Why do my knees ache after a run?
A mild ache that settles within a day is a normal response to load, not a sign of damage, and cartilage adapts to running over time. Pain that is sharp, swells the joint, or worsens across runs is worth getting checked.
Is walking better for my knees than running?
Both support joint health, and walking is a fine choice, especially while building up. The evidence does not show that recreational running harms the knees, so the better option is the one you will do consistently.
How much running is safe for my knees?
The research links everyday recreational running to healthier knees, while very high mileage over many years carries more risk. Building up gradually, training the legs for strength, and managing body weight keep the demand within what the joint can handle.

The bottom line

The idea that running wears out the knees does not match the evidence. In a review of more than 125,000 people, recreational runners had less hip or knee osteoarthritis than sedentary adults, and running did not speed up joint damage even in people who already had knee osteoarthritis. The real risks lie at the extremes of very high mileage and in ignoring genuine pain. For most people, running is one of the better things you can do for your knees, as long as you build up sensibly and train the muscles around the joint.

Run strong, protect your knees
At DT Fitness London we build running and strength plans that keep your joints healthy and your training progressing safely. Book a consultation at www.dtfitnesslondon.com and train with a plan you can trust.

Sources

  • Alentorn-Geli E, et al. The Association of Recreational and Competitive Running With Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis. Journal of Orthopaedic and Sports Physical Therapy, 2017. pubmed.ncbi.nlm.nih.gov
  • Lo GH, et al. Is There an Association Between a History of Running and Symptomatic Knee Osteoarthritis? A Cross-Sectional Study From the Osteoarthritis Initiative. Arthritis Care and Research, 2017. pmc.ncbi.nlm.nih.gov
  • Lo GH, et al. Running does not increase symptoms or structural progression in people with knee osteoarthritis: data from the osteoarthritis initiative. Clinical Rheumatology, 2018. pmc.ncbi.nlm.nih.gov
  • NHS. Osteoarthritis, living with. nhs.uk
Back to blog