Runners who had undergone knee or hip surgery or had a previous hip or knee injury that prevented running were most likely to have arthritis, researchers found. Family history of arthritis, higher body mass index (BMI), and older age were also associated with increased risk of the condition.
The study was presented at the American Academy of Orthopaedic Surgeons 2023 Annual Meeting.
It has generally been thought that running may increase risk of osteoarthritis because it puts more load on joints than walking or standing, noted Grace Hsiao-Wei Lo, MD, an assistant professor of immunology, allergy, and rheumatology at the Baylor College of Medicine, Houston, who was not involved with the work. Research in this area has yielded mixed results: A 2017 analysis of multiple studies found that competitive runners did have higher rates of arthritis than recreational runners, while another study conducted by Dr. Lo found that runners did not have an increased risk of knee osteoarthritis, compared with nonrunners. A 2018 study showed that marathon runners had lower instances of arthritis, compared with the general population.
In this new study, researchers surveyed 3,804 runners who participated in the 2019 or 2021 Chicago Marathon about their running history, average mileage per week, and average running pace. The survey also asked about known risk factors for osteoarthritis, including BMI, family history of arthritis, and past knee and hip injuries that prevented running.
Runners, on average, were about 44 years old and ran 27.9 miles per week. The largest proportion of respondents had completed 2-5 marathons (37.3%), around 21% of respondents had finished 6-10 marathons, and 17% were running their first marathon. Study participants had an average of 15 years of running experience, 1,892 reported a previous hip or knee injury, and 413 had undergone knee or hip surgery. Overall, 36.4% reported experiencing hip or knee pain in the past year, and 7.3% had been diagnosed with arthritis.
Researchers found that there was no association between the risk of osteoarthritis and weekly mileage, years spent running, number of marathons completed, or running pace. Respondents who had undergone knee or hip surgery had the highest risk of osteoarthritis (odds ratio, 5.85; P < .0001), followed by those with a history of knee or hip injuries that prevented running (OR, 5.04; P < .0001). Other identified risk factors were family history of arthritis (OR, 3.47; P < .0001), BMI (OR, 1.10; P < .0001), and older age (OR, 1.08; P < .0001).
The news should be encouraging for runners, said Matthew Hartwell, MD, an orthopedic surgeon at the University of California, San Francisco, who led the research. If someone does not have injuries or surgeries that keep them from running, “you can still continue to run,” he said. “There may not necessarily be this dose-response relationship where the more you run, the more you break down your knee or your hip.”
Still, 24.2% of runners reported that their physician had advised them to reduce their mileage or stop running altogether. Most runners (94.2%) said they planned to run another marathon.
“The results of this study are consistent with the experiences of many lifelong runners and observations of sports medicine professionals that osteoarthritis is not an inevitable consequence of distance running,” said Brett Toresdahl, MD, a sports medicine physician at the Hospital for Special Surgery in New York, who was not involved with the study.
Still, he emphasized that more research is necessary to understand whether running contributes to the risk of developing osteoarthritis. The participants in the study were current marathoners, he noted, so it is likely they have healthy joints that can tolerate running longer distances. “If there is a subset of people who have joints that are negatively affected by running, they wouldn’t likely be registering for a marathon,” he said in an email interview.
Dr. Lo added that comparing these marathoners to a group who did not run would help assess whether running can be harmful to joints. “To be fair, this is a challenging subject to study,” she said. “Osteoarthritis has a long natural history, and so it is difficult to evaluate this kind of question over many years of running and many years of evaluation of arthritis.”
While the research does not answer the question of whether running can lead to osteoarthritis, it helps show the need for long-term research on how running affects joints over time as well as one’s general health, Dr. Toresdahl noted. “I would not be surprised if future longitudinal research will come to the same conclusion that running for the majority of patients is a net benefit for overall health and at least net neutral for joint health when done in moderation,” he said.
Dr. Hartwell, Dr. Lo, and Dr. Toresdahl report no relevant financial relationships.
A version of this article originally appeared on Medscape.com.