Running does not appear to cause sustained wear and tear of healthy knee cartilage, with research suggesting that the small, short-term changes to cartilage after a run reverse within hours.
A systematic review and meta-analysis published in the most recent issue of Osteoarthritis and Cartilage presents the findings involving 396 adults, which compared the “before” and “after” state of healthy knee cartilage in runners.
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Running is often thought to be detrimental to joint health, wrote Sally Coburn, PhD candidate at the La Trobe Sport & Exercise Medicine Research Centre at La Trobe University in Melbourne and coauthors, but this perception is not supported by evidence.
For the analysis, the researchers included studies that looked at either knee or hip cartilage using MRI to assess its size, shape, structure, and/or composition both in the 48 hours before a single bout of running and in the 48 hours after. The analysis aimed to include adults with or at risk of osteoarthritis, but only 57 of the 446 knees in the analysis fit these criteria.
In studies where participants underwent MRI within 20 minutes of running, there was an immediate postrun decrease in the volume of cartilage, ranging from –3.3% for weight-bearing femoral cartilage to –4.1% for tibial cartilage volume. This also revealed a decrease in T1 and T2 relaxation times, which are specialized MRI measures that reflect the composition of cartilage and which can indicate a breakdown of cartilage structure in the case of diseases such as arthritis.
Reversal of short-term cartilage changes
However, within 48 hours of the run, data from studies that repeated the MRIs more than once after the initial prerun scan suggested these changes reversed back to prerun levels.
Sally Coburn
“We were able to pool delayed T2 relaxation time measures from studies that repeated scans of the same participants 60 minutes and 91 minutes post-run and found no effect of running on tibiofemoral joint cartilage composition,” the authors write.
For example, one study in marathon runners found no difference in cartilage thickness in the tibiofemoral joint between baseline and at 2-10 hours and 12 hours after the marathon. Another showed the immediate post-run decrease in patellofemoral joint cartilage thickness had reverted back to prerun levels when the scan was repeated 24 hours after the run.
“The changes are very minimal and not inconsistent with what’s expected for your cartilage which is functioning normally,” Ms. Coburn told this news organization.
Sparse data in people with osteoarthritis
The authors said there were not enough data from individuals with osteoarthritis to be able to pool and quantify their cartilage changes. However, one study in the analysis found that cartilage lesions in people considered at risk of osteoarthritis because of prior anterior cruciate ligament reconstruction were unchanged after running.
Another suggested that the decrease in femoral cartilage volume recorded at 15 minutes persisted at 45 minutes, while a separate study found significantly increased T2 relaxation times at 45 minutes after a run in those with knee osteoarthritis but not in those without osteoarthritis.
Senior author Adam Culvenor, PhD, senior research fellow at the La Trobe Centre, said their analysis suggested running was healthy, with small changes in cartilage that resolve quickly, but “we really don’t know yet if running is safe for people with osteoarthritis,” he said. “We need much more work in that space.”
Dr. Adam Culvenor
Overall, the study evidence was rated as being of low certainty, which Dr. Coburn said was related to the small numbers in each study, which in turn relates to the cost and logistical challenges of the specialized MRI scan used.
“Study of a repeated exposure over a long duration of time on a disease that has a long natural history, like osteoarthritis, is challenging in that most funding agencies will not fund studies longer than 5 years,” Grace Hsiao-Wei Lo, MD, of the department of immunology, allergy, and rheumatology at the Baylor College of Medicine in Houston, said in an email.
Dr. Lo, who was not involved with this review and meta-analysis, said there are still concerns about the effect of running on knee osteoarthritis among those with the disease, although there are some data to suggest that among those who self-select to run, there are no negative outcomes for the knee.
An accompanying editorial noted that research into the effect of running on those with osteoarthritis was still in its infancy. “This would help to guide clinical practice on how to support people with osteoarthritis, with regard to accessing the health benefits of running participation,” write Jean-Francois Esculier, PT, PhD, from the University of British Columbia, Vancouver, and Christian Barton, PhD, with the La Trobe Centre, pointing out there were a lack of evidence-based clinical recommendations for people with osteoarthritis who want to start or continue running.
It’s a question that PhD candidate Michaela Khan, MSc, is trying to answer at the University of British Columbia. “Our lab did a pilot study for my current study now, and they found that osteoarthritic cartilage took a little bit longer to recover than their healthy counterparts,” Ms. Khan said. Her research is suggesting that people with osteoarthritis not only can run, but even those with severe disease, who might be candidates for knee replacement, can run long distances.
Commenting on the analysis, Ms. Khan said the main take-home message was that healthy cartilage seems to recover after running, and that there is not an ongoing effect of ‘wear and tear.’
“That’s changing the narrative that if you keep running, it will wear away your cartilage, it’ll hurt your knees,” she said. “Now, we have a good synthesis of scientific evidence to prove maybe otherwise.”
Ms. Coburn and Dr. Culvenor report grant support from the National Health & Medical Research Council of Australia, and another author reports grant support from the U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases. The authors, as well as Dr. Lo and Ms. Khan, report relevant financial relationships.