Any runner will tell you at one time or another someone has warned them, “You’ll wear out your knees!” However, a new study led by Dr. Grace Hsiao-Wei Lo, assistant professor of medicine at Baylor College of Medicine found that running as a habitual exercise at any stage in life does not increase a person’s risk of developing knee osteoarthritis and may even help protect a person from developing the painful disease.

The findings were presented recently at the American College of Rheumatology Annual Meeting in Boston.

Some people think running will cause knee osteoarthritis, which is caused by cartilage breakdown in the knee joint. Factors that can increase the risk of knee osteoarthritis include: being overweight, age, injury or stress to the joints and having a family history. It is a form of osteoarthritis (OA) which is the most common joint disease affecting middle-age and older people.

Past research on a possible connection between running and knee OA has focused on elite male runners, so those findings may not apply well to the general population, the study’s authors noted. Concern that regular running might contribute to knee OA focuses on the fact that chronic, mechanical overloading of the knee joints might be damaging. Yet runners typically have a lower body mass index, or BMI, a factor that protects against developing knee OA.

“Recent CDC guidelines recommend that all adults participate in regular physical activity, as there is definitive evidence that increased physical activity is associated with reduced cardiovascular events and mortality,” said Lo. “However, the influence of these physical activities on knee OA is unclear.  Since running is a common leisure physical activity that involves repetitive loading, which could be harmful to the joint, I was particularly interested in studying how habitual running relates to the development of knee OA.” 

To address this question, Lo and her colleagues used data from 2,683 participants of a multicenter observational study, the Osteoarthritis Initiative.  Twenty-nine percent of the participants reported that they ran at some time in their lives. 

Patients were given knee X-rays, symptom assessments, and were asked to complete surveys on lifetime physical activity they performed at different age ranges. Knee X-rays were taken and then scored for evidence of radiographic OA using the Kellgren-Lawrence (KL) grade scale. Participants with KL grades of two or higher were considered as having radiographic OA (ROA).

The researchers also measured if participants had frequent knee pain. Researchers considered a participant to have symptomatic OA (SOA) if they had at least one knee with both radiographic OA and frequent knee pain. Anyone with a total knee replacement was classified as having frequent knee pain, ROA and SOA.

After collecting all the data, the researchers reported that runners, regardless of the age when they ran, had a lower prevalence of knee pain, ROA and SOA than non-runners. For people who had run at any time in their lives, 22.8 percent had signs of knee OA compared to 29.8 percent of non-runners. People with the lowest BMI scores were the most likely to report being habitual runners.

Regular running, even at a non-elite level, not only does not increase the risk of developing knee OA but may protect against it, the researchers concluded.

“This does not address the question of whether or not running is harmful to people who have pre-existing knee OA,” said Lo. “However, in people who do not have knee OA, there is no reason to restrict participation in habitual running at any time in life from the perspective that it does not appear to be harmful to the knee joint.” 

The collaborators on this study include: Jeffrey B. Driban and Timothy E. McAlindon,Tufts Medical Center; Andrea Kriska, University of Pittsburgh; Kristi Storti, Indiana University of Pennsylvania; Richard Souza, University of California, San Francisco; Charles B. Eaton, Memorial Hospital of Rhode Island; Nancy J. Peterson, Baylor College of Medicine; and Maria E. Suarez-Almazor, The University of Texas MD Anderson Cancer Center.

Funding sources for this study included National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) of the National Institutes of Health; the Center for Innovations in Quality, Effectiveness and Safety; and the Michael E. DeBakey VA Medical Center in Houston.