The United States population has become profoundly physically inactive in recent years. This has contributed to an increase in health problems such as heart disease and diabetes. This is true not just in the US, but extends worldwide. Many of the world’s leading causes of death can be traced to lifestyle behaviors, with physical inactivity accounting for between 6% and 10% of the major non-infectious diseases including heart disease, type 2 diabetes, and cancers of the breast and colon (Lee 2012).
The benefits of increased physical activity are numerous and, when sustained over long periods of time, improve quality of life and longevity. Increasing global physical activity by 25% would be estimated to avert more than 1.3 million premature deaths per year (Lee 2012).
Current physical activity guidelines for adults state that “for substantial health benefits, adults should do at least 150 minutes to 300 minutes per week of moderate-intensity, or 75 minutes to 150 minutes per week of vigorous-intensity aerobic physical activity, while additional health benefits are gained by engaging in physical activity beyond the equivalent of 300 minutes of moderate-intensity physical activity a week”. There are no specific modes of exercise required to meet the aerobic guidelines, which means we have plenty of options to choose from based on people’s preferences, abilities, and accessibility.
Unfortunately, these choices can be limited by certain pre-existing musculoskeletal conditions, or from fear of developing them as a result of exercise. This is especially true for running, where individuals frequently express concern over the risk of knee pain, or even damage to the joint due to “high impact”. While there is never a zero risk of injury when participating in exercise and sport, running can be a great form of physical activity that offers potential health benefits that far outweigh injury risks.
Running and Health
Running may be the most popular and accessible aerobic activity after walking, and is often what comes to mind when people think of exercise in general. It does not have to be one of the aerobic activities you participate in, but if you enjoy running and have access to the equipment and space necessary to run, it can be an excellent way to fulfill these guidelines. There is evidence that running even in the smallest doses (once per week, less than 50 minutes per week and slower than 6 miles per hour) reduces risks of premature death from any cause, from heart disease, and from cancer by 27%, 30% and 23%, respectively (Pedisic 2020). Additionally, running decreases resting blood pressure (a regular screening measure we advocate for) in both individuals with normal and high blood pressure (Igarashi 2020).
Individuals diagnosed with osteoarthritis tend to be in the same groups at risk for premature disease and death (Lo 2018), so participation in an aerobic activity in addition to regular strength training is vital. An exploration of the effects of running on the joints and risk of osteoarthritis, particularly in the knee, is important to address misconceptions surrounding this topic and decrease the perceived barriers to participation.
Running and its Relationship with Knee Osteoarthritis
Osteoarthritis is often defined as a degenerative process involving the cartilage and surrounding tissues of bony joints. It is associated with the loss of the cartilage that covers the ends of bones that meet to form a joint, changes to the bone underneath the cartilage, formation of bone spurs, weakening of nearby muscles and ligaments, and, in some cases, inflammation of the joint itself (Litwic 2013). Healthcare professionals often use imaging tests when diagnosing osteoarthritis, since bones are visible on x-ray, and soft tissues are more visible on magnetic resonance imaging (MRI). The severity of arthritis as it appears on X-rays does not strongly correlate with the symptoms experienced by the person. These symptoms include joint pain, stiffness and limitation of movement. Someone with “severe” arthritis on an X-ray may therefore have little to no pain symptoms, while someone else who experiences more intense pain symptoms may have a relatively benign-appearing X-ray. To return to a theme we emphasize regularly: pain symptoms often lack a neat and tidy explanation via a compromised structure like thinned cartilage or bony changes visible on imaging tests.
Unfortunately, running is often considered to be a direct cause of knee osteoarthritis despite contrary evidence. A systematic review and meta-analysis by Timmins compared runners to non-runners and found no association between running and the diagnosis of osteoarthritis or other problems visible on imaging tests. There were no strong conclusions regarding the experience of osteoarthritic symptoms among those who ran. While this isn’t a ringing endorsement of running not being a risk factor in injury, they did not find a clear correlation between running and joint pain, either. On the other hand, they did find that runners had 50% lower odds of undergoing joint surgery due to osteoarthritis.
In another review and meta-analysis, Alentron-Geli looked at runners vs. non-runners, while separating “runners” into recreational and elite groups. “Elite” runners were simply defined as those who competed professionally and/or internationally. The main findings of this study included:
- Overall prevalence of hip and/or knee osteoarthritis was 3.66% in runners and 10.23% in non-runners. That is, runners had fewer findings of arthritis than those who did not run.
- Overall prevalence of hip and/or knee osteoarthritis was 13.3% in the competitive runners and 3.5% in recreational runners.
From this we can make a conclusion that recreational running appears to be protective against osteoarthritis when compared to sedentary activity and competitive running. We should be cautious when interpreting the competitive running findings, since we do not have data that quantifies the exposure and distinction between competitive and recreational running. It is safe to say most of us do not fit the criteria of “elite”, nor does professional competition fit many individuals’ health goals.
With the prevalence of knee osteoarthritis in runners vs. non-runners established, what about individuals who already have knee osteoarthritis?
Running with Knee Osteoarthritis
Fortunately, there’s some research to suggest that running does not worsen symptoms or X-ray findings in individuals diagnosed with knee osteoarthritis (Lo 2018). In this study, individuals who identified as runners did not have increased odds of worsening radiographic findings or new knee pain, and actually demonstrated improvement in knee pain compared to non-runners. Additionally, body mass index (BMI) was not different among runners compared to non-runners, so this is not likely an important mediator of the possible benefits of running. Subjects included individuals 50 years or older and identified “running or jogging” as one of their top three most frequently performed physical activities, although we do not have specifics about running intensity or volume. Of the runners included, 74.6% reported running for 6 or more years, 92.7% reported running 5 to 12 months per year, 88.4% ran more than 4 times per month, and 13.0% participated in running competitively.
Conclusions
Evidence suggesting that running increases the risk of developing or worsening knee osteoarthritis does not exist. This does not mean that it is impossible to develop new knee pain while participating in running, particularly if an individual attempts to do “too much, too soon” – as with any other physical activity. For this reason, the exercise dosage must be adjusted and progressed based on the individual’s abilities and goals. Also, this does not mean if someone has a history of knee osteoarthritis that there is a 0% risk of developing a new episode of pain or an increase in symptoms. Rather, the evidence suggests that long-term risks to the joints are low, especially when contrasted against a sedentary lifestyle that markedly increases health risks. In fact, the data referenced above showed more joint pain among those who did not run when compared with runners. Bones, joints, and muscles benefit from any physical activity, especially when the dosage of volume and intensity are appropriate for the individual.
If you are a runner currently experiencing knee pain, with or without a diagnosis of knee osteoarthritis, there are probably a number of things you could change that would allow for more tolerable training and long-term benefits. These include adjusting programming variables like pace, duration and frequency, the addition of strength training into your weekly program, environmental conditioning (inclines, terrain, surface), cadence, and equipment (such as footwear). If you want to run for aerobic conditioning or enjoyment, there are a number of ways for you to get started. A popular place to begin is using walk-jog intervals and progressing frequency, duration, and intensity slowly over time.
A more thorough treatment of rehabilitation strategies and running programming is beyond the scope of what we will cover here. However, running’s reputation as the great destroyer of knees is unwarranted. The opposite may well be true.
Participation in any physical activity is better than avoiding it, and finding what is sustainable and enjoyable for each individual is most important. If running is already a part of your life or you are interested in adding it to yours, you are not fated to experience knee pain or a diagnosis of osteoarthritis. If you are dealing with knee pain in relation to running and in need of assistance, we are happy to help guide the path via the Barbell Medicine Pain and Rehab department. Be sure to check out our running podcast as well.
Thanks to Austin Baraki, MD for his assistance in editing this article.
References
Alentorn-Geli E, Samuelsson K, Musahl V, Green CL, Bhandari M, Karlsson J. The Association of Recreational and Competitive Running With Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther. 2017 Jun;47(6):373-390.
Igarashi Y, Nogami Y. Running to Lower Resting Blood Pressure: A Systematic Review and Meta-analysis. Sports Med. 2020 Mar;50(3):531-541.
Lee IM, Shiroma EJ, Lobelo F, et al. Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy. Lancet. 2012;380(9838):219-229. doi:10.1016/S0140-6736(12)61031-9
Litwic A, Edwards MH, Dennison EM, Cooper C. Epidemiology and burden of osteoarthritis. Br Med Bull. 2013;105:185-99.
Lo GH, Musa SM, Driban JB, Kriska AM, McAlindon TE, Souza RB, Petersen NJ, Storti KL, Eaton CB, Hochberg MC, Jackson RD, Kwoh CK, Nevitt MC, Suarez-Almazor ME. Running does not increase symptoms or structural progression in people with knee osteoarthritis: data from the osteoarthritis initiative. Clin Rheumatol. 2018 Sep;37(9):2497-2504.
Pedisic Z, Shrestha N, Kovalchik S, et al Is running associated with a lower risk of all-cause, cardiovascular and cancer mortality, and is the more the better? A systematic review and meta-analysis British Journal of Sports Medicine 2020;54:898-905.
Timmins KA, Leech RD, Batt ME, Edwards KL. Running and Knee Osteoarthritis: A Systematic Review and Meta-analysis. Am J Sports Med. 2017 May;45(6):1447-1457.
