By Alison Gillespie, PT, DPT
One of the most common statements runners hear is that running causes knee damage and, “You will wear out your joints!” But is this really true?
A 2018 Canadian study1 interviewed health care practitioners (HCP) and the general public about whether they felt running caused knee osteoarthritis (OA). Both groups showed a high degree of uncertainty and negative perceptions about the relationship between running and arthritis. The study included runners and non-runners for both the public group and the HCP group.
Of particular interest, between 17 to 30% of HCP (doctors, PTs, chiropractors and athletic trainers) think marathon running increases knee OA risk. Personal experience with running strongly affects this opinion. As you might expect, health care practitioners who run felt the most favorably about running and joint health. As an aside, among the providers, physical therapists were among the most likely to be runners, the least likely to experience knee OA and the least likely to view running as detrimental to knee cartilage.
For the general public, the same overall trend holds true. Fifteen percent of non-runners and approximately 10% of runners think marathon running definitely leads to knee OA, and nearly 50% of both groups were uncertain.
So, what does the evidence say? Does running cause knee osteoarthritis?
A deep dive into the current research available via PubMed and the NCBI database (and lots of coffee) unearths evidence to the contrary! Systematic reviews are tools that researchers use to sum up current research papers on a topic, including assessing the quality of each study, collecting secondary data and synthesizing all the findings. They aim to provide a complete summary of the evidence pertaining to a specific research question, which makes them especially useful for practicing evidence-based medicine and for defining further research opportunities.
A systematic review2 of 25 previously published papers encompassing more than 125,000 individuals revealed that the overall prevalence of hip and knee OA is 10.2% in non-runners, 3.5% in “recreational” runners and 13.3% in “competitive” runners (defined as professional, elite or ex-elite athletes).
What? 3.5% for most runners?
In other words, running (for the grand majority of us) is NOT shown to be causally related to onset of knee OA. Let’s say that again. Recreational runners develop knee OA at one-third the rate of sedentary people.
Phew! “Ok, well, that’s great!” you say as you lace up your shoes to head out for a lap around Greenlake. But, what are the risk factors for knee OA? (And why doesn’t running at a recreational level appear to damage cartilage?)
Researchers from The Orthopedic and Arthritis Center, Boston University and Harvard Medical School designed a tool3 to estimate your individual risk of developing knee osteoarthritis based on epidemiological studies. In no particular order, the risk factors include:
Age. Half of the population with arthritis is over 65 years old. However, not all arthritic joints are painful!
Female gender. The peak prevalence of OA (17%) occurs in women between 60-74 years old.
Obesity. An increase in weight creates an exponential increase in OA risk. An increase in BMI of two points increases knee OA risk by 36%4.
Occupational exposure. Repeated bending, squatting and lifting increases knee OA risk by a factor of 1.283
History of traumatic knee injury. This includes ACL tears/repairs, meniscus tears or other significant knee injuries, which increase knee OA by a factor of 2.393.
Family history/genetics. The presence of a close family member with knee OA increases risk by a factor of 1.723
If you want to investigate your own risk factors and visualize the interaction of each factor, the online calculator created by the Orthopaedic and Arthritis Center for Outcomes Research (OrACORe) can be found at http://calculator.oarisk.org.
There are several interesting and very useful implications of this research. First, many health care practitioners and the public have either negative feelings or uncertainty toward running as a risk factor for knee OA. However, strong evidence suggests that runners experience significantly lower rates of knee OA. This is a prime opportunity to connect the dots between research findings and clinical advice!
Second, there are much larger and more relevant risk factors for developing knee OA, some of which can be minimized. You can’t pick your family history, age, or your born gender, but addressing undesired weight gain, optimizing squat/movement mechanics and thoughtful rehabilitation of knee injuries are all factors that can be improved. This is really where physical therapists can have a meaningful impact on prevention and management of knee osteoarthritis.
As with nearly all injuries, the onset of knee osteoarthritis has many factors, some of which overlap and interact. I’m just happy that running isn’t one of them!
Because one blog post just isn’t enough, stay tuned for Running and Knee Arthritis Part Two where we take a closer look at the response of knee cartilage to running, the role of physical therapy to maximize joint health for runners, and practical applications to your daily run training.
If you are interested in assessing your risk factors for running-related injury, contact us at Prevail Physical Therapy! We specialize in research-driven, quantitative analysis of running and walking, including video gait analysis, plantar pressure mapping, and EMG measurements of muscle activity. All of our clinicians have completed advanced clinical training in movement analysis and rehabilitation of conditions related to movement dysfunction and are certified running coaches through RRCA or USATF.
1.) Esculier, Jean-Francois et al. “What are the perceptions about running and knee joint health among the public and healthcare practitioners in Canada?” Plod one vol. 13, 10 e0204872. 1 Oct. 2018, doi:10.1371/journal.pone.0204872
2.) Alentorn-Geli, Eduard et.al. “The Association of Recreational and Competitive Running with Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis” Journal of Orthopaedic & Sports Physical Therapy 2017 47:6, 373-390
3.) Losina, Elena et al. “Development and feasibility of a personalized, interactive risk calculator for knee osteoarthritis” BMC musculoskeletal disorders vol. 16 312. 22 Oct 2015, doi:10.1186/s12891-015-0771-3
4.) Pandey, Rajesh et al. “Impact of obesity and diabetes on arthritis: An update” Health vol 5, 1(2013): 143-156