What to say when someone says, “running is bad for your knees.”

When someone tells you they believe “running is bad for your knees,” first take a moment to think about where that person is coming from. She or someone she knows may experience knee pain while running. Recognize her experience. Please fight the overwhelming urge to ask them if they are also a “Flat Earther” (someone who believes Earth is flat).

A better response: “You are right. Science actually supports your claim in a way. Knee pain is the most common painful body part or injury runners report. But, you are not totally correct, and we should clear up some confusion.”

Wait for their response… “What do you mean?”

First clarify that you are likely talking about her fear of osteoarthritis (OA). You could go ahead citing a long list of scientific evidence supporting the benefits mechanotransduction related to optimally loading human tissues, but they will probably stop listening.  Help them get their head out of the sand with the following analogy:

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You ask: “Have you ever had a blister on your foot?”

Her response: “Yes”

You ask: “Why did you develop the blister.”

Her response: “My shoes didn’t fit right.” “My socks got wet.” “I hiked 5 miles.”

You say: “Exactly.” “It was too much stress, but it heals because that is what you are built to do.”

Her response is completely logical.  Her confidence that a blister heals likely from past experience means  she has a sense of control over the situation; no fear.  She will see if she needs a different sized shoe. She will buy wool or synthetic fiber socks. She won’t go out and hike the same distance right away. She ultimately will reduce stress on the area. She will ADAPT and go on the same 5 mile hike eventually if she wants to bad enough and probably not get a blister if she made the right changes.

Whether running is good or “bad” for your knees simply boils down to the individual’s ability to adapt to mechanical stress and his or her genetic makeup. Too much stress without enough recovery is “bad.” Not enough stress is “bad.” THE OPTIMAL LOAD IS UNIQUE TO EACH INDIVIDUAL AT ANY GIVEN POINT IN TIME.

 If that person experiences pain while running, tell that person, “ YOU DON’T HAVE TO RUN IN PAIN. SEE A PHYSICAL THERAPIST.”   In short, establishing the cause of your metaphoric “blister” and reducing your fear to move is what a physical therapist does. Demystifying, educating, and empowering people to move is a physical therapist’s  societal responsibility.

So, is running “bad for your knees?” No studies are absolutely definitive because there is so much individual variability to control.   We do know that weight loss is associated with improved knee symptoms and slowed cartilage degeneration in those whose BMI is over 25 kg/m2.1  Research has shown no statistical difference in knee cartilage thickness between triathletes with >3 years of training at least 10 hours per week and matched “inactive” subjects.2  Cross sectional running studies suggest no association with OA.3  It really just depends on whether one’s body adapts to the mechanical stresses imposed.

We used to believe that our heart only beat a finite number of times before it stopped working for crying out loud. Turns out that was wrong and the Earth is also round.

  1. Gersing AL, et al. Progression of cartilage degeneration and clinical symptoms in obese and overweight individuals is dependent on the amount of weight loss: 48-month data from the Osteoarthritis Initiative. http://dx.doi.org/10.1016/j.joca.2016.01.984
  2. Muhlbauer R, Lukasz S, Faber S, Stammberger T, Eckstein F. Comparison of knee joint cartilage thickness in triathletes and physically inactive volun- teers based on magnetic resonance imaging and three-dimensional analysis. Am J Sports Med 2000; 28(4):541e6.
  3. Shrier, Ian. Muscle Dysfunction Versus Wear and Tear as a Cause of Exercise Related Osteoarthritis: and Epidemiological Update. British Journal of Sports Medicine. 2004. Vol. 38. pp. 526-535.


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