I’m sure you’ve heard it all before:
“Running is so bad for your knees”
“You really shouldn’t run if you don’t want to get knee replacements”
“All of that wear and tear is going to add up one day”
But is any of this true?
Certainly, we know that repetitive use at extreme levels can cause musculoskeletal problems to
arise. But unless you are spending each waking our training and running, does this apply to
In a recently-published study based in the UK, researchers examined the knees of first-time
marathoners for London. These runners were symptom-free and were considered “sedentary”
meaning they were not regular exercisers(1). At the beginning of the study, they each received
a 3-Tesla MRI which is the most powerful and detailed image possible.
Then each runner participated in a 4-month standardized training plan for the London
Marathon. There was some dropout from the study, but this is to be expected with any
marathon training plan. Following completion of the marathon, they all went back and had
another MRI to compare the images.
Here’s what the researchers found:
- 36% of knees BEFORE the marathon had meniscal tears (we’ve written tons of blogs on
the dangers of MRI scans and false-positives!)
- There were NO significant differences in knee meniscal tears pre- and post- marathon
- More than half of knees imaged had “cartilage damage” before the race, and while
some did worsen, so did the knees of people who did not complete the marathon or
- Tendon “injuries” were present before the marathon in 42% of people, and there was
no significant worsening following the race
- 42% of knees had ligament “damage” before the race, with no significant change after
- Subchondral bone marrow edema was found in 41% of knees prior to the training (this is
a measure of bone and joint health), and IMPROVEMENT was noted in this following the
So, what does all of this mean?
- Plenty of healthy, pain-free people have “bad” findings on an MRI of the knee involving
tendon, ligament, cartilage, meniscus, and bone marrow. Remember they have NO pain.
- Marathon training and running did not worsen these “bad” findings any more than just
sitting on the couch did
- In fact, training for the race improved the bone marrow edema of several participants,
indicating improved bone health!
The next time someone tells you that running is bad for your knees, now you will have some
evidence-based rebuttals to provide!
Thanks for reading,
1. Horga, L. M., Henckel, J., Fotiadou, A., Hirschmann, A., Torlasco, C., Di Laura, A., ... & Hart, A. (2019).
Can marathon running improve knee damage of middle-aged adults? A prospective cohort study. BMJ
open sport & exercise medicine, 5(1).