I've read somewhere that ultra running is bad for your body, and that even marathons take their toll. Does this mean that if I don't care about the glory of finishing marathons and ultramarathons I could just as well never (or seldom) participate in such events?

Some background information… I'm not an elite runner, so my main reasons to run are to stay healthy for as long as possible and to enjoy the physical exercise. In most of my 200 races so far I've pretty much run in the middle of the pack, and only won twice in my life (through lack of competition, though).

I've only run two marathon races in the past 15 years (10 and 5 years ago), both of which I didn't really enjoy. I'm much more comfortable doing races up to the half marathon distance, since, for me, they never last longer than two hours. I occasionally do longer training runs (28km), but find those utterly boring, not fun to do, and my experience is that they are rather stressful on my body.

Additional information: Many blog posts I found on this subject seem to be based on this study by the Mayo Clinic from 2012,

Since I'm not a sports scientist, I cannot judge how valid this study is.

I supposed that since how much distance is too much depends on the person, no blanketed statement can be made above what weekly distance running becomes a health issue.

Furthermore, one can find articles that claim athletes can prepare for ultras with a modest weekly mileage, based on the philosophy of Crossfit Endurance. It seems that the high volume of training distance in preparation is what makes marathons and ultra-marathons such a health risk, though I haven't seen any scientific studies backing up this claim.

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    I remember reading a paper showing a mirrored J-curve for running: general health risks drastically decrease with moderate exercise, reaching an optimum low at about 1.5 to 3 hours of running per week; after that, there's a slight increase, but not very significant. At the professional level it's usually not very healthy.
    – Wood
    Jan 30, 2020 at 11:38

2 Answers 2


For the most part, the science is still unclear on the long term effects of things like long distance running on the body. Some studies have suggested that it can be bad for knee cartilage (in beginners), but goes on to say that their findings were likely not clinically relevant due to experimental error (http://www.ncbi.nlm.nih.gov/pubmed/24045919).

Other studies suggest that activities like marathon running, or ultramarathoning, over the long term, can have negative effects on the heart such as arrhythmias and patchy myocardial fibrosis (thickening of the heart muscle in a bad way) (http://www.mayoclinicproceedings.org/article/S0025-6196(12)00473-9/abstract).

However both studies essentially were inconclusive and made a point to note that life long exercisers generally have lower mortality rates (although some other trials have shown that marathon runners are at a higher risk for calcium deposits in their arteries).

In Exercise in Cardiovascular Disease: Cardiovascular Effects of Exercise Training- Molecular Mechanisms (Stephan Gielen, MD; Gerhard Schuler, MD; Volker Adams, PhD) there is even note that "lifelong physical activity prevents the development of diastolic [left ventricle] dysfunction in older age."

I've also seen studies that investigate lower back pain in runners, and find that runners have fewer instances of lower back pain than the regular population.

Here would be my take-away from much of the science that's out there at the moment: most of the consensus is that exercise is a net positive for health over the long term (unless you are acutely overloading the heart/ body's systems so much that it causes injury- meaning if you hop into an ultramarathon after no training, there is potential for serious injury. That could be what many of the studies are eluding towards, remember that the 1st one I talked about only tested beginning runners). The way to mitigate that risk would be to progressively increase training intensity over time, giving yourself enough time to work up to where you want to be. With that in mind, it's not clear that ultra-long distance events are bad for health.

So if you enjoy running, I would continue to enjoy the sport, and some positive health benefits as well!

  • So, I assume you mean that if one slowly builds up endurance and strength it is not so bad for one's health as some articles would like us to believe. If true, I guess the titles of those articles are meant as link-bait for unsuspecting readers who lack scientific background in the matter. Jul 7, 2014 at 15:27
  • Yes, I agree about the click bait. Unfortunately many fitness/health sites try to get clicks by saying "this thing you thought was true could be really bad, click here to find out why." Even in articles that summarize a study or experiment, they will often throw out overreaching claims- either because they really don't understand what the study looked at, or they just need the views. I've seen individuals who were endurance runners survive massive heart attacks because the other parts of their heart were strong enough to compensate for the dead tissue (anecdotal evidence aside hah). Jul 7, 2014 at 15:46

"I've read somewhere that ultra running is bad for your body"

From where? Is the source credible?

Generally speaking, I think there's a perception that long distance running is bad for you. However, I've never seen any credible science backing this up - and I keep an eye on the science.

Bear in mind that there's solid evidence that running long distance was how our ancestors got to eat I find it difficult to believe that it does serious damage.

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    Since you seem to be into science, can you add some reference in your answer to this "solid evidence that running long distance was how our ancestors got to eat"? Jul 5, 2014 at 8:51
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    Here is an interesting article about just that- sciencedaily.com/releases/2004/11/041123163757.htm Jul 5, 2014 at 15:50
  • Good find, @user3194712 Jul 7, 2014 at 15:23
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    Just because our ancestors had to run to eat doesn't mean it's safe in the long-term. Evolution doesn't care one whit about having healthy joints at age 60.
    – half-pass
    Oct 5, 2014 at 19:16

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