Marathons and the female heart


As of September 2017, new Sweat Science columns are being published at Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


Is marathon running good or bad for your heart? That question has become a hot topic over the past few years thanks to a few studies showing negative effects like heart scarring and artery hardening in veteran marathon runners. One of those studies was a conference presentation last year that looked at 25 male runners who had each completed the Twin Cities marathon 25 years in a row. Compared to matched controls, the runners had greater plaque volume in their coronary arteries.

Now the same group of researchers has followed up with a similar study of 25 female runners who have run a marathon each year for the past 10 years. In this case, the result (as presented at the American Health Association conference) is exactly the opposite: the runners have fewer coronary plaques than matched controls.

So what to make of this? Neither study has been published in a journal yet, so it’s difficult to analyze the results in detail. It’s possible that the conflicting results are simply a result of the fact that the male marathoners were older, on average, that the female marathoners. Or it may be a physiological gender difference. Or it may have something to do with training history. Or it may be a complete fluke: in the male group, the key difference in the plaque volume was 274±176 vs. 169±170. Those are rather large ranges of uncertainty.

But the real question is none of the above: it’s whether these findings about elevated risk factors translate into compromised health. So far, I’m not aware of any study that links marathon running, or any form of endurance exercise, to elevated risk of death (or any other serious ailment) from any cause. That doesn’t mean such risks don’t exist (they could easily be hidden by the overall positive effect of exercise’s other health benefits). Still, as I wrote in the Globe and Mail a few months ago (and probably reflecting my “wishful thinking” bias), I can’t bring myself to get too worried about these apparent risks in the absence of any direct evidence. As Amby Burfoot wrote, “show me the bodies in the streets.”

10 Replies to “Marathons and the female heart”

  1. Was there any mention of diet in this study? Just because one runs marathons does not automatically mean that the diet is cleaner than that of a non-runner. Just a thought.

  2. 25 runners is not a statistically-significant sample size (as evidenced by the large uncertainties). However, I’d also be curious about the difference between elite marathoners and not-so elite marathoners. Elite marathoners tend to be far better prepared to put their body through the demands of a marathon race. Just because you run a marathon every year does not mean you are properly prepared to do so, and a lot of masters athletes have major trauma or death due to the fact they are not prepared for the rigors of competition, and that could be the cause of scarring and build up of plaque.

  3. Yes, I wonder the same thing about whether adequate training has a protective effect against the damage done in competition, or whether it’s the training itself that causes the alleged damage. I’d certainly like to think it’s the former, but I don’t have any particular evidence either way.

  4. @alex – likely both do the damage, but only because likely a lot of people train beyond what they are prepared for. People who have not been training at some level all of the sudden deciding they are going to run a marathon in 3 months likely a) ramp up training too quickly for what their bodies are prepared for, and b) are likely less capable of dealing with stresses on their bodies because they do not have years of training behind to have their body learn to repair and adapt efficiently.

  5. Such a promising title, such a pedestrian text! Shouldn’t that be attached to something by Verdi?

  6. the health effects of chronic endurance training seem to be neutral at best. people who are passionate about this pursuit tend to wear themselves down in various ways.

  7. I won’t go as far as to say that this study was flawed, but I will say that it seems very limited and shaky. If there was money on the line, I would be willing to bet that a marathoner (or any other actively fit individual) has a better shot against heart disease than your average couch-dweller.

  8. I believe there are a lot of contributing factors for that a death to occur while running. It could be a combination of a lot of health factors and of course we can not dispute the occurrence of over exertion which can result to damaging the heart and raising the possibility of having a stroke or a worst scenario… sudden death.
    That is why it is best to take things slow and then increase the pace gradually.

Comments are closed.