October 24, 2010
Beware Marathon Heart Injury

If you haven't built up to a marathon with a lot of training you can inflict heart damage on yourself that'll take up to 3 months to heal.

Montreal - Is running a marathon good for you or can it damage the heart?

A team of researchers and runners from the Heart and Stroke Foundation have come up with a practical way of answering the question. They used data from magnetic resonance imaging (MRI) to find out what is really going on in the marathoner's heart as the kilometers pile up.

"Marathon runners can be a lot less fit than they think," Dr. Eric Larose today told the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

Lack of real aerobic fitness may directly impact the ways the heart organizes itself to survive the stress of marathon running, says Dr. Larose.

His research found that the magnitude of abnormal heart segments was more widespread and significant in a group of less fit runners. During the marathon, they had signs the heart might be at greater risk of damage than that of runners who had better training or at least had better exercise capacity.

It can take up to 3 months to recover from exercise-induced heart injury. I had no idea.

"Without proper training, marathon running can damage your heart. Fortunately the exercise-induced injury is reversible over time," said Dr. Larose. "But it could take up to three months to completely recover."

Any reader have a better understanding of just how severe exercise injury to muscles can be? Does an 18 year old need to worry? A 40 year old? When does it become a concern?

Share |      Randall Parker, 2010 October 24 11:33 PM  Aging Exercise Studies

Jake said at October 25, 2010 3:40 AM:

The long term damage done by distance running is due to years of carb loading. Carb loading wrecks the blood sugar/insulin control system and is highly inflammatory. This inflammation creates arterial plague.

Lou Pagnucco said at October 25, 2010 9:48 AM:

I don't have the reference, but I recall a study done about 15 years ago on the longevity of olympic marathoners.

They found that marathoners' mortality rate was decreased (w.r.t. the general population) until the age of 60 - then their mortality rate went up. So it appeared they were reducing their maximum life expectancy.

Olympic competitors may be a special case, though, and not representative.

Tuck said at October 25, 2010 12:21 PM:

See here:


Running appears to protect against all causes of mortality and disability. I've never heard of anything else that is as good for you as running.

But you should certainly train adequately before doing a marathon. ;)

Dan said at October 25, 2010 4:05 PM:

Tuck -

That study looks at runners, not marathoners. Some were training as little as 76 minutes a week, not nearly enough to prepare someone for a marathon. I ran my first marathon at 21, but I stopped because a) it takes up way too much time and b) at 25, I've already begun to see the damaging effects of excessive running and carbohydrate intake. Now, I eat much better and limit my runs to about 3 hours a week.

TT said at October 26, 2010 11:34 AM:

This was a presentation at a conference of upcoming or in-progress research. It's good for hype and publicity, but any meaningful commentary is impossible until the full study is published in a peer-reviewed medical journal.

Dana H. said at October 26, 2010 11:47 AM:

I have run a few marathons, but I never fooled myself into thinking that running a marathon is good for me. I did it for the challenge. After each one, it took about a month to recover my previous fitness level to the point that I could train as hard as before. So I'm not surprised that researchers have found signs of damage that takes months to recover from.

These days, I focus on the half-marathon distance, which is a universe away from the full 26.2 miles. You can go hard for the whole distance without completely beating up your body. And the training is much less demanding.

Tuck said at October 26, 2010 12:37 PM:


It may be the case that some level of running is excessive, but there's no scientific evidence I've found to support that premise, and you'll note that if that were the case, you would expect to see that result in the Stanford study. That is to say, excessive runners would do worse than moderate runners or non-runners. But that is not the result they found. All runners did better than all non-runners. Even runners who quit prior to starting the study did better than non-runners.

FrancisT said at October 26, 2010 12:56 PM:

In my experience as a long distance runner (I run at least a marathon 3-4 times a year plus half marathons, long trail races etc.) there is a significant hump that hits most people after about 20 miles (30km) of distance and/or 2.5 hours of continuous exertion. The precise time/distance varies and may depend on training but it happens to most people who run for this distance/length of time and as Dana H says there is a significant recovery period required after a marathon or similar that is far far worse than if you really push yourself but stay below the hump distance/time.

I'm not sure if the problem is muscular or cardiovascular but it certainly exists and it is worth bearing in mind

Dana H. said at October 26, 2010 2:42 PM:


I don't need a scientific study to tell me how drained I feel for weeks after a marathon. My n=1 sample is all I need. Having said that, neither my own experience nor the Heart and Stroke Foundation study gives any evidence of *permanent* damage from running an occasional marathon.

One other point: the Heart and Stroke Foundation study found damage specifically in under-trained marathoners. So the Stanford study of regular runners is not germaine.

Finally, it's not clear whether the Stanford study reverses cause and effect. Rather than running leading to increased health, it may simply be that healthier people are more likely to be runners (e.g., because they are more health-conscious in general, because running for them is not painful, etc.).

I'm not against running. As I said, I'm a regular half-marathoner. But in anything short of a double-blind, placebo-controlled trial, it is notoriously difficult to get firm conclusions that stand up to statistical scrutiny. So I take claims from any less controlled study with a large grain of salt.

Alan said at October 26, 2010 4:45 PM:

I am close friends with dozens of marathoners, from slowpokes to elites, and don't know anyone who carb loads in any way that would damage their bodies. Carb loading in most cases means a few large pasta meals a day or two before the race. Mostly they eat healthy, lean diets and try to balance healthy caloric intake with what their bodies need to recover and rebuild. Except in my case where I eat like a 7 year old left home alone with the keys to the pantry and the deep freeze. (Pizza and ice cream baby.)

As far as the recovery times go my first marathon took weeks to recover from. My second, four months later, took a couple days. My third, three weeks later, didn't take long at all.(I paced a friend for 25 miles of their first 100 mile race the next weekend.) Now doing a 25-30 mile run every week or two is standard. I'm not running all out but I do the distance in semi-respectable times.

Anthony said at October 26, 2010 10:44 PM:

As Glenn Reynolds pointed out when linking to this post, look what happened to the original Marathon runner. I've seen a couple of bloggers who otherwise are pretty into exercise and healthy eating hammer on marathon running as dangerous, and one pointed out a fairly large number of deaths in marathons. So I'm not surprised at the results, especially since they say "without proper training". There's lots of things that are bad for you without proper training.

CJ said at October 27, 2010 12:59 AM:

To go off an a tangent, I've found it a bit interesting that there have been several events this year celebrating the 2500th anniversary of the first marathon. The Battle of Marathon occurred in 490 BC, but since there was no Year 0 the 2500th anniversary will actually be next year.

Bill Chunko said at October 27, 2010 4:44 AM:


I don't suppose you'd be interested in citing the sources you use to support your claim.

willis said at October 27, 2010 8:38 AM:

How about a study showing the dangers of flying a plane without flight instruction?

Steven said at October 27, 2010 4:18 PM:

"I've seen a couple of bloggers who otherwise are pretty into exercise and healthy eating hammer on marathon running as dangerous, and one pointed out a fairly large number of deaths in marathons."

One of the things that bother me about this is the strong bias in reporting marathon deaths over other exercise deaths. Marathons are big public spectacles and it makes the news when someone dies. On the other hand, the middle-aged guy that had a heart attach and died at my gym (not running!) did not make the news. Whether marathoning is more dangerous than other forms of exercise, I really don't know since I don't think there are enough statistics to make a valid comparison.

I also agree with other runners here--it is fairly easy to recover from a marathon if you are use to a high volume of running. Most marathons, in my experience, do not have a suitable base to be running the distance. Hence the problems.

john personna said at October 28, 2010 8:41 AM:

I'm not sure if I got this idea from one of the paleo guys, or invented it myself, but my shorthand has become:

"Avoid any sport or exercise that resembles a survival event."

The body will do a lot, sacrifice a lot, when it thinks survival is at stake. Running for hours has to be that, and ultra-anything.

The converse:

"Seek sports and exercise that resemble 'hunts' or 'gathering' or even 'building.'"

john personna said at October 28, 2010 8:44 AM:

(I feel comfortable doing 1.5 hr mountain bike loops for this reason.)

Tony said at October 30, 2010 12:55 AM:

To the carb eaters: if you actually researched carbohydrate metabolism, you wouldn't be so positive about carb loading, and having a group of friends as subjects is hardly science. These discussions are meaningless and speculative at best without some sort of parameters. If you think endurance running doesn't cause damage, then why are marathoners dying?

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