Google+ Running in Cork, Ireland: Running marathons may cause damage to your heart

Wednesday, December 07, 2011

Running marathons may cause damage to your heart

"Running Marathons may cause damage to your heart"..........or at least that's what the headline was for a piece that appeared in the Irish Independent newspaper.

The article said..."Running marathons could permanently damage the hearts of some endurance athletes, scientists believe. New research suggests extreme physical activity can scar the right ventricle of the heart in susceptible individuals. Athletes taking part in high-endurance activities, such as marathons or triathlons, could be at risk without knowing it. Scientists in Australia and Belgium studied 40 elite athletes who were planning to compete in one of four endurance events. All were highly trained with no known heart problems. Test results showed that immediately after racing the athletes' hearts had changed shape and right-ventricle function decreased. Right-ventricle function recovered in most athletes after a week, but in five (which is 12.5% of total) there was evidence of potentially permanent scarring. Study leader Dr Andre La Gerche, from the University of Melbourne, Australia, said: "Virtually all of the changes in the athletes' hearts had resolved one week after having taken part in a competitive event."
Comparison of the heart size in two 23 year olds – a non-athlete and a young professional cyclist. Note the 10mm marker as a reference.  The non-athlete’s heart is approximately 15 x 12cm vs. 25 x 18 for the athlete!

The BBC also picked up on the study and ran a story with the headline..."Marathon training 'may pose a heart risk'. Their take on it was..."Doing extreme endurance exercise, like training for a marathon, can damage the heart, research reveals."

I first heard this earlier in the morning while the daily newspapers were being reviewed on a radio station. It was read out as if it was a matter of fact......running in Marathons is closed.
However when you go digging into the story, you see that they are talking about tests done on elite athletes and not the average runner. Not for the first time, the headlines used are misleading.

In another article written by Dr Andre La Gerche on exercise, he used the following basic graph...
In fact, by far the most dangerous thing you can do is to do nothing at all. So the couch potatoes reading the article and tut-tutting the Marathon runners are the ones most likely to drop dead on the spot! Dr La Gerche states..."There is no doubt that moderate exercise is good for you.  Exercise reduces your risk of heart attacks, stroke, diabetes and some cancers.  The promotion of exercise as a positive and powerful health intervention has never been more important given the explosive increase that we are seeing in disease states which are related to under-activity such as obesity and diabetes. Very light exercise is proven to be benefical to your heart. "

Now the point shown on the graph is the PROVEN point of benefits. Dr La Gerche continues..."The benefit of exercise is likely to extend to high levels of exercise but is there a point where the benefits start to plateau or even reverse? Note, however, that it is unlikely that any level of exercise will increase risk to the level of a sedentary person. With current evidence, I would not advise that any level of exercise is unhealthy.  At the same time, I think that it is important to recognize that some things remain unanswered."

In concluding, he states.......
- Mild and moderate exercise provides considerable health benefits to everyone
- Prolonged, intense exercise (such as the levels practiced by competitive athletes) is also likely to be safe but it has not been well studied.

As with most studies like this, the usual advice is everything in moderation. If someone is involved in a high level of prolonged training...i.e. a serious athlete...then they should consider the findings of this recent survey. For the vast majority of runners doing say 1 to 2 Marathons then it's unlikely to be an issue. As always, if in doubt, consult your doctor.


Anonymous said...

interesting article. very hard to get a definite answer on these things. if you were a runner who does 4/5 marathons a year would you be inclined to cut down or stop?

John Desmond said...

4-5 Marathons a year?.....if they are in effect just extended long runs done at conversational pace then they are probably ok. Running 4-5 close to your Marathon personal best time is probably too much.