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Untrained marathoners may risk temporary heart damage


After last week's Nike Women's Marathon, my Facebook page was peppered with celebratory status updates from runners. I was impressed, of course, that twenty thousand women would willingly run 26.2 miles through fog and rain in hilly San Francisco. But as I looked through photos of the event on my computer, wrapped in a blanket and sipping tea, I couldn't help thinking that not running is a very nice activity.

Today, I found a tiny glimmer of justification for my laziness. Time's Alice Park reports on a Canadian study (release) showing long distance events may pose certain risks for untrained runners in particular. In looking at 20 marathoners before, during and after a race, Eric Larose, MD and his team documented:

...many signs of a heart in distress, similar to the changes that might occur during a heart attack. In the runners, levels of an enzyme called troponin, which rises in response to a strained heart and reduced flow of blood, were highest immediately after the marathon. The pre-marathon imaging tests showed that the heart was functioning at below normal capacity, not pumping blood as efficiently and struggling to battle inflammation. All of these factors caused damage to the heart muscle. “There is temporary damage to the myocardium, not in all regions but in over 50% of the heart,” says Larose.

But it turns out the conclusion I was hoping for (running is bad; relaxing with book and hot drink is good) may not be justified:

While the results were sobering, the scientists were encouraged by the fact that at the three-month follow up, the damage induced by the marathon appeared to have dissipated, and the heart had resumed its normal functions. It's still not clear whether the cumulative effect of running repeated marathons may eventually take a toll on the heart, but for now, the findings suggest that there may be a minimum fitness level needed beyond which the heart can bounce back from the strain of training and running a long race.

Minimum fitness level? That sounds like work.

Photo by iCanfoto

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