By CBC News

Marathon runners who lack proper training can temporarily damage their heart, Canadian researchers have found.

Cardiologist Dr. Eric Larose, a professor of medicine at Laval University in Quebec City, presented the findings on Monday at the Canadian Cardiovascular Congress 2010 in Montreal.
Lack of aerobic fitness may impair how the heart copes with the stress of running a marathon, Larose and his colleagues said.

"This is not a permanent injury that will leave any type of scar," said Larose.

The researchers compared marathon runners who were less physically fit to those who were fitter.

Those who were less fit showed abnormal functioning in more than half of the 17 segments in the heart's left ventricle versus the fitter competitors, the team found.

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Do these findings discourage you from continuing to run marathons or from getting involved in the sport? Let us know.