Marathon training may pose a heart risk

Doing extreme endurance exercise, like training for a marathon, can damage the heart, research reveals.
MRI scans on 40 athletes training for challenging sporting events like triathlons or alpine cycle races showed most had stretched heart muscles.
Although many went on to make a complete recovery after a week, five showed more permanent injuries.
The researchers told the European Heart Journal how these changes might cause heart problems like arrhythmia.
They stress that their findings should not be taken to mean that endurance exercise is unhealthy.
In most athletes, a combination of sensible training and adequate recovery should cause an improvement in heart muscle function, they say.
But they believe more investigations are now needed, since their small study in Australia did not look at any associated health risks.