Exercise: do you know when to stop? [news]
Too much exercise can scar the heart and increase the risk of sudden death, US experts say. Research shows that extreme endurance sports such as marathons, triathlons and long-distance bicycle races can cause structural changes to the heart and large arteries. Usually recovery occurs within a week. But for some individuals, repetitive injury over months and years of training and competition can lead to patches of fibrosis, or scarring, in the heart, say US scientists. Advertisement: Story continues below This can lead to an increased likelihood of potentially fatal abnormal heart rhythms.