Too much exercise can ‘scar heart and up risk of sudden death’

Too much exercise can scar the heart and increase the risk of sudden death, experts claim.

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 scientists.