Extreme exercise such as marathons may permanently damage the heart and trigger rhythm abnormalities, warn researchers.
They say the safe ‘upper limit’ for heart health is a maximum of an hour a day - after which there is little benefit to the individual.
A review of research evidence by US physicians says intensive training schedules and extreme endurance competitions can cause long-term harm to people’s hearts. Read more
Excessive Exercise Harms the Heart, Say Scientists
It's about time we quit congratulating marathoners and triathletes and began pitying them instead. Excess exercise "hurts the heart" and cause dangerous long-term harm, say scientists. Of course, this is exactly what people used to think before the running boom of the 1970s. Short, intense activities, such as sprinting, are much better.