EXTREME exercise such as marathons may permanently damage the heart and trigger rhythm abnormalities, warn researchers. Experts said exercising for between 30 and 60 minutes a day is ideal and beyond that would lead to ‘diminishing returns’.
People who run marathons and cycle long distances risk long-term damage to their hearts and are at greater risk of suffering a heart attack in the two years after their race, they were warned.
A review of research on endurance exercise conducted by a team at the respected Mayo Clinic in Rochester, America, found extreme endurance exercise such as marathons, iron man distance triathlons, and very long distance bicycle races may cause structural changes to the heart and large arteries.
The Daily Telegraph revealed last week that surgeons are seeing an increase in the number of middle-aged fitness fans who are wearing out their knee joints by playing tennis and running into their 40s and 50s.  Published in the journal Mayo Clinic Proceedings it was found that some athletes suffer temporary changes in their heart function which return to normal in the week after their race, however for others permanent scarring occurs.  Lead author Dr James H. O’Keefe, of Saint Luke’s Hospital of Kansas City, said: “Physically active people are much healthier than their sedentary counterparts.  “Exercise is one of the most important things you need to do on a daily basis.            –TG