ISLAMABAD - Too much exercise may damage your heart, doctors have warned, suggesting that rather than adding years to their lives, fitness freaks could be working themselves into an early grave.

Experts warn that exercising intensely for more than an hour or two can damage the heart, causing its tissue to stretch, tear and scar and raising the odds of dangerous changes in heart rhythm.

"A routine of moderate physical activity will add life to your years, as well as years to your life. In contrast, running too fast, too far and for too many years may speed one's progress towards the finish line of life," doctors said.