An excessive,  and unsupervised exercise routine might not be as healthy as it seems. Emerging science suggests there is a threshold of distance, intensity or duration for even the hardiest fitness fanatic, and overshooting this can have a serious impact on cardiovascular health.

In a review published in the journal Heart, two leading U.S. cardiologists looked at the heart health of 50,000 people over 30 and found that the 14,000 runners in the study were likely to live longer than non-exercisers, but only if they ran between five and 20 miles a week, not more.

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

Read more: http://www.dailymail.co.uk/health/article-2501428/Men-turn-mid-life-fitness-fanatics-actually-HARMING-health.html#ixzz2kbndFcGx