We've all heard the horror stories of seemingly healthy people collapsing during or immediately after marathons. It's ironic that these deaths have been attributed to heart attacks when distance runners should be the portrait of cardiac health. Although still relatively rare—two runners out of over 25,000 participants died during the Philadelphia Marathon in November 2011—it's still troubling enough to deter some potential marathoners from hitting the pavement. However, according to a study led by Dr. Aaron Baggish of the Cardiovascular Performance Program at Massachusetts General Hospital, long distance races didn't increase a person's chances of having a heart attack. In fact, long distance runners were less likely to have a heart attack than people participating in other sports and even casual joggers. And as a bonus, a runner who suffered a heart attack had a 71 percent fatality rate while the normal average is 92 percent. The study looked at over 10.9 million marathon runners and found that those who had suffered heart attacks usually had either hypertrophic cardiomyopathy, a condition where the walls of the heart are thicker making it harder for the heart to pump blood, or were older runners whose heart vessels had built up plaque. While these conditions can get worse by exercising often, people without any underlying conditions didn't increase their chances of having a heart attack by running. Ultimately, Baggish concluded that physical activity offered more benefits, but he did advise anyone considering distance running to talk to a doctor about any potential risks.