Running Marathons Won’t Kill You  Marathons are hard on the
heart, but recent deaths of long-distance racers are the
exception rather than the rule    • Share   • Read Later Getty
Images  It’s one of the more puzzling ironies of exercise —
tragic news of people dying during or after completing a
marathon. In 2009, four runners died during half-marathons in
San Jose, Cal. and Detroit, and last year, two runners died at
the Philadelphia Marathon, one at the finish line and another
about a quarter-mile from completing the race, all from apparent
sudden heart attacks.  Isn’t running supposed to improve your
fitness and lower your risk of succumbing to cardiac arrest?  In
a new study published in the New England Journal of Medicine,
researchers explain the paradox of why a seemingly high number
of marathoners have heart attacks. They analyzed heart attacks
among 10.9 million racers running either half-marathons or
marathons between 2000 and 2010, and found that such long-
distance races actually did not lead to an