NEW YORK (AP) - It's dramatic news when a marathon runner keels over with no pulse. Now a big study finds such calamities are rare and are usually due to a pre-existing heart problem.
The study also found such incidents to be increasingly common as more runners try to go the distance.
The work included runners in American marathons or half marathons from 2000 to 2010. Researchers looked for reports of runners falling unconscious with no pulse while racing or just after finishing. They found 59 incidents, of which 42 were fatal. That's out of 10.9 million runners during the decade. Most of the victims were not aware of the heart problem that caused their cardiac arrests.
The study appears in Thursday's New England Journal of Medicine.