Researchers at the University of Illinois say they're learning more about the toll the high stress work of firefighting can take on the human heart.

In a study published in the journal Vascular Medicine, researchers say three hours of firefighting stiffens arteries in even young firefighters.

Researchers Gavin Horn of the Illinois Fires Service Institute and kinesiology professor Bo Fernhall found that the damage was likely the result of a combination of stresses.

A 2007 study conducted at Harvard University found that firefighters are up to 100 times more at risk for a heart attack when they are fighting a fire than when they're not.

Fernhall says researchers will look at whether firefighters can take baby aspirin before emergency calls to lower their risk.