http://health.propeller.com/story/2007/11/08/runners-high-may-also-strengthen-hearts Endorphins and other morphine-like substances known as opioids, which are released during exercise, don't just make you feel good -- they may also protect you from heart attacks, according to University of Iowa researchers. http://media-images.nscpcdn.com/media/ns-logo-rss.gif http://www.propeller.com en-us Copyright 2006-2007 Propeller Propeller.com