Greg Welch is an Ironman champion, an Ironman Hall of Fame inductee and one of the best all-around triathletes to ever squeeze into a pair of racing flats. In 1999 he finished 11th in Kona and ran a 2:46 marathon off the bike, but that’s just the beginning of the story. During the race he was forced to stop three times each during the swim and run and then another dozen or more times during the bike ride. Why? He was getting light headed and was having problems breathing because, as he found out later, his heart was beating out of control and was topping out at over 300 beats per minute.