34 | Lou Peyton

Lou Peyton was one of the first women to complete the Grand Slam of ultrarunning, completing four 100-mile races in the summer of 1989. And in fact, she went on to complete a fifth 100-miler that same year. Peyton started running just a few weeks after her first child was born in 1968. She's also the co-founder, with her husband, of the Arkansas Traveler, a 100 mile race that's still going on today.