One study from 1992 had female marathon runners drawing level with men by 1998, to complete the 42.195km course in just under two hours and two minutes.
There was an emotional tribute today to the victims of the Boston Marathon bombing at the city's Fenway park before the start of the Red Sox baseball game.
Step by step, it takes a mara-ton of effort, it's like you're never out of the woods and if you're not an ultramarathoner, you'd be Barkleying of the wrong tree to try.