Muscles. Women and girls are catching up, though. Joshua Cheptegei has the men's 5000 WR with 12:35.36 and Gudaf Tsegay with 14:00.21 holds the women's WR. However, in a pro half marathon the other day the winner ran :57, the fourth fastest in history. The first woman in (around 30 years old) ran something like 1:04. Katelyn Tuohy, the fabulous XC and middle distance runner at NC State used to win SE New York high school cross meets running splits that were faster than all but a handful of boys, out of hundreds. Within the past few years women have begun to win ultra races competing against men. Most long distance swimming records are held by women.
