What Will It Take to Run a 2-hour Marathon?

The current world record of 2:02:57, set by Kenyan Dennis Kimetto this year in Berlin, works out to 4:41.5 per mile; a sub-two would require less than 4:35 per mile. Will a human ever run that fast? Some fascinating number-crunching, and some great conclusions/predictions too. What Will It Take to Run a 2-hour Marathon? →