It seems like common sense that to prepare for a marathon—an event that includes a heck of a lot of running—your training should also include a heck of a lot of running. That’s why marathon preparation dogma preaches that you need to do one long, 12 to 26 mile run each week.
The problem: That often puts too much mileage on your body, says Mark Conover, director of the cross-country and track-and-field programs at California Polytechnic State University.
“The key is to get to the starting line fresh,” says Conover. “You don’t want to arrive at the marathon as damaged goods.”