Relentless Forward Progress: A Guide to Running Ultramarathons

Marathons have become too easy for some runners. What was once the pinnacle of achievement in a runner’s life is now a stepping stone for extraordinary adventure in ultramarathoning. The number of ultrarunners—those running distances of 50k (31miles), 50 miles, 100k (62 miles), or 100 miles—is growing astronomically each year.

Dean Karnazes’ Ultramarathon Man and Chris McDougall’s Born to Run have inspired tens of thousands to try these seemingly superhuman distances. But to date, there has ...