Due to last-minute design changes, some of the text in the print version (June 2012, Issue 80) of this excerpt was repeated and deleted. We are very sorry, and offer this complete and correct online version.

Last Saturday near San Francisco, the 17th running of the Miwok 100K surprised veterans of the race with a radically revamped course that many called “brutal,” “epic” and “knock-your-socks-off tough.” How tough? Consider that four-time winner Dave Mackey of Boulder, Colorado, set a course record there in 2008 of 7:53, and his previous slowest time on the course was 8:28. This year, he won the race in 9:14.

Seven days of running and hiking across vast desert terrain, covering some 250 kilometers while carrying calorie-dense food and essential gear on your back, isn’t for everyone. But a growing number of extreme trail runners and fastpackers view a multi-day, self-supported race as the next frontier in adventure and challenge.