We asked a few elite runners who frequently do both.
Sage Canaday is a two-time U.S. Olympic Trials Marathon qualifier and an elite ultra-distance trail runner.He won the 2014 The North Face
They've made their name in ultras, but they're leaving the trails behind for one day in Boston.
The California race had a loaded field that overcame wet and muddy conditions.
Here are 5 men and 5 women to keep an eye on at the North Face Endurance Challenge Championship on Saturday.
After an epic trail run on the Kauai coast, Sage Canaday goes through everything he takes with him.
Get an inside look at running on one of the United States' most stunning trails.
Photos from The Rut 50K, one of the hardest trail races in the U.S.
Check out these great shots from one of California's most scenic off-road courses.