Participants in The North Face Endurance Challenge crossed the finish line near Lake Samish on Saturday short of breath, with shoes and legs caked in mud.

Bent over with his hands on his knees and the sweat still dripping from his brow, half-marathon runner Joah Spearman described the 13-mile race.

“It’s not like running. It’s climbing, it’s pushing, it’s pulling,” said Spearman, who finished the race in about two hours and 45 minutes. “It’s both brutal and incredible.”

The North Face Endurance Challenge, which took place at Camp Lutherwood, 1185 Roy Road, included four races of different lengths — a 10K, a half marathon, a 50K and a 50-mile race.

Spearman, who traveled from Washington, D.C., to participate in the half marathon, said that no matter how much anyone trained for the race, no one could have been prepared for it.

“The trail kept going up, up and up,” Spearman said. “I totally underestimated this course.”

Chip Jackson, 17, of Shoreline completed the half marathon in two hours 25 minutes, placing third.

Jackson, who had never competed in a trail run before, said the race began slowly with a steep, uphill climb, but the pace picked up as the trail led downward.

The most difficult part of the race was not knowing when the trail would end, Jackson said.

At one point, Jackson said, he could see the finish line and was excited to think he was almost done, but the trail turned and he still had another loop to run.

The purpose of the race was to give people the opportunity to push their limits, said Katie Ramage, who participated in the 10K and is senior manager of sports marketing at The North Face, an outdoor clothing maker.

The 50-mile course, which reportedly included scenic views of the San Juan Islands and Canadian mountains, ran through Whatcom and Skagit counties.

The top male finisher, Brian Morrisson of Seattle, completed the 50- mile race in seven hours 58 minutes, said Brandon Friese, Gore-Tex tour manager.

The top female finisher in the 50- mile course, Nikki Kimball of Boseman, Mont., had a time of eight hours and 58 minutes, Friese said.

They each won $1,000 and a trip to San Francisco to participate in the Endurance Challenge Championship on Dec. 6.