Frostbite. Sleep deprivation. Harrowing descents in pitch blackness. It's all part of the strange allure of the Arrowhead 135: an extreme ski, bike or foot race in far northern Minnesota that begins before dawn on Monday morning.
It's one of the nation's craziest endurance races, and a huge challenge for participants.
Let's start with the cold. Last year, overnight temperatures plummeted to minus 25 degrees. During the 2010 race, it was minus 35. That's the year Jason Buffington, a Duluth doctor who was biking the route, saw friend and fellow bike racer Charlie Farrow stopped on the trail.
"I came up on Charlie in the last 20 miles of the trail, standing and waving his legs back and forth trying to get circulation back in his toes," Buffington said.
Farrow, 52, stayed in the race and crossed the finish line — about two hours later. Buffington, who is 10 years younger than his friend, was there to meet him and quickly helped him take off his boots.
"His toes were swollen and purple like a plum," Buffington said. "He lost probably about half of the skin off his big toe, about two or three months later."
Said Farrow: "My toenail never came back, so I'm a man without a toenail."
As Farrow and Buffington recalled that race, they primed their equipment for this year's event at a Duluth park. Farrow's bike is outfitted with fat snow tires as wide as his fist. This year, Buffington will go on foot, pulling a sled he has rigged for the race. Each racer is required to carry survival gear for the extreme cold.
"You get what's called the kennel cough," Buffington said. "Where your lungs get frozen, your eyeballs, your corneas get a little frostbite, and everyone kind of walks around, and everything's real foggy, and you just have this ... dry coughing going the whole time."
Then there's the lack of sleep. The walkers and skiers take nearly two days to complete the 135 miles, and may only sleep a couple hours during the race. The fastest bikers take nearly 20 hours, and don't rest at all.
Farrow, a high school social studies teacher in Esko, Minn., has ridden the race six times, only missing the inaugural event. Every year, he said, his fatigued mind starts playing sinister tricks.
"I have a reoccurring hallucination regarding the Wizard of Oz," Farrow said. "I always have this vision of the trees coming after me ... and then I also have this vision of the Emerald City.
"I'm completely serious," he said. "They usually start kicking in about 20 hours into it, and I have to really, really fight falling asleep."
Racers also have to endure isolation. The course follows a snowmobile trail from International Falls to near Tower. Buffington said the racers are spread miles apart.
"That's definitely the biggest danger," he said. "Both years that I've biked it, even though it's taken less than 20 hours, there are times where for six and a half hours, in the middle of the night, [it's] 20 below, you don't see a soul. And if anything happens, you're out there on your own."
So racers have to be extremely prepared and careful. Jeremy Kershaw, 40, completed the race the last three years -- first by ski, then bike, and last year on foot. With about 20 miles to go, Kershaw said he caught up to a racer struggling on the side of the trail.
"He was kind of frantically trying to get new clothes on and eat," said Kershaw, a Duluth cardiac nurse. "It was a scary situation, because I was really at the last several hours of the race, and so I was really at the end of my reserves."
The racer had a cell phone, and Kershaw was able to contact a support crew that hauled the racer to safety by snowmobile. But Kershaw said it was a good reminder of how things can go wrong.
"If you're not paying attention, things can go south very quickly," he said, "particularly when it's that cold and you're that tired."
About half the racers who depart International Falls Monday morning won't reach the finish line. Believe it or not, that's partly what attracts athletes like Kershaw.
"I'm more drawn to it by the fact that there's so much carnage, that people don't finish, that it's so tough," he said. "That's an instant draw to do it."
There might not be as much carnage this year as in past races.
Overnight temperatures are only forecast to drop into the teens above zero. So, maybe it's a good time for Kershaw to take this year's race off. He's skipping this year's balmy Arrowhead 135 to train for a 300-mile bike race across Iowa on gravel roads.
MAP OF RACE
• More about the course here.