See more of the story

Maybe you've heard of Bold North. How about Old North?

Early Monday morning, two Minnesotans in their 70s will be at the starting line of the Arrowhead 135, a winter wilderness trek starting in International Falls, described as one of the world's toughest endurance races.

About 160 racers will try to bike, ski or run 135 miles on the Arrowhead snowmobile trail, traveling around the clock, hauling their own food and survival gear through the North Woods near the Canadian border. Held in one of the coldest places in the country, the Arrowhead race frequently involves temperatures well below zero, making hypothermia and frostbite a risk.

The upside? If racers are lucky, they'll be seeing wolf tracks and the Northern Lights.

One of the racers will be 75-year-old Erwin "Erv" ­Berglund, a retired Minnesota DNR hydrologist from Fridley who will be riding a fat-tire bike in the race.

Berglund is the oldest person to finish the event.

He has started it four times before, the first when he was 69. He finished twice. Twice he had to drop out at about the halfway point. The last time he finished the race, in 2014, it took him nearly 37 hours.

"I'm two for two," he said. "I figure if I do it this year, I'll be three out of five, and that's a better number."

Even if he finishes the race within the required 60-hour time limit, that won't be the end of Berglund's toils for this winter. He's also signed up to do the Susitna 100, a 100-mile winter wilderness bike race on Feb. 17 in Alaska.

"I figured if you're training for one, you might as well do the other," he said. "It's called not knowing when to quit."

Berglund said his son, who lives in Anchorage, encouraged him to do the Alaska race. "He told me, 'Just think of it as a pretty ride in the woods,' " he said.

Berglund has survived some cold conditions biking in International Falls, the so-called "Icebox of the Nation."

"I finished one where it was super-cold. In fact, I didn't even finish last," he said.

While he rides, he eats bacon-cheese chunks rolled in crushed coconut.

"You're looking for a lot of calories," he said.

Berglund has been knocked out of races by snowstorms. Once, he flew over the handlebars in the middle of the Susitna race and hurt his shoulder so severely that he couldn't keep riding. He had to be evacuated by air.

"I had the chance to fly in a ski plane. That was kind of nice," he said.

He was signed up to do the Arrowhead and the Susitna races last year, but he fell in a training ride and broke a thigh bone. But he has recovered and is feeling strong for this year's race.

"I'm hoping this is his last one," said his wife, Sue Berglund.

"You've got to weigh it year by year," Berglund said. "You get to be my age, you could be dead any day now."

By bike, by foot

At 70, Ron Thorsett is a bit younger. But he'll be trying the much harder task of doing the Arrowhead 135 on foot.

Thorsett, a retired lawyer from Eden Prairie, has started the race six times before, but he hasn't gotten to the finish line. He's had to drop out at about the halfway point on each of his races.

Sometimes he's stopped because of problems with his feet, such as blisters or plantar fasciitis. Other times, he's been knocked out by stomach problems that made it hard for him to eat the peanut butter and jelly sandwiches he carries to fuel his exertions.

"Ultramarathons have been called eating contests more than running contests," Thorsett said.

Thorsett took up ultramarathons as a way to keep active after he retired from the Army Reserve. He was in the Army for 35 years, serving as a colonel in special operations.

He specialized in civil affairs and psychological operations with deployments to Iraq and Haiti. He also served as a field artillery officer in Vietnam in 1968.

He has had more time to train since retiring from his law practice. In this, his seventh attempt, he predicts he'll finally finish the Arrowhead 135.

He hopes to get it done in about 55 hours, including a couple of breaks in which he will pull a sleeping bag (rated for 20 degrees below zero) out of his backpack to try to nap on the side of the trail for an hour or so.

"You literally fall asleep while you're walking if you don't take that break," he said.

Thorsett has finished other long races, such as the Tuscobia Winter Ultra last December in northern Wisconsin. The 80-mile trail race took him more than 26 hours to finish.

Thorsett said he likes the quiet and the solitude of these long, North Woods races in the middle of winter.

"It's the personal challenge," he said. "I think I needed it after I retired from the Army."

Richard Chin • 612-673-1775