Photo by Jenn Millas
Outdoor winter runners know the pain of wind-stung skin, bloodless toes, and cranky-cold muscles. They’ll accept the discomfort of January elements over the monotony of a treadmill jog for a few miles. But for those who crave a survival challenge, there’s the Arrowhead Ultra 135, an endurance race that takes place on the last weekend in January across the Arrowhead State Trail, a 135-mile groomed snowmobile route from International Falls to Tower through the hilly Kabetogama State Forest.
Racers can compete on bike, cross-country skis, or foot. “Foot is the hardest,” says Ken Krueger, who has co-directed the race with his wife, Jackie Krueger, for the last 12 races. He speaks from experience as someone who has finished the race once on foot, once on skis, and seven times on his bike. Krueger was the fourth athlete to achieve the Arrowhead à Trois, a trophy awarded to those who complete the race in all three disciplines.
The difficulty is the whole point. Scheduled to take place during the coldest part of the winter, extremely low temperatures can drive the race’s finish rate below 50%. Warmer conditions bring challenges, too, like sloppy snow that forces runners to wear garbage bags over their feet and drags down the momentum of their survival gear sleds.
Adversity attracts athletes from around the world and the Midwest. “Finishing is not a given,” says Emily Kratz, 46, an endurance athlete from Burnsville, and the first woman to finish the Arrowhead Ultra 135 in 2024. For Kratz—who has completed many endurance events, including the Cocodomo 250 ultramarathon in Arizona; Marathon des Sables, a multiday race through the Sahara Desert; and Tor des Géants, a trail race through the Italian Alps—the difference between the Arrowhead Ultra 135 and other races is the need to think eight hours ahead of time. Kratz manages her exertion so she’s not sweaty when the temperature drops at night, and has cultivated the mental toughness to endure long, lonely, subzero stretches. Out on the trail, runners can go 12 hours without seeing another person. Kratz won by running all day and night while wearing neoprene toe warmers and ski goggles, riding her sled downhill in the dark, and focusing on the beam of her headlamp to manage her end-of-race hallucinations.
Surviving the trek comes down to calories and clothing, explains Daniel Craighead, assistant professor of exercise physiology at the University of Minnesota. “We make heat as we exercise and that helps us stay warm in cold weather. But a 135-mile race is a big challenge because you’re out there exposed to the elements for so long.” The human body can’t create a ton of heat at the slow pace that an endurance race requires.
Photo by Jenn Millas
To prepare for an ultra-endurance wintry challenge, Craighead recommends that athletes exercise in the cold in order to habituate to trail conditions. For Kratz, that means running loops on a suburban park trail for six hours at a time on weekends. “I get up in the fours most days of the week to fit in my training,” she says. “It’s a lifestyle, to sleep, eat, and rest well.” Athletes from warmer climates will arrive in Minnesota weeks before the race to acclimate to winter. Krueger recalls a group of Italian athletes who slept in the parking lot of their hotel during the infamous 2019 polar vortex to get accustomed to using their sleeping gear in the cold.
Volunteers manage three checkpoints where athletes can rest and refuel. The first is Gateway General Store, a convenience store that’s turned into a locker room for the race. Then comes Melgeorge’s Elephant Lake Lodge and Resort at the race’s midpoint, where athletes can sleep. The last checkpoint consists of wall tents right after the longest, hilliest
portion of the race.
Is the Arrowhead Ultra 135 good for runners? Not really! “We don’t see any health benefits from chronic cold exposure,” says Craighead. Cold air can damage lungs, constrict blood vessels, and hinder muscle function. To mitigate those risks, Craighead recommends wearing a balaclava, which helps warm the air before it hits the lungs, consuming enough calories to maintain a high level of effort throughout the race, and wearing insulating layers.
So, why embark on an extreme endurance challenge? For Kratz, training for the Arrowhead Ultra 135 helped her learn to enjoy the extreme cold. And for Krueger, the race keeps him busy and motivated during the darkest months. Plus, just attempting the race garners bragging rights. The Arrowhead Ultra 135 is part of a trio of races that comprise the “Bad World Cup,” along with the Brazil 135 and Death Valley’s Badwater 135, which claims to be the hardest foot race in the world. But hardest is subjective. Every year, the Arrowhead Ultra 135 participants include a few elite athletes who have completed 100 100-plus-mile races. According to Krueger, “More than one of them have said, ‘This is the hardest thing I’ve ever done in my life.’”
Photo by Emily Kratz
