![BRIAN PETERSON • brianp@startribune.com INTERNATIONAL FALLS, MN - January 31-Feb. 2nd ] The Arrowhead 135 Ultra Marathon, from International Falls to Tower Minnesota, follows the scenic and rugged Arrowhead State Snowmobile Trail and attracts some of the best ultra-athletes in the world. Competitiers can Bike, run or ski the 135 mile race that challenges the body and the mind and presents participants with some of the coldest conditions in ultra marathon racing. (IN THIS PHOTO](https://arc.stimg.co/startribunemedia/2OBHN6ESA4P3JV6YZ7L2NOA3RA.jpg?&w=1080)
The Arrowhead 135, an ultramarathon that takes participants through the wilds of northern Minnesota, will have its largest field when it begins Monday in International Falls.
Some of the cyclists, runners and skiers who line up have added an extra challenge, said race director Ken Krueger.
"For this year, we added an option where racers can go completely unsupported for the entire duration of the race," Krueger said. "I thought we'd get four or five. We had 44 people."
Generally considered in the adventure sports world as one of the toughest races in the world, the Arrowhead has 170 competitors (88 cyclists, 73 runner, nine skiers) this year. The race runs 135 miles from International Falls to Tower, and has three checkpoints for its field. All competitors still must check in, but this year some have the option to continue on rather than break for sleep and/or nourishment.
Historically, a little more than half the racers finish the race, known for its winter weather extremes. This year appears to be another one of temperate weather. January's thaw, too, followed by below-freezing weather has made for a rut-filled Arrowhead State Trail even though it is regularly groomed.
"The weather looks like it is going to be warmer than we want," Krueger said.
Go online to arrowheadultra.com.
