Ranging in elevation from 6,210 feet to 6,530 feet, the Garden of the Gods 10 Mile Run is widely regarded as one of the most difficult courses.
And after the 37th running of the event, the top finishers in the men's and women's races admitted that right from the start the race was one of the most challenging courses the veteran runners had ever tackled.
Even Belainesh Gebre, who won the race for her third time Sunday and broke her previous overall women's course record of 58:49, didn't believe her mark when she crossed the finish line in Manitou Springs' Memorial Park.
"I don't think I broke it today," Gebre said. "In the beginning 5 miles, it's tough. This race is not easy, it's tough course, but this is my favorite race."
But Gebre, 25, broke her record by four seconds to finish in 58 minutes 45 seconds.
For first time participants and native Kenyans Lenoard Korir and Ernest Kebenei, the hills and high altitude were some of the most difficult aspects of the course.
Korir, 26, set a course record for his age group of men 25-29 with a time of 50:46. Kebenei, 28, running his first ever 10-mile race, finished closely behind at 50:55. The old record was 50:59 set in 2010.
After living and training in Colorado Springs, Korir was used to the altitude and eventually passed his friend in the final mile.
"At the end, there was a half-mile hill down there, and I felt like I couldn't breathe," Kebenei said. "So I reduced a little bit and my friend used that opportunity, and I lost."
Though Korir has adjusted to the altitude, he wasn't quite prepared for the combination of the course's never-ending hills.
"It takes a lot out of you," said Korir, a two-time NCAA Champion in the 5K and 10K at Iona College. "I think you use a lot of energy because you feel some burning in your quads. It's unlike most of the races where you're running in the flat and you don't feel as much."
Fountain's Ross Osborne also struggled with the steep descents on the course, but as the race's first wheelchair entry, he faced different challenges.
Osborne, 40, has been racing in his wheelchair since June 2011, and contacted the race organizers about a week before the event.
"When I called the organizers, they said, 'we've never had a wheelchair racer,' and I said, 'well I do stupid things all the time,'" Osborne said. "It felt so good to finally finish and come over that line."
Osborne didn't compete in the 10-miler as he originally planned, but instead entered in the event's second running of the accompanying 5-kilometer race and finished in 33:02.
For Osborne, the biggest challenge on the descents was maintaining control and not colliding with other runners. He also needed help getting up some of the hills.
"If it wasn't for some of the people on the course helping me up those monstrous hills, I'd still be out there," he said.
Though those colossal hills put runners to the test in every division, in the end, Korir, Kebenei, Gebre and Osborne were all able to overcome the challenge to break personal boundaries and set records.