There are marathons -- 26.2 miles -- and ultramarathons -- 50 miles, even 100 -- and those events, which tax runners physically and torment them emotionally, are crucible enough for most folks.
But those distances rate as mere warm-ups compared to the almost inconceivable challenge that unfolds this week at the Alaska Dome, where 45 runners are scheduled to compete in the Six Days in the Dome.
That's exactly what it sounds like -- runners will cover as many miles as they can in six days.
"It's going to be a bi-polar experience,'' Joe Fejes acknowledged. "You're going to have your manic highs and manic lows.''
He's an authority. Fejes, 48, an attorney from Georgia, in the final days of 2013 and the opening days of 2014 won the Across the Years six-day race in Phoenix, Arizona. He covered 555-plus miles to set an American record for a six-day, non-track race. The previous year at Across The Years, he set an American record by running 329-plus miles in the 72-hour event. He has run 55 ultramarathons.
So Fejes knows the drill -- how little sleep he needs, which foods he can keep down the first day of the race, the aches he can anticipate, the blisters he awaits.
"I'll have a bad stomach the first day, probably get some dry heaves,'' he said, matter-of-factly. "As the days go on, your body adjusts, and it's off to the races.''
The six-day event begins at 9 a.m. Monday and ends at 9 a.m. Sunday.
Accompanying races of 48 hours (eight entrants) and 24 hours (19 entrants) will also be run during the week.
As co-race director, Fejes said his research led him to the Alaska Dome because it offered everything he sought in a venue, namely a controlled environment where heat wouldn't become a factor.
"Something that's cool, something on a track, something that's completely flat,'' he said. "It turned out to be the nirvana, the Holy Grail of venues.''
The six-day race has drawn some of the most notable runners in events that last between one day and six.
Liz Bauer, 55, of Georgia, won the women's division and was fifth overall earlier this year at Across The Years, covering nearly 397 miles in six days. Martina Hausmann, 54, of Germany, finished third among women in that race at 321 miles. Connie Gardner, 50, of Ohio, is a 12-time national champion at various distances and last year was the national champ in the 100-mile trail run and the 24-hour run.
Martin Fryer, 52, of Australia, made 720 miles in a 10-day race in New York last year. Valmir Nunes, 51, from Brazil, is the current record-holder at the Badwater 135-mile in Death Valley, finishing in less than 23 hours in 2007.
New to the six-day ranks is David Johnston, 44, of Willow, an accomplished ultramarathoner. In February, he set the course record in Iditarod Trail Invitational (ITI), banging out 350 miles in 4 days, 1 hour, 38 minutes. Less than two weeks before that, he set the record in the Susitna 100-miler in 18 hours, 22 minutes.
Inside the Alaska Dome, Johnston plans to follow his game-plan from those winter races: Run until he's gassed, sleep two hours, and get back to running.
"If I can get away with sleeping for two hours a day, over five days, I think I'll be sitting pretty,'' Johnston said.
And then he laughed because, well, c'mon, read that quote again.
Johnston said he hopes to run 110 miles the first day. He has a pretty good idea what he's getting into.
"For me, the last two years in the ITI, I went all out,'' Johnston said. "It was the first two days I had to get through. If I could get over that two-day hump, it was OK. The third day, everything started to go numb.''
And he laughed again.
Johnston said he'll get support from his crew member, his 12-year-old son David Jr., and visits from his wife, Andrea Hambach.
"I told her to only give me tough love -- 'Don't give me any compassion,' " Johnston said.
Johnston said his employer, Geneva Woods Health Care, has pledged to donate $10 for every mile he runs to the Muscular Dystrophy Association in Anchorage.
The race will provide runners with three meals per day inside the Alaska Dome. Runners can sleep trackside.
Two of the people helping Fejes co-direct the race, Zane Holscher, 35, and Collette Zimmer, 35, both of Southern Pines, North Carolina, will be racing 24 hours for the first time.
"I expect it's going to be very difficult physically and mentally,'' Zimmer said. "But I'm just going to try to enjoy it.''
Holscher said the event can always use more volunteers. Anyone who wants to help can just show up.
And anyone who wants to check out the races is welcome -- there's no fee to get into the Alaska Dome for the six days because the race has rented the facility.
"But if they want to bring cookies, that would be cool,'' Holscher said.
Reach Doyle Woody at email@example.com and check out his blog at adn.com/hockey-blog