"After I ran 24 hours for the first time," explained Mark Godale, "it felt as if I had broken my body completely. It was as if I had jumped off a skyscraper and hit the street below, but was alive."

Godale was standing trackside at the Alaska Dome in Anchorage, as 40 competitors ran and walked past on a 400-meter track they would circle, not for 24 hours, but for six days. Even by ultra-running standards, the idea of running for 144 hours is on the extreme end of the scale, but for some of the participants, it was almost routine. In 1990, Bill Schultz completed a 3,000-mile transcontinental run in 95 days; Rimantas Jakelaitis once needed "just" 16 days to run 1,300 miles. These were people with an entirely different concept than most of us of what constituted endurable pain.

The event, which took place Aug. 4-10, was the brainchild of Joe Fejes, who in his first six-day race at the beginning of this year completed 555 miles to defeat Yiannis Kouros -- a legend nonpareil among ultra-runners and the holder of almost every ultra world record. His goal was to both honor and better Stu Mittleman's 30-year-old U.S. record of 577 miles, and perhaps even touch the rarely achieved goal of 600 miles: a feat that would require running four marathons a day for six days, give or take a marathon or two.

"This is a stress-response test," said 60-year-old Gary Cantrell, the "poet laureate" of ultra-running, who also goes by the nom-de-plume Lazarus Lakes. "You know how you tap your knee to check that your leg twitches? This is a test of your brain. If your brain is working right, you quit."

Day 1

If your assumption was that the worst of the suffering would manifest toward the end of Day 5, by which time competitors would be barely able to walk, you'd be wrong.

The pain kicked in far earlier than that.

"Between around mile 17 and mile 22 is when I'll likely go through the worst part, and then again around mile 31," Fejes said, and he was hardly alone. With the race only seven or so hours old ("only," of course, being a purely relative concept) some runners already looked as if they were half-dead, shuffling rather than running or even walking. It was hard to believe they would last five hours, let alone five days.

Zipping in and out of the pack, Zach Bitter was free of the burden of trying to survive for the duration; among the six-day runners were 24- and 48-hour racers, but Bitter's would be the light that burned brightest and briefest of all. The 28-year-old from Wisconsin came to the Dome looking to break the 100-mile world record time of 11:28:03, and after six hours he was on course to do so by four minutes.

But there was a problem on the horizon. Despite maintaining a rigid diet, he had apparently allowed the smallest amount of non-sanctioned food to enter his system before the race, and it was wreaking havoc. He spent several hours alternating between the track and the bathroom.

"[At] about mile 70, it really hit me," he said afterward. "I started doubling over, I was cramping so much."

He finished with a time of 12 hours and 8 minutes, still the third-fastest 100 miles run by an American, and not far off four consecutive 3-hour marathons. As bad days went, it was pretty good.

"You have to go into these things not thinking, 'If something goes wrong, I'll have wasted my time.' You just have to learn from each experience," Bitter reflected afterward. "This is Six Days in the Dome, and I'm really lucky they let me race for just 12 hours."

Day 2

Traci Falbo was running in her first 48-hour race, and she was killing it.

With just a few hours to go, Falbo was on pace to destroy the women's world indoor and U.S. records; she completed 907 laps for 233.1 miles to take the former with 40 minutes to spare, and 234.9 miles to claim the latter.

And then, despite operating on a total of about one hour of sleep in the previous 47 and a half, she did something that amazed even the hardened ultra-runners in the arena.

She ran faster.

Traci Falbo ran 242 miles in 48 hours, setting American and world indoor records. Jeffrey Genova

She ran a lap in 2:25, then another in 2:06, straining to put daylight between her and the old record, fighting to become only the second woman in history to run 240 miles in two days.

Her fellow athletes cheered her on as her body, which four hours earlier had begun the strange, sideward lean characteristic of ultra-runners reaching the limits of their endurance, now contorted itself into a fiercely bent, misshapen approximation of a human form. Falbo's smiles as she broke the records had been replaced by the grimace of a prey struggling to escape a pursuing predator. She completed 942 laps and then, utterly spent from the twin strains of marching relentlessly forward and trying to keep herself upright, she toppled into her waiting husband, who gently lowered her, drained of every last molecule of energy, to the ground.

She had run 242.09 miles. She would not -- could not -- run one step more.

Day 3

In the late 1800s, six-day racing was the biggest spectator sport in the land; what is now called ultra-running was then known as pedestrianism, and thousands of spectators would fill Madison Square Garden to watch their favorite competitors. In 2014, the best six-day runners in the world were circling the inside of what looked like a giant inflatable UFO in an Anchorage parking lot.

Along the far side of the track was a line of crew tables, where runners could sit and rest, or help themselves to their personal supplies of drinks or snacks. In one corner, the aid station provided three, freshly cooked, carbohydrate-heavy meals every day; it was not uncommon to see exhausted runners shuffling around the track sleepily eating bowls of pasta.

A quarter of the huge infield was set aside for the runners' camping area, a semi-private sanctuary where they could retreat to change clothes or sleep -- although the most sought-after sleeping spots were on a high-jump landing pad by the side of the track. During the day, the arena echoed to the sounds of local sports team and first-grade summer campers; at night, the only sounds remaining were the constant beeps, like a supermarket checkout, of the runners' electronic tags registering laps, and a weary collective shuffling.

Watching a group of people struggling emotionally and physically with the ridiculous demands they had placed upon themselves can be uncomfortably voyeuristic. But then a strange thing happened. On the fourth morning, the runners seemed to have an extra spring in their step and a new lightness to their psyche. This is apparently a common phenomenon in multi-day events, as if the worst is somehow over and the rest is all muscle memory.

"Welcome to Day 4," smiled Cantrell. "The day when everyone rises from the dead."

Day 4

"He wants some pho," Rich Schick said to Mike Dobies. "What's pho?"

Schick and Dobies were Fejes' crew. Schick, a retired physician's assistant in the military, was his trainer and attender to his physical pains; Dobies was the numbers guy, creating a race plan with tightly calculated splits and rest periods. On Day 2, Fejes and former 100K world-record-holder Valmir Nunes convinced each other that they could only drink sparkling water and urged Schick to head into town and buy bottles of the stuff; now, Fejes decided that he really wanted a bowl of Vietnamese soup and Dobies set out in the team's rented RV to find a nearby restaurant.

Crew members might not have been pounding the hard indoor track, but they had their own battle to wage against fatigue; they could not sleep until their runners did, and had to maintain sufficient cognitive awareness in the face of extreme tiredness to provide sage advice as needed and food and drink as desired. Meanwhile, volunteers furiously calculated time or laps required for personal bests or age group records, cooked meals and helped tend to each competitor's requirements, grabbing whatever shut-eye they could. The barrier between athletes and support staff was permeable: Just hours after his 12-hour run, Zach Bitter was staffing the aid station; after four days as event cook, Andrew Snope took to the track and ran for 24 hours barefoot, clocking 136.98 miles and setting a Guinness World Record.

Day 5

The race had taken its toll.

Day 1 leader Valmir Nunes, who had to drop out because of injury, helps eventual winner Joe Fejes get relief. Jeffrey Genova

Connie Gardner had been forced to abandon her attempt to reclaim the U.S. women's 24-hour record, her body seizing up with just two and a half hours remaining. Valmir Nunes had powered into the lead on Day 1 and taken his total distance past 170 miles when his ankle swelled to the size of a grapefruit, and his race was done. For one competitor, the endless circling and lack of sleep or natural light begat hallucinations; she paused long enough for the voices in her head to disappear, and then she returned to the race.

When Nunes departed, the lead passed to Kenji Okiyama, who reached 180 miles in his first 36 hours, but soon crashed as a result of his early pace. For the best part of the next four days, Okiyama looked as if he were auditioning for a role in "The Waking Dead," dragging his body reluctantly around the track, again and again and again. Yet, somehow, each time it seemed as if he could surely go no further, he willed himself to pick up the pace, his head down, his feet somehow moving, as he slogged onward.

The men's race was down to Fejes and Alaska's Dave Johnston, who earlier in the year had completed the Iditarod 350-mile trail race in just over four days. Johnston had earned the sobriquet "Smilin Dave" from those at trackside for his easy demeanor, but as Day 5 progressed, that smile was just a little bit less wide. He was within 20 miles of Fejes, but was becoming unhappy with the way Fejes frequently ran behind other runners, feeling it proffered an unfair advantage. His discontent went unnoticed, however, until he stepped off the track on Friday night, packed up his stuff, withdrew from the race and left the arena.

Day 6

By Day 4, Fejes had fallen off the pace he needed to reach 600 miles. In fact, he was falling so far behind his ideal schedule that Schick and Dobie were concerned he might not even reach Mittleman's figure of 577 miles.

Fejes changed his schedule, from one two-hour break daily to a 30-minute rest after every 10 completed miles. With Nunes, Fryer and Johnston out of the race, he was over 100 miles ahead of his nearest challenger -- the apparently invincible Okiyama -- and the extra recuperation allowed him to be more productive during the time he was on the track.

With 24 hours to go, 578 miles seemed a foregone conclusion, and it was secured with an hour to spare. The achievement's inevitability sapped some of the drama from the accomplishment; Fejes allowed himself an understated wave to the applauding assemblage, briefly stopped, and decided to continue on a bit more.

"A nice, round 580, and we'll call it a day," he said, matter-of-factly. Those final two miles, however, would be secured at a veritable snail's pace, as he walked slowly around the circuit, the pressure easing off him but no longer propelling him. He looked and felt remarkably fresh; sure, he'd had blood in his urine for five days, but apart from that, he was fine.

As the clock ran down, one competitor after another exulted as the physical finish line, crossed so many times, became a temporal and conclusive one. Yolanda Holder, six days of smiles and perfect form, met her goal of walking 400 miles. Jameelah Abdul-Rahim Mujaahid somehow turned on the afterburners, running faster than she had all week to claim an age-group record. And in the perfect bookend to the blistering early-week performances of Bitter and Falbo, Stacey Costa logged 130 miles over 24 hours -- and then ran one more lap.

And then, suddenly, it was over.

Legs that had carried bodies for days could barely move another step. Feet that had pounded track for miles were too tender to make contact with solid ground. Yet one more task awaited: Race director Zane Holscher asked everyone to break down the infield camp as soon as possible, because the arena was about to be set up for a track meet.

There was a perfectly timed comedic pause before a voice piped up.

"Can we enter?"