As she circled the track inside the Alaska Dome on Wednesday morning, Traci Falbo had been running nearly non-stop for 48 consecutive hours, her only respite a handful of naps that, combined, didn't amount to an hour of sleep.
Yet, inexplicably, having already covered more than 200 miles, Falbo accelerated her pace.
She covered a lap of the 413-meter track, unofficially, in 2 minutes, 23 seconds. Soon, she clocked a lap in 2:15. And then she reeled off a couple of 2:06s.
"Traci! Traci! Traci!'' fellow ultramarathoner Ed Ettinghausen chanted as Falbo passed him.
Runners and spectators applauded and shouted encouragement each time Falbo passed the start-finish line, where an electronic timing mat logged her progress from the timing chip attached to her ankle bracelet.
Falbo's effort exacted its toll. Her upper body listed increasingly to her right as she ran. Her mouth opened wider as she gulped air. With about four minutes left in her 48-hour run, she collapsed into the arms of her husband, Mike, at the start-finish line. She was spent, physically and emotionally, and she cried, seemingly from both exhaustion and elation.
The women's world record for most distance covered indoors in a 48-hour run was Falbo's. And so was the American women's record for distance in any 48-hour race.
She had run 242.09 miles.
That equated to 389.61 kilometers, topping the previous women's world indoor standard (375 kilometers) and the U.S. women's record (377.89 kilometers) for a 48-hour race on any surface and venue.
"I gave it everything I had,'' Falbo said as she cried. "I don't have any more.''
Falbo competed in the Six Days at the Dome, an ultramarathoning festival of sorts here all week. Some runners compete to run as far as they can in 24 hours or 48 hours. A majority of the more than 70 runners are competing in the six-day division, which is exactly what it sounds like, and every bit as mind-boggling.
Falbo's peers were astonished -- by her performance, her resolve and her tenacity. Also, this was Falbo's debut in a 48-hour race.
"That's crazy,'' marveled six-day competitor David Johnston of Willow. "That's how you do it -- leave it all on the track.''
A few minutes after Falbo collapsed, her husband and a volunteer helped her to her feet, Falbo's right arm stretched around her husband's shoulder, her left arm perched on the shoulder of the volunteer. They steered her to a heavily-padded high-jump landing pit nearby for a soft landing. An unzipped sleeping bag was wrapped around her shoulders and a blanket was draped across her legs.
"She's using my blanket,'' crowed Karl Gustav, a 76-year-old Swede running in the six-day event. "I will never wash it.''
Falbo, 42, is a pediatric physical therapist from Charlestown, Indiana. She lost 80 pounds about a decade ago and decided to run a marathon. She hasn't stopped racing since.
She's won 18 marathons in the last decade and run a 26.2-miler in each of the 50 states -- Falbo finished fourth among women in the 2012 Mayor's Marathon in Anchorage.
She began running ultramarathons late in 2011. Last year, she represented the U.S. and finished fourth at the 24-Hour World Championships in the Netherlands, covering 142 miles.
Tuesday evening, when Falbo had already run for more than 30 hours and was getting diminishing returns, her husband coaxed her into a nap.
"I said, 'You're basically pushing a car,'' Mike Falbo recounted. " 'Take a few minutes, stop at the gas station, and get going again.' "
The nap didn't last a half-hour, Traci Falbo said, but it revitalized her.
"You always have low points,'' she said. "The point of ultramarathoning is to ride it out, suck it up and move on.''
And that's how Falbo came to be running increasingly quicker lap times inside the last hour of her 48. Supporters encouraged her to finish strong.
"They said, 'Pick it up, pick it up,' " Falbo said. "So I did. I thought, 'Crap, I can't hold this (pace) for 45 minutes.'
"It was peer pressure. The last eight laps, I was literally trying not to fall over.''
When she finally did fall, she had taken down a world record and an American record.
"Way cool,'' Falbo said.