American Zach Bitter crushed the 100-mile world record this Saturday with a time of 11:19:13, beating the previous mark by almost 10 minutes.

The 33-year-old has been the American record holder for the past six years after running a time of 11:40:55 at the Desert Solstice Invitational.

Bitter broke the record as part of the Six Days in the Dome event in Wisconsin.

After six years as the reigning American 100-mile record holder, Zach Bitter can finally claim the world record, too, after running a time of 11:19:13 at an indoor track in Milwaukee as part of the Six Days in the Dome event.

The world record had eluded the 33-year-old since he unexpectedly took the American record in 2013 at the Desert Solstice Invitational, where he ran a 11:40:55. That was only his second 100-mile event, but when it sunk in that he had the American record, he wanted to do whatever it took to beat the mark set in 2002 by Russian Oleg Kharitonov with a 11:28:03.



Nearly every year since then, Bitter has attempted to break the record. But this year, he was training for September’s Spartathlon in Greece when he received a call from the race director of the Six Days in the Dome event in his home state of Wisconsin.

Bitter figured he’d attempt the race as a tuneup for Greece. But after a few solid training blocks, he started getting antsy for the record.

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“I was in the heart of Phoenix summers where it would get to like 100 degrees and was running for 3 to 3.5 hours and still hitting 6:30 paces,” Bitter told Runner’s World. “In a four-week training block, I hit 134, two 150-mile weeks, and one other loaded week, so I felt like I was in the best shape I’d ever been in.”

Courtesy of Zach Bitter

Bitter would have ideal race conditions at Pettit National Ice Center in Milwaukee, which is home to the Olympic long track speed skating facility. A running track sits on the outside, boasting temperatures kept at a comfortable 55 degrees.

“About five to six weeks out, I decided that if the opportunity presented itself at the race, I wouldn’t pass it up,” he said. “Once my mind shifted to that, it became the main race for me, and I started thinking that it could happen.”



The day went perfectly. The temperatures kept him cool, his all-liquid fueling strategy—he had water mixed with scoops of Xendurance every few hours from the beginning, and after five hours, he added a yerba mate based drink called Unicity every hour for energy and caffeine—kept him hydrated and moving, and his legs felt great as he came through the 50-mile mark in 5:40:38.

Even though Bitter tends to have positive splits of 10 to 20 minutes in the second half of 100-milers, his pace was slower than he was used to. Though he was still on pace, doubts crept in from time to time.

“Around 50 miles, I wasn’t super confident that I could double back on that,” Bitter said. “I had a few good laps after that, and when I got to the distance of my longest long run, I got into a really good headspace. It was the mental break I needed to stop thinking about the last dozens of miles as a 100-miler, and think of it as something I do on the weekends.”

Around and around he went around the 443-meter track, battling through that last long run until he reached the 100-mile mark. His time read 11:19:13, beating the previous record by nearly 10 minutes. Averaging a mile pace of 6:48, he ran a negative split on the second half with a time of 5:38:35, too.

“It was a huge weight off my shoulders,” Bitter said. “It’s been a huge part of my training for six years, so when I got through it, it was like finally putting the last puzzle piece together.”

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But with the record in the bag, Bitter didn’t stop: With the 12-hour distance record within his grasp, Bitter slowed down, but kept running for another 40 minutes to beat his own world record by running 104.8 miles in 12 hours. Yep, he captured both world records in half a day.

Bitter celebrated in his home state accordingly with a dairy-filled buffet of cheese at his parents’ home nearby. He is recovering well—just some minimal soreness and tightness—but is overall feeling great.

Though he is happy to have the record, he has a message he wants to share with the ultrarunning community.

“Aside from getting the record myself, I hope this put a spotlight on these events,” Bitter said. “Trails get all the love, but legends of ultras weren’t afraid to take on flatter courses, so if I can motivate some to take a swing at this, I think there are definitely guys in this sport who can go under 11 hours. I’m curious to see what the human body can do in this sort of race.”

Andrew Dawson Gear & News Editor Drew covers a variety of subjects for Runner’s World and Bicycling, and he specializes in writing and editing human interest pieces while also covering health, wellness, gear, and fitness for the brand.

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