Round and round he went on the oval track in Milwaukee, and when the race was over, ultrarunner Zach Bitter owned the 100-mile world record and had bettered his own 12-hour world record.

Bitter accomplished the feat Saturday during the Six Days in the Dome event in Milwaukee, setting the world record of 11 hours, 19 minutes and 13 seconds, lowering Oleg Kharitonov’s 2002 record by almost 11 minutes and Bitter’s own American mark of 11:40:55. Bitter slowed down, but continued for another 40 minutes to improve his 12-hour distance world record to 104.8 miles.

Overall, he covered 363 trips around the track over the 100 miles, 378 total by his wife’s count. The 33-year-old used a 6:47 pace to top Kharitonov’s 11:28:03 mark and had some doubts around the halfway mark but found a way to run the second half of his 100-mile quest faster than the first half. The Dome event consists of 24-hour, 48-hour and six-day races, and Bitter was entered in the 24-hour event.

“I’m typically targeting the shortest event of the day,” he told The Post in a phone interview. “I joke around when I finish, ‘Well, wait for these guys to finish. I’m only doing one-twelfth what they are.’ I’m the sprinter of the ultra world.”

There’s a different kind of mental component to a race of that distance.

“When you have a race that’s that long, if you’re counting each lap or counting your split on each lap, you’re expending a little bit of mental energy doing that. You have to be careful about burning yourself out early on by getting too focused on specifics,” he said. “So with that said, when you’re targeting a very specific time, you need to be within range. What I do before an event like this is I look at the track lap distance and calculate my range. …

“Once I have that, I’ll start the race and check pretty frequently for the first maybe eight to 10 laps to kind of calibrate the intensity to the splits. Once I have that calibrated, then I try to kind of zone out and stop looking as frequently. I’ll still spot check every once in a while just to make sure I’m not drifting out.”

That calibration extends to his bathroom breaks, too. Factor into his time that he took three Saturday, losing about 90 seconds by his estimation from his times. About halfway through the 100-miler, he decided to challenge his own 12-hour record of 101.8 miles, set in 2013, on a day when conditions were ideal for him.

Nearly six years... In 2013, I first tested the flat 100 mile waters with the goal of breaking the American Record at...

Posted by Zach Bitter on Sunday, 25 August 2019

As he explained on social media, his quest, which began six years ago, is “a steppingstone on the path to discovering how fast a human can cover 100 miles” and along the way there were “many” failures.

A Manitowoc, Wis., native who lives with his wife, Nicole, in Phoenix, Bitter had been training in the Arizona heat for the Spartathlon in late September in Greece when the director of the Six Days in the Dome invited him to run in the event at Milwaukee’s Pettit National Ice Center, the Olympic long track speed skating facility that also houses a track for running and walking. Bitter had been trail running rather than road or track running.

“When you focus on trails, it takes away from your skill set on the flats and vice versa. I’d been on the trails from late January through June, so I hadn’t done any trail running at all and I didn’t know how quickly that fitness was going to come back,” he said. “It returned a lot quicker than I thought, and I decided that if I felt really good on that day in the Dome, I’m not going to hold back. I’m going to go for it.”

Circumstances and Bitter himself were different Saturday, and he used the lessons of other races to help him along the way.

“The difference between a really solid run for 100 miles and one of your best performances really comes down to how many times can you push past the self-doubt. As the race goes on, those doubts pop up more often, and sometimes you reach a point you just can’t push past anymore and you slow down. … That was the biggest difference in my run Saturday and my previous fastest. That time I got to around the 80, 81 miles, I kind of hit the wall of not being able to push the pace down. I kind of slowed down the last 20 miles or so.

“On Saturday, I was actually speeding up at the end. … When I hit mile 70 on Saturday, then my next goal was 80 because last time I was in this position, I let it slip. So I was hyper-motivated not to let it slip again. Even though I wasn’t racing against a person, I had a lot of points of reference to reflect back on.”

Still, ultraracing raises the question of why anyone would want to run for such a long distance or for days on end, and he agrees that it isn’t easy to describe.

“It’s not like you wake up one day and decide, ‘Okay, I’m going to run 100 miles,’ much less 100 miles on a track,” he said. “It kind of evolves and your interests evolve with it. When I got into the sport of ultrarunning originally, it was basically just because when I did high school and college track and cross-country, my favorite workouts of the week were the long runs. When I finished college, I didn’t have that kind of team and competitive atmosphere so I just started doing what I enjoyed the most. That meant I was doing longer sessions at a slower pace and that led me into doing my first ultramarathon.

“I think if you ask any person who has done years of ultramarathons, they’ll tell you it’s a bit of a slippery slope, where you do a 50-miler or a 50K or something. Sometimes you spend time trying to optimize that distance or course, but usually the increase in distance draws you. ’Maybe I’ll try a 100k or a 100-miler.’ You get the motivation to see what you can do, there’s a curiosity component to it. For me in just under the last six years, I got really interested in just how fast can I run 100 miles when most of the variables are controllable. On a track you get to eliminate as many of those as you can and see how fast you can do it.”

Bitter said he hopes his accomplishment puts “a spotlight on these events,” even if it means that he is no longer the record holder.

“One of my goals is to get other people interested so we can have a situation where we can really see how fast a human can run 100 miles, and by the way, I’m very content with being a steppingstone along the way to that,” he said. “I think it would be cool when I run my last ultramarathon to look back and say I was part of the catalyst that drew people toward the fast side of things in the modern era. I think I would take more satisfaction from that than holding onto the world record as long as possible.”

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