The treadmill is on trial this weekend in Chicago and Vincent Mauri has been appointed as its defense attorney.

Until April the most notable accolade on the Ohio native’s resume was a 13:34 to finish seventh in the second 5000m heat at the Valentine Invitational at Boston University. Now he is being held up as a likely candidate to break the American marathon record of 2:04:43.

How did this happen so quickly?

A 2:05:54 marathon debut—the fastest ever by an American—at the aforementioned Glass City Marathon changed everything. That performance launched Mauri into instant legend status, but his public training log on Strava has only added to the mythology.

Running over 130-mile weeks is nothing extraordinary anymore for the best distance runners in the world. Aided by shoe technology and encouraged further by the success of Kelvin Kiptum’s regular diet of 180+, athletes are exploring new thresholds to challenge their bodies. But for Mauri it’s the way he is running his high mileage that is turning heads.

East African distance runners have famously taken their easy runs remarkably slow with an emphasis on recovery. In contrast, Mauri rarely runs above six-minute pace for anything. But most remarkable is his short recovery during workouts. It would be a standard recommendation in many programs to take a minute rest for each mile of threshold work between reps. (For example, if doing 3 x 3 mile reps, then jog 3 minutes between.) Mauri takes between 20 to 60 seconds between his efforts.

A Mauri threshold session of 4 x 20 minutes might only include 20 seconds of rest between each rep—so short it almost seems pointless. How much can one’s heart rate fall in the blink of an eye?

Then there’s the single-day volume. He’s logged too many 30+ mile days to count, peaking at 45 in one day during this build. These figures become even more impressive (or maddening) when you factor in that the majority of this historic buildup has been done on a treadmill at Planet Fitness.

For most runners the treadmill is reserved for snow days or hotel gyms, but it’s become an increasingly more popular training tool for elite athletes. Mauri is not the only one in this race who relies heavily on treadmill running for the majority of their training. The treadmill marathon world record holder, CJ Albertson, will also be doing his best to defend the value of the training modality. And these two notable belt boys will be joined by the upstart Canadian Thomas Nobbs, who came out of nowhere to win the McKirdy Micro last spring in 2:09.25.

Treadmills were a routine part of Mo Farah and the Oregon Project’s training, and it has become increasingly used as a controlled environment for athletes training to specific lactate levels. If it works for Jakob Ingebrigtsen and the OAC, then it must work, right? Mauri appears to merely be taking this concept to its logical extreme.

But “marathons are about toughness,” you protest. “It’s about learning to grind and push yourself through the pain!” That’s how the marathon is marketed, at least. How are we to square that notion, which lauds athletes for braving wind, rain, and hills, with athletes running like lab rats? Maybe gaining fitness is more like a science than your high school cross country coaches would have led you to believe during their motivational pre-race speeches!

But rather than bemoan this potentially confounding development, let’s instead embrace it. For years fans have been saying the sport needs more storytelling, and there probably isn’t a better story out there heading into the weekend than Mauri’s. A guy who has never won anything of significance, nor beaten anyone you have ever heard of, has all of us on the edge of our seats believing he can take his body somewhere that no American has gone before. Because he’s probably run more sub-five minute treadmill miles than any American in history.

We know that running one pace on a treadmill is not the same as racing it outside, just like rowing on an erg is not the same as racing in a boat. One of treadmill running’s biggest proponents, Yaseen Abdalla, said something to this effect recently. He knows, Vinny knows, and we all know—but for some reason we still believe it’ll convert.

And yet, if Mauri runs well, then it’ll be so obvious why… it’s right there on Strava. Similarly, if he blows up or is a non-factor, suddenly everyone will have perfect 20/20 vision. All the signs will have been there. It was that damn treadmill!

But treadmills aren’t new. In addition to their ability to deliver a steady tempo basically forever, training exclusively on them comes with an additional training benefit.

At the 2000 Olympic Marathon Trials, a 37-year-old mother of two who worked as a pathologist did her training block on the ‘mill due to the unfavorable weather conditions in Anchorage, Alaska. On a warm day in South Carolina, somewhat ironically the Alaskan athlete was best prepared to handle the heat, and Christine Clark ran a personal best by seven minutes in an epic upset against a field of full-time professionals.

With warmer conditions expected in Chicago this weekend, and temperatures expected to rise from 61 to 72 degrees over the course of the race, there is one important variable to consider when making a prediction: there are online reviews complaining that the Planet Fitness in Warren, Ohio, sets its thermostat too warm: to 72 degrees.

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