Backyard Ultramarathons Push the Limits of Running

The "finish line" at the Big Dog Backyard Ultra. Kevin Liles/Sports Illustrated/Getty Images

Ultra races like Big Dog and Run O’Clock neutralize speed advantages and inspire record-breaking feats of human endurance.

Stéphanie Simpson knew something was wrong. The 2020 Canadian champion of the Big Dog’s Backyard Ultra knew she was running, but in her periphery, unmistakably, a sailboat had appeared. There were no waves, there was no water, but there was the unmistakable mirage of a boat bobbing up and down beside her through the trees.

It was the second night of a backyard ultramarathon race that, on paper, has no end. Competitors line up on the hour, every hour, to run just 4.167 miles—a distance that works out to exactly 100 miles, were you to line up every hour for 24 hours. Gary Cantrell, who goes by the nom de guerre Lazarus Lake, designed the race that way when he sought a new, zany challenge for trail runners hoping to travel extreme distances.

In a backyard ultra, anyone not on the start line on the top of the hour is disqualified, and the race proceeds, lap after lap, until only one runner remains. For Simpson, that meant lining up a total of 43 times over 43 hours. She started hallucinating the second night, and had no crew, which meant hurriedly stuffing napkins in her sports bra to stay warm when it rained for hours and sticking her feet in plastic bags to prevent blisters. She also won the race and qualified for the 2021 world championships, the Big Dog’s Backyard Ultra, hosted by Cantrell in his 140-acre Tennessee backyard on October 16.

The race follows a complex, specific, and sometimes hotly contested set of qualifiers, based on golden tickets that can be earned by winners of pre-selected ultras around the world. Cantrell says his backyard can only hold 75 athletes and their crew, so that’s how many invitations he extends each year. 

A portrait of Lazarus Lake
Laz Lake, the founder of the Big Dog’s Backyard Ultra. Fabian Weiss/Laif/Redux

Cantrell, whom most runners call “Laz,” is also the brains behind the Barkley Marathon, a race so difficult it had no finishers for 10 years. The start time is random, the course changes yearly, and legend has it that each loop is longer than advertised. Cantrell says the biggest challenge of the race isn’t its elevation or chilly temperatures, but the fact that so little is within runners’ control. 

“The biggest thing is that they’re always a little bit off their confidence, out of their comfort zone, they’re not positive [they’re on course]. To be able to deal with uncertainty is a good life skill,” he says. But uncertainty hasn’t deterred runners hoping to enter, and he’s had to warn away spectators after a 2014 documentary spurred the race’s popularity.

Many ways to ultra race

The Big Dog race touches upon one of science’s biggest questions about endurance runners: How far can a human being run? It’s a question not easily answered, even by a multitude of ultra races, defined by distances over the standard, 26.2-mile marathon. Different types of races allow for different methods of in-race recovery. For backyard ultras, any time not spent running each 4.167-mile lap or “yard,” can be used to rest, eat, change shoes, and recover. 

“The format is favorable for covering a lot of distance in most ways because it enforces that you don’t pace yourself poorly. There’s no point in going out too fast because you’re just going to do four miles every hour,” Cantrell says. Backyard ultras, however, also limit recovery time. Unlike conventional ultras, runners must toe the line on the hour, every hour. There’s no time for lengthy naps or problem solving.

In a conventional ultra, runners can cover the distance however they wish, as long as they finish within a time limit, typically somewhere from 18 hours for a 50-mile race to 48 hours for a race like the 100.5-mile Hardrock 100. There are also skyrunning events, with a minimum average grade of 6 percent and six-day races, which allow participants to cover as much distance as they can (often on a lapped course) over that six days. The longest known race is New York City’s Self-Transcendence 3,100 Mile Race, which gives participants 52 days to cover the distance by running a short loop in Queens.

Slow and steady wins the race

When it comes to going the distance, science supports backyards’ paced approach. Grégoire Millet, an exercise physiologist at Switzerland’s University of Lausanne, has studied running form, economy, and mechanics in ultra runners, including those tackling mountain-based ultras and six-day races. 

Very long races are done at low intensity, which helps limit systemic inflammation caused by faster, more forceful running.

Millet points to four leading, limiting factors in long-distance running: efficiency or form, fuel and nutrition, sleep, and mental state. The biggest limiting factor, especially in races over 100 miles, he says, may actually be sleep deprivation. 

His past research has shown that decreases in muscle strength in knee extensors, quadriceps, or calf muscles were lower after races that lasted 100 hours or more than after shorter, higher-intensity races of, say, 15 to 30 hours because very long races are done at such low intensity, which helps limit systemic inflammation caused by faster, more forceful running.

“Especially when you have uphill or downhill [routes],” Millet says, the main mechanism inducing muscle fatigue, is the eccentric contraction, the downhill path. “And since, when you run over six days instead of over one or two days, your intensity is about twenty percent lower,” he says. “That means if you are running slower, you have less muscle damage, less inflammation and then less fatigue.” Millet says this tipping point allows runners to continue running hour after hour, day after day. After approximately 15 hours, they reach a point when running is no longer adding to their muscle fatigue. 

Hardrock 100 trail running competition
A scene from the Hardrock 100. Daniel Sohner

Of course, this isn’t limitless, which is why Millet says it’s not muscle fatigue but injuries, often driven by inflammation and sleep deprivation, that cause runners to drop out of races. 

While he emphasizes that inflammation is a primary driver of injuries that lead to drop-outs, Millet also says that varying levels of inflammation in runners are still poorly understood. Faster runners don’t necessarily show higher levels of inflammation than slower runners during the six-day races Millet has studied, even when comparing athletes on the same course. 

“We don’t really know what can be the reason for individual variability in inducing inflammation,” he says. “Intensity is probably one of the keys, but if you compare people who have the same intensity level, or running speed, you have a lot of variation.”

Falling asleep, if only for a moment

Backyard ultra runners run the risk of injury, but sleep deprivation is a bigger limiting factor affecting all competitors. And with sleep deprivation comes a host of mental challenges, as runners struggle not only to remember to fuel and care for themselves appropriately, but more fundamentally what they’re doing and why. Most bring crews of family and friends to help manage details as the hours wear on. 

“I would say it’s more of a stubbornness game.”

“You can take a five-minute nap and buy a lot of time because you develop a powerful need to go to sleep,” Cantrell says. “But you don’t necessarily have to get a lot of sleep.” A study of ultra marathoners who competed in a three-day, 120-mile Arctic race found that the amount runners slept was not related to their rate of injury during the race. Participants averaged only about four hours of sleep over the entire three day period. 

Millet says falling asleep represents full-body relaxation, an important skill. “If you can fall asleep for five minutes, or if it takes you 15 minutes to go to sleep, that makes a difference,” he says. Cantrell cited one runner who leaves a chair by the finish line, falls into it and is immediately asleep, waking only when the bell for the next lap rings. In an interview published by her sponsor, the shoe company Salomon, ultramarathoner Courtney Dauwalter reported sleeping for eight to 10 minutes per hour during her 68-hour run.

A portrait of Courtney Dauwalter
Ultrarunner Courtney Dauwalter at the Tahoe Trail 200. Max Whittaker/The New York Tim​es/Redux

Runners like Sarah Moore, who traveled to Tennessee for Big Dog from her home outside Detroit, say that if you can’t fall asleep, the next best thing is not to stress about it. 

“In the nighttime, sometimes, especially … where it’s flat, you can kind of sleep-run, and just close your eyes for, you know, however many strides, and let your mind take that rest. It’s like meditation; it can recharge you for sure,” she says. “So, just trying to sleep is also key.”

Mindset matters

When it comes to mindset, as with running, the training begins before the race. Moore prepared for this year’s Big Dog by focusing less on increasing miles and more on learning to be more comfortable running long distances, and spending long hours running alone. 

“I think the biggest thing is facing your fear. You’ve got to just do it more, suffer more, get used to being in your own head.” Rather than ramping up her miles, she’s focused on solo workouts that mimic the long hours of running, increasingly alone, as competitors drop out. After watching world records set by talented but not necessarily well-known runners, she says, “I would say it’s more of a stubbornness game.”

Morten Klingenberg competed at Big Dog this year, and also organizes Run O’Clock, a backyard ultra in northern Denmark. Like Moore, he focused his training not on increasing mileage, but on quality, both in carefully monitored, low-intensity weekly mileage and in his mindset.

“What I can see from my participants is that people who come with a set goal, say ‘I would like to do 10 laps’—they tend to drop out after 10 laps,” he says. “To some extent, it’s just too easy to say, ‘Yeah, well, I did make my goal and that’s perfectly fine. It’s okay for me to just stop now.’” For Big Dog, Klingenberg’s “interim goal” was 48 laps—nine rounds longer than his qualifying time—but he, too, was hoping to be the last person standing.

As for backyard ultras, “If you asked me two years ago, I would say 80 hours was clearly the limit,” Klingenberg says, but last summer, at the Suffolk Backyard Ultra in England, runner John Stocker completed 81 loops, or about 337.5 miles. (The runner-up competitor, Cantrell says, became so exhausted that he simply forgot he was participating in a race and stopped running during his final lap.) Now, Klingenberg says, “I think I wouldn’t be surprised if 100 hours would be broken. But I think, at least with the knowledge we have right now, I think that will be around the limit. That’s, that’s still four total days and then, then a bit extra.”

“Every time someone goes further, it’s been done. So you know it can be done,” Cantrell says, wryly noting that his own Barkley marathon had no finishers for its first decade. “The runners had built the belief in their mind that it couldn’t be done. And the guy who came and did it, Mark Williams from England, he simply didn’t understand that it was impossible.” 

After his win, it’s been done by 14 more people over the years, Cantrell notes. “It’s right at the edge, but knowing it can be done makes it more doable.”

Big Dog runners often swear by a regimen of positive thinking, visualization, and self-talk that helps guide them through long nights and painful efforts. Asked before the race if she believed she could win this year’s Big Dog, Simpson said, “You know what? If you go and you don’t think you have any chance, then you won’t win for sure. So, yeah.” 

A lesser gender divide

Simpson’s mindset isn’t wishful positivity. Cantrell boasts that his backyard format removes speed and strength as primary factors in who can win, making it possible for people of any gender to compete alongside one another. In 2019, fan favorite Courtney Dauwalter won the event outright, completing 68 laps, or 283.4 miles. In the same year, she also conquered the Ultra Trail du Mont Blanc (UTMB), winning the race by covering 106 miles through the Alps in France, Italy, and Switzerland. Her winning run, which included 6.2 miles of elevation gain, took 24 hours and 34 minutes. 

A runner at Ultra Trail Mont Blanc
A runner at the scenic UTMB in France. Jeff Pachoud/Getty Images

Research shows that extreme-distance races capitalize on women’s athletic strengths, but women are still underrepresented in ultramarathons, making it difficult to tell whether they can ultimately surpass male opponents. Ultra triathlete (think 10 Ironman-distance races in 10 days) and endurance performance researcher Beat Knechtle says, “A sex difference of about 10–12 percent will always remain, depending upon the sample size investigated and the level of performance.” 

When the best men and the best women are compared for different distances, for example, there is a gap between the sexes. “During the last decades, this gap could only be reduced in long-distance open-water swimming, but not in running in ultra-distances,” Knechtle says.

“Many fast, elite runners avoid the backyard format because they lose their speed advantage and would have to extend their typical suffer-time beyond twenty-four hours.”

“It’s not about speed,” says Moore. “In the end, it’s how long do you want to hang out there, and are you good with this break every hour? Sometimes, the fast guys aren’t so keen on that. So in general, my personal opinion is that women can suffer better.” 

Millet, who wasn’t familiar with the newer backyard ultra format, seemed skeptical that backyard athletes could be as hardy as elite racers who compete in six-day staged events, or ultra runners racing through mountainous courses. 

“The six-day races, people have gone over six hundred [miles] in six days. Not very many people have done it, so I think that’s certainly within the range of possibility [for a backyard ultra],” Cantrell says. 

And while Cantrell has never shied away from elevation—the Barkley has one of the highest elevation gains of any U.S. ultra race—the difficulty of the backyard world championships isn’t climbing toward spectacular vistas. It is, per Cantrell himself, the few steps from the recovery tent to the starting line. 

Backyard enthusiasts have their own opinions about how these races compare.

An athlete sleeping
An athlete sleeps during the Barkley Marathon in Tennessee. Fabian Weiss/Laif/Redux

“Many fast, elite runners avoid the backyard format because they lose their speed advantage and would have to extend their typical suffer-time beyond twenty-four hours. Not many competitors are willing to give up their advantage,” says Vincent Barrientos, a San Francisco-based runner who raced in the Big Dog’s Backyard ultra this week. “The backyard format is a great neutralizer of speed.” 

However runners chase new distances and find ways to cope with new levels of suffering along the way, it seems that backyard ultras are just the latest attempt to nudge the limits of human running endurance. The race is on, not only for athletes to prove they can continue to expand their limits but for scientists like Millet to find new ways to help them mitigate the mind-bending effects of sleep deprivation, the pain of injuries, and the challenges presented by steep climbs, high altitude, and unpredictable weather. 

But is the quest to run longer, in whatever format, just a self-flagellating suffer-fest? “Nobody likes to hurt, but sometimes to get what you want, you have to pay the price it takes to get it. It’s about wanting. Wanting to achieve your best more than you want to be comfortable,” Cantrell says. 

“Exploring how far you can go, whether it’s only two yards or a hundred, is fun,” he says. “The discomfort is just what you have to do. Life shouldn’t always be comfortable.”

Editor’s note: Just before this story went to press, Harvey Lewis, a teacher from Cincinnati, Ohio, won the 2021 Big Dog’s Backyard Ultra with a world record-setting run of 85 laps, or 354.2 miles. As for the other runners mentioned in this piece, Dauwalter, Barrientos, Klingenberg, Simpson, and Moore finished their races with 42, 38, 31, 29, and 26 laps, respectively. 

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