If a sweat-drenched tank top is the sign of a solid workout, then Tough Mudder Bootcamp (TMB) delivers. I popped in for a class at the City Park fitness studio on May 9, the fourth day of its soft opening. Before long, the warmup had my heart rate up and my muscles ready, and I was racing owner Brian Anglin across the orange turf that runs through the center of the space while my workout partner did side planks. By the time we finished the second round of the six-station circuit, bracing ourselves through the last few sandbag thrusters and lunge holds, my tank top was soaked and sweat was dripping into my eyes.

The TMB studio on East Colfax is the first in the Denver metro area and just the fourth in the world. But the concept has been in the works since 2016, when then-CEO Will Dean approached Tough Mudder training director Eric Botsford with a problem: People were signing up for Tough Mudders but not showing up to the events.

“We found out that most people just felt unprepared for Tough Mudder,” Botsford says. After researching the issue of low attendance, they also learned that a lot of Tough Mudder participants didn’t have gym memberships.

Before long, Tough Mudder built a beta testing gym in its Brooklyn headquarters, and in October 2016, Botsford started testing his programming. Members of the Tough Mudder team also checked out existing fitness studios in Brooklyn, paying attention to everything from how they were greeted at the door to setup and lighting—and, of course, the workouts.

“We did not find anybody who was doing partnership and teamwork-style workouts,” says Dan Henry, director of franchise sales and development for TMB.

That’s part of what sets TMB apart from other bootcamp studio fitness concepts: Every workout has a partner or teamwork element. “That’s kind of the ethos of Tough Mudder,” Henry says. “You can’t get through it by yourself.”

When franchise owner Brian Anglin signed up for his first Tough Mudder in 2014, his mindset was a competitive one: He was going to prove to himself that he could do a tough race with mud and barbed wire and the possibility of being electrocuted. But his experience changed his perspective.

“[Competition is] not really what it’s about,” Anglin says. “It’s about that teamwork, that camaraderie. If you’re doing the Tough Mudder and you’re not stopping to turn around and lend that helping hand, you’re not doing it right.”

Anglin and his wife Libby, both former horticulturalists, own and run TMB’s Denver location. They signed on after Anglin, who has now done four Tough Mudders, decided to start a new career in fitness. They hit dead ends pursuing an obstacle course idea, among others, and then an email about opening a TMB franchise landed in Anglin’s inbox. A few phone calls later, they headed to Brooklyn and ran through a sample workout at Tough Mudder’s headquarters.

“I was excited about the Tough Mudder name, but I’d say it was the workout that really sold me on it,” Anglin says.

All of TMB programming is done by Botsford, who has served as Tough Mudder’s training director for about five years and has owned his own CrossFit affiliate for more than 10 years. Botsford designs TMB programming in three-week chunks, focusing on a particular goal—strength, power, aerobic capacity, endurance—for three-month periods that roughly align with Tough Mudder’s event season.

There are six types of classes: three strength-focused “Build” classes that target either the upper body, the lower body, or the core; and three “Challenge” classes that use tabata-style timing (a type of high-intensity interval training), a teammate pace-setter, and one-minute intervals in a variety of ways. Every class is different, but the exercises (a variety of bodyweight, dumbbell, and kettlebell exercises) are grouped intentionally to accomplish a particular fitness goal, and everything is scalable so anyone can participate regardless of fitness level or ability.

At the class I attended, we rotated through six stations, five of them with two movements that you were supposed to take turns doing with your partner. It might seem like a lot to keep track of, but it wasn’t completely overwhelming. After the coach led us through the warmup, he walked us through every part of the workout, explaining and demonstrating the movements and how many times or how long we would be doing each one. We didn’t have to commit anything to memory, because each station was equipped with a screen displaying a clock, the number of repetitions we were going for, and GIFs of Botsford himself doing the movements. This guidance is consistent throughout the program. Along with a Tough Mudder-trained coach to physically walk you through each step and keep an eye on your form, there are visual reminders for every aspect of the workout.

That’s the good news. The not-as-good news: There’s no mud or obstacles to be found in TMB—and that’s not a plan slated for the future. But TMB on Colfax might be getting a team together to run the next nearby Tough Mudder (in Littleton on August 10 and 11), so if you want to run with a fun crew, now’s the perfect time to join.

If you go: Tough Mudder Bootcamp is located at 3805 E. Colfax Ave.