Controlled chaos defines this efficient, 35-minute interval workout in the North Loop

My colleague Hannah and I were terrified to try a Basecamp Fitness class after reading the description: Pedal hard on a stationary "assault" bike that "fights back" for a minute, then do strength exercises for a minute, then return to biking. Repeat for the 35-minute class. And hey, the strength exercise changes each interval.

We almost talked ourselves out of giving this compact gym in the North Loop a whirl, but in the end, curiosity won out. Plus, a friend who tried it told me she used the time on the bike to take breaks during her first class so she could get through it. Still, I worried. I'm only moderately fit. But Hannah is training for a triathlon, and she seemed nervous, too. Would we survive with our pride intact?

We were greeted warmly by staff, shown where to change (although most people come dressed for a workout) and led down a hall to the gym. Our bikes were set for our height and tagged with our names — very welcoming. There's a coach for each class, and ours introduced me to my next-door neighbor, a buff woman who identified herself as a regular and gave me a quick bike demo.

The coach told us that today's interval exercises would all focus on abs. At Basecamp, the strength lineup changes every week, from full-body to isolation workouts, with an aim of offering a complete body regimen over time. That frees you from having to plan your workouts to target all muscle groups, since Basecamp does it for you.

The coach set a challenge for Hannah and me: Pedal at least 5 miles during class. He assigned us to the B group, one of three that would be alternating on the bikes and doing exercises. He also told us to high-five someone each time we transitioned from bike to floor. The class is a community, he said, and we needed to encourage and support one another.

I started with a leisurely warmup pedal, but all too soon the music kicked in, signaling the start of class. My neighbor's bike whirred as she set her jaw in determination. I glanced at Hannah two bikes down. Sensing this was serious, we picked up the pace. Images appeared on the TV screens in front of the bikes. Each screen was labeled by group and showed what exercise was coming up.

Honestly, the exercises didn't seem like anything I couldn't handle, and the pedaling was fun. I thought: We've got this!

In a flash, it was time to transition from bikes to exercises. I pinched my heel between the bike pedal and its wheel as I got off, but made it to the floor to grab a medicine ball for Russian twists. I wasn't sure how much weight to take, so I opted for the lowest available — there's a bit of a scramble as everyone rushes to grab equipment. The coach demonstrated the move, but I kept my eyes on the B group screen, where an instructor demonstrated it on a loop.

By the time I got the move down, it was time to transition again. I high-fived the guy next to me and hurried back to the bike. Our next transition was to an exercise where we squatted to lift a weighted rubber ball above our heads and then threw it down hard. Hannah seemed to be enjoying the throwing, but I was timidly placing the ball on the ground. The coach swung by to correct me, then it was back to the bike. The next move was a 60-second plank. Then biking.

And so it went. I learned later that each class usually has only one or two complicated exercises. Keeping moves simple and not too technical allows for better focus in each 60-second time frame.

I didn't look at the clock much, in fact, because I was too busy pedaling and pondering the next move. If I wanted water (and I did), I had to slow my pedaling or miss a few reps on the strength training, because the pace was quick and unrelenting. About halfway through, I was sweaty and breathing hard.

Hannah looked equally red-faced and sweaty, so I hoped my reaction must be normal. But my confidence started to falter. I wasn't sure how on Earth I'd hit 5 miles on the bike, because I was slow even when I was trying to go fast, and, yes, I was using the bike to sneak in recovery breaks.

In the last third of the class, I realized I had to stop holding back on the bike or risk the humiliation of not reaching the 5-mile goal. I looked at my neighbors for inspiration and pushed harder.

I made it through several more sets of ab work, some using weights and some not. I had to modify a few moves, and I'll admit to slowing down and/or skipping some reps. But I kept going, motivated by the music and the high-fives and, mostly, the fear of looking like a lightweight.

And then, the music wound down and we were done — except for the 10-minute ab portion added to every class that was about to begin. Somehow we'd picked a full class of ab work followed by more ab work. I was a spent puddle. I declined the extra ab work. I mean, really, people?

In all, we completed 30 intervals.

I barely eked out the 5 miles of biking, but I did it. And, all in all, I felt like I'd gotten an effective workout in an efficient way, and the transitions helped keep me focused on keeping up instead of giving up. The cheerful high-fives really did boost the energy level and the mood in the room.

Hannah and I agreed that it would be helpful to have guidelines for how heavy of weights to use for the strength training. Also, that this class is good for people who know their bodies, and that we'd like advice on whether to modify or skip certain exercises.

The coach was watching, and he did correct us and tell us to slow down or modify as we needed, but there was a lot of activity and movement, so it seems better to start low and slow. Still, we agreed we'd like to take the class again, and take advantage of partnering up on a goal. If you work with a partner to hit a collective 10 miles, say, you're motivated not to let that other person down.

High-five!

The background: The Basecamp concept was formed around mixed martial arts workouts. Initially, it was developed for professional athletes as a tough workout that puts the least amount of impact on the body, said president and CEO Jedidiah Schmidt. "We adapted it and brought it to the masses," he said. "It combines strength and cardio in one functional fitness workout."

Plus, he said, it addresses the three main challenges to working out: time, planning and motivation. Its 35 minutes (plus the optional 10-minute ab work,) targets the whole body and gives you goals and a chance to work with a partner. "You can become an athlete doing it, and it also challenges athletes," Schmidt said. When I told him I'd needed breathers, he said, "Anyone can regress on any of the exercises." You can make the workout fit your fitness level.

The details: Basecamp Fitness North Loop (basecampfitness.com) offers nine classes a day, the first at 5:15 a.m. and the last at 7:15 p.m. The target demographic is age 24 to 50, and there's an even split of male and female participants. Your first class is free. Packages from four classes up to an unlimited number run from $70 to $199 a month. A new studio is slated to open in Edina in the fall.