What is it: Fly Feet Running is a high-intensity interval training workout that includes running, strength and mobility training and stretching.

Description: Obviously, it involves running (or fast walking), but that's only part of this full-body exercise regimen. Treadmills (which founder Kristin Shane calls "the great equalizer") are used during the warmup and for cardio blasts. But the 60-minute class also includes traditional gym exercises (pushups, lunges, squats, etc.) and suspension training exercises.

The theory: Fly Feet doesn't rely on heart monitors, FitBits or other tracking devices to measure your workout. "They blunt your intensity," said Aaron Leventhal, head of fitness and coaching. Instead, the coaches push you to run as fast as you can or do as many pushups, rows and lunges as you can in short periods (usually 60 seconds, with a decreasing amount of rest time in between). You track your results in chalk on the floor behind your treadmill and try to beat your time or increase the number of lifts each successive round. "This way, you find out what your true maximum is," said Leventhal.

Trial run: I have to admit I was intimidated to take the "Tread & Shred" class, which is billed as "hard-charging," because I've given up running. But Shane assured me I could walk fast or crank the elevation on the treadmill instead of running. After a fairly easy warmup, we started in to the intervals, which were short, fast and tough — and got tougher. But the momentum never flagged as we jumped on and off the treadmills, the hour went surprisingly quickly, and by the time we were into our stretching, I felt like I'd really accomplished something.

What I liked: Leventhal, who played soccer for the Minnesota Thunder, thoroughly explained each exercise, then the two other coaches demonstrated the form. Leventhal asked everyone in the class to practice each move before the routine began. During the workout, the three coaches moved around the room, correcting our form on the pushups and lunges, shouting encouragement to keep going during the fast-paced running segments, guiding us off and on the treadmills. They quizzed class members about injuries or limitations and offered alternative exercises when necessary.

Who it's for: Runners will love this, especially those who are looking to increase pace, build stamina and get a full-body workout to supplement their cardio. But even non-runners (or former runners like me) will get a boost out of the fast-paced, form-first workout that pushes you to your limit.

Who it's not for: If you don't like guided group workouts, this may not be the gym for you.

The place: The new boutique gym boasts bright colors, a selection of hard-to-find athleisure wear and a welcoming atmosphere. (Before the noon-hour class, they even offer to order lunch — a salad, of course — for you to eat in the seating area or take back to work.)

Cost: $179 per month for unlimited classes. There also are intro packages (three classes for $30) as well as 10- and 20-class passes.

Location: Fly Feet Running, 15 S. 5th St., downtown Minneapolis, flyfeetrunning.com, 612-333-3786.

Connie Nelson • 612-673-7087 • @StribCNelson