There must be something wrong with my machine, because it’s sliding and shaking while every one else’s is completely still. This thought passed through my head a second before I realized that, along with my Megaformer apparatus, my quads, glutes, and every other muscle south of my rib cage was also shaking.

“Keep that machine still!” urged our class instructor Stacey.

I nearly laughed out loud. She might as well have told me to kiss my own ass.

If you’re not familiar with the Megaformer, it looks a bit like a treadmill-sized mandoline slicer. It also moves like a mandoline: A platform section—the part you stand, kneel, sit, and groan on—slides on a track between two fixed anchors. The platform is also connected to a network of tension-adjustable bands and straps, which you employ during a structured 50-minute series of movements designed to work almost every muscle in your body to exhaustion.

It’s a little awkward at first, and requires some balance. But you get the hang of it in a hurry.

“It’s similar to those Total Gyms Chuck Norris used to sell, just with the intensity turned up a thousand percent,” says Stephanie Tolar, owner of Philadelphia’s Sculpt Fitness Studio. She’s only slightly exaggerating. Midway through my first class at Tolar’s studio, my knees were wobbling so much I looked like an Elvis impersonator. My gray cotton T-shirt was also several shades darker than it had been at the start of class, thanks to the bucket of sweat I’d lost.

Similar to the “Reformer” apparatus used in Pilates, the Megaformer requires lots of subtle, zero-impact movements that target those small support muscles most guys neglect. “Every move is done slowly and with control so you get into muscles that most men don’t work when they’re doing large dynamic movements,” Tolar says. In particular, Megaformer strengthens your “core”—the various abdominals, obliques, and adductors that lace into your spine and support your trunk.

Launched in 2010 by Sebastien Lagree, a Frenchman and former bodybuilder, Megaformer workouts have taken off in Los Angeles and New York, and studios are gradually popping up everywhere else. Most of them—like SFS in Philly—house 10 machines and offer structured classes that will seem familiar to anyone who’s tried spinning, Pilates, or other instructor-lead workouts.

Tolar recommends two or three Megaformer sessions a week, which may seem lame compared to the masochistic six-day-a-week programs to which Cross Fit and INSANITY adherents are accustomed. But before you scoff, understand that your legs, abs, and shoulders are going to need a day or two to recover. As a guy who lifts weights a few times a week and mixes in runs and long bike rides, I figured I’d be sore in a few new places the day after my first Megaformer class. I did not expect my abs, back, and lower body to be hot mush for three full days.

“I can’t get this level of intensity in the gym,“ remarked one of the women in my class after we’d slumped off our machines and limped toward our lockers.

That’s the truth. For guys looking to supplement their macro weight-and-cardio workouts with a program that targets the micro muscles those miss—basically, guys like me—a weekly Megaformer session is a great way to go.