“Which cardio machine burns the most fat?” It’s a personal trainer’s least favorite question because there’s no right answer.

Still, research suggests there may be a winner in the fat-burning sweepstakes after all, and surprise: It’s the vertical climber (of which VersaClimber is the leading brand). Yes, that odd-looking contraption in the corner of your gym that resembles the Leaning Tower of Pisa (it's got a near-vertical rail with pedals and handles) may be the most underrated and effective tool yet for getting lean.

Made in a mechanical engineer’s garage in 1981, it's still wildly popular because it offers a ridiculous power, strength, and cardio workout.

“It doesn’t let you hide,” says Devore. Meaning: If it doesn’t kill you, it makes you stronger. That’s a big “if.”

What's more, a Washington State University study found that subjects’ maximal heart rates were jacked up higher when doing VersaClimber intervals than when running intervals on a treadmill, and their VO2 max—a measure of how fast the body consumes oxygen, which correlates with calories burned—was “significantly greater” when climbing than when training on a treadmill or a rowing machine.

“The VersaClimber burns more calories than anything else out there,” says Jason Walsh, C.S.C.S., a trainer who teaches cardio classes exclusively with the VersaClimber, dubbed Rise Nation, in L.A. “I’d estimate between 600–800 for a 30-minute session.”

The body position, at a 75-degree tilt as opposed to seated on a rower or exercise bike is rare among cardio machines; the vertical climber also offers no impact, which relieves the joints. As a result, “it allows greater range of motion, utilizing push-and-pull movements that work the shoulders, torso, hips, and legs,” says Walsh.

“Sure,” you say. “But can’t the same be said for the elliptical?” Not quite. The vertical climber has no speed limit; the handles and pedals move as fast as you’re able to push, allowing for greater progression and variance in workout intensity. And adjusting your speed down doesn’t have the lag time associated with other machines like a treadmill, on which you hit the down button and five seconds later it slows its pace.

And therein lies the true magic of the vertical climber: not just its ability to burn calories, but its potential to keep you interested in burning them—safely—workout after workout, until you see results. It'll shred your glutes, quads, back, arms, and core. To suffer for yourself, try this agonizing routine below. And if you're really short on time, go for 2 minutes at near-max effort. 

30-minute Vertical Climber workout 

Warmup: Perform long-range strokes (about 18 inches) for 4 min. at a pace of 130 feet/min.

3-minute total
45 sec. of short-range strokes (about 12 inches), 200 feet/min + 45 sec. of long-range strokes, 130 feet/min.
Repeat both intervals once more

Rest 30 sec.

3-minute total
30 sec. short-range strokes, 200 feet/min + 30 sec. short-range strokes, 150 feet/min.
Repeat twice more

Rest 30 sec.

4-minute total
20 sec. short-range strokes, 220 feet/min + 10 sec. short-range strokes, 120 feet/min.
Repeat both intervals 7 more times

Rest 1 min.

3-minute total
30 sec. long-range strokes, 140 feet/min + 60 sec. long-range strokes, 200 feet/min.
Repeat once more

4-minute total
4 minutes short- range strokes, 150 feet/min.

Rest 30 sec.

3-minute total
20 sec. short-range strokes, 220 feet/min + 60 sec. short-range strokes, 140 feet/min.
Repeat once, then only perform the 20-sec. interval one more time

Rest 30 sec.

3-minute total
45 sec. short-range strokes, 130 feet/min + 30 sec. long-range strokes, 230 feet/min.
Repeat once, then perform the 45-sec. interval one last time