Equinox instructor Gia-Ninh Chuang demos a punching move in Bethesda.

In military speak, DEFCON3 means the nation’s security has been elevated above normal. In Equinox speak, MetCon3 means your body’s heart rate is elevated above normal.

What it is: The health club’s newest class gets its name from the metabolic conditioning that taxes all three of the body’s energy systems (the phosphagen, glycolytic and oxidative pathways). “We like to geek out,” explains instructor Gia-Ninh Chuang. What it all translates into is a workout that consists of a series of 10 exercises — each performed for one minute — repeated three times. “Just as you’re at fatigue, when the lactic acid in your muscles is building up and your form is breaking down, we switch to something totally different,” he says. “You can hit reset and give full-out effort.”

Moves: The particular exercises and props students use change with each class, but the structure remains the same, as does the goal to boost strength, flexibility and core stability all at once. “Having those be separate things is so 2000 and late,” Chuang says. At the end of the third circuit, you need to make it through the “metabolic finisher” — a short, but utterly draining final exercise — before you get to cool down and stretch.

Be prepared to do anything, often while doing something else. Many of the exercises are compound joint movements, which pair an upper-body action with a lower-body one, such as overhead presses and squats.

Workout: Whatever the exercise, Chuang always offers two options, one more challenging than the other. Then, he encourages his “overachievers” to try an even tougher version (as in, “Overachievers, give me a double push-up!”).

“I think it’s awesome that it’s high intensity the entire time. I feel burned out after 45 minutes,” said 31-year-old Steve Lucas at a recent class. Bita Nakhai, 48, who was wearing a heart rate monitor, reported that she had just torched 500 calories. But because you’re doing each action only for a minute — albeit three times — it never seems like you can’t get to the finish line.

Crowd: The wide range of options means the students who pack the room have very different fitness abilities. But no matter which exercises they go for, they attack the moves with the intensity of top athletes.

Offered at Equinox’s Bethesda and Tysons Corner locations. For schedules and more info, see Equinox.com.