Terri Walsh has been developing her Active Resistance Training method for 25 years, precisely because she knows you don’t have that kind of time.

“When people come to a class, they don’t have time to dice things up into pieces anymore,” the trainer says. “That’s why it has to encompass flexibility, strength, endurance and cardio.”

The B in B-Method, the name of her class at Crunch gym, stands for “block” — actually a pair of yoga blocks that she says is “how I trick people into the room.” They’re also the key to creating a workout with baked-in variable intensity. If you’re not flexible, the blocks essentially bring the floor up to meet you; for someone more advanced, they make push-ups tougher through extending range of motion by putting the floor farther away. “Blocks can assist or become an agent of resistance,” Walsh explains.

By propping yourself up on the blocks during planks, keeping it pressed tightly between your hands during lunges, squeezing them between your knees for sit-ups and more, you’re creating four active resistance points: feet, navel, ribs and shoulders. Being conscious of keeping these engaged is your goal — not that you have to be reminded to tighten your core when balance is almost always a factor.

The workout can also complement a yoga practice. “With yoga, there is a lot of problems with hands, wrists, elbows and shoulders ... which weren’t really meant to be treated like feet,” Walsh explains. “So if you’re a yogi, this is going to use the skills you have, but it’s also going to build up the areas where you’re weak and protect the areas that may have been overused.”


Inside the Workout: B-Method

For a week after this class, I was walking like the Tin Man looking for his oil can — but it wasn’t because of pain. As promised, I didn’t feel like I’d been “hit by a truck,” but the muscles in my stomach, butt and thighs (inner and back) were so stiff that I genuinely needed help picking things up from the floor. (My shoulders and triceps were barking too, though not to the same extent.)

Terri often had us place the blocks at asymmetrical spots — under one elbow and beneath the opposite knee for arm and leg extensions, which raises the difficulty level exponentially by forcing you to abandon any hope of momentum assisting you. (That tactic would send you crashing off the blocks.)

The hour-long class doesn’t involve routines or set a strict pace; the idea is not to watch yourself or the instructor in the mirror but to perform every movement mindfully. The effect was to keep everything from the core out through each limb taut, always pushing on the blocks as you curse every ounce of flesh you’re having to balance on 4-by-6-inch foam platforms. They’re propped under your butt to extend your usual stretches; they’re under your elbows during reverse push-ups. They’re wretched — and they get results.

The bottom line: You’ll recognize many of the movements as the bread and butter of body-sculpting classes — what you’ll be surprised by is what a difference a few inches make to how much harder you’re working. As an exercise writer, variety in workouts is a job requirement, but I’ve not felt as worked over before or since B-Method.

B-Method classes are held at two Crunch locations in NYC, 80 Leonard St. and 220 W. 19th St., as well as San Francisco and Miami. Check their online schedule.