Amanda Freeman, the founder and chief executive of the in Midtown Manhattan and SoHo, said she felt the same way and was inspired by her own thrill-seeking instincts to introduce New Yorkers last year to what she called “Pilates on crack.” SLT — it stands for strengthen, lengthen and tone — is designed to offer the benefits of Pilates along with a rigorous, calorie-burning cardio element. “I never felt like I got a hard enough workout with Pilates and always had to work out again after I took a class to really feel the burn,” Ms. Freeman said recently. A machine called the Megaformer is the central component of 50-minute classes at SLT for no more than 10 people. Ms. Freeman said that the machine, with its sliding platform, adjustable handlebars, resistance bands and bungee cord, helped work the core and sculpture the entire body without adding bulk. The workout and the machine were created in Los Angeles by a Pilates instructor, . He named his program Lagree Fitness and opened astudio, where he soon developed a cult following. Ms. Freeman said she became addicted to the classes on her trips to the West Coast and decided to open a studio in New York so she could get her fix. The sessions are set to hip-hop, pop and rock music. And though the routines change, a common thread is that instructors work the muscles to their limit. “You’ll do three exercises for the left obliques to really exhaust them before moving on the right side,” Ms. Freeman said. A core-shaping exercise, for instance, has the students stand on the moving platform with one leg crossed over the other. They hold onto the front handlebars and use the obliques to push the platform away and pull it back in for one minute. An activity to work the legs, called the hydrant, has the students on their hands and knees. They lift up a leg to the side and put it back down repeatedly for one minute. The quick succession of moves and the transition from one to another is what really raises the heart rate andhas won fans among ever-skeptical New Yorkers. Scott Lesser, 36, who lives in Chelsea and works at an Internet start-up, said he ditched his pricey personal trainer and lifting routine when he discovered SLT through friends. “I was looking to get ripped and tight, and thanks to the classes, my arms and abs are more defined than they ever have been,” he said. “It might sound easy or girlie, but it’s a really challenging, sweaty workout.” Rebecca Serle, 27, a young-adult author who lives in Union Square, said she appreciated that the classes were intense but not high-impact. “I got a stress fracture in my foot last year from doing too much impact,” she said. “I used to do a lot of boot camp classes and wasn’t sure that I’d be able to find something as hard that was easier on my body, but SLT is definitely it.” New students can try a Megaformer workout at the SLT studio in Midtown Manhattan for $20; .