If you like Pilates sessions on the Reformer, then you’ll love SPX Fitness classes on a Megaformer. I recently tried one at SLT: Strengthen, Lengthen, Tone here in New York City. The studio describes the classes as "the love child of Pilates, cardio, and strength-training"—and I totally agree. During the 50-minute small-group session (only 10 students per session) I did lunges, hydrants, rows, side planks, and more—all on my own Megaformer. (The machine resembles a traditional Pilates Reformer, but it has more springs and pulleys, a longer gliding carriage, and two sets of bars.) Thanks to the quick pace, my heart rate spiked up and I was sweating. And by the end of my last set, my legs were shaking—a sign of a good workout in my book. To find a gym offering SPX in your area, visit to spxfitness.com.