30/60/90, created about two years ago by Kristi Molinari, is by far the best class I have ever taken from any gym. Althought this class is offered at many Equinox locations, I take it at the SoHo Equinox on Tuesdays at 6:30pm. "For those of you who haven't taken this class before; it's really hard," Kristi yells into the microphone. "If you need to take a break, do so, but just don't do it in the last 10-15 seconds each exercise). These last 10-15 seconds is when you get the anaerobic exercise and your body sees the results."

As the title suggests, the class is run on intervals of 30, 60 and 90 seconds. Kristi walks around the class with her stopwatch and makes sure everyone is using 100 percent of their energy. The items needed for the class include a step pad, hand weights and medicine ball...and a gallon of water and towels to soak up the excessive sweat.

She starts the class with a quick warm-up and then the class goes full force into the timed intervals. For the first two minutes we jumped up and down and back and forth on the back of the step pad, which began to work my quads and hamstrings—a variation of squats and lunges. Then each interval took us through pushups using the side of the step pad, jumping lunges with weights held above the head, side-to-side with weights held high, some arm exercises, dips on the pad and many other strenuous, torturous cardiovascular exercise (with weights). In between each cardio/weight jumping sequence was another weight exercise.

Now, I had done the wedge class the day before I took this class, so I was already kind of sore. The side-to-side lunges were almost painful for me and the entire breathing thing became hard. When the time came for us to do a 7-minute plank routine (plank is a yoga position where you get into a push-up position, but don't go down for the actual push-up). I almost died. Luckily, I am pretty good at plank and incorporate it into my daily routine; otherwise, I would have fallen on my face. Next was side plank where you hold your body up by one arm, on leg is on top of the other leg with feet flexed, giving you an oblique workout. Then we had to run in place while still in plank. I really wasn't joking about the 7 minutes.

Have you ever heard of a squat thrust? Well, it starts with a simple jump in the air, down into push-up position, push-up, then back to the jump. This is a pretty difficult thing to do for 90 seconds, so Kristi decided to bring a medicine ball into the mix, so instead of just a regular push-up, we had to balance on a medicine ball.

I have a love/hate relationship with this class and I highly recommend it.