Centerstage - Chicago's Original City Guide

It's no big surprise that the treadmill can get tedious. But what's the alternative? The Stairmaster? How about an alterna-workout all together? These gyms offer less tried-and-tired ways to get in shape. Plus, by committing to a weekly class, you'll make an appointment with exercise that you'll feel guilty breaking, bringing you one step closer to svelte swimsuit shape.

Go sloooooow at Cheetah Gym (Wicker Park)
If you're dedicated enough to be at the gym by 6:30 a.m. on Wednesday—or lucky enough to be able to work out from 9:30-10:30 a.m. on Tuesday—the slow weight-lifting session Pump It! is for you. Designed to push your muscles to failure (read: your arms shake until they collapse), in this challenging class you'll slowly sink into a squat for eight counts—then excruciatingly rise for eight counts. You'll build muscle while upping calorie burn...and feel plenty of the burn yourself. Tip: Be sure to take it from Annie, whose encouraging prodding you'll love to hate.

Discover your core at Exhale Spa
Core Fusion, a trademarked class designed to produce "long, lean muscles, washboard abs and a high, lifted butt," combines yoga, pilates and core work. You'll start with a 10-minute upper body warm up (believe me, three pound weights are all you need for this one), then, using a mat and strap, focus on 25 minutes of leg and rear exercises and 20 minutes of core conditioning, like sit with your back against the wall and try to raise your legs off the ground. You'll moan…and quickly learn what your core is. Tip: To see results in your booty, follow Exhale's recommendations and commit to three classes a week for at least a month.

Work those muscles at David Barton Gym
This oh-so-hip gym by trainer-to-the-stars David Barton places a mean emphasis on working with trainers and weights. So it's no surprise that its classes are trainer-taught and often weight-centric. For a killer all-over workout, try Pain & Pleasure, offered every day but Tuesday and Saturday. Using medium and heavy weights, you'll target major muscles groups by doing an almost unthinkable number of lunges, squats, chest presses and bicep curls. Tip: Experience the pleasure part afterward in the aromatherapy steam room.