Seven Silly Fitness Fads

The verdict: Sure, it's fun, but it's probably better as a novelty activity at bachelorette parties and group outings than something for dedicated gym rats.

3. The Bodyblade . Take the long, swordlike plastic bar, hoist it overhead and shake vigorously for a trunk-targeted workout that supposedly causes up to 270 muscle contractions per minute, giving you washboard abs and ropey shoulders that are rounded, not chiseled. The device uses physics as its premise: once set into motion, the oscillating bar must be stopped by your effort to overcome its inertia. That straining is the workout. Though it's making the rounds as the "new" thing, Bryant says Bodyblade-like bars have been around in physical therapy practices for years. "It helps you challenge the neuromuscular system—how the nerves communicate with the muscles, and relearning that process," he says. What if you're just looking for core stability? White, who's never tried the Bodyblade, says he has one client who bought into the trend—for a while. "To be honest, I think she used it for about a month and then moved on," he says.

The verdict: Can be good for physical therapy but otherwise a fickle fad. If you don't mind looking like an idiot, and not knowing how many calories it burns (the makers disclose no numbers, saying it's "difficult to calculate"), give it a spin.

4. Cirque du Soleil-Inspired "Aerial Aerobics." The breathtaking stunts of the world's best-known circus acrobatics troupe first inspired workouts at trendy gyms like Crunch and Equinox and have now spawned "aerial fitness studios" where you tone up by defying gravity. The premise of "fabric aerobics" is simple: just shimmy to the top of a cloth lanyard, wrap it around your feet and hang, limbs dangling. Sounds easy, right? Maybe not: "They told me it was Pilates but with hanging hammock things," says my colleague Jessica Bennett, who tried it, "but you seriously had to be an acrobat." The bare-minimum skill level for a workout like this—the class is called "Fabric" at Crunch—might be good enough to get you into the circus.

The verdict: The greatest of ease? Yeah, right. "It can backfire from the standpoint that you feel really inadequate," Bryant says—and who needs one more reason not to exercise?

5. Wind-Relieving Asana . Thought fiber was the only natural remedy for expelling excess gas? Think again: this series of yoga postures assumed in asana-based classes assists air in exiting your digestive tract—in a room full of people. The motions involve lying flat on your back and pulling your left, right or both knees into your tensed stomach, squeezing out the stale air or, in instructor's lingo, engaging your abdominal region to assist with elimination. The poses are also said to enhance supine strength and flexibility, making them optimal for those with both bad backs and Metamucil in their pantries (read: old people). "It could certainly be helpful with some individuals in terms of [their] low backs," says Bryant. "But the whole flatulence aspect—I'm not so sure that there's a great deal of physiological support for that being a need."

The verdict: Group flatu-fitness? We'll pass.