A favorite of A-list celebs, the Equinox gym chain prides itself on being top-of-the-line: The showers are stocked with Kiehl's products, many weight machines are custom-made, and the trainers are known for whipping supermodels into shape. And yet, one of the gym's more popular features might be its goofiest: Urban Rebounding, a staple of 3 a.m. infomercials.

Go figure. The $1 billion infomercial exercise business has gone mainstream, with some of the biggest names in fitness now toning up with the gizmos. The Urban Rebounder, as any insomniac will recall, is a child-size trampoline that sells for less than $100. At Equinox, the Rebounding class is so popular that members have to sign up beforehand, says Carol Espel, director of group fitness. (Urban Rebounding says fitness experts have vouched for its workout.)

And it's not just gyms jumping on this; big-box retailers now stock a slew of "As seen on TV" workout gadgets (Walmart.com alone carries 36), and many products are racking up Facebook fans and YouTube views online. Experts say some do live up to the hype; the $30 Perfect Pushup, for instance, a set of rotating handles, can help alleviate wrist and shoulder pain. But don't put away your running shoes just yet the American Council on Exercise maintains that some products' claims are "complete bunk."

Video: How TV Fitness Products Shape Up

We tested three as-seen-on-TV workouts, now appearing at a gym near you. (Watch video)