Passive Exercise: Whole-Body Vibration and More (cont.)

Still, Gerard Varlotta, DO, remains unconvinced that whole-body vibration can replace conventional exercise.

"We know that walking 2 miles a day is an effective way to build bone -- and I think it's OK to use this equipment as an adjunct to your normal exercise routines -- but to rely on it solely, we're not there yet," says Varlotta, director of physical therapy at the Rusk Rehabilitation Center at New York University Medical Center.

Chi Machines

As with whole body vibration, these machines shake the body from the ankles up. The big difference is that the moving and shaking goes on while you're lying down.

How It Works: You lie on the floor (or a treatment table) and place your ankles on top of a small square box that basically vibrates your body from the feet up.

The Promise: The benefits are supposed to include improved metabolism, weight reduction, increased energy, muscle relaxation, increase in cell oxygenation, and stimulation of the sympathetic nervous system. Some proponents say that just five minutes on the Chi machine is the aerobic equivalent of walking for 30 minutes.

Chi machines are also advertised as being beneficial for those with diabetes, fibromyalgia, lymphodemia, and migraine headaches, as well as those who want to tone their muscles and lose weight -- all while lying down for just 15 minutes a day.

What the Experts Say: "This is a totally passive way of supplying increased circulation to a muscle and that's all," says Varlotta. "It will not give you increased strength, and it could never replace exercise done standing on your own two feet."

Quist likens it to the "jiggly belts" used in the 1950s, which simply caused your body to shake.

"I don't think they ever proved scientifically that those belts did anything for weight loss, and I think the effect is similar with the Chi machines," says Quist.

Bryant agrees: "Part of the thinking here centers on the Eastern philosophies of energy centers and those are being stimulated by this movement activity, but I have not seen anything even close to science on that," he says.

He adds that if you just lie on the floor and kick your legs, you would probably get a similar circulatory effect, along with some muscle toning.

Electronic Muscle Stimulators: Ab Stimulating Machines

It's hard to miss the ads for these products -- svelte, toned guys and gals in bikinis, showing off their "six pack" abs, ostensibly delivered courtesy of electronic ab stimulation.

How They Work: You strap on a wide belt wired to a battery. Stimulation is provided by tiny electrical "shocks" delivered at timed intervals, designed to stimulate muscle contractions.

The Promise: You'll not only have stronger, firmer, more visible abs in 30 days, but you can achieve this without ever getting off your couch, some manufacturers say. One company says you can tone all the muscles in your abdomen in a few weeks using the machine just 30 minutes a day -- while you "watch TV, fold laundry, or help your kids with their homework."

What the Experts Say According to Bryant, the principal behind ab stimulators comes directly from physical therapy, where it's used to help contract injured muscles. However, he cautions that what works on a damaged muscle will have minimal effects, at best, on a healthy one.

"While you may see some mild improvement, the only way to see 'six pack abs' is to lose the belly fat -- and these stimulators will not help you to do that," says Bryant.

Quist adds that the amount of stimulation necessary to tone healthy muscles would be so great that you would likely burn or injure yourself in the process. "I see no real value for healthy muscles," says Quist.

Varlotta agrees. "If you go back to the basic principals of muscle stimulation, it's to help bring nutrients into the injured area and increase blood supply," he says. "But the studies have failed to show any increase in strength or endurance. So, from a healing standpoint, it may help if you have an injury, but that's about it."

Moreover, in 2003, the makers of three ab stimulators -- Fast Abs, Ab Tronic, and Ab Energizer --agreed to pay more than $5 million to settle Federal Trade Commission charges brought against them for false advertising claims.

Inversion Boots

They first came to public attention in the 1970s as a way to supposedly alleviate chronic back pain. Today, inversion boots -- as well as inversion "racks" -- are resurfacing as a way to not only relieve pain, but to tone and condition muscles involved in posture and core strength.

How They Work: The boots, which are really ankle supports strapped to your lower leg, are designed to hook into a "rack" that allows you to invert your body up to 40 degrees. (Think a patio chaise longue that puts your legs in the air while pushing your head toward the ground). For the real pros, the boots are hooked into a rack that literally leave you dangling in the air, your head about 2 feet off the ground.

The Promise: Essentially, the goal is supposed to be to allow your muscles and joints to "decompress" after a day of gravity-crunching compression, plus, increase circulation.

What the Experts Say: "In principle, it's a way of using your own body weight to reverse the effects of gravity -- which does work, temporarily. Unfortunately, the minute you resume your normal position, all the effects are lost," says Varlotta. Moreover, he adds, that to gain lasting results, the amount of time you would have to spend upside down would be dangerous.

Bryant agrees. "For the chronic back pain sufferer, it might be worth a try, but under no circumstances should it be considered a long-term fix," he says. And, he says, anyone with high blood pressure, diabetes, or whose backaches are caused by excess weight should never use an inversion boot or table.

"This can cause a kind of increased pressure, particularly in the ocular [eye] area, that can be especially dangerous for people with these health problems," says Bryant.

Medically Reviewed December 4, 2007.

SOURCES: Ben Quist, DPT, director, Form and Fitness Health Club and Rehabilitation Center, Milwaukee, Wis. Gerard Varlotta, DO, director, sports rehabilitation, NYU Medical Center's Rusk Institute of Rehabilitation Medicine/Hospital for Joint Disease; clinical associate professor, NYU School of Medicine. Cedric Bryant, PhD, chief science officer, American Council on Exercise. WebMD Medical News: "Vibrate to Keep Fat Off? Study Weighs In."

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Last Editorial Review: 12/4/2007