IN the pantheon of wacky fitness contraptions, the Power Plate deserves a special place of honor. The pulsating, vibrating exercise machine promises to jiggle even the semi-indolent into shape without so much as a lunge or squat.
In the four years since its introduction in the U.S., the device has struck a responsive chord among slackers and elite athletes alike. Madonna reportedly used it to whip her 48-year-old body into its current Mighty Mouse condition. A gaggle of other celebrities and models -- such as Sean "Diddy" Combs and Heidi Klum -- have been unofficially linked to it.
An increasing number of gyms and trainers report using them: More than 20,000 of the machines have been sold worldwide since 2002. Other types of vibrating exercise equipment are also on the market, such as the Wave and the Soloflex Whole Body Vibration platform.
Vibration research and technology isn't new. For more than four decades scientists have been exploring the effects of whole body vibration on various groups including astronauts and transportation workers.
Within the medical community, there's growing acceptance of various types of vibration machines for the treatment of cerebral palsy, osteoporosis, chronic pain, back injuries, kidney stones and more.
But manufacturers of the Power Plate and other vibrating exercise devices say their machines can also buff up the body. Just standing on the machine can tone muscle and increase flexibility, they say -- music to any slacker's ears.
The Power Plate is based on the premise that when the body senses instability (in this case a vibration) the muscles involuntarily contract to compensate. The result, in theory, is improved muscle strength and performance.
It is not an entirely nutty idea.
"Conceptually, it has merit," says Cedric Bryant, chief science officer for the American Council on Exercise.
The problem, he says, is there currently isn't sufficient high-quality scientific research to support the theory.
Dr. Aurelia Nattiv, a professor of sports medicine and team physician at UCLA agrees that more research is needed.
"We have data," she says, "but the results are inconsistent, and most of the studies have looked at one specific area, like knee extensor strength and jump height. And even the results on those tests have been mixed."
In addition, experts say, there are a number of important unknowns.
"We don't know what the optimal training protocol would be in terms of frequency and duration and what types of exercises and positions are most effective," Bryant says. And, he adds, there also isn't a lot of literature on groups for which the device might be contraindicated. "Those types of questions haven't been addressed sufficiently in my mind," he says.
Of particular concern, says Philip Clifford, professor of physiology at the Medical College of Wisconsin, are animal studies -- undertaken, in part, to study the consequences of operating jackhammers -- that have linked vibration to circulatory problems.
The Power Plate has a great pitchman in Marc Altieri, who demonstrates the device for me on a recent afternoon at the ultra-tony Spectrum Club in El Segundo.
A perfect physical specimen with bulging biceps and a rakish goatee, Altieri is a perpetual motion machine as he quickly rattles off the machine's features: It generates 30 to 50 vibrations per second, he says. The vibrations are both up and down and side-to-side. The level of intensity can be adjusted.
He turns on the machine and demonstrates exercises that can be done on it, such as squats and hamstring stretches. He stretches out on the floor and does push-ups on the machine.
With some reluctance, I get on.
"Bend your knees," he tells me. "Hold on to the handlebar." Then he turns on the machine -- and suddenly I know what my old cartoon pal Wile E. Coyote felt like when he would hit a wall and vibrate like a tuning fork.
Altieri is ticking off more information: "You have to follow a recommended protocol: 10- to 15-minute sessions, no more than four days a week," he says. "If you train on it every day, it's going to start breaking down your muscles. You've got to stay in that sweet spot."
I ask him a question, and my voice sounds like a digitally altered voice in a mob documentary.
As he answers, I take inventory: My teeth are clenched, my hands are gripping the bar like a first-time hang glider and my knees are locked-up. I just hope I don't have any loose fillings.
Next to the machine is a poster listing all the people who should not use the machine: those with open wounds, skin disease, migraine, thrombosis, heart pacemakers, brain pacemakers, artificial limbs, tumors, epilepsy, screws and plates, contraceptive coils, those who are pregnant or breast feeding, plus those who've had a coronary bypass or who suffer from diabetes.
I'm trying to remember if I have any artificial limbs but I'm too rattled to take a count.
