Being shaken vigorously, pneumatic drill-style is something of a departure from the holistic road to health nirvana down which we have been guided in recent years. For those who have not stepped on a Power-Plate - the device that is usurping the unassuming fitness ball as the workout accessory du jour - this is equipment that claims to get you trim in sessions of just 12 to 15 minutes by vibrating your body so intensely that you can feel your tonsils buzz.
Madonna reportedly used the device to hone her 48-year-old body into looking half its age for her last tour. Indeed, the material girl is now said to take all her telephone calls while standing on one. Celebrities such as Sean "P Diddy" Combs, Claudia Schiffer and Gaby Logan have declared Power-Plate to be part of their fitness regimes. It is also a favourite of Celtic FC footballers and members of gyms such as the Holmes Place, Fitness First and David Lloyd chains. A Power-Plate fitness studio recently opened in Harrods, where groups of four can book 25-minute sessions with a qualified trainer. In addition, an estimated 10,000 of these or similar vibration exercise machines - the VibroGym and the Soloflex Platform, which cost around £2,600 - were sold for private use across Europe in the past year.
Kevin Barclay-Webb, a personal trainer and director of the Fitness Lounge gyms in London and Glasgow, uses the VibroGym in most of his programmes. He says: "They vibrate around 4,000 times a minute, which transfers energy to the body and triggers rapid muscle contractions. The upshot is that you work harder all over when you're on it. In a 12-minute workout, you can effectively train every muscle."
Whole body vibration (WBV), to use the term given to the Power-Plate effect, is not a new concept. Exercise scientists have been studying the effects of intense vibrations for around four decades. Russian scientists first discovered its benefits in the 70s when trying to find a workout that could be done in space. Until then, the weightless atmosphere had predisposed astronauts to osteoporosis, but scientists found that standing on a vibrating platform stimulated muscle and bone development. Since then, some trials have shown that regular use of vibration training methods increases muscle strength by 20 to 30% more than ordinary weightlifting - and in 85% less time.
Within the medical world, there is growing acceptance of various types of vibration machines for the treatment of cerebral palsy, osteoporosis, chronic pain and back injuries. Specialists treating people with spinal injuries and multiple sclerosis at the Royal National Orthopaedic hospital in Stanmore, Middlesex, have had some promising results using the Power-Plate.
George Waylonis, a clinical professor of physical medicine and rehabilitation at Ohio State university in the US, studied the effects of WBV on patients with fibromyalgia, a disease that causes constant full-body pain. He used the Power-Plate and the Galileo, another vibration exerciser, in his trials, and was impressed by the results. It "seems to be a way for people in pain to exercise their muscles and feel better," he said.
Less convincing is the claim that it will get you fit in the time it takes to get changed for your usual gym session. Will standing on such a machine really tone muscle, increase flexibility and generally buff up your body in little more than 10 minutes, as the manufacturers would have us believe?
Cedric Bryant, chief exercise physiologist for the American Council on Exercise, a watchdog for the US fitness industry, has been looking into the benefits of such equipment. He says "conceptually, it has merit", but that there is insufficient scientific research to support the fitness claims made for it. "This is not a magic bullet that helps people to lose weight without doing anything," he says. "If you are a healthy individual, WBV training should be a supplement to a sensible diet and exercise programme." And while it might be good for one muscle group, it could strain another. "Those types of question haven't been addressed sufficiently in my mind," he says.
Sam Howells, a sport scientist for Leisure Connection, agrees. He says that while WBV training is useful "for some people and during rehabilitation from some injuries", in other instances "it doesn't have much benefit and can even be harmful if used incorrectly or with poor technique".
Professor Aurelia Nattiv, a sports medicine expert at the University of California, Los Angeles, says more research is needed. "We have data, but the results are inconsistent, and most of the studies have looked at one specific area, such as knee extensor strength and jump height. And even the results on those tests have been mixed."
Some researchers, such as Philip Clifford, professor of physiology at the Medical College of Wisconsin in the US, cite animal studies showing that extreme vibration is linked to circulatory problems, raising the question of whether the same problems might arise in people who use these machines.
Bryant and others also question whether WBV devices will get you fit in minimal time. "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," he says.
You cannot just stand still on the Power-Plate and hope to step off with abs and legs like Madonna's. "You won't get aerobically fit no matter how often you use the machine because it doesn't drastically raise your heart rate," Howells says. "You would need to do some aerobic activity as well."
The best approach is to do exercises you would do on the floor - squats, tricep dips, push-ups, lunges - on the machine's platform, advises Barclay-Webb. Because your muscles get tired more quickly, the routine will be shorter, but the continual vibration causes you to tense and relax your muscles up to 50 times a second just to keep your balance. "You will be surprised how hard you feel you have worked," he says.