But maybe it’s not so silly, exercise physiologists say. Although they don’t really know why vibrations should work, researchers report that they actually seem to slightly improve performance in the few minutes after a person gets off the machine.
The problem, though, is that there is little consensus on how fast the vibrations should be or in what direction platforms are supposed to vibrate. Some studies have failed to show any effects from vibrations. And then there is the question of what exactly vibrations are doing to muscles and nerves.
“It certainly is intriguing, and a large portion of the evidence would support that something is happening,” said Lee E. Brown, director of the Center for Sports Performance at California State University, Fullerton. But he added, “We are still trying to figure out exactly what the mechanism is.”
Meanwhile, several companies make the vibrating platforms, and they are being used at gyms and by some athletes.
One company, Power Plate, proclaims that stars like Serena Williams and Justin Morneau, of the Minnesota Twins, train with its device. A testimonial for another company, Wave, says the United States ski and snowboard teams used its vibrating plates in training for the 2010 Winter Olympics.
But researchers are wary.
“There is something to it,” said William J. Kraemer, a professor of kinesiology at the University of Connecticut and the editor in chief of The Journal of Strength & Conditioning Research, calling it “another tool” for athletic conditioning. But he added that other conditioning methods might yield the same or better results.
“If you think of conditioning as a toolbox, there are lots of tools,” he said. “But when companies are selling something, they want to pretend that one tool does everything.”
Experts who have tried the platforms describe them in different ways. The sensation is nothing like using a jackhammer, said Hugh Lamont, a sports biomechanist at Eastern Tennessee State University. Most vibration plates move no more than 50 times a second and feel like the vibrations in a seat over the wheel hub on a bus, Dr. Lamont said.
Others say the vibrations remind them of downhill skiing — they get the same sort of the rattling in their legs and feet. For Jeffrey M. McBride, an associate professor of biomechanics who is director of the neuromuscular laboratory at Appalachian State University in Boone, N.C., the word that comes to mind is “weird.”
“You can feel your muscles contract,” he said. “It sort of fatigues you.”
But if there is an effect, the researchers said, it seems to be short-lived. People seem to be slightly faster sprinters immediately after standing on a platform. They also seem to be able to jump a bit higher. Vibrations also seem to help people warm up before more strenuous exercise.
“The effect wears off very quickly,” Dr. Brown said. “We are not talking about using this to play a 90-minute soccer match. One sprint and the effect would be gone. You’d play for one minute and still have 89 minutes to go.”
But it could make a difference, he said, if an athlete is about to try a penalty kick in soccer or swing a bat in baseball.
And Michael G. Bemben, chairman of exercise science at the University of Oklahoma, said that “one thought was if you were, say, a high jumper on your third trial in the Olympics and you are at 7 feet 2 inches and need to get to 7 feet 3, this might give you the power for that jump.”
Investigators say they can only guess why vibrations might improve performance. Their leading hypothesis is that it somehow mimics the effect of following a difficult task with an easier one — a simple technique that has been in use for years.
“If you pick up something heavy and then pick up something considerably lighter,” Dr. Lamont explained, “you might be able to throw the lighter weight farther.”
Or if you want to jump, he continued, you might first put a huge weight on a training rack, do a quarter squat, partway down, and then, for three to five seconds, try to push up and lift the weight. You would be doing an isometric contraction of your leg muscles. After that, you might jump higher.
But does it matter? Why not just warm up in the normal way, or do isometric contractions before jumping, or pick up a heavy weight before trying to throw a lighter one?
Or why not combine everything and do warm-ups on a vibrating platform, or try isometric contractions between periods of vibration?
Researchers have thought of that, and say they are investigating. Meanwhile, they say, people should be appropriately skeptical about the effects of standing on a vibrating platform.
“We don’t know a lot about prescribing it,” Dr. Kraemer said. “There’s the rub.”
And yet it is being used many times without an understanding of how to do it best or what the long-term training effects will be.
“Research,” Dr. Kraemer said, “is trying to catch up.”
