Health clubs and gyms open to professional and amateur athletes use balance training to condition muscles and improve reflexes that keep users on their feet.
But, although researchers think the training has benefits, they temper their enthusiasm with warnings that balance training has limitations.
"There are all kinds of data to demonstrate that balance can be improved. It's the technique in which they go about improving that is not well-understood," said researcher Walt Thompson, professor exercise science at Georgia State University.
Balance training can be as simple as standing on one foot or as complex and competitive as gymnastics. But the current trend is core conditioning.
Techniques called core conditioning focus on strengthening muscles of the trunk and legs, especially ones that control the spine. Along with this, the training lets participants practice using feedback from the eyes, ears, nerves and muscles that control balance.
For athletes, particularly those in sports such as skiing, balance is vital. The U.S. Olympic ski team has a varied program that includes gymnastics, yoga and jumping. The skiers also stand and jump on devices found in health clubs, such as the Bosu Balance Trainer, an inflated plastic bubble mounted on a flat base 25 inches in diameter.
To reach the Olympic level, an athlete already must have excellent balance. But there still may be weaknesses that can be strengthened.
Demonstrating that training works is harder than setting up the regimens, said Andy Walsh, the ski team's sports science director.
"Anecdotally, some of the athletes say they have improved," he said, but proof would require continued balance tests on expensive equipment that the ski team does not have.
For the not-so-gifted rest of the world, the benefits of training in balance probably would be greater, Walsh said.
Balance, an adjustment from one leg to the other, is directly related to physical condition, so working out should reduce falling down, Thompson said. Equipment that gets the legs and trunk used to balance should help.
As for whether training equipment also will speed nerve-muscle reactions involved in balance, Thompson said he has not seen scientific proof of this. However, he said, "it makes sense intuitively," especially for people who are out of shape.
More Americans are out of shape than are in shape, so core conditioning and the equipment on which to do it are potential exercise growth areas.
"Health club marketing people are brilliant," Thompson said. "Sometimes the longevity of new programs doesn't work out, but I'm happy to see this one."
Clubs typically offer a range of programs such as yoga, Pilates and step training classes on platforms. One example is the Reebok Core Board, a low, elliptical wobbly plastic form 22 inches across. The board is sold for home as well as club use. Another is the Bosu half dome, which so far is only in clubs.
"We know the importance of core stability training to improve the quality of life and daily activities, such as sitting at your desk, improving posture, or to lift your dog to pet him," said Norris Tomlinson, national director for group exercise at the 4 million-member Bally Total Fitness chain.
The Bosu program that the chain started about 18 months ago is growing so fast that it soon will rival aerobics mainstay Step in popularity, Tomlinson said.
However, Thompson warned that there may be risks with stability program benefits, especially for older people. For instance, he would like to see grab bars near the equipment to help prevent falls
"If it's an older person, you put them on one of these devices and they may end up falling and breaking something," he said.