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Stability training yields uneven results

Devices that challenge users to keep their balance help build abdominal strength, but they pose risks for beginners.

September 13, 2004|Jeannine Stein | Times Staff Writer

They are the current "it" products of the fitness world -- core training and stability equipment that purport to strengthen muscles around the midsection and help improve balance. Stability balls, Reebok Core boards and Bosu Balance Trainers have become standard equipment at gyms and at home, as people attempt to wobble their way to fitness.

But these exercise tools won't work magic. Their best use seems to be for strengthening abdominals and providing a greater range of motion, studies suggest. They don't rate as well when it comes to improving balance. And workout novices beware -- going it alone on one of these devices may result in injury.

It's long been known that strong core, or trunk, muscles are essential to overall fitness. They come into play in almost every small and large activity we do, from walking and sitting to running and biking, and they're the basis for good posture and strong backs. Pilates and yoga especially rely on sturdy midsections.

Some fitness experts say that adding the element of instability can take core strength to a higher level. By doing crunches or lifting dumbbells on an unstable surface, such as a stability ball, the body must use more muscles to compensate for the wobbling movements. Some also maintain that because we deal with unstable surfaces every day -- lumpy lawns, bumpy sidewalks -- exercising on an uneven surface might help develop better coordination.

The best application for stability equipment may be for pure core training. In a 2001 study at San Diego State University, the stability ball ranked third in effectiveness among 13 abdominal exercises, done with and without equipment. Topping it were the bicycle maneuver, in which legs move in the air in a bicycle-pedaling motion, and the captain's chair -- in which you lift your knees to your chest while supporting yourself on armrests in an apparatus that looks like a seatless chair.

The ball also did well in a study done by researchers at the University of Texas at Austin. They discovered that doing abdominal exercises using a stability ball resulted in significantly stronger abdominal muscles than traditional exercises on the floor.

"Life is not a stable dynamic," says UT researcher Dixie Stanforth, "and if all we do is train in a way where everything is controlled for us, that may not be doing much for people in real life."

Stability balls can also provide a greater range of motion during some exercises, says Jeff Schlicht, an assistant professor of health promotion and exercise sciences at Western Connecticut State University. "When you're lying on the ball, you can get your head beyond 180 degrees" by dropping it below the ball, something that can't be accomplished while lying on the floor. "That provides an increased range of motion for the abdominals to work through, and will make the exercise more difficult if you do it correctly."

Stability equipment might have applications for sports-specific training. Basketball players, for instance, occasionally practice passes and throws while sitting on a stability ball, hoping to gain better motor control that can be used during a game.

But those skills may not always transfer to other sports and activities. "Research involving motor control suggests some limitations in transferring balance skills," says Peter Francis, professor emeritus in the department of exercise and nutritional sciences at San Diego State University. "If I learn how to balance for tennis, that may not help me on the diving board. So the closer you create your training to what you're going to do, the better off you're going to be."

Non-athletes might not benefit as much from using this equipment for balance training. A study of men and women 60 and older, for example, found that there were no measurable differences in strength or coordination after participants worked out on a stability ball compared with the same exercises done on the floor. Schlicht, who led the study, doesn't rule out the possibility that the balls may help some older people improve their balance and agility, but adds that those still could be compromised by variables such as vision and medication.

Trainers routinely use equipment like the dome-shaped Bosu ball or wobble boards with clients in one-on-one settings. Some gyms also incorporate them into group exercise classes, but experts caution that those may not be suited for novice exercisers, older people or those recovering from injuries, because there may not be enough supervision.

"The Bosu is used as an advanced version of Step," explains Daniel Torres, fitness manager at Equinox in Pasadena, noting that the unstable surface provides greater degrees of difficulty for dynamic and static movements. "We expect teachers to explain to students how they can modify the exercise if they need to."

But even he's sustained ankle injuries on the Bosu while jumping from the floor onto the ball with one foot. "Two feet would be OK," he adds. "But one foot presents considerable challenges."

Fitness experts say that this equipment's greatest asset may be in its ability to get and keep people's interest in exercise. "It's a challenge," says Francis, "and overcoming challenges is positive for the human condition."

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