As people age, they begin to lose their sense of balance and become ever more likely to take a dangerous fall. But now researchers have hit on a technique that could help the older generation stay on their feet. They found that gently stimulating the bottom of the feet with random pokes increases a person's stability.
Standing utterly still is physically impossible; everyone, young and old, sways at least a little bit. The brain monitors several telltale signals to keep the wobble under control, including balance signals from the inner ear, visual cues, and small changes in pressure detected by the leg muscles and feet. But researchers suspect that these sensors become less sensitive as people age, and the body sways more before the automatic balance correction kicks in.
Hoping to compensate for this breakdown, a team of researchers tried a trick long known to engineers: adding random background noise to boost the weak signals. Bioengineer James Collins of Boston University and colleagues monitored 14 20-somethings and 16 senior citizens as they stood on a perforated platform in their bare feet. In half of the trials, volunteers were poked in a random pattern by small nylon rods extended through the holes in the platform. This prodding was so gentle that volunteers didn't feel it. No prodding occurred in the other half of the trials.
In an upcoming issue of Physical Review Letters, the team reports that the random stimulation reduced the amount that the older people swayed and that they approached the stability of the younger group. Encouraged by these results, the researchers are developing randomly vibrating insoles that could be placed in the shoes of the elderly to improve their balance.
The work could have a significant benefit for the aging U.S. population, says neurologist John Milton of the University of Chicago. "In 10 to 15 years, the health care system is going to be swamped with costs related to falls," Milton predicts. A device that uses noise to improve the balance system, like the one proposed by Collins's group, could be a cheap and practical way to cut down on the looming problem--and it's much simpler than more radical proposals like neural transplants, he says.