London A buzz in the soles may keep elderly people on their toes and reduce the risk of debilitating falls, preliminary research suggests.
The experiment, outlined this week in The Lancet medical journal, found that elderly people showed signs of better balance when they stood on a pair of battery-operated randomly vibrating insoles.
Although users aren't conscious of the subtle buzz, the idea is that the vibrations amplify balance-related signals between the feet and the brain that become dulled with age or illness.
Experts said that the research showed promise but that scientists needed to see whether the technique improved balance when people walk, turn or reach, which is when they are most vulnerable to a fall.
When a person leans or sways to one side, the pressure on the sole of that side increases. Normally, the nervous system senses the change in pressure and sends a message to the brain so the posture can be adjusted.
Those messages can be blunted by age, stroke or conditions such as diabetes.
"I think the vibrating insole holds promise and is definitely worth studying," said Dr. Mary Tinetti, chief of geriatrics at Yale University school of medicine, who was not connected with the study.
The research, funded by the U.S. National Institutes of Health, was conducted by scientists at Boston University and Harvard Medical School.
They recruited 27 healthy volunteers -- 15 people in their 20s and 12 elderly people -- to stand on the gel-based insoles, which were placed on the floor for the experiment. The volunteers were told to keep their eyes closed and their arms by their sides. The insoles were connected to a large battery pack and each was implanted with three small vibrating discs.
The intensity of vibration was set individually so that it was just below the threshold that could be felt. The scientists conducted before and after tests on various tasks involved in balance control.
The young volunteers showed some improvement with the vibrating insoles, but the elderly people showed more improvement, said James Collins, a professor of biomedical engineering at Boston University who directed the project.
"The improvements we are seeing in the elderly -- that is, we move them down to, or close to, the level in the young -- we view as being very positive," Collins said.