Falls are the leading cause of death by injury amongst seniors, and those falls are in turn typically caused by poor balance or an irregular gait. Taking things back yet another step, problems with balance and gait are often caused by diminished sensation in the feet. Now, however, a new study indicates that subtly-buzzing insoles may help seniors regain some of that lost sensation, and thus be less likely to fall down.

The research was conducted by scientists from the Institute for Aging Research (IFAR) at Hebrew SeniorLife, Beth Israel Deaconess Medical Center, the Wyss Institute for Biologically Inspired Engineering at Harvard University, Harvard Medical School, and Merck Sharpe and Dohme (MSD) Consumer Care, Inc.

It's based around the phenomenon of stochastic resonance, in which weak signals can be made easier to detect through the careful addition of low-amplitude white noise. In this case, the vibrations made by the insoles weren't even consciously perceptible. They did, however, constitute just the right amount of white noise to allow the wearers to better detect tactile stimuli in the soles of their feet.

In an earlier study, similar results were achieved by buzzing the feet of both young and elderly test subjects, who had balance/gait problems due to diabetic neuropathy or stroke. In that case, a large power supply was required for the vibrating apparatus, limiting the portability of the system.

This time around, the researchers embedded thin piezoelectric actuators within the medial arch region of commercially-available urethane foam insoles. A rechargeable battery and a circuit in the tongue of each shoe sent an electrical signal down to the actuators, which converted it into mechanical movement – the source of the subtle vibrations.

When tested while using the insoles, a group of 12 volunteers aged 65 to 90 reportedly showed significant improvements in the reduction of sway, the reduction of gait variability, and the speed at which they could stand up from sitting, walk three meters (9.8 ft), turn around, walk back, and sit down again.

"Although loss of sensation in the feet is a common problem among elderly people that can impair balance and gait and result in falls, there are currently no interventions available that can reverse sensory impairments and prevent these dangerous consequences," said study lead author and IFAR director, Dr. Lewis Lipsitz. "We were very excited to discover that small amounts of vibratory noise applied to the soles of the feet may be able to do just that."

A paper on the research was published this week in the journal Archives of Physical Medicine and Rehabilitation.