Vibratory stimulation applied to the soles of the feet reportedly improved balance in older adult study participants, reducing postural sway and gait variability.

The findings appear in the Archives of Physical Medicine and Rehabilitation.

According to a news release from Peters Communications, the vibratory stimulation is delivered by a urethane foam insole with embedded piezoelectric actuators, which generates the mechanical stimulation. The study was conducted by researchers hailing 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, and Harvard Medical School, all in Boston; and Merck Sharpe and Dohme (MSD) Consumer Care Inc, of Memphis, Tennessee.

The release emphasizes the study’s findings in light of the direct relation between poor balance and irregular gait with fall risk.

According to Lewis Lipsitz, MD, while the loss of sensation in the feet is a common issue among older adults that can impair balance and gait and result in falls, there are currently no interventions available that can reverse sensory impairments and prevent the dangerous consequences of falls.

“We are very excited to discover that small amounts of vibratory noise applied to the soles of the feet may be able to do just that,” Lipsitz says.

The release notes that the current study follows up on earlier research that examined how the physical principle of stochastic resonance could be applied to mitigate deficits in the human somatosensory systems that develop due to injury, disease, or age.

Additionally, earlier studies conducted by Wyss Institute Core Faculty member James Collins, PhD, a professor of Medicine and Biomedical Engineering at Boston University, indicate that imperceptible vibratory noise applied to the feet can improve balance in healthy young and older adult subjects, as well as patients with stroke and diabetic neuropathy. IFAR researchers, the release says, demonstrated that this approach could significantly reduce the stride-, stance-, and swing-time variability exhibited in walking by older adults with a history of falls. Yet, the devices that delivered the stimulation in the earlier IFAR studies required large energy sources.

After experiments were conducted on these early devices, the device was completely redesigned by Wyss Institute researchers to use piezoelectric actuators to improve portability and energy efficiency. Piezoelectric actuators are designed to convert electrical energy into mechanical signals, such as pressure or movement of some kind, the release says. These actuators, when inserted into a typical insole using a standard manufacturing process, are driven by a small encasement on the tongue of the shoe that contains a tiny circuit and rechargeable battery.

The current study encompassed a total of 12 older adult volunteers in good health, between the ages of 65 and 90 years old. Two piezoelectric actuators were placed in the medial arch region of commonly available insoles to deliver the vibratory stimulation. The participants then underwent a battery of tests that measured their balance and assessed their gait. The release states that they were also given a timed “Get Up and Go” test.

The release reports that the study’s results suggest the vibratory insoles significantly improved performance on the timed “Get Up and Go” test, which reduced the range of postural sway and reduced the variability of walking. Additionally, researchers say, the effect of the insoles persisted throughout the day.

[Source(s): EurekAlert, Institute for Aging Research, Hebrew SeniorLife]