How do humans perform complex physical actions without consciously thinking about the position of their arms and legs in space? Through a sensory process called proprioception. Specialized nerve receptors called proprioceptors throughout the body–including the muscles, joints, tendons, skin, and inner ear–sense physiological information and relay it back to the brain’s motor control centers. Proprioceptors respond to pressure, touch, and pain, and also vibration.
Proprioception deteriorates as people age, which likely contributes to standing instability and loss of balance associated with aging. Several studies suggest that poor proprioception contributes to lower back pain, a condition common in older adults. Researchers at the Nagoya Institute of Technology in Japan have designed a device and protocol that stimulates proprioceptors using controlled external vibration therapy. The research team completed a pilot study that suggests their system may improve lower back pain in seniors.
Conducted over three months and published in the journal Electronics, the study involved six older individuals suffering from low back pain. The new system consists of a balance board and vibration devices that interface with a computer. The researchers first assessed the balance of each individual while standing on a balance board before strapping the devices to the participant’s legs and trunk.
The team explored a range of vibration frequencies to determine how many cycles per second were needed to improve proprioceptive function. During each session, the team increased the vibrations from 20 Hz to 300 Hz and recorded the postural response of each patient. At the end of the session, the researchers removed the devices, comparing proprioceptive postural control before and after the treatment.
Over the course of the study, three participants showed that higher vibration frequencies improved their proprioceptive control. Because these early-stage findings suggest the protocol could improve lower back pain, the researchers began a larger clinical trial. The 3-year study, which started in April 2021, will further investigate their system’s potential as a treatment for low back pain and a tool for diagnosing poor proprioceptive function. This could lead to a non-pharmaceutical approach to treating back pain while also potentially reducing the risk of fall for seniors.