VIBRATION OF THE FOOT SOLE AS AN INTERVENTION TO IMPROVE OLDER ADULTS’ POSTURAL STABILITY
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Increase of postural instability is one of the significant issues related to aging, due to its relevance concerning risk for falls and associated impacts on life quality and health care costs in the U.S. Sub-threshold vibration stimulation, a passive, non-invasive countermeasure to sensorimotor decline has shown promising results related to the improvement of stability in healthy older adults and in neuropathic patients. To date, no studies have systematically investigated the potential benefits or functional limitations of this vibration intervention, and potential interactions with healthy aging processes in more demanding postural tasks. Those tasks mimic real-life situations where postural stability is challenged and actual falls might occur in older adults. The objectives of this study were to compare postural performance and control characteristics between older and younger healthy individuals, and to investigate potential changes when a vibration intervention is introduced. The effects of aging, foot sole vibration, and potential interactions were investigated in (1) a sensory conflict postural task, (2) a dual-task environment, and (3) a postural perturbation task (support surface translation). The study was performed on 10 younger adults (25.1±2.3 years) and 10 older adults (78.6±5.4 years). Vibration to the feet was delivered via custom-made rubber soles with embedded vibrotactile chips. Results indicate that (1) sensory conflict task characteristics are associated with age and vibration affects specific postural outcomes in the older group; the intervention improves postural performance when conflicting visual information is provided; (2) specific outcomes are associated with age in dual-tasking, but vibration does not affect those outcomes; (3) age is associated with specific spatial outcome measures when a postural perturbation is introduced, older adults are able to maintain stability, although they allow for more sway throughout the task; vibration does not affect performance or control characteristics. The study provides novel insight about the potential of sub-threshold vibration to the feet, and its effects on two different age groups. More research is needed to evaluate the potential of vibrating soles in more severely (balance-) impaired individuals.