The effects of vibrating shoe insoles on standing balance, walking, and ankle-foot muscle activity in adults with diabetic peripheral neuropathy

Background: Peripheral neuropathy is one of the most common complications of type 2 diabetes, which can lead to impaired balance and walking. Innovative footwear devices designed to stimulate foot sensory receptors, such as vibrating insoles, could offer a new route to improve motor impairments in people with diabetic peripheral neuropathy (DPN). Research question: Does wearing vibrating insoles for the first time alter measures of balance, walking, and anklefoot muscle activity, in people with DPN? Methods: A randomised cross -over study was conducted with 18 ambulant men and women with a diagnosis of DPN. Participants performed tests of standing balance (Bertec (R) force platform) under four conditions (foam/firm surface, eyes open/closed) and level-ground walking (GAITRite (R) instrumented walkway), whilst wearing vibrating and non-vibrating (control) insoles on two separate occasions (one insole/session). Electromyography (EMG) was used to assess soleus, medial gastrocnemius, tibialis anterior, peroneus longus activity during balance tests. Outcomes included centre of pressure (CoP) sway, EMG amplitude, spatiotemporal gait patterns, and Timed Up and Go test. One sample t-tests were used to explore %differences in outcomes between insole conditions. Results: Wearing vibrating insoles led to a reduction (improvement) in CoP elliptical area, when standing on a foam surface with eyes closed, relative to non-vibrating insoles ( P =0.03). Applying perceptible vibrations to the soles of the feet also reduced the EMG amplitude in soleus ( P =0.01 and P =0.04) and medial gastrocnemius ( P =0.03 and P =0.09) when standing with eyes closed on firm and foam surfaces. Significance: Our findings of signs of improved balance and altered muscle activity with suprasensory vibrating insoles provides new insights into how these devices can be used to inform innovative rehabilitation approaches in individuals with DPN. This will be strengthened by further research into possible clinical benefits of these devices - given that the effects we detected were small with uncertain clinical meaning.