Effects of the site and extent of plantar cutaneous stimulation on dynamic balance and muscle activity while walking

• We examined the effect of zonal textured insoles on walking.
• Lateral stimulation of the rearfoot in the first half of gait changes the kinetics in the second half of the gait cycle.
• Medial stimulation of the rearfoot had no effect on kinetics in the gait cycle.
• Perturbed vision increased Centre-of-Pressure variability, indicating postural instability.

BackgroundPrevious studies have demonstrated that stimulating the cutaneous plantar sensory receptors of the foot through textured insoles improves human balance and walking. This study investigated the effect of medial and lateral zoned textured insoles using tibialis anterior/peroneus longus surface electromyographic activity and Centre-of-Pressure as indicators of postural stability while walking.Methods15 asymptomatic subjects were tested using a within-subject randomised repeated measures design. The effect of lateral and medial zoned insoles of varying heights (control, 2, 4 and 6 mm) on stability while walking under normal and impaired visual conditions was assessed.ResultsImpaired vision resulted in an increase in foot CoP variability while walking (p < 0.05). The laterally zoned insole was associated with a significant (repeated measures ANOVA p < 0.05) increase in the rate of medial–lateral CoP change.ConclusionThese findings suggest that the site of stimulation of the plantar foot cutaneous receptors may increase postural instability during walking. This should be considered in the design of insoles that aim to improve balance and reduce falls risk. The importance of vision in balance control has been highlighted and using impaired vision may serve as a way of trialling clinical products in the healthy population.