ANKLE BRACES CHANGE THE SPECTRAL QUALITIES OF SWAY 154

Abstract

Ankle bracing has been reported to increase, decrease and not affect proprioception. Studies addressing bracing and proprioception have not attempted to isolate and measure the sensory modalities that control balance. The purpose of this study was to estimate sensory modality activity under selected ankle brace conditions: Active Ankle, AirCast, McDavid, and no brace. Twelve male volunteers (age = 18 to 26 yrs.) without ankle injuries served as subjects. AP and ML center of pressure values measured during three 16 second, one-legged, modified Romberg tests performed under six variations. The six variations were designed to systematically conflict or eliminate the three sensory modalities that control posture. Center of pressure data, from the first 12.8 seconds of data, were converted to the frequency domain using an FFT. Five frequency bands representing sensory modality activity were used:< 0.1 Hz, otolith, 0.1 - 5.0 Hz, semicircular canals, 0.03 - 0.3 Hz, vision 1, 0.5 - 1.0, vision 2, and 0.7 - 1.2 Hz, somatosensory. Mean amplitude within each band was used for analysis. We observed changes in spectral quality attributable to ankle bracing during AP sway only. Semirigid ankle braces cause less semicircular canal activity than no brace during AP sway (F(3,838)= 2.71, p = 0.04). Any type of ankle brace decreases the amount of vestibular activity (F(3,838) = 4.43, p < 0.001) and visual input necessary to control AP sway (F(3,838) = 4.99, p < 0.001). We conclude that, normal individuals may receive better somatosensory feedback when wearing ankle braces, thereby, reducing their reliance on the other systems. This finding supports the usage of ankle braces as a method to increase somatosensory feedback.