Effects of External Ankle Support on Plantar Flexed Inversion

Abstract

PURPOSE: To prevent ankle injury, many athletes wear external ankle support. The majority of studies examining ankle support, however, have not tested braces at the position in which ankle injury most often occurs; plantar flexed inversion (Verhagen, et al. 2001; Wiley & Nigg, 1996). The purpose of this study was to test two non-rigid stabilizers, the McDavid Lightweight® brace (ML) and Bioskin TriLock® brace (BT), at two plantar flexion (PF) angles and determine the effects of the two braces on ankle inversion, both in pre and post exercise conditions. METHODS: Fourteen subjects were tested while standing at 20° and 30° of PF on an inversion platform, which inverted to 35°. All subjects performed all conditions, including a bare ankle condition (platform angles x brace x pre/post exercise). Ten trials were performed for each condition. A Biometrics twin axis electrogoniometer (1000 Hz) were used to record maximum inversion (ROM), maximum inversion velocity (Vmax) and time to maximum inversion (Trom) via Datapac Software (Run Technologies). Data were filtered at 18 Hz and analyzed via a 2 × 3 × 2 repeated measures ANOVA. IRB approval was obtained and participants signed consent forms. RESULTS: Statistically significant differences were noted between brace and angle conditions for ROM and Vmax. ROM was on average 12% lower for the two brace conditions, and Vmax was lower by 18%, at 30° PF in comparison to 20° PF. Both brace conditions had significantly lower Vmax than the bare ankle condition (24%), but not from each other. However, ROM was not significantly different between the braces and bare ankle, although the BT brace did decrease ROM by 12% and 9%, respectively, to the bare ankle and ML brace at the 20° angle. No significant differences were noted for pre to post exercise, nor for time to max inversion. CONCLUSION: The two braces appear equally effective in keeping the rate of inversion lower, for both PF angles. The differences noted between PF conditions were interesting, considering the ankle is considered to be less stable with greater PF, but the ROM and Vmax were less in the greater PF condition, regardless of brace or no brace. The BT brace may be slightly better at reducing ROM at 20° PF angle, but the actual change in ROM was small. Personal preference of brace style showed an even split PMong participants.