A144: Effect of Reduced Plantar Cutaneous Sensation on Balance ControlAmong People with Chronic Ankle Instability

<bold>PURPOSE:</bold> This study aimed to determine whether reduced plantar cutaneous sensation could influence static balance control among people with and without chronic ankle instability (CAI). <bold>METHODS:</bold> Thirty-one people with CAI (female=7, age=22.03±1.73 years, height=174.41±9.83 cm, body mass=71.79±14.95 kg) and twenty-nine people without CAI (female=5, age=22.86±1.59 years, height=172.81±7.99 cm, body mass=69.04±11.32 kg) were recruited. Static balance controls were represented by the mean displacement of the center of pressure (CoP) in the anteroposterior (AP) and mediolateral (ML) directions on a force plate during unilateral standing with eyes open. The participants placed their bare foot on shaved ice for 10 minutes to reduce plantar cutaneous sensation. Plantar cutaneous sensation at the 5th metatarsal was measured with a set of twenty Semmes-Weinstein monofilaments (SWM) to confirm reduced sensation levels. A higher value of SWM indicated a decreased sensation and higher threshold. Plantar cutaneous sensation threshold and standing tests were conducted before (pre-ice) and after (post-ice) ice immersion. Two-way repeated ANOVA tests were used to analyze data. <bold>RESULTS:</bold> Plantar cutaneous sensation threshold in the CAI group (pre-ice: 3.11±0.34 gauge, post-ice: 4.15±0.29 gauge, <italic>p</italic> &lt; 0.001, <italic>d</italic>=3.29) and non-CAI group (pre-ice: 2.95±0.34 gauge, post-ice: 4.10±0.34, <italic>p</italic> &lt; 0.001, <italic>d</italic>=3.38) significantly increased after ice immersion, indicating a significant reduction in the plantar cutaneous sensitivity. A significant interaction was detected in the mean displacement of CoP in the AP direction (<italic>p</italic> = 0.047, η² = 0.069). Compared to pre-ice, the mean CoP displacement in the AP direction (pre-immersion: 7.29±0.22, post-immersion: 6.62±0.22, <italic>p</italic> = 0.002, <italic>d</italic> = 3.05) decreased in the CAI group while remaining unchanged in the control group after ice immersion. <bold>CONCLUSION:</bold> The reduction in plantar cutaneous sensation induced by ice immersion enhanced static balance control in individuals with CAI, with no observable effect on those without CAI. The results of this study suggest that people with CAI produced adaptive changes compared to people without CAI, which allows them to maintain balance to avoid injury.