A125: Effects of HD-tDCS Combined with Bosu Ball Training on Balance in Individuals with CAI

Abstract

Chronic ankle instability (CAI) is a prevalent condition characterized by postural instability, recurrent sprains, and maladaptive neuroplasticity in sensorimotor cortices. This study aimed to evaluate the effects of a 6-week intervention combining high-definition transcranial direct current stimulation (HD-tDCS) targeting the central nervous system regions (e.g., M1/S1 cortices) with Bosu ball training on balance in individuals with CAI. Forty participants with chronic ankle instability (CAI) were recruited and randomly assigned to HD-tDCS+Bosu (n=20) or Bosu (n=20) groups using a computer-generated sequence. The HD-tDCS+Bosu group received active HD-tDCS (2mA, 20min) combined with Bosu ball training, while the Bosu group received sham HD-tDCS paired with identical Bosu training. Both groups underwent the intervention for six weeks, with three 20-minute sessions per week. The data on the postural stability were assessed at baseline (week0) and post-intervention (week 7). The postural stability was quantified by the root mean square (RMS) of the center of pressure (CoP) displacement during the single-leg stance test on a force plate. Two-way ANOVA with repeated measures was adopted to analyze the data. Significant group-by-intervention interactions were detected in the CoP-RMSml (p =0.009, η²p = 0.205). Post hoc comparisons showed that compared with week0, CoP-RMSml was reduced at week 7 in both the HD-tDCS + Bosu group (week0: 14.207 ± 2.695, week7: 9.459 ± 2.260, p = 0.002, d = 1.203) and the Bosu ball training group (week0: 14.105 ± 2.514, week7: 12.315 ± 2.482, p = 0.025, d = 0.721). The HD-tDCS + Bosu group showed a greater decrease in CoP-RMSml (p = 0.003, d = 1.152). In addition, a main effect of time was observed for CoP-RMSap (p = 0.015, η²p = 0.183), with decreases in both groups (HD-tDCS + Bosu group: week0: 9.440 ± 1.442, week7: 8.473 ± 1.882; Bosu group: week0: 9.459 ± 2.272, week7: 8.576 ± 1.151 The 6-week HD-tDCS combined with Bosu ball training significantly enhanced postural stability in individuals with CAI, demonstrating greater efficacy than sham HD-tDCS paired with identical Bosu training. The combined neuromodulation-targeting intervention (M1/S1 cortices) achieved superior rehabilitation outcomes for central sensorimotor integration deficits. These findings substantiate the clinical value of dual-pathway interventions that synchronously enhance corticospinal plasticity and task-specific motor adaptation in CAI management