Effects Of Combined Transcranial-direct-current-stimulation With Bosu-ball-training On Cortical Activation Among People With Chronic Ankle Instability

PURPOSE: Maladaptive changes have been detected in the premotor cortex (PMC) and supplementary motor area (SMA) among people with chronic ankle instability (CAI), which is related to impaired motor performance. Transcranial-direct-current-stimulation (tDCS) is an effective way in directly modulating brain activities. Combined tDCS with physical training might modulate brain activities more significantly than applied tDCS alone. Bosu ball training (BBT) is one of the common rehabilitation methods for CAI. Therefore, this study aims to explore the effects of combined tDCS with BBT on the cortical activation of PMC & SMA among people with CAI. METHODS: Thirty-one participants with CAI were recruited and randomly divided into the tDCS+BBT group (n = 17, 20.1 ± 1.3 years, 175.3 ± 8.2 cm, and 71.14 ± 8.35 kg) and BBT group (n = 13, 21.2 ± 1.7 years, 173.2 ± 11.9 cm, and 68.9 ± 11.6 kg), who completed 6 weeks of tDCS combined with BBT or sham tDCS combined with BBT intervention. Before (week0) and after (week7) the intervention, the hemodynamic data in the PMC & SMA (channel 1-4, 11-14) were measured using a functional near-infrared spectroscopy system during single-leg stance (SLS). Two-way ANOVA with repeated measures were used to analyze data. RESULTS: Significant group-by-intervention interaction were detected in channel 3,12 (p = 0.047, η2p = 0.154). Post hoc analysis showed that average change values of oxyhemoglobin (ΔHbO2, mmol*10-7) increased in the tDCS+BBT group (week0 = -2.17 ± 3.55; week7 = 1.65 ± 3.10, p = 0.007, d = 1.146) while remained unchanged in the BBT group (week0 = -0.07 ± 3.66; week7 = -0.21 ± 3.66, p > 0.05) from week0 to week7. Significant time effects were detected in channel 1,11 (p = 0.017, η2p = 0.188) and channel 4,14 (p < 0.001, η2p = 0.319). Average ΔHbO2 increased in both groups in channel 1,11 (tDCS+BBT group: week0 = -1.60 ± 2.82; week7 = 0.13 ± 2.33; BBT group: week0 = -0.98 ± 3.22; week7 = 0.85 ± 3.17, p = 0.017, η2p = 0.188) and channel 4,14 (tDCS+BBT group: week0 = -2.19 ± 4.07; week7 = 0.93 ± 2.81; BBT group: week0 = -1.47 ± 2.38; week7 = 0.69 ± 2.76, p = 0.001, η2p = 0.319). CONCLUSIONS: BBT can improve the cortical activation of PMC & SMA in channel 1,11 and 4,14 among people with CAI during SLS. The application of concurrent tDCS had an additional effect, reflected by more enhanced activation in channel 3,12 than BBT alone.