Background: Chronic ankle instability (CAI) is a common peripheral joint injury and there is still no consensus on the mechanisms. It is necessary to investigate electrocortical parameters to provide clinical insight into the functional alterations of brain activity after an ankle sprain, which would greatly affect the implementation of rehabilitation plans. The purpose of this study was to assess cortical activation characteristics during drop-jump landing among soccer athletes with CAI. Methods: A total of 24 participants performed the drop-jump landing task on a force platform while wearing a 64-channel EEG system. The differences of power spectral density (PSD) in theta and alpha (alpha-1 and alpha-2) bands were analyzed between two groups (CAI vs. CON) and between two limbs (injured vs. healthy). Results: CAI participants demonstrated significantly higher theta power at the frontal electrode than that in healthy control individuals (F_(1,22) = 7.726, p = 0.011, η²p = 0.260). No difference in parietal alpha-1 and alpha-2 power was found between groups (alpha-1: F_(1,22) = 0.297, p = 0.591, η²p = 0.013; alpha-2: F_(1,22) = 0.118, p = 0.734, η²p = 0.005). No limb differences were presented for any frequency band in selected cortical areas (alpha-1: F_(1,22) = 0.149, p = 0.703, η²p = 0.007; alpha-2: F_(1,22) = 0.166, p = 0.688, η²p = 0.007; theta: F_(1,22) = 2.256, p = 0.147, η²p = 0.093). Conclusions: Theta power at the frontal cortex was higher in soccer athletes with CAI during drop-jump landing. Differences in cortical activation provided evidence for an altered neural mechanism of postural control among soccer athletes with CAI.

This study aimed to evaluate the impacts of a 4-week transcranial direct current stimulation (tDCS), balance training (BT), and an integrated program combining tDCS with BT on static and dynamic postural control in athletes suffering from chronic ankle instability (CAI); as well as to explore whether the combined program produces superior effects compared to either single intervention. Forty athletes with CAI were randomized into four groups: tDCS group, sham tDCS (s-tDCS) group, tDCS + BT group, and s-tDCS + BT group. Twenty minutes of 2 mA anodal or sham tDCS was applied either independently or in conjunction with a 20-minute progressive hop-to-stabilization balance (PHSB) training program over 12 supervised sessions spanning 4 weeks. Primary outcomes were the total score of the Balance Error Scoring System (BESS) and the composite reach distance (COMP) in the Y-Balance Test (YBT). Secondary outcome measures included error scores of single-limb and tandem stance on firm and foam surfaces, as well as mean normalized reach distances in the anterior (ANT), posteromedial (PM), and posterolateral (PL) directions. Compared to baseline measures, the tDCS, tDCS + BT, and s-tDCS + BT groups scored fewer errors on posttest measures for single-leg stance on a firm surface (Sfi), single-leg stance on a foam surface (Sfo), tandem stance on a firm surface (Tfi), tandem stance on a foam surface (Tfo), and the total BESS (p < 0.05). Additionally, both the tDCS + BT and the s-tDCS + BT groups showed greater PM, PL, and COMP in posttest measures compared to pretest measures (p < 0.05). However, no significant differences were found among the tDCS group, the tDCS + BT group, and the s-tDCS + BT group in the posttest measures (p > 0.05). tDCS, BT, and the combination of these two interventions can significantly improve static postural stability in athletes with CAI. However, only intervention methods incorporating BT were effective in enhancing dynamic stability. The combined program offered no additional benefits.

Our understanding of the impact of chronic ankle instability (CAI) on dynamic postural stability remains limited, primarily due to the absence of reliable