A152: Effect of Stroboscopic Visual Perturbation on Posture Control in Patients with Chronic Ankle Instability

Chronic ankle instability (CAI) is a common sports injury, often accompanied by reduced proprioception, muscle weakness, and impaired balance. Its etiology is often attributed to inadequate rehabilitation following initial ankle sprains, resulting in ligament laxity or damage. This study aimed to investigate whether stroboscopic visual disturbance influences static and dynamic postural control in individuals with CAI, thereby exploring the relationship between visual input and postural stability. Method: Thirty college students with unilateral CAI (9 males, 21 females; age: 21.3±1.2 years, height: 168.1±9.8 cm, weight: 63.5±11.6 kg) were recruited. Their static and dynamic postural control was measured in three conditions: eyes open (EO), eyes closed (EC), and stroboscopic vision (SV). Static postural stability was measured during single-leg standing and represented by maximum displacement of the plantar center of pressure (COP), average velocity in anteroposterior (AP) and mediolateral (ML) directions of COP. Dynamic postural stability was measured during the Y-balance, represented by the relative reach distance. One-way repeated measures ANOVA was conducted on the variables of interest to assess the main effect of visual conditions. For the Y Balance Test, significant reductions were observed under SV compared to EO conditions in anterior reach (EO: 0.68 ± 0.83 vs. SV: 0.62 ± 0.60, p < 0.05), posteromedial reach (EO: 1.04 ± 0.91 vs. SV: 0.96 ± 0.97, p < 0.05), posterolateral reach (EO: 1.10 ± 0.82 vs. SV: 1.02 ± 0.86, p < 0.05), and composite scores (EO: 0.94 ± 0.72 vs. SV: 0.87 ± 0.70, p < 0.05). For static postural control, COP maximum displacement and average velocity in the AP and ML directions exhibited significant differences between SV and EC conditions compared to EO (p < 0.05), though no significant differences were observed between SV and EC. Stroboscopic visual perturbation significantly compromised postural control in individuals with CAI. These results indicate that visual perturbation heightens injury risks in individuals with CAI, highlighting the necessity for targeted interventions addressing the visual system within rehabilitation programs.