Visual Disruption Affects Physiology Complexity And Postural Control In People With Chronic Ankle Instability

PURPOSE: This study aimed to determine whether stroboscopic glasses(SG)-induced visual disruption could influence physiology complexity and postural control among people with chronic ankle instability (CAI). METHODS: Twenty-two people with CAI (18 male, 4 female, age = 21.9 ± 1.0 years, height = 173.8 ± 6.5 cm, body mass = 69.8 ± 12.9 kg; Cumberland Ankle Instability Tool (CAIT) score = 16.6 ± 1.4) and another twenty-two people without CAI (18 male, 4 female, age = 21.9 ± 0.8 years, height = 175.1 ± 8.9 cm, body mass = 73.2 ± 16.5 kg; CAIT score = 27.5 ± 1.0) were recruited. Their physiology complexity and postural control were represented by the sample entropy and the mean displacement of the plantar center of pressure (CoP)in the anteroposterior (AP) and mediolateral (ML) directions during single-limb standing.Larger sample entropy values represent more regular physiological complexity (i.e. more automated postural control), smaller mean displacements represent greater postural control.They were measured in two conditions with or without SG, during the SG conditions, SG were employed, operating at a frequency of 3 Hz, alternating between 0.100 seconds of clarity and 0.233 seconds of opacity. Two-way ANOVA with repeated measures was used to analyze data. RESULTS: The sample entropy of CoP in the anteroposterior (AP) direction (SG: 0.051 ± 0.029 mm, non-SG: 0.072 ± 0.068 mm, p = 0.012, d = 0.402) significantly decreased in people with CAI while remaining unchanged in those without CAI from non-SG to SG conditions. In addition, significant condition main effects were detected. From non-SG to SG conditions, people with and without CAI significantly decreased their sample entropy of CoP in the ML direction(p < 0.001, η2p = 0.327)and significantly increased their displacement of CoP in the AP(p = 0.002, η2p = 0.204) and ML direction(p = 0.003, η2p = 0.194)directions. CONCLUSIONS: Physiology complexity is affected by SG-induced visual disruption in people with CAI, but not in those without CAI. Additionally, our study found that sample entropy of CoP maybe can better differentiate between people with and without CAI compared to traditional CoP measures.