Decoding Dynamic Postural Control: Diagnostic Insights From Y-Balance Test and Force Plate Measures in Chronic Ankle Instability Publisher



Khanmohammadi R ; Sarkhosh S S ; Beyraghi Z ; Faghihi R
Source: BMC Sports Science, Medicine and Rehabilitation Published:2026

Abstract

Background: Chronic ankle instability (CAI) impairs dynamic balance and anticipatory postural control, yet the diagnostic utility of clinical versus laboratory-based measures remains unclear. Objectives: To compare dynamic balance and anticipatory postural adjustments (APAs) during gait initiation (GI) between athletes with CAI and healthy controls, and to evaluate the diagnostic accuracy of the Y-Balance Test (YBT) and force plate–derived center-of-pressure (COP) parameters. Methods: Sixty-two athletes with CAI and 31 healthy controls completed the YBT in three directions—anterior, posteromedial (PM), and posterolateral (PL)—as well as force plate assessments of COP displacement and velocity during the anticipatory phase of GI. Receiver operating characteristic (ROC) analyses were used to evaluate the discriminatory power of each measure. Results: Both higher and lower CAI participants showed significantly reduced PM and PL reach performance compared with healthy controls (p < 0.001; ηp² = 0.250–0.531), while only the higher-instability group showed a deficit in anterior reach (p = 0.002). ML COP displacement and velocity were also lower in both CAI groups (p ≤ 0.033; ηp² = 0.073–0.554). No significant differences were found between the CAI subgroups, and AP COP measures were non-significant, with low power. ROC analyses showed that PL reach had the highest diagnostic accuracy (area under the curve [AUC] = 0.957; sensitivity = 0.905; specificity = 0.900), followed by PM reach (AUC = 0.857). ML COP velocity also demonstrated good diagnostic ability (AUC = 0.783). Neither YBT nor COP measures effectively distinguished higher- from lower-instability CAI. Conclusions: Posterior directions of the YBT, particularly the PL reach, and ML COP velocity are the most reliable indicators for identifying balance deficits associated with CAI. Clinically, the PL YBT provides a practical, high-accuracy screening tool, while COP measures offer complementary mechanistic insights. Integrating both clinical and laboratory assessments may enhance evaluation, although routine field screening can rely primarily on the YBT. Trial registration: IRCT20210604051488N1 registered on 2021-06-28. © The Author(s) 2026.