Contributing factors to Star Excursion Balance Test performance in individuals with chronic ankle instability

The purpose of this study was to determine the contributions of strength, dorsiflexion range of motion (DFROM), plantar cutaneous sensation (PCS), and static postural control to Star Excursion Balance Test (SEBT) performance in individuals with chronic ankle instability (CAI). Forty individuals with CAI completed isometric strength, weight-bearing DFROM, PCS, static and dynamic balance assessments. Three separate backward multiple linear regression models were calculated to determine how strength, DFROM, PCS, and static postural control contributed to each reach direction of the SEBT. Explanatory variables included dorsiflexion, inversion, and eversion strength, DFROM, PCS, and time-to-boundary mean minima (TTBMM) and standard deviation (TTBSD) in the medial-lateral (ML) and anterior-posterior (AP) directions. Criterion variables included SEBT-anterior, posteromedial, and posterolateral directions. The strength of each model was determined by the R²-value and Cohen's f² effect size. Regression models with an effect size ≥0.15 were considered clinically relevant. All three SEBT directions produced clinically relevant regression models. DFROM and PCS accounted for 16% of the variance in SEBT-anterior reach (f²=0.19, p=0.04). Eversion strength and TTBMM-ML accounted for 28% of the variance in SEBT-posteromedial reach (f²=0.39, p<0.01). Eversion strength and TTBSD-ML accounted for 14% of the variance in SEBT-posterolateral reach (f²=0.16, p=0.06). DFROM and PCS explained a clinically relevant proportion of the variance associated with SEBT-anterior reach. Eversion strength and TTB ML explained a clinically relevant proportion of the variance in SEBT-posteromedial and posterolateral reach distances. Therefore, rehabilitation strategies should emphasize DFROM, PCS, eversion strength, and static balance to enhance dynamic postural control in patients with CAI.