Changes in Star Excursion Balance Test Performance After Balance Training Alone Versus Combined Balance and Plyometric Training In Recreational Athletes With Functional Ankle Instability

Abstract

Background: Persistent symptoms and recurrent episodes of giving way after lateral ankle sprain are commonly conceptualized within chronic ankle instability (CAI), a heterogeneous condition involving sensorimotor, mechanical, and perceptual deficits. Evidence supports balance exercise for improving dynamic postural control, but it remains unclear whether adding plyometric exercise provides additional benefit beyond balance training alone.

Objective: To describe changes in Star Excursion Balance Test (SEBT) reach distance after 6 weeks of balance training alone or combined balance and plyometric training in recreationally active men with unilateral functional ankle instability, and to distinguish within-group improvements from evidence of a comparative between-group treatment effect.

Methods: Eighteen recreationally active men with unilateral functional ankle instability (mean age, 22.6 ± 1.8 years) were allocated by a closed-envelope number draw to balance training (n = 9) or combined balance and plyometric training (n = 9). Anterior, posterolateral, and posteromedial SEBT reach distances were measured before and after 6 weeks, and the mean of three successful trials in each direction was analyzed. No formal a priori sample-size calculation was available for review. Because participant-level outcome data and the variance-covariance information required for a valid group-by-time analysis were unavailable, the reported within-group tests were treated as descriptive. An explicitly exploratory sensitivity analysis was then used to reconstruct between-group change estimates from reported summary statistics.

Results: In the balance-training group, posterolateral reach increased from 74.4 to 83.6 cm (+12.4%; p = 0.026), whereas anterior reach changed from 77.8 to 79.1 cm (+1.7%; p = 0.280) and posteromedial reach from 67.8 to 69.2 cm (+2.1%; p = 0.685). In the combined-training group, anterior reach increased from 75.2 to 83.8 cm (+11.4%; p = 0.030), posterolateral reach from 76.3 to 85.4 cm (+11.9%; p = 0.018), and posteromedial reach from 69.3 to 77.5 cm (+11.8%; p = 0.042). Exploratory reconstructed between-group differences in change (combined minus balance) were +7.3 cm for anterior reach (95% CI, approximately -0.4 to 15.0; p approximately 0.061), -0.1 cm for posterolateral reach (95% CI, approximately -9.8 to 9.6; p approximately 0.983), and +6.8 cm for posteromedial reach (95% CI, approximately -3.3 to 16.9; p approximately 0.172).

Conclusion: Posterolateral SEBT reach improved descriptively in both groups, whereas improvements across all three directions were observed only within the combined-training group. However, the available data do not establish that adding plyometric exercise is superior to balance training alone because the original participant-level group-by-time analysis could not be reproduced and the reconstructed comparative estimates were imprecise. These findings should therefore be regarded as hypothesis-generating.