Region-specific textured insoles enhance static stability in young adults with chronic ankle instability

Chronic ankle instability (CAI) impairs postural control through sensorimotor deficits, yet region-specific plantar stimulation strategies remain underexplored. This randomised crossover trial examined the differential effects of textured insoles targeting specific foot regions on static and dynamic stability in 24 young adults with CAI (age: 22.3 ± 2.5 years; Cumberland Ankle Instability Tool score: 16.0 ± 3.3). Participants completed three functional assessments (static single-leg stance, Y-balance test, and jump-landing task) under four experimental conditions: forefoot-textured, midfoot-textured, rearfoot-textured, and smooth control insoles. Results showed that forefoot-textured insoles significantly improved static postural control, reducing total centre of pressure (COP) sway velocity by 8.9 % (54.2 ± 11.7 vs. 49.4 ± 9.3 mm/s, p = 0.024) and COP ellipse area by 15.6 % (223.6 ± 60.8 vs. 188.8 ± 48.3 mm², p = 0.012) compared to control. However, no significant improvements were observed in dynamic stability metrics during jump landing (all p > 0.05) or Y-balance test composite scores (p = 0.075). Subjective stability and comfort ratings did not significantly differ across conditions (p > 0.05). These findings indicate an acute, task-dependent effect of plantar stimulation; the apparent forefoot advantage may reflect a general cutaneous facilitation of balance rather than a CAI-specific mechanism. Dynamic tasks may require complementary training or longer exposure, and the clinical significance remains to be established.