Chronic ankle instability (CAI) poses challenges in sports. Textured insoles are a promising intervention for optimizing ankle muscle activity and enhancing ankle proprioceptive ability in individuals with CAI. This study investigated the effects of different types of insoles on ankle muscle activity and ankle inversion proprioception during drop-landing tasks. Thirty-two soccer players (16 CAI, 16 non-CAI) participated in the study. Electromyographic (EMG) activity of the tibialis anterior (TA), medial gastrocnemius (MG), and peroneus longus (PL) muscles was recorded during drop-landing tasks using the ankle inversion discrimination apparatus for landing (AIDAL) with textured insoles (TI) and standard flat insoles (SI). Ankle inversion proprioception was assessed using the AIDAL. Muscle activity was analyzed for pre- and initial contact phases. CAI players showed significantly reduced TA activity compared to non-CAI players during both pre-initial (2.62 ± 1.86 vs. 5.53 ± 5.15; p = 0.04) and initial contact phases (18.7 ± 13.6 vs. 29.9 ± 20.6; p = 0.01). CAI players also exhibited greater MG activity during pre-initial (16 ± 6.15 vs. 12.5 ± 6.38; p = 0.03) and initial contact phases (60.8 ± 32.5 vs. 41.5 ± 14.8; p = 0.004), and higher PL activity during the pre-initial contact phase (7.39 ± 4.75 vs. 4.28 ± 2.83; p = 0.003). No significant CAI/insole main effects or interactions (p > 0.05) were observed in AIDAL proprioceptive scores. Overall, CAI players showed significant alterations in ankle muscle activity during drop-landing tasks. Increased PL activity during the pre-initial contact phase may serve as a compensatory strategy to enhance ankle stability, while reduced TA and increased MG activation during pre-initial and initial contact phases may contribute to the high incidence of recurrent ankle sprains in CAI individuals. Additionally, the lack of immediate effects from insoles on muscle activity suggests that their influence on sensory input and foot positioning may require prolonged use to induce measurable neuromuscular adaptations.
