Longer reaction time in peroneal muscles in chronic ankle instability: Mechanoreceptor signaling delay as a primary contributor over nerve conduction Prolongation-A cross-sectional cohort study

Chronic ankle instability (CAI) is associated with longer peroneal- muscle reaction time (PRT), with two hypotheses explaining its mechanism: (1) delayed mechanoreceptor signaling during sensory encoding, or (2) prolonged nerve conduction during signal transmission. This study aimed to distinguish whether longer PRC in CAI individuals arises from mechanoreceptor signaling delay or nerve conduction prolongation. Cross-sectional cohort study. Thirty-one participants with CAI (5 females and 26 males, age = [21.0 ±1.6] yr, height = [177.5 ± 8.5] cm, mass = [69.8 ± 12.7] kg, CAIT = [15.1 ± 4.8]) and 32 controls (4 females and 28 males, age = [21.7 ± 1.8] yr, height = [176.2 ± 1.6] cm, mass = [68.7 ± 10.7] kg, CAIT = 29.3 ± 0.7) were recruited from Shandong Sport University from July to September 2024. PRT was measured via trapdoor tests, the nerve conduction time was measured via H-reflex tests, and the mechanoreceptor signaling time was calculated as the difference between the PRT and nerve conduction time. Independent-sample t-tests were used to detect between-group differences. CAI individuals showed significantly longer PRT ([85.6 ± 18.9] ms vs. controls. [70.3 ± 7.1] ms, p < 0.001) and mechanoreceptor signaling time ([42.9 ± 19.0] ms vs. [28.9 ± 9.7] ms, p < 0.001) than controls, with no significant difference in nerve conduction time ([42.7 ± 5.6] ms vs. [41.3 ± 5.4] ms, p = 0.314). People with CAI exhibit delayed mechanoreceptor signaling without prolonged nerve conduction in peroneal muscles.