Peroneal architecture may predispose individuals to the impaired ankle function that leads to chronic ankle instability (CAI). But, it is unclear if CAI individuals exhibit different peroneal and ankle function than healthy controls. This study determined peroneal muscle architecture and dynamic ankle function for 30 (12 CAI, 18 CON) participants. Each participant had peroneal architecture (physiological cross-sectional area (PCSA), volume, stiffness), ankle strength (both maximum dorsiflexion and eversion), and ankle biomechanics (peak plantarflexion and negative ankle work during a 30 cm drop landing) quantified. Each variable was submitted to independent t-tests to determine group differences and linear discriminant analysis to determine whether peroneal architecture and dynamic ankle function could accurately identify CAI status. CAI individuals exhibited weaker dorsiflexors (p=0.049), but no differences in peroneal architecture (PCSA p=0.546, volume p=0.488, stiffness p=0.653) or ankle function (negative work p=0.383, peak plantarflexion rotation p=0.958). Yet, 75% (9/12) of CAI and 66.7% (12/18) of CON participants were accurately identified from peroneal muscle architecture and dynamic ankle function. Considering 75% of CAI individuals were accurately identified, specific peroneal and ankle function measures may predispose individuals to CAI
