Biomechanical analysis during non-anticipated stop-jump cutting before and after exercise fatigue in functional ankle instability and healthy populations

• Exercise fatigue increases ankle inversion and alters lower limb joint kinematics during stop-jump cutting, particularly in individuals with functional ankle instability. • Fatigue reduces hip, knee, and ankle joint stiffness, impairing dynamic stability and shock absorption, especially in the functional ankle instability group. • Statistical parametric mapping revealed time-specific changes in ankle angle and ground reaction forces, highlighting critical phases of increased injury risk. • Functional ankle instability individuals exhibit altered movement patterns under fatigue, potentially explaining their higher risk of recurrent ankle sprains.