Kinematic and muscle synergy patterns of the lower limbs during jump-landing with side-cutting in individuals with functional ankle instability

Individuals with FAI adopt a protective movement strategy characterized by increased flexion and abduction to enhance stability. Muscle synergy analysis reveals an asymmetric activation pattern with reduced early activation, prolonged late compensation, and a proximal-dominant, delayed distal control pattern. Although the Coper group demonstrates movement characteristics more similar to healthy controls, mild over-flexion and delayed responses remain.