Plantar pressure measurements and surface electromyography (EMG) were used to determine the effects of muscular fatigue induced by high-heeled gait. The medio-lateral (M/L) stability of the foot was characterized by measuring the M/L deviations of the center of pressure (COP) and correlating these data with fatigue of lower-limb muscles seen on EMG. EMG measurements from habitual high-heeled shoe wearers demonstrated an imbalance of gastrocnemius lateralis versus gastrocnemius medialis activity in fatigue conditions, which correlated with abnormal lateral shifts in the foot-ground or shoe-ground COP of these women.