Muscle co-contraction, defined as the simultaneous action of agonist and antagonist muscles crossing the same joint, 9 is the mechanism that participates in the regulation of joint stiffness 10 and postural stability. 8 however, inappropriate and excessive co-contraction may impair gait performance by reducing gait speed and increasing metabolic cost. 10, 11 the estimation of muscle co-contraction is a useful clinical tool to better understand how pathology can affect the muscle strategies during gait. 12 Whereas co-contraction is related to the ratio of agonist/antagonist muscle s troke is the leading cause of long-term disability. 1 hemiparesis is one of the most common impairments after stroke that contributes significantly to reduce gait performance. 2 a percentage of 52 to 85 of hemiparetic patients regain their capacity to walk, but their gait pattern is different from that of healthy individuals. 3 hemiparetic gait is characterized by reduced speed, cadence, and stride length; 4, 5 asymmetry in temporal, spatial, kinematic, and kinetic gait variables; 6, 7 and abnormal muscle co-contraction. 8