Inclusion Criteria:  at least 6 months since stroke three or fewer incidents of unilateral stroke confirmed by taking the participant's medical history ability to follow the researcher's instructions the ability to flex and extend the paretic lower limb and ankle Modified Ashworth Score (MAS) ≦3 for the ankle joints a Mini-Mental State Examination (MMSE) score of 24 or higher no other orthopedic or neurological disorders Brunnstrom stage 4 no participation in other experimental rehabilitation or drug studies  Exclusion Criteria:  unstable cardiovascular conditions uncontrolled hypertension (190/110 mm Hg) severe orthopedic or pain conditions dementia (Mini-Mental State Examination score < 22) aphasia with inability to follow researcher's commands Visual dysfunction severe joint contracture of bilateral lower limb extremities that would impact the movement performance of the lower limb extremities