A new electromyography (EMG)-driven neuromuscular electrical stimulation (NMES)-cycling system is introduced to stroke survivors for lower-limb rehabilitation. The system will generate NMES to targeted muscle according to the user's voluntary intention, represented by the EMG signal during cycling.

Inclusion Criteria:

1. diagnosis of ischemic brain injury or intracerebral hemorrhage shown by magnetic resonance imaging or computed tomography after the onset of stroke;
2. sufficient cognition to follow simple instructions as well as understand the content and purpose of the study;
3. significant gait deficit (Functional Ambulatory Category, FAC, scale <4 [person cannot walk independently]).

Exclusion Criteria:

1. any additional medical or psychological condition that would affect their ability to comply with the study protocol, e.g., a significant orthopedic or chronic pain condition, major post-stroke depression;
2. severe hip, knee or ankle contracture that would preclude passive range of motion of the leg;
3. implanted cardiac device (e.g. pacemaker and internal defibrillator).