Fig. 1

Biofeedback system. a Participants walked on an instrumented treadmill with a thin divider to more accurately detect left and right heel strikes. Reflective markers were attached to the ankles to measure step length at heel strike. b Example asymmetry conditions for individuals with chronic stroke. Both left and right step length targets were adjusted to achieve the correct step length asymmetry while keeping the summation of left and right step lengths constant. c An example of a step that hit the target. As the right leg moved forward, the gray bar grew proportionally. The participant’s heel strike occurred when the gray bar reached the step length target, and the target exploded to indicate correct step length. The yellow bar for the right leg changed position to show where the step length occurred for the next right step length. d An example of a step that missed the target. As the participant moved the left leg forward, the left gray bar grew proportionally. The participant’s heel strike was before the target, and the target turned red. The yellow bar was adjusted to show the left step length, indicating to the participant to take a longer left step