Sideways Treadmill Training to Improve Paretic Leg Stepping in Persons Post-Stroke

Stroke survivors living in the community are at high risk for falling. Falls are considered to be one of the most prevalent post-stroke complications. Fall history in this population has been associated with developing activity limitation, decreased independence and increased fear of falling. The ability to step in response to an equilibrium disturbance is considered to be critical to prevent a fall. Stroke survivors tend not to step with their paretic limb when their standing equilibrium is perturbed. Training the paretic limb to step in response to perturbations has had limited success in stroke survivors. In response to sagittal plane perturbation training, stroke survivors continued tend to step with their non-paretic leg even when cued or induced to step with paretic leg. This tendency decreases their flexibility to respond to perturbations and also makes it difficult to train the paretic limb. In contrast, coronal plane perturbations may be a useful way to induce paretic limb stepping. Acceleration and deceleration of a treadmill has been used to train reactive stepping in all directions persons with Parkinson's Disease. Coronal plane perturbations may elicit greater responses from the paretic limb but this has never been investigated in the stroke population. In this study participants will engage in 6 training sessions over 2-3 weeks. They will stand sideways on the treadmill with their paretic leg towards the front of the treadmill belt, which will be suddenly accelerated for 3 seconds to a predetermined velocity. Participants will perform 80 trials each session under one or more of the following four training conditions. NON-ENCOURAGED TREADMILL ONLY: These trials are defined as trials when the subject is instructed to respond as necessary to remain on the front half of the treadmill while maintaining their balance without using external supports, but are not given any specific instructions about which limb to use to initiate stepping when the treadmill begins to move. NON-ENCOURAGED USE TREADMILL PLUS SECONDARY TASK: All the same procedures for non-encouraged use treadmill only trials will be used with the following addition. Just after the subject attains equal weight bearing, the subject will be engaged in a cognitive task to name as many items in a category as they are able. During this time period, the treadmill will be started randomly. ENCOURAGED USE TREADMILL ONLY TRIALS: These trials are defined as trials where subjects will be instructed to respond as necessary to remain on the front half of the treadmill while maintaining their balance without using external supports AND to initiate stepping with his or her paretic leg when the treadmill begins to move. ENCOURAGED USE TREADMILL PLUS SECONDARY TASK: All the same procedures for encouraged use treadmill only trials will be used with the following addition. Just after the subject attains equal weight bearing, the subject will be engaged in a cognitive task to name as many items in a category as they are able. During this time period, the treadmill will be started at randomly. In pilot testing, this protocol has been tolerated by most community dwelling stroke survivors and the encouraged use trials with feedback consistently elicited paretic leg reactive steps.