Characteristics of Balance Control to Unexpected Loss of Balance During Standing and Walking in Post-stroke Individuals

aim: To examine the effect of a perturbation-based balance training on balance reaction characteristics in post stroke individuals.

60 stroke subjects from the neurology rehabilitation unit at Loewenstein hospital will be randomly allocated to one of two groups: 1) perturbations based balance training 2) weight shifting and gait training without external perturbations (control).

Group 1 - Perturbations based balance training Subjects will complete a perturbation based balance training while standing and walking on the BalanceTutor (MediTouch). Perturbation level will be individually adjusted and progressed according to subject's abilities. Progression occurs by increasing perturbation level (increase distance, velocity and acceleration). At each practiced level subjects will be exposed to random right/left/forward/backward unannounced platform translations while standing and to right/left perturbations (in defined events in gait cycle) while walking. In order to examine adaptation to repeated perturbations, kinematic data will be collected in the first session.

Group 2 - Weight shifting and gait training Subjects will complete a balance training program that includes voluntary weight shifting while standing on a computerized posturography (NeuroCom) and walking on a treadmill. Weight shifting toward a target will be adjusted and progressed according to subject's abilities. Progression in difficulty level will occur by increasing the distance to target without changing the base of support. At each practiced level weight shifting will be conducted to right/left/forward/backward directions. In the gait part of the session, subjects will be asked to walk at their preferred treadmill walking speed.

Subjects in both groups will complete 10-12 training sessions, 4-5 per week for 3 weeks. Each session will last 30 minutes and will include practice in standing and walking. Subject's activities will be documented in each session in both groups. Furthermore, in each session subjects will be asked to rate their perceived level of challenge on a 0-10 scale.

Pre- and post-intervention measurements will be conducted. A follow-up measurement will be conducted 3-6 weeks post intervention.

The following measurements will be administered:

1)Compensatory balance reaction kinematic measurement:

Compensatory balance reactions will be measured using the BalanceTutor (MediTouch). The BalanceTutor is a mechatronic device consisting of a computerized treadmill with a horizontal movable platform and an operator station. Measurements will be taken in two conditions:

Standing. Subjects will be instructed to stand and will be exposed to random unexpected platform translations. The platform translations will be increased systematically and controlled. The increases in platform translation will be adjusted by the examiner to the subject's ability to recover from perturbations. Participants will be asked to respond in a "natural" manner to perturbations.

Walking. Subjects will be instructed to walk comfortably (self-paced) on the treadmill, and will be exposed to random unexpected platform translations. The platform translations will be increased systematically and controlled and will be adjusted by the examiner to the subject's ability to recover from perturbations. Compensatory balance reaction characteristics (reaction time, swing time, compensatory step time, step length etc.) will be collected through a three-dimensional motion analysis system. During examination subjects will wear a loose safety harness that will prevent a fall and yet allow the execution of balance recovery reactions.

In addition, clinical measures will be used: Berg Balance Scale, 6 minute walk test, 10 meter walk test, the Fugl-Meyer test for motor recovery after stroke and the ABC (Activities-specific Balance Confidence) scale. Normalized lesion data will be computed using the ABLE module within MEDx software (Medical Numerics).

Eligibility Criteria:
Inclusion Criteria:

For measurements taken while standing, post stroke subjects will meet the criteria of being able to stand independently or with supervision for at least 2 minutes.

For measurements taken while walking, post stroke subjects will meet the criteria of being able to walk for at least 10 meter with supervision/independently without walking aids.

* 3 weeks-6 months post stroke (hemorrhage/infarct)
* First stroke
* Age 25-75 years
* Able to understand research instructions
* Stable clinical/metabolic state

Exclusion Criteria:

* - A history of neurological diseases amongst peripheral neuropathy
* Significant skeletal system diseases, such as severe osteoporosis
* Uncontrolled atrial fibrillation
* Unstable ischemic heart disease
* Significant visual deficiency
* Dizziness
* Pregnancy
* Body weight above 135 kg