Development of a Resistive Force Paradigm for the Treatment of Hemiparesis

Abstract

Hemiparesis is weakening of one side of the body as a result of a stroke that contributes to a decrease in propelling forces (i.e. propulsion) while walking. Existing research to improve propulsion of individuals post-stroke has implemented single-belt and split-belt treadmills, various walking speeds, asynchronous belt speeds (on split-belt treadmills), and a variety of methods for inducing resistive force upon a paretic limb in an attempt to strengthen the paretic limb and improve overall gait symmetry. However, despite this concerted effort of clinicians and scientists, gait deficits remain. Novel methods are required to improve reduced propulsion of individuals post-stroke.

Recently, we have used backward directed resistive forces to challenge the gait of individuals post-stroke. However, the methods used to date require expensive robotic devices. The primary aim of this research was to develop and refine a passive resistive device for use in a novel rehabilitation paradigm. Additionally, this inexpensive alternative needed to be compact and readily portable, requiring only minimal training without compromising safety in any way. It was also desired to dynamically adjust the resistive force exerted. A secondary aim of this investigation was to test the device for safety and feasibility of use with single belt treadmills.

In this document we describe the development of a device that is portable, easy to get into and out of, safe for the user, and allows a clinician or scientist the capability to increment force to the desired amount using only passive mechanical devices. Further, we experimentally tested the device on five community dwelling individuals walking on a treadmill while experiencing a range of backward directed resistive forces at 0%, 5%, 10%, and 15% of their body weight. We quantified the step-by-step peak propulsive ground reaction forces of a two minute trial for every body weight trial. Individuals were able to get into and out of the device efficiently and, with targeted backward-directed resistive force, we observed a linearly increasing peak propulsive force. Success of the device testing suggests that we can use this in clinical and research settings to test novel paradigms to improve propulsion in post-stroke gait.