The Effect of Resistance to Participant-Supported Reaching on Workspace of the Hand in Severe Chronic Stroke

Disturbances in movement coordination are the least well understood but often the most
debilitating with respect to functional recovery following stroke. These deficits in
coordination are expressed in the form of abnormal muscle synergies and result in limited
and stereotypic movement patterns that are functionally disabling. The result of these
constraints in muscle synergies is an abnormal coupling between shoulder abduction and elbow
flexion (i.e. the flexion synergy), which significantly reduces the reaching function of an
individual with stroke when they lift up the weight of the impaired arm against gravity. The
investigators previous neurotherapeutic research, supported by a NIDRR Field Initiated
research grant, has shown that the abnormal synergy between shoulder abduction and elbow
flexion can be significantly reduced thus increasing total reaching range of motion in
individuals with severe stroke. The previous work established progressive abduction loading
as a key element to the rehabilitation of reaching. Although individuals with severe stroke
benefited from the investigators previous work, residual flexion synergy continued to hinder
normal arm function in most participants with severe stroke. This study will utilize the
ACT3D robot, developed as part of the investigators previous NIDRR project, to incorporate
resistance to reaching while accounting for the known benefits of progressive abduction
loading. The investigators propose to randomize forty participants with severe stroke into
two closely related interventions. The groups will both practice reaching under abduction
loading, however, the experimental group will also move against resistance while reaching.
Rigorous and quantitative investigation of therapeutic elements such as resistance to
reaching and progressive abduction loading is only possible with a device such as the ACT3D.
the investigators will be able to standardize the delivery of each intervention using
kinematic and kinetic parameters, which will allow for a clear identification of the
therapeutic effect of resistance to reaching. the investigators hypothesize that resistance
to reaching in combination with progressive abduction loading will further increase dynamic
multi-joint strength, increase total reaching range of motion, and increase arm function
thus enhancing actual amount of use of the arm, participation in life roles, and quality of
life in individuals with severe stroke.