Use of a novel robotic system for quantification of upper limb work area following stroke.

The effect of gravity on the expression elbow/shoulder synergy patterns results in discoordination during movements following stroke. This is believed to be related to the shoulder abduction torques generated when lifting the arm against gravity, which results in a concurrent elbow flexion (i.e., the flexion synergy). The Arm Coordination Training 3-D (ACT^3D) robotic system is a novel way of recording movement patterns while a subject generates varying amounts of shoulder abduction torque. This system is used to provide preliminary results that show increased shoulder abduction forces reduce a stroke subject's available work area in a way that is consistent with the flexion synergy. Implications and clinical applications are briefly discussed.