Mechanisms underlying discoordination, expressed in the form of obligatory coupling between the shoulder and the elbow muscles following stroke, are probed by simultaneously recording 163-channel EEG together with elbow/shoulder torques and EMGs from the upper arm. With this unique experimental protocol, we were able to have strict post hoc control of a subject's motor performance. Using this novel approach, this paper provides the first evidence of a linear relationship between an overlap in the cortical activities and obligatory shoulder/elbow torque coupling. Furthermore, results obtained from an 8 weeks multi-degree of freedom isometric training protocol showed that a well-designed treatment intervention could reduce obligatory torque coupling following stroke. Preliminary data indicates that this change in torque coupling appears to be associated with brain reorganization. Other potential rehabilitation methods based on an increased understanding of the mechanisms underlying discoordination following stroke are discussed.