Abnormal joint torque patterns in the paretic upper limb of subjects with hemiparesis

This study presents the results of a novel paradigm for characterizing abno rmal coordination in subjects with hemiparesis. Subjects generated maximum voluntary torques (MVTs) isometrically in four randomly ordered blocks cons isting of elbow flexion/extension, shoulder flexion/extension, shoulder abd uction/adduction, and shoulder external/internal rotation. A 6-degree-of-fr eedom (DOF) load cell was used to measure torques in secondary DOFs at the elbow and shoulder, as well as in the torque direction the subject was atte mpting to maximize. This allowed characterization of the multijoint torque patterns associated with the generation of MVTs in the eight directions exa mined. Significant differences were found between the torque patterns exhib ited by the paretic limb of the hemiparetic group (n = 8) and those observe d for the nonparetic limb and control group (n = 4). Potential neural and b iomechanical mechanisms underlying these abnormal torque patterns are discu ssed along with implications for the functional use of the paretic limb. (C ) 2001 John Wiley & Sons, Inc.