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Fri Aug 05

Speaker: Andrew Tan

Title:  Evaluation of abnormal lower limb isometric torque patterns and muscle activation and their association to post stroke gait.

Abstract:  The first aim of the study seeks to compare within and across joint volitional torque patterns of individuals with chronic stroke to those of able bodied control subjects. Volitional torque will be measured isometrically  using a computer controlled, motorize, instrumented exoskeleton.  Across-joint torque coupling will be quantified by measuring secondary torques at the knee and ankle during hip torque target matching. Similarily secondary torques at the knee and hip will assessed during the ankle and knee target matching protocols.  Electromyograms will be recorded during the isometric tasks and will be related to functional movements during treadmill walking. We hypothesize that torque generation following stroke is characterized by both within-joint and across joint abnormalities and that these contribute to deviations in overground gait metrics.

The second aim of the proposed study seeks to identify muscle synergies underlying post-stroke lower limb activation and evaluate their association with muscle activation during gait. Earlier studies suggests that the dimensionality of motor control in humans may be reduced through the use of muscle synergies. A modular and hierarchical control structure with similar dimensionality maybe used to describe motor output in both healthy subjects and stroke survivors. These structures may be altered by stroke.  Independent component analysis will be used to identify muscle synergies from the EMG data collected during the target matching protocols in the first aim. We seek to show that  abnormal across joint torque coupling reflects the emergence of abnormal synergies following stroke.