Methods: Sixteen participants with chronic stroke and nine age-matched controls performed three trials of functional reach-to-grasp. The amount of variability was quantified by computing the standard deviation of shoulder, elbow, wrist and index finger flexion/extension joint angles. The temporal structure of variability was determined by calculating approximate entropy in shoulder, elbow, wrist and index finger flexion/extension joint angles.
Findings: Individuals with stroke demonstrated greater standard deviations and significantly reduced approximate entropy values as compared to controls. Furthermore, motor impairments and kinematics demonstrated moderate to strong correlations with temporal structure of variability.
Interpretation: Changes in the temporal structure of variability in upper-extremity joint angles suggest that movement patterns used by stroke survivors are less adaptable. This knowledge may yield additional insights into the impaired motor system and suggest better interventions that can enhance upper-extremity movement adaptability.
Sethi, Amit; Patterson, Tara; McGuirk, Theresa; Patten, Carolynn; Richards, Lorie G.; and Stergiou, Nikolaos, "Temporal structure of variability decreases in upper extremity movements post stroke" (2013). Journal Articles. 32.