title: Bilateral synergy as an index of force coordination in chronic stroke.
abstract: Dysfunction in bilateral coordination post-stroke is responsible for impaired bilateral movements. This study examined bilateral synergies using the uncontrolled manifold (UCM) approach while individuals in a chronic stage after stroke executed bilateral isometric force control at three submaximal force levels. Nine patients with stroke and nine age-matched healthy controls performed 24 trials of wrist and fingers extension at 5, 25, and 50% of MVC. The UCM findings revealed: (a) decreased bilateral synergies in patients with stroke as compared to controls at 50% of MVC and (b) reduced good variability and increased bad variability components in patients with stroke at 50% of MVC. Moreover, correlation analyses across both groups showed that a reduction of bilateral synergies was related to increased force error at 50% of MVC and an inconsistent force ratio between the two hands across multiple trials correlated with increased good and bad variability at 5% of MVC. Current findings indicate that quantifying bilateral synergies may provide meaningful profiles for estimating impairments as well as improvements of cooperative behaviors between two hands post-stroke.
authors.affiliation: Laboratory for Rehabilitation Neuroscience, University of Florida, Gainesville, FL, USA.|Motor Behavior Laboratory, Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA.
authors.forename: Nyeonju
authors.initials: N
authors.lastname: Kang
authors.affiliation: Motor Behavior Laboratory, Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA. cauraugh@ufl.edu.
authors.forename: James H
authors.initials: JH
authors.lastname: Cauraugh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016022:Case-Control Studies; D002908:Chronic Disease; D056228:Feedback, Sensory / Q000502:physiology; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology*; D018737:Hand Strength; D006801:Humans; D008297:Male; D008875:Middle Aged; D011596:Psychomotor Disorders / Q000209:etiology*; D013223:Statistics as Topic; D020521:Stroke / Q000150:complications*; D034941:Upper Extremity / Q000503:physiopathology*
keywords: Bilateral force control; Bilateral synergies; Coordination; Stroke; Uncontrolled manifold; Upper extremity