Experimental Brain Research

, Volume 235, Issue 5, pp 1501–1509 | Cite as

Bilateral synergy as an index of force coordination in chronic stroke

  • Nyeonju Kang
  • James H. Cauraugh
Research Article


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.


Stroke Bilateral force control Uncontrolled manifold Bilateral synergies Coordination Upper extremity 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interest.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  1. 1.Laboratory for Rehabilitation NeuroscienceUniversity of FloridaGainesvilleUSA
  2. 2.Motor Behavior Laboratory, Department of Applied Physiology and KinesiologyUniversity of FloridaGainesvilleUSA

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