title: Bimanual isometric force control: asymmetry and coordination evidence post stroke.
abstract: OBJECTIVE
  This study determined the nature of bimanual deficits during visually-guided isometric force production in chronic stroke.
  
  
  METHODS
  Stroke survivors and age-matched controls performed bimanual isometric wrist/finger extension contractions for 20s to target submaximal force levels. Force asymmetry was indexed by the proportion of force contributed by the impaired hand to total force. Force coordination was determined by computing time-series cross-correlations and time-lag between force outputs of both hands.
  
  
  RESULTS
  The stroke group demonstrated greater asymmetry and reduced coordination in force produced by each hand. The extent of asymmetry in the force magnitude remained constant across the three submaximal force levels in both groups. Bimanual force coordination increased at higher forces in controls but not in stroke. Finally, the less-impaired hand forces time-lagged the impaired hand.
  
  
  CONCLUSIONS
  Bimanual motor impairments in chronic stroke are characterized by increased asymmetry and reduced coordination between individual hand forces. Distinct control mechanisms are involved in the production and coordination of forces following stroke.
  
  
  CONCLUSIONS
  An implication involves rehabilitation protocols that emphasize bimanual coordination for training the hands to produce symmetric forces that are temporally coordinated.
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32611, USA. lodhaneha@hhp.ufl.edu
authors.forename: Neha
authors.initials: N
authors.lastname: Lodha
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Coombes
authors.forename: James H
authors.initials: JH
authors.lastname: Cauraugh
mesh_terms: D000368:Aged; D002908:Chronic Disease; D003627:Data Interpretation, Statistical; D005260:Female; D005385:Fingers / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D009068:Movement / Q000502:physiology; D009069:Movement Disorders / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology; D020521:Stroke / Q000503:physiopathology*; D014160:Transducers, Pressure; D014953:Wrist / Q000503:physiopathology