title: Task-specific modulation of anticipatory postural adjustments in individuals with hemiparesis.
abstract: OBJECTIVE
  To study adaptation of anticipatory postural adjustments (APAs) in paretic and non-paretic muscles of individuals with hemiparesis to changes in the direction of the self-initiated perturbation and additional manual support.
  
  
  METHODS
  Electrical activity of leg and trunk muscles on both sides of the body and ground reaction forces were recorded in 10 patients with hemiparesis and a group of matched control subjects. Subjects released a standard load, held in the hand of the extended relatively unimpaired arm. The load was released either in front of the body or to the side, with or without the impaired arm touching an external stable surface.
  
  
  RESULTS
  APAs were reduced in individuals with hemiparesis, especially on the paretic side. In paretic muscles, the modulation of APAs with the direction of the perturbation was decreased or showed atypical patterns. Also the effects of touch were decreased in patients. Center of pressure displacements shortly after load release were similar in control subjects and patients.
  
  
  CONCLUSIONS
  The results suggest that the ability of individuals with hemiparesis to prepare for a self-initiated predictable perturbation is reduced and that they may use alternative strategies of postural stabilization.
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, University Park 16802, USA.
authors.forename: Harm
authors.initials: H
authors.lastname: Slijper
authors.forename: Mark L
authors.initials: ML
authors.lastname: Latash
authors.forename: Noel
authors.initials: N
authors.lastname: Rao
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Aruin
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000368:Aged; D004576:Electromyography; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010291:Paresis / Q000175:diagnosis / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance; D016474:Weight-Bearing