title: Relationship of chronic ankle instability to muscle activation patterns during the transition from double-leg to single-leg stance.
abstract: BACKGROUND
  Impaired muscle activation may predispose subjects to develop chronic ankle instability. It has been suggested that impairments are found not only in structures around the injured ankle but also around the more proximal joint complexes.
  
  
  OBJECTIVE
  Subjects with chronic ankle instability were expected to show later onset times for lower limb and trunk muscle activation when compared with control subjects. They were expected to show less variability in muscle activation patterns compared with the control group.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Thirty control subjects and 10 subjects with chronic ankle instability participated in the study. The onset of muscle activity of 14 muscles of the lower limb and trunk was measured during the transition from a double-leg stance position to a single-leg stance position in eyes-open and eyes-closed test conditions.
  
  
  RESULTS
  Subjects with chronic ankle instability showed significantly later onset times for the ankle, hip, and hamstring muscles compared with control subjects. They used a similar muscle activation pattern in both test conditions, whereas control subjects adjusted their activation pattern according to the condition.
  
  
  CONCLUSIONS
  Differences in muscle activation patterns between subjects with chronic ankle instability and control subjects occur not only around the ankle but also around other joints. Subjects with chronic ankle instability show less variability in muscle activation patterns between test conditions.
  
  
  CONCLUSIONS
  Knowledge of muscle activation patterns in the whole lower limb and trunk in noninjured subjects and the differences found in chronic ankle instability subjects broadens the physical therapy approach to the treatment of chronic ankle instability.
authors.affiliation: Department of Rehabilitation Sciences, Katholieke Universiteit Leuven, Belgium. sara.vandeun@faber.kuleuven.be
authors.forename: Sara
authors.initials: S
authors.lastname: Van Deun
authors.forename: Filip F
authors.initials: FF
authors.lastname: Staes
authors.forename: Karel H
authors.initials: KH
authors.lastname: Stappaerts
authors.forename: Luc
authors.initials: L
authors.lastname: Janssens
authors.forename: Oron
authors.initials: O
authors.lastname: Levin
authors.forename: Koen K H
authors.initials: KK
authors.lastname: Peers
mesh_terms: D000328:Adult; D000843:Ankle Joint; D016022:Case-Control Studies; D002908:Chronic Disease; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007866:Leg / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D013647:Task Performance and Analysis