title: Eccentric plantar-flexor torque deficits in participants with functional ankle instability.
abstract: BACKGROUND
  Inversion ankle sprains can lead to a chronic condition called functional ankle instability (FAI). Limited research has been reported regarding isokinetic measures for the plantar flexors and dorsiflexors of the ankle.
  
  
  OBJECTIVE
  To examine the isokinetic eccentric torque measures of the ankle musculature in participants with stable ankles and participants with functionally unstable ankles during inversion, eversion, plantar flexion, and dorsiflexion.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Athletic training research laboratory.
  
  
  METHODS
  Twenty participants with a history of "giving way" were included in the FAI group. Inclusion criteria for the FAI group included a history of at least 1 ankle sprain and repeated episodes of giving way. Twenty participants with no prior history of ankle injury were included in the control group.
  
  
  METHODS
  Isokinetic eccentric torque was assessed in each participant.
  
  
  METHODS
  Isokinetic eccentric testing was conducted for inversion-eversion and plantar-flexion-dorsiflexion movements. Peak torque values were standardized to each participant's body weight. The average of the 3 trials for each direction was used for statistical analysis.
  
  
  RESULTS
  A significant side-by-group interaction was noted for eccentric plantar flexion torque (P < .01). Follow-up t tests revealed a significant difference between the FAI limb in the FAI group and the matched limb in the control group. Additionally, a significant difference was seen between the sides of the control group (P = .03). No significant interactions were identified for eccentric inversion, eversion, or dorsiflexion torques (P > .05).
  
  
  CONCLUSIONS
  A deficit in plantar flexion torque was identified in the functionally unstable ankles. No deficits were identified for inversion, eversion, or dorsiflexion torque. Therefore, eccentric plantar flexion strength may be an important contributing factor to functional ankle instability.
authors.affiliation: Indiana University, Bloomington, IN 47408, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Fox
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Docherty
authors.forename: John
authors.initials: J
authors.lastname: Schrader
authors.forename: Trent
authors.initials: T
authors.lastname: Applegate
mesh_terms: D000328:Adult; D000842:Ankle / Q000033:anatomy & histology / Q000503:physiopathology*; D016512:Ankle Injuries / Q000175:diagnosis* / Q000503:physiopathology; D001265:Athletic Injuries; D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D005528:Foot / Q000473:pathology*; D018409:Foot Injuries / Q000175:diagnosis* / Q000503:physiopathology; D006304:Health Status; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D053581:Muscle Strength Dynamometer; D013180:Sprains and Strains / Q000150:complications* / Q000503:physiopathology; D019415:Torque