title: Alterations in neuromuscular control at the knee in individuals with chronic ankle instability.
abstract: BACKGROUND
  Few authors have assessed neuromuscular knee-stabilization strategies in individuals with chronic ankle instability (CAI) during functional activities.
  
  
  OBJECTIVE
  To investigate the influence of CAI on neuromuscular characteristics around the knee during a stop-jump task.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Research laboratory. Participants or Other Participants: A total of 19 participants with self-reported unilateral CAI and 19 healthy control participants volunteered for this study.
  
  
  METHODS
  Participants performed double-legged, vertical stop-jump tasks onto a force plate, and we measured muscle activation around the knee of each limb.
  
  
  METHODS
  We calculated the integrated electromyography for the vastus medialis oblique, vastus lateralis, medial hamstrings, and lateral hamstrings muscles during the 100 ms before and after initial foot contacts with the force plate and normalized by the ensemble peak electromyographic value. Knee sagittal-plane kinematics were also analyzed during a stop-jump task.
  
  
  RESULTS
  Compared with control participants, the CAI group demonstrated greater prelanding integrated electromyographic activity of the vastus medialis oblique (CAI = 52.28 ± 11.25%·ms, control = 43.90 ± 10.13%·ms, t36 = 2.41, P = .021, effect size = 0.78, 95% confidence interval = 0.11, 1.43) and less knee-flexion angle at the point of initial foot contact (CAI = 7.81° ± 8.27°, control = 14.09° ± 8.7°, t36 = -2.28, P = .029, effect size = -0.74, 95% confidence interval = -1.38, -0.07) and at 100 ms post-initial foot contact (CAI = 51.36° ± 5.29°, control = 58.66° ± 7.66°, t36 = -3.42, P = .002, effect size = -1.11, 95% confidence interval = -1.77, -0.40). No significant results were noted for the other electromyographic measures.
  
  
  CONCLUSIONS
  We found altered feed-forward patterns of the vastus medialis oblique and altered postlanding knee sagittal-plane kinematics in the CAI group. These observations may provide insight regarding sensorimotor characteristics that may be associated with CAI.
authors.affiliation: Musculoskeletal Health and Movement Science Laboratory, University of Toledo, OH.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Terada
authors.forename: Brian G
authors.initials: BG
authors.lastname: Pietrosimone
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Gribble
mesh_terms: D016512:Ankle Injuries / Q000150:complications / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology*; D007719:Knee Joint / Q000294:innervation* / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D012189:Retrospective Studies; D055815:Young Adult
keywords: feed-forward pattern; feedback; sensorimotor control