title: Altered Kinematics and Time to Stabilization During Drop-Jump Landings in Individuals With or Without Functional Ankle Instability.
abstract: BACKGROUND
  It has been proposed that altered dynamic-control strategies during functional activity such as jump landings may partially explain recurrent instability in individuals with functional ankle instability (FAI).
  
  
  OBJECTIVE
  To capture jump-landing time to stabilization (TTS) and ankle motion using a multisegment foot model among FAI, coper, and healthy control individuals.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Participants were 23 individuals with a history of at least 1 ankle sprain and at least 2 episodes of giving way in the past year (FAI), 23 individuals with a history of a single ankle sprain and no subsequent episodes of instability (copers), and 23 individuals with no history of ankle sprain or instability in their lifetime (controls). Participants were matched for age, height, and weight (age = 23.3 ± 3.8 years, height = 1.71 ± 0.09 m, weight = 69.0 ± 13.7 kg).
  
  
  METHODS
  Ten single-legged drop jumps were recorded using a 12-camera Vicon MX motion-capture system and a strain-gauge force plate.
  
  
  METHODS
  Mediolateral (ML) and anteroposterior (AP) TTS in seconds, as well as forefoot and hindfoot sagittal- and frontal-plane angles at jump-landing initial contact and at the point of maximum vertical ground reaction force were calculated.
  
  
  RESULTS
  For the forefoot and hindfoot in the sagittal plane, group differences were present at initial contact (forefoot: P = .043, hindfoot: P = .004). At the hindfoot, individuals with FAI displayed more dorsiflexion than the control and coper groups. Time to stabilization differed among groups (AP TTS: P < .001; ML TTS: P = .040). Anteroposterior TTS was longer in the coper group than in the FAI or control groups, and ML TTS was longer in the FAI group than in the control group.
  
  
  CONCLUSIONS
  During jump landings, copers showed differences in sagittal-plane control, including less plantar flexion at initial contact and increased AP sway during stabilization, which may contribute to increased dynamic stability.
authors.affiliation: Whitworth University, Spokane, WA;
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Wright
authors.affiliation: Indiana University School of Health and Rehabilitation Sciences, Indianapolis;
authors.forename: Brent L
authors.initials: BL
authors.lastname: Arnold
authors.affiliation: University of North Carolina at Greensboro.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Ross
mesh_terms: D000704:Analysis of Variance; D016512:Ankle Injuries / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology; D005260:Female; D005528:Foot / Q000503:physiopathology; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D012189:Retrospective Studies; D013177:Sports / Q000502:physiology; D013639:Tarsal Bones / Q000503:physiopathology; D055815:Young Adult
keywords: ankle sprains; ankle-sprain copers; chronic ankle instability