title: Ankle-dorsiflexion range of motion and landing biomechanics.
abstract: BACKGROUND
  A smaller amount of ankle-dorsiflexion displacement during landing is associated with less knee-flexion displacement and greater ground reaction forces, and greater ground reaction forces are associated with greater knee-valgus displacement. Additionally, restricted dorsiflexion range of motion (ROM) is associated with greater knee-valgus displacement during landing and squatting tasks. Because large ground reaction forces and valgus displacement and limited knee-flexion displacement during landing are anterior cruciate ligament (ACL) injury risk factors, dorsiflexion ROM restrictions may be associated with a greater risk of ACL injury. However, it is unclear whether clinical measures of dorsiflexion ROM are associated with landing biomechanics.
  
  
  OBJECTIVE
  To evaluate relationships between dorsiflexion ROM and landing biomechanics.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Thirty-five healthy, physically active volunteers.
  
  
  METHODS
  Passive dorsiflexion ROM was assessed under extended-knee and flexed-knee conditions. Landing biomechanics were assessed via an optical motion-capture system interfaced with a force plate.
  
  
  METHODS
  Dorsiflexion ROM was measured in degrees using goniometry. Knee-flexion and knee-valgus displacements and vertical and posterior ground reaction forces were calculated during the landing task. Simple correlations were used to evaluate relationships between dorsiflexion ROM and each biomechanical variable.
  
  
  RESULTS
  Significant correlations were noted between extended-knee dorsiflexion ROM and knee-flexion displacement (r  =  0.464, P  =  .029) and vertical (r  =  -0.411, P  =  .014) and posterior (r  =  -0.412, P  =  .014) ground reaction forces. All correlations for flexed-knee dorsiflexion ROM and knee-valgus displacement were nonsignificant.
  
  
  CONCLUSIONS
  Greater dorsiflexion ROM was associated with greater knee-flexion displacement and smaller ground reaction forces during landing, thus inducing a landing posture consistent with reduced ACL injury risk and limiting the forces the lower extremity must absorb. These findings suggest that clinical techniques to increase plantar-flexor extensibility and dorsiflexion ROM may be important additions to ACL injury-prevention programs.
authors.affiliation: Athletic Training Services, Boston University, MA, USA.
authors.forename: Chun-Man
authors.initials: CM
authors.lastname: Fong
authors.forename: J Troy
authors.initials: JT
authors.lastname: Blackburn
authors.forename: Marc F
authors.initials: MF
authors.lastname: Norcross
authors.forename: Melanie
authors.initials: M
authors.lastname: McGrath
authors.forename: Darin A
authors.initials: DA
authors.lastname: Padua
mesh_terms: D000842:Ankle / Q000502:physiology; D000843:Ankle Joint / Q000502:physiology*; D016118:Anterior Cruciate Ligament / Q000033:anatomy & histology / Q000502:physiology; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D007718:Knee Injuries / Q000503:physiopathology; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009043:Motor Activity; D009068:Movement; D009142:Musculoskeletal Physiological Phenomena; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular; D055815:Young Adult