title: Altered knee and ankle kinematics during squatting in those with limited weight-bearing-lunge ankle-dorsiflexion range of motion.
abstract: BACKGROUND
  Ankle-dorsiflexion (DF) range of motion (ROM) may influence movement variables that are known to affect anterior cruciate ligament loading, such as knee valgus and knee flexion. To our knowledge, researchers have not studied individuals with limited or normal ankle DF-ROM to investigate the relationship between those factors and the lower extremity movement patterns associated with anterior cruciate ligament injury.
  
  
  OBJECTIVE
  To determine, using 2 different measurement techniques, whether knee- and ankle-joint kinematics differ between participants with limited and normal ankle DF-ROM.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Sports medicine research laboratory.
  
  
  METHODS
  Forty physically active adults (20 with limited ankle DF-ROM, 20 with normal ankle DF-ROM).
  
  
  METHODS
  Ankle DF-ROM was assessed using 2 techniques: (1) nonweight-bearing ankle DF-ROM with the knee straight, and (2) weight-bearing lunge (WBL). Knee flexion, knee valgus-varus, knee internal-external rotation, and ankle DF displacements were assessed during the overhead-squat, single-legged squat, and jump-landing tasks. Separate 1-way analyses of variance were performed to determine whether differences in knee- and ankle-joint kinematics existed between the normal and limited groups for each assessment.
  
  
  RESULTS
  We observed no differences between the normal and limited groups when classifying groups based on nonweight-bearing passive-ankle DF-ROM. However, individuals with greater ankle DF-ROM during the WBL displayed greater knee-flexion and ankle-DF displacement and peak knee flexion during the overhead-squat and single-legged squat tasks. In addition, those individuals also demonstrated greater knee-varus displacement during the single-legged squat.
  
  
  CONCLUSIONS
  Greater ankle DF-ROM assessed during the WBL was associated with greater knee-flexion and ankle-DF displacement during both squatting tasks as well as greater knee-varus displacement during the single-legged squat. Assessment of ankle DF-ROM using the WBL provided important insight into compensatory movement patterns during squatting, whereas nonweight-bearing passive ankle DF-ROM did not. Improving ankle DF-ROM during the WBL may be an important intervention for altering high-risk movement patterns commonly associated with noncontact anterior cruciate ligament injury.
authors.affiliation: Department of Exercise and Sport Science, University of North Carolina at Chapel Hill;
authors.forename: Karli E
authors.initials: KE
authors.lastname: Dill
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Begalle
authors.forename: Barnett S
authors.initials: BS
authors.lastname: Frank
authors.forename: Steven M
authors.initials: SM
authors.lastname: Zinder
authors.forename: Darin A
authors.initials: DA
authors.lastname: Padua
mesh_terms: D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D000843:Ankle Joint / Q000503:physiopathology*; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D007717:Knee / Q000503:physiopathology*; D007718:Knee Injuries / Q000150:complications*; D008297:Male; D009142:Musculoskeletal Physiological Phenomena; D016059:Range of Motion, Articular; D013178:Sports Medicine / Q000379:methods; D016474:Weight-Bearing
keywords: anterior cruciate ligament; jump landing; knee flexion; knee valgus; knee varus; squat