title: Shank-rearfoot joint coupling in young adults with chronic ankle instability: a cross-correlation analysis.
abstract: OBJECTIVE
  Chronic ankle instability (CAI) has been associated with changes in gait kinematics which may be associated with the continued instability in this population. Abnormalities in shank-rearfoot joint coupling during gait may be associated with CAI. Cross-correlation analysis provides an estimate of both synchronous and asynchronous coherency between shank and rearfoot motion during gait. The aim of this study was to identify the coupling relationship between transverse plane shank and frontal plane rearfoot motion throughout the entire gait cycle using cross-correlation analysis.
  
  
  METHODS
  Twenty-eight active adults (CAI, N.=15, control, N.=13) participated. Using a 12-camera motion analysis system and an instrumented treadmill, shank rotation and rearfoot inversion/eversion kinematics were collected during walking and jogging. Cross-correlation coefficients with lag times ranging from +15% to -15% were generated from subject means across three strides and compared between the healthy and CAI groups at each speed.
  
  
  RESULTS
  During walking, the CAI group demonstrated stronger cross-correlation coefficients than the control group from lag +10 to +15 (P<0.05). Likewise, during jogging, the CAI group exhibited stronger cross-correlation coefficients than the control group at lags +6 to +15 (P<0.05).
  
  
  CONCLUSIONS
  The CAI group demonstrated stronger asynchronous coupling relationships between shank rotation and rearfoot inversion-eversion than the control group during both walking and jogging. The more pronounced coupling behavior in the CAI group may indicate less functional variability in shank and rearfoot kinematics during gait due to a more constrained and less adaptable sensorimotor system.
authors.affiliation: University of Virginia, Exercise and Sport Injury Laboratory, Charlottesville, VA, USA - cch2jd@virginia.edu.
authors.forename: C C
authors.initials: CC
authors.lastname: Herb
authors.forename: J
authors.initials: J
authors.lastname: Hertel
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D016138:Walking / Q000502:physiology*; D055815:Young Adult