title: Joint kinetics of the ankle and knee when running over obstacles.
abstract: OBJECTIVE
  When running over obstacles of increasing height, heelstrike (HS) runners switch to a forefoot (FF) landing pattern once a critical obstacle height is reached. The primary purpose of this study was to determine whether ankle or knee joint kinetic variables trigger the gait change from a HS to a FF striking pattern as obstacle height increases.
  
  
  METHODS
  Ten subjects were filmed from the sagittal plane as they ran at their preferred running speed over a force platform during 6 obstacle height conditions ranging from 10% to 22.5% of standing height, as well as an additional baseline condition with no obstacle (0%). An inverse dynamics approach was utilized to calculate ankle and knee joint kinetics at each condition.
  
  
  RESULTS
  Differences in joint kinetics did not occur until a height was reached at which the landing strategy changed from a HS to a FF landing pattern. Most differences occurred at the ankle joint, at which there was a greater maximum plantar flexor moment and a greater amount of energy absorbed when obstacles of sufficient height to require a FF landing pattern were negotiated.
  
  
  CONCLUSIONS
  Although no variables were found which met all of the criteria necessary to be considered a determinant of the gait transition, there were variables which distinguished between a HS and FF strike landing pattern as obstacle height increased.
authors.affiliation: Department of Kinesiology and Health Science, California State University, Sacramento, CA 95819-6073, USA. ahreljac@hhs4.hhs.csus.edu
authors.forename: A
authors.initials: A
authors.lastname: Hreljac
authors.forename: N
authors.initials: N
authors.lastname: Stergiou
authors.forename: S
authors.initials: S
authors.lastname: Scholten
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D012420:Running / Q000502:physiology*