title: Effect of head and neck position on vertical ground reaction forces and interlimb coordination in the dressage horse ridden at walk and trot on a treadmill.
abstract: BACKGROUND
  Little is known in quantitative terms about the influence of different head-neck positions (HNPs) on the loading pattern of the locomotor apparatus. Therefore it is difficult to predict whether a specific riding technique is beneficial for the horse or if it may increase the risk for injury.
  
  
  OBJECTIVE
  To improve the understanding of forelimb-hindlimb balance and its underlying temporal changes in relation to different head and neck positions.
  
  
  METHODS
  Vertical ground reaction force and time parameters of each limb were measured in 7 high level dressage horses while being ridden at walk and trot on an instrumented treadmill in 6 predetermined HNPs: HNP1 - free, unrestrained with loose reins; HNP2 - neck raised, bridge of the nose in front of the vertical; HNP3 - neck raised, bridge of the nose behind the vertical; HNP4 - neck lowered and flexed, bridge of the nose considerably behind the vertical; HNP5 - neck extremely elevated and bridge of the nose considerably in front of the vertical; HNP6 - neck and head extended forward and downward. Positions were judged by a qualified dressage judge. HNPs were assessed by comparing the data to a velocity-matched reference HNP (HNP2). Differences were tested using paired t test or Wilcoxon signed rank test (P<0.05).
  
  
  RESULTS
  At the walk, stride duration and overreach distance increased in HNP1, but decreased in HNP3 and HNP5. Stride impulse was shifted to the forehand in HNP1 and HNP6, but shifted to the hindquarters in HNP5. At the trot, stride duration increased in HNP4 and HNP5. Overreach distance was shorter in HNP4. Stride impulse shifted to the hindquarters in HNP5. In HNP1 peak forces decreased in the forelimbs; in HNP5 peak forces increased in fore- and hindlimbs.
  
  
  CONCLUSIONS
  HNP5 had the biggest impact on limb timing and load distribution and behaved inversely to HNP1 and HNP6. Shortening of forelimb stance duration in HNP5 increased peak forces although the percentage of stride impulse carried by the forelimbs decreased.
  
  
  CONCLUSIONS
  An extremely high HNP affects functionality much more than an extremely low neck.
authors.affiliation: Equine Hospital, University of Zurich, CH-8057 Zurich, Switzerland.
authors.forename: M A
authors.initials: MA
authors.lastname: Weishaupt
authors.forename: T
authors.initials: T
authors.lastname: Wiestner
authors.forename: K
authors.initials: K
authors.lastname: von Peinen
authors.forename: N
authors.initials: N
authors.lastname: Waldern
authors.forename: L
authors.initials: L
authors.lastname: Roepstorff
authors.forename: R
authors.initials: R
authors.lastname: van Weeren
authors.forename: H
authors.initials: H
authors.lastname: Meyer
authors.forename: C
authors.initials: C
authors.lastname: Johnston
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D005552:Forelimb / Q000502:physiology; D005684:Gait; D006257:Head / Q000502:physiology; D006614:Hindlimb / Q000502:physiology; D006736:Horses / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008297:Male; D009333:Neck / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000379:methods / Q000502:physiology*; D011187:Posture; D018709:Statistics, Nonparametric; D016138:Walking / Q000502:physiology*