Abstract: REASONS FOR PERFORMING STUDY: No data exist on the GRF-kinematics relation due to changes caused by equestrian interventions. HYPOTHESIS: Through the judicious use of draw reins the rider can influence the kinematics of the horse to meet stated goals of dressage training. Relating the results to previously published kinetic data of the same experiment implies a possible relationship between kinetics and kinematics. METHODS: The kinematics of 8 sound Swedish Warmblood horses were measured whilst the horses were being ridden with and without draw reins. Three conditions were evaluated: 1) draw reins only (DR), 2) combination of draw reins and normal reins (NR+DR) and 3) normal reins only (NR). RESULTS: Head and neck angles were significantly decreased by the draw rein but 4-5 times more so for DR when with NR+DR. The forelimb position at hoof lift-off was significantly more caudal with DR. In the hind limb the hip joint extended more quickly and the hock joint flexed more with NR+DR than with NR. Compared to DR the hip joint angular pattern was not significantly different, but the pelvis was more horizontal. CONCLUSION: Riding with a draw rein can have significant influence on the kinematics of the horse. Some of the observed changes can be coupled to changes in kinetics. The hock joint angle seems to be a fairly reliable indicator of load on the hind limb and the angle of femur appears important for hind limb propulsion, when considered in conjunction with the orientation of the pelvis. POTENTIAL RELEVANCE: These findings are important for riders and trainers, as kinematic changes are what trainers observe. It is thereby important to ascertain which kinematic changes are consistently coupled to changes in kinetics in order for trainers to be able to judge correctly the success of intended goals. Further studies are warranted to validate and confirm suggested relationships between kinetics and kinematics.

Abstract: REASONS FOR PERFORMING STUDY: 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. POTENTIAL RELEVANCE: An extremely high HNP affects functionality much more than an extremely low neck.