Abstracts Category : Other

Analysis of movement in pace and tlt in the Icelandic horse

by Reynisson 1974 Gunnar

The Icelandic horse is a gaited horse breed and in addition to walk, trot and gallop it has the ability to tlt and pace. These two gaits are from a biomechanical standpoint very similar and it is therefore not always easy to distinguish between them. The aim of this thesis was to objectively measure the major spatial and temporal variables that characterize the gaits tlt and pace. High quality horses were compared to low quality horses in tlt and pace and objective measurements of these gaits were compared to subjective assessments of judges. Simultaneous kinematic analysis and a subjective evaluation was carried out for pace and various speeds in tlt. Nineteen sound Icelandic horses in tlt and 49 horses in pace were evaluated and measured on a straight track. Each run was judged by two international certified judges and data was obtained with a high speed video camera (200 Hz) and inertial motion sensors. Footfall events were then determined and noted from the video footage. Attributes such as beat, stride length, stride frequency, speed, suspension and the ratio between stance phases of the frontlimbs and hindlimbs were analyzed and compared to subjectively scored data Horses in high quality tlt (score 9) had a much higher range of speed, compared to horses in low quality tlt (score 7.5), 2.7 m/s 9.14 m/s and 3.31 m/s 6.23 m/s, respectively and a greater ability to increase stride length. Beat was measured as the time interval between the contact of ipsilateral limbs (lateral advanced placement: LAP) whereas 25% is a perfect four beat. The horses in high quality tlt also had a clearer four beat and moreover, kept the clear four beat throughout the speed range (Mean LAP = 24.8% 2.3%). Whereas the low quality tlt had a more lateral movement and became pacier with increased speed (Mean LAP 16.8% 2.9%). High quality tlt also had shorter stance durations of the front limbs compared to hindlimbs than low quality horses, especially in slow speeds. The data from the additional subjectively estimated scores for beat, stride length in high speed and speed capacity show a fairly high correlation with measured variables in tlt, but scores for stride length in slow tlt did not. High quality pace (score 9) had a slightly higher average speed and stride length when compared with low quality pace (score 7.5). On the other hand there was no significant difference for LAP, LAL (lateral advanced lift off), stride frequency and suspension between the two groups. Suspension increased with speed and stride length, and had a negative correlation with LAP. On the other hand, LAP had not a significant correlation with increased speed. For LAP the mean value for the highest score for beat was 12.53% 2.41. There were only weak correlations between scores for beat and stride length and the measured variables. The correlation between scores for suspension and measured suspension was very low and non-significant in pace. Only scores for speed capacity had a high correlation with actual measured speed. The