Forelimb Kinematics of Galloping Thoroughbred Racehorses Measured on Dirt, Synthetic, and Turf Track Surfaces (P235)

Abstract

Forelimb kinematics of four three-year-old galloping Thoroughbred racehorses were compared between dirt, synthetic, and turf racetrack surfaces. Joint angles and angular velocities of the fetlock (metacarpophalangeal), carpal, elbow, and shoulder joints of the lead forelimb were extracted from high-speed video data. Linear mixed effect ANOVA models were used to assess the effect of track surface on the maxima, minima, and temporal components of the joint angles and angular velocities during the stance phase of stride. Joint angles at heel strike and the speed of the distal end of the proximal phalanx (P1) at heel strike were also analysed. Least square mean differences were used for pairwise comparisons between surfaces. Significant differences in the forelimb kinematics of Thoroughbred racehorses on dirt, synthetic, and turf track surfaces were found, but most differences were timing-related. For all joints, the joint angle maxima occurred later in stance for the dirt and synthetic surfaces than for the turf surface, and the joint angles at heel strike were significantly larger for the turf surface than for the synthetic surface. The time of the fetlock maximum extension angle was smaller (P<0.05) for the turf surface (mean ± SE, 41.9 ± 2.1% of stance) than for the dirt (49.9 ± 2.3%) and synthetic surfaces (48.2 ± 1.9%). The time of fetlock maximum flexion velocity was smaller (P<0.10) for the turf surface (76.8 ± 3.0%) than for the dirt surface (85.8 ± 3.1%). Results indicate differences in the timing of joint angle and angular velocity maximums are more prevalent than differences in the maximum magnitudes, and timing differences may result from differences in the deformability of the surfaces. Differences in kinematics may affect propensity for soft tissue injury. [ABSTRACT FROM AUTHOR]