Does the angle of the hock alter depending on the width of the fence, throughout each phase of the jump?

Introduction: According to previous research, horses alter the action of their hindlimbs to suit clearance of fences of differing heights. Little research exists, on the action of the hindlimb over differing widths of fences. Therefore, this study aimed to evaluate differences in the angle of the hock throughout each phase of the jump; take-off, bascule and landing, over a vertical and an oxer fence during a competition.
Materials & Methods: Conducted in a competition environment, hock angles of 16 horses were captured with high definition GoPro cameras over an upright and an oxer fence. Using the landmarks of the points of the stifle joint, the tuber calcaneus, and the abaxial surface of the lateral, proximal sesamoid bone the relative angle of the hock was drawn down using Dartfish Software for each stage of the jump. The Wilcoxans matched pairs analysis was used to establish whether differences existed between the oxer and the vertical, for each of the three phases of the jump. The Friedman test with Wilcoxon post hoc analysis were employed to determine whether, for each fence type, a significant difference existed between the three phases.
Results: A significant difference of the relative hock angle was found between each phase of the jump stride for both fences investigated; vertical: take-off (126.48±11.78), bascule (113.86±9.39) and landing (83.34±62.33) and oxer: take-off (117.29±9.62), bascule (99.68±11.82) and landing (62.33±9.16). Differences were also found between the two fences for the bascule (p≤0.05) and landing (p≤0.001) phases of the stride.
Discussion & Conclusion: Significant differences were found throughout all phases of the jump over both fences and also between the vertical and oxer fence. It is therefore possible to establish that the horse alters its hock angle over differing widths of fences during all phases of the jump; differences between the two fences were found for the bascule and landing phases but not the take-off phase. These findings allow for a greater understanding of the horse during the jump, to help advance areas including equipment, training techniques and methods to reduce injury. Further research can now be conducted to refine the areas of analysis to improve the understanding of the horse’s hind limb over fences.