Shortening of the forelimb in the horse during the stance phase.

The researchers conducted an analysis of the compressions in the leg of a trotting horse, finding that a longer impact time and a smaller impact force corresponded to successive loadings from beneath.

Research Methodology

• The researchers used high-speed cinematography to examine the forelimb of a horse trotting at a speed of 3.7 m/s. This technique allowed them to capture every detail of the motion with high precision and clarity.

Findings and Conclusions

• Based on a diagram of shortenings, it was inferred that successive loadings in the longitudinal direction from beneath lead to a longer duration of impact and smaller impact forces. This was compared with a hypothetical situation where the limb was stiff. This highlights that the horse’s leg absorbs the impact more effectively with subsequent loadings.
• The study proposes that the horse’s limb passively absorbs the impact force up until the point where the load is applied to the elbow joint. This occurs about 30 milliseconds after the hoof initially makes contact with the ground. Prior to this period, the rest of the limb, such as the shoulder or the hoof, absorbs the impact. Post this time, the forces are primarily absorbed by the elbow joint. This characterizes the sophistication of the equine locomotion system which efficiently distributes the impact forces over time, significantly minimizing the chances of injury.