Contribution of the forelimbs and hindlimbs of the horse to mechanical energy changes in jumping.

The research study investigates the contribution of a horse’s forelimbs and hindlimbs to energy changes during a jump. The study collected and analyzed kinematic data from 5-year-old Warmblood horses jumping over a fence to determine how much energy was produced, stored, and utilized in different parts of the horse’s body.

Methodology

• The researchers made observations on 23 Warmblood horses, each with an average mass of 595 kg. These horses were allowed to perform free jumps over a 1.15 m high fence.
• They collected kinematic data at a rate of 240 Hz during these jumps. The data set includes changes in mechanical energy, limb length, and joint angles.
• To estimate the force carried by the forelimbs and the energy stored in them, they used the distance between the elbow and the hoof, assuming that this section of the leg behaved as a linear spring.

Forelimb Energy Changes

• During the forelimb push, the total energy first decreased by 3.2 J kg(-1) and then surged again by 4.2 J kg(-1) until the forelimb push was complete.
• The kinetic energy, due to the horizontal velocity of the center of mass, was 1.6 J kg(-1) less at the end than at the start.
• The effective energy contributing to jump height was greater by 2.3 J kg(-1).
• The researchers then investigated these changes to understand if they were related to passive spring-like behavior in the forelimbs.

Energy Storage and Usage

• The energy stored and re-utilized in the distal tendons during the forelimb push averaged at 0.4 J kg(-1) in the trailing forelimb and 0.23 J kg(-1) in the leading forelimb. This shows that a significant amount of energy was first dispersed and then regenerated by muscles.
• The triceps brachii muscle was likely the main contributor to energy regeneration.

Hindlimb Energy Changes

• The hindlimb muscles primarily produced energy during the jump. The total increase in energy was 2.5 J kg(-1), reaching a peak power output of 71 W kg(-1).
• The findings suggest that the hindlimbs’ primary role in jumping is to generate energy, while the forelimbs store and then re-utilize it.

Conclusion

• This research provides valuable insights into the contributions of a horse’s forelimbs and hindlimbs to energy changes during a jump. Understanding this can help in enhancing a horse’s performance in activities that involve jumping.