Effect of walking velocity on hindlimb kinetics during stance in normal horses.

This research investigates how walking speed influences the forces and power in the hind limbs of healthy horses during stance (the phase when the foot is in contact with the ground), and uses this data to predict how these factors change with different walking speeds.

Methodology

• The researchers collected data from five healthy horses walking across a force plate at various speeds – a device that measures the ground reaction forces generated by a body standing on or moving across them.
• A total of 56 trials were conducted, combining videographic data with force measurements. This combination allowed the researchers to examine the forces at work and the movements of the horses in great detail.
• The forces and movements were then analyzed using an inverse dynamic solution, a method used in biomechanics to quantify the net joint moments (the turning effect produced by a force) and joint powers (the rate at which work is done or energy converted) in the hindlimb of the horses during stance.

Findings

• In the early stance, the study found significant increases in a number of variables as the walking speed increased. These included the extensor moment and positive power at the hip, flexor moment and positive power at the stifle (knee joint in horses), extensor moment, negative and positive power at the tarsus (equivalent to human ankle), and flexor moment and negative power at the fetlock (joint equivalent to the human wrist).
• In the late stance, the peak magnitudes of the following variables were observed to increase with velocity: flexor moment at the hip, negative power at the stifle, and flexor moment and positive power at the tarsus.
• The hip was found to generate more energy as the speed of walking increased, and the tarsus showed increased energy generation as well as absorption.

Conclusion

• The study concludes that an increase in walking speed in horses is associated with increases in the peak magnitudes of the net joint moments and joint powers in the hindlimb.
• A crucial finding is that the energy generated at the hip contributes the most to the increasing velocity, highlighting the importance of this joint in the mobility of horses.