Effect of walking velocity on ground reaction force variables in the hind limb of clinically normal horses.

The research article investigates how the speed of walking impacts the ground reaction force (the force exerted by the ground on a body in contact with it) variables for the back legs of perfectly healthy horses. Specifically, the researchers collected data to predict the force variables at different walking velocities.

Methods of Research

• The experiment involved five clinically normal horses. The researchers collected kinematic data (which relates to the motion of objects without considering the forces that cause the motion) and force data together.
• Each horse was led over a force plate at various walking velocities, and the stance duration and ground reaction force data for the right hind limb were recorded.
• Different force variables were standardized to the horse’s body mass and shoulder height to eliminate the influence of the horse’s size on the results.
• Walking speed was also standardized to height at the shoulders and referred to as velocity in dimensionless units (VDU). The stance duration was similarly expressed in dimensionless units (SDU).
• The researchers then performed a simple regression analysis, where stance duration and force variables were dependent variables, and the velocity in VDU was the independent variable.

Results and Conclusion

• The results were derived from fifty-six trials recorded, which captured a velocity range of 0.24 to 0.45 VDU (0.90 to 1.72 m/s).
• The simple regression models between the measured variables and VDU showcased significant results (R2 > 0.69) for the stance duration (SDU), the first peak of vertical force, the dip between the two peaks of vertical force, vertical impulse, and the timing of the second peak of vertical force.
• These results confirmed that a horse’s walking speed only affects the vertical force components.
• In upcoming studies, the differences between forces measured in lame horses with those calculated for a similar speed will be compared. By doing so, the researchers aim to determine if these equations can be employed as diagnostic criteria for assessing lameness in horses.