CIRCLES AND SOUNDNESS: WHY GAIT MATTERS

Work on a circle, both at liberty and under saddle, is an important part of training for horses in most disciplines. But the potential effects of the associated concussive forces on joints, tendons, ligaments and hooves are always a concern.

Now, a Michigan State University study suggests that when it comes to the force and pressure on a horse’s hooves, their gait of travel matters.

For the study, pressuremapping Tekscan sensors were secured under the front shoes of nine horses. “Our Tekscan sensors can measure two things,” says Alyssa Logan (BS, MS, PhD Candidate). “How much force is applied, and over what area the force is applied. The [computer] program can then calculate the pressure from the force and area.”

With the sensors in place and calibrated, the researchers led each horse in a straight line at the walk and trot, then worked them in a round pen in a 32-foot diameter and a 49-foot diameter circle. Data was collected for a series of 10 steps, three separate times, in each set of conditions.

The resulting data showed that during all types of work, the walk resulted in greater average hoof pressure than the trot or canter. When analyzing only the walk, the researchers found greater loading of the hooves when the horses moved on a straight line than when they circled. On average, a larger area of each horse’s outside front limb was loaded when they circled at a canter, compared to when they circled at a walk or trot.

“This study found that ‘gait’ impacted our outputs (force, area, pressure) more than the exercise type (straight, small circle, large circle),” says Logan. “We did not control speed at all; we encouraged each horse to travel at the specific gait we requested and then let them travel at a speed they were comfortable with.”

The finding that the walk resulted in more pressure on the hooves might seem counterintuitive, says Logan, but

reflects the biomechanics of the gait and limitations of dynamic measuring systems. “The trot is a two-beat diagonal gait that has been found to be more stable and the preferred gait to use in gait analysis due to this. In our study our results are an average of multiple steps. Given that the walk is slower, the sensor may have had more time to collect values for the walk average than the trot.”

And while this study did not conclusively determine which leg is more stressed when a horse circles at a canter, Logan says it did provide some clues. “We found that when cantering on a circle, the horses loaded a greater area of the outside front hoof than the inside front hoof. This suggests that horses would be pushing off more with their outside front limb than their inside front limb. These findings help to demonstrate the asymmetrical loading of front limbs during circular exercise. This is not a surprising finding, as other studies have shown that horses push off more with their outside front limb when circling. When the hoof is loaded in a reduced area, such as the inside front hoof when cantering in this study, there is a potential for uneven forces to be placed on the joints and bones of the leg, which could lead to a higher risk for joint injury and osteoarthritis”

Logan adds that this study measured only forces within the hoof, not torque or stress on the joints higher in the leg. “We did not look at forces within the joints,” she says, adding, “it certainly is reasonable to expect that forces in the hoof could impact the joints above it.

However that is data we did not have the technology to collect in this current study.”

More work is needed to determine the broader effects of circling work on limbs, says Logan. “These findings are truly the tip of the iceberg when it comes to circular exercise, and we have a lot more questions that we want to look into now: What is happening in the hind limbs? What if we are longeing? What if we are riding? This study didn’t evaluate the effects of long-term circling: It would be very interesting to see how force, area, and pressure outputs change from the beginning to the end of a 30-minute longeing session.”

For now, she says, this study underscores the importance of using common sense when it comes to training horses. “My personal take away, as a horse trainer as well as scientist, is ‘everything in moderation.’ The way that the horse travels when performing circular exercise is important, there’s a lot of research showing increased lean angle means increased push-off from the outside limb and potentially uneven limb loading,” Logan says. “I work with a lot of young horses and absolutely recognize the need for round pens, riding circles, and longeing if a round pen isn’t available. However, when using these methods I take into consideration my circle size, the training of the horse, and the gait at which they are traveling.” Reference: “Impact of gait and diameter during circular exercise on front hoof area, vertical force, and pressure in mature horses,” Animals, December 2021