Horses are big, sturdy animals capable of carrying hundreds of pounds of weight. They've hauled us around for centuries, across battlefields, farmland, and show rings. But just how do the forces applied by saddle and rider affect a horse's performance and welfare? With advent of electronic pressure-measuring devices, researchers are now able to answer that question.

At the 9th Annual International Society for Equitation Science, held July 18-20, at the University of Delaware, in Newark, Hilary Clayton, BVMS, PhD, Dipl. ACVSMR, MRCVS, Mary Anne McPhail Dressage Chair in Equine Sports Medicine at Michigan State University, reviewed recent research findings on what she calls the rider-saddle-horse interface.

Clayton first introduced the cutting-edge equipment researchers use to measure force and pressure distribution on a horse's back: a wireless, electronic saddle pressure mat with Bluetooth transmitter. Each of this device's 256 sensors is capable of 60 readings a second—that adds up to a whopping 15,360 force and pressure measurements per second.

But how do we define force and pressure, and why are they important?

"Force is exerted between two objects in contact and causes a change in movement, direction of movement, or shape," Clayton explained. The pressure mat only registers the force component applied perpendicular to its surface.

For instance, "At trot the horse and rider are airborne in the suspension phase, then the rider descends into the saddle in the stance phases (when a diagonal pair of hooves are in contact with the ground)," she said. "Total force increases and reaches a maximum as the horse starts to push up into the next suspension and the saddle pushes against the rider's seat to provide an upward thrust. Maximal total force is approximately twice the rider's weight in trot and three times the rider's weight in canter."

Pressure is the force distributed over an entire area—in this case, the horse's back. Electronic pressure mats show pressure distribution in the form of a colored scan. Clayton said localized and/or continuous pressure to a horse's back can have such negative effects as ulcer development, tissue necrosis (death), and muscle damage.

In recent years researchers have used force and pressure measurements to study the effects of different saddles, pads, and riding styles on the horse's back. Clayton summarized the following significant findings:

  • In a 2009 study of four different saddle pad materials, Austrian researchers determined that foam and gel pads lowered the maximum overall force in 44% of horses at the walk, and gel and reindeer fur lowered the maximum overall force in 61% of horses at the trot. 
  • In a 2010 study looking at saddle pressure and signs of back pain, Swiss researchers measured saddle pressure at the walk, trot, and canter in three groups of horses: those with dry spots under the saddle after exercise, indicative of an ill-fitting saddle; those with clinical signs of saddle pressure (e.g., pain, heat, inflammation); and control horses with well-fitting saddles. They found that average and maximum saddle pressure values were highest in the two groups of horses with back problems and poorly fitting saddles, and these values have been used to establish pressure thresholds.
  • In 2011 the same researchers determined that reindeer fur was the best material for reducing maximum overall force
  • In recent unpublished studies, Clayton determined that sheepskin saddle pads spread forces more evenly across the horse's back than when the same saddle is used without a pad and helped reduce pressure peaks.
  • In a 2013 study of sitting the trot in either a conventional saddle or bareback, Clayton and colleagues found that riding bareback was associated with higher average and maximal pressure on the horse's back than riding with a saddle, and the pressure was concentrated beneath the rider’s seat bones. The team concluded that bareback riding might increase the risk of pressure-induced injury to the horse's back muscles in the mid-back beneath the area where the rider sits.

In summary, Clayton said, force and pressure measurements are "of value to equitation scientists because they have applications in improving the horse's comfort, understanding the effects of different types of tack and riding techniques, and reducing the risk of back injury in ridden horses."

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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