Norman, your 17-hand gelding, comes out of his stall as usual--full of beans. Refusing to stand still, he dances around you while you try to get on. In exasperation, you finally grab the saddle flap and heave yourself up with one foot in the stirrup just as he begins to trot away. But at least you're up there, soon to get settled for your ride, and that's all that counts. Or is it?
While many riders subject their time in the saddle to microscopic examination, poring over every aspect of position and performance, one area of riding gets hardly a second thought: mounting. Riders rarely examine the technique they use to get from ground to saddle and their horses' responses to having to stand for it. But is the way we make the journey up onto our horses' backs really that significant? Or does mounting, as reflexive as it may become with experience, have deeper implications than we realize?
The Physics of Mounting
To really look at the science of mounting, we have to travel back in time to 1669 when a fresh-out-of-college kid named Isaac Newton formulated the basic laws of motion that still stand today. The Newtonian law regarding acceleration helps explain the difficulties associated with mounting: When a rider mounts a horse from the ground, he's accelerating upwards against gravity, and the entire body weight has to be lifted by energy. The heavier the person is or the greater the distance he is below the horse's back, the more energy is required to lift him and the more effort the horse must invest to withstand it. Jeff Thomason, PhD, associate professor of biomechanical science at the Ontario Veterinary College in Guelph, Canada, estimates that a person mounting a horse from the ground could actually exert up to double his own weight on the stirrup. The resulting force pushes down the stirrup, pulling the saddle both down and toward the rider. This leads to another aspect of acceleration, torque, or twisting, wherein a linear force (pressure in the stirrup) tends to rotate a body (the horse's body) rather than just pull on it. The farther the rider's center of mass is from the horse's side, the greater will be the unbalancing twist applied to the horse's body.
The design of the equine body--fairly long, with the feet close together--makes horses longitudinally stable but laterally precarious. In other words, it's easier to pull a horse over sideways than to roll him end to end. And like a bicyclist, the horse balances best when he is in motion. Thomason explains that mounting from the side inevitably throws the horse off balance to some degree. A light pull on the saddle causes the horse's weight to shift to his left legs, lightening his right side. To counteract the pull, he must raise his back on the left side. If the rider's toe digs into the horse's ribs, the resultant cringing to the right may complicate the horse's reactive mechanics still further. If enough weight is behind the torquing action, the horse could be forced to step toward the rider or to the right as the rider's weight pivots atop the saddle. The horse is reacting to the feeling he's toppling over and adjusting his base of support to compensate. Additionally, by gathering up the reins, the mounting rider restricts the horse's natural rebalancing maneuvers: stepping forward and/or extending his head and neck or swinging them to the opposing side as a counterweight.
How We Hurt Each Other
During mounting, then, the saddle, as it torques toward the rider, presses against the spine (especially the withers) on the off side and digs into the muscles on the near side. The horse twists to the right, his right-side muscles sink to avoid the pressure from the panels, while those on the left of the spine hump up as the horse attempts to support the weight of the mounting rider. In the last few years, some riders, veterinarians and therapist have wondered if this daily pull against the muscles and spine could have some damaging effect on the horse's back. Joyce Harman, DVM, a Flint Hill, Va., veterinarian, certainly thinks that it could.
Harman, who practices equine acupuncture and chiropractic in addition to conventional veterinary medicine, has gathered data about pressures of mounting, using a high-tech sensor pad connected with a computer. The instrument registers in pounds per square inch (psi) the amount of pressure exerted on a horse's back by various configurations of saddles, pads and riders. Unmounted saddle pressure ranges from 0 to .5 psi depending on the weight and fit of the saddle and tightness of the girth. Normal riding pressures range from 2.5 to 4.5 psi. Using her short self (five feet, three inches tall), her tall horse (17½ hands) and her English saddle with the stirrups set at her regular riding length, Harman tested the consequences of different mounting techniques. Her findings:
- The highest back-pressure scores--around 4.5 psi--occurred when she mounted from the ground.
- Mounting from a mounting block created about 3.5 psi of pressure on the horse's back.
- The leg up produced the least pressure, registering only 2.5 psi even when performed at its clumsiest.
- The areas receiving the most pressure were the right side of the withers and the portion of the left trapezius muscle underlying the point of the saddle tree. The trapezius is involved in shoulder movement.
- Another high-pressure point was the right rear of the saddle when the cantle was gripped during ground mounting.