Why is Good Footing so Important?
Reprinted by permission from Equine Monthly Magazine
Good footing is more than something to consider when choosing which shows you'll compete in. It's so vital to your horse's well-being that you want it under his feet for every step he takes - especially when he's working.
In its simplest terms, good footing starts with a firm, level base that gives your horse's feet a reliably solid platform from which to push off. The base anchors a top layer or cushion that absorbs much of his footfalls' concussion and provides traction he can depend on when changing direction or jumping. If well constructed (as we'll explain), these two layers create footing that's usable under most weather conditions.
Good footing is safer for your horse and boosts his confidence. How does bad footing affect him?
- If it's hard, he'll shorten stride to minimize jarring (and modify his jumping form to avoid the sting of landing). Hard footing will also stress his joints.
- If it's too deep, it'll strain his soft tissues - tendons, ligaments, and muscles. Additionally, it can make getting him in front of your leg more difficult.
- If it's slippery, he'll feel insecure, so he'll move cautiously.
- If it has an uneven base, at the least it'll interfere with a consistent ride by forcing the two of you to compensate for its hills and hollows; at worst, your horse may step into a hole and injure himself.
Here are some Biomechanical Considerations;
During the impact phase of a step, the forward movement of a horse's leg is suddenly decelerated, causing a shock wave to travel up the leg. This shock wave is potentially damaging to the bones and joints of the leg, and is thought to be a major contributor to the development of degenerative joint disease--osteoarthritis--in performance horses.
After the initial impact phase comes the loading phase, when the leg accepts the horse's weight as compounded by the amount of thrust. The push-off or unloading phase follows. As the term suggests, this is when the leg pushes off the ground, elevating the horse, to maintain forward momentum. Tendons, ligaments and muscles experience the most strain during the loading and unloading phases. Toward the end of the unloading phase, the heels of the hoof rotate around the toe in the breakover.
The Physical Properties of Surfaces
The perfect formula for footing considers the biomechanics of a horse's step as well as the physical properties that influence performance and soundness: impact resistance, shear resistance and friction. Impact resistance indicates the density of compaction--the hardness--and the amount of concussion it causes. A hard surface, such as concrete or sun-baked clay, has a high impact resistance because it absorbs little, if any, of the impact energy. Consequently, the impact shock wave of the loading phase of a step must be absorbed almost entirely by the loaded leg. Therefore, high impact resistance is associated with large concussion.
Horses working on such surfaces tend to move conservatively in order to avoid excessive shock to their limbs. Under these conditions riders find that their normally free-moving horses have become short strided and stiff--often stumbling unaccountably--as they struggle to protect themselves against the unfriendly footing. This is what occurred in the late-summer show in the Midwest where the warm-up rings sat on a dry, sun-baked surface. Over time, horses working on hard surfaces are likely to develop bone and joint problems, especially degenerative joint disease, a frequent reason for dressage horses' premature retirement.
At the other end of the scale, deep wood shavings create a surface that has low impact resistance--which means that it absorbs the energy of the footfall. This is ideal for reducing concussion on legs, but it is very poor for preserving energy. Normally, a horse's leg stores some elastic energy in the ligaments and tendons during loading that is released to bounce the leg off the ground during unloading. To imagine what it is like for your horse to work on deep wood shavings, think of running on a track covered in pillows. A low-impact surface absorbs so much energy that your--or your horse's--muscles work much harder to provide sufficient propulsion. It has the effect of transforming a bouncy basketball into a medicine ball, and when this happens, there is a premature onset of fatigue.
The indicators of fatigue--raised heart rate, increased respiration, labored movement, inexplicable profusion of sweat-- need to be seriously regarded. To do otherwise is to flirt with strained muscles, tendons and ligaments. Suspensories,check ligaments, stiffles and backs are put at risk, and the potential for tying-up is increased.
Shear resistance describes the resistance of the surface to penetration by the toe of the hoof during the push-off phase of a stride. Ideally, the toe should be able to penetrate the surface in the terminal part of the push-off. It is at this time that the navicular region experiences the highest forces. The higher the density of compaction of the footing, the higher is the shear resistance--factors that explain why horses with navicular disease cannot perform well on hard footing. However, when the footing can be deformed by the toe during push- off, the force on the navicular bone is relieved because the hoof angle changes.
On a loose surface, such as deep, dry sand or shavings, the sheer resistance is low so the toe penetrates easily, but because the footing continues to yield during the critical push-off phase, it provides no support to the foot. Consequently, the soft tissue structures of the horse's legs must work harder to produce the necessary propulsion. Low shear resistance--a condition referred to on racetracks as a "cuppy track" --not only leads to fatigue, but because of the instability invites excessive lateral movement in the joints and thus increases the possibility of sprains--a condition exacerbated by fatigue.
Friction between the hoof and the ground determines the amount of resistance there is sliding over the surface. When the hoof makes impact with the ground, it is traveling forward. (The forward velocity is higher in the front hooves than in the hind hooves.) High friction stops the foot abruptly (it's like trying to waltz in sneakers) and low friction allows the foot to slide uncontrollably (like waltzing on rollerblades). Ideally, the hoof needs to be able to slide, but not to the extent that it cannot be controlled. With a high coefficient of friction, the impact of shock waves increases dramatically.
Either too much or too little friction reduces your horse's confidence in the surface and causes him to step shorter, keeping his feet low to the ground. In a word, he shuffles, losing impulsion altogether. It often takes a horse a while to regain his trust in his footing, so even if the footing in the showring is inviting, when you have to warm-up on slippery grass or trappy mud, your horse may go through an entire test before he feels secure enough to "loosen up." Too much time spent riding on high or low friction surfaces risks making long-term changes in your horse's posture and locomotion.
To avoid injury or poor performance, ride on the correct footing whenever possible.
Excerpts from articles in Practical Horseman July, 2002 By Sandra Cooke and Dressage Today February 1998 By Dr. Hilary Clayton & Elizabeth Madlener.
Written by Rahn Greimann, Equine Monthly Magazines.