Muscles of Balance
The horse evolved for one purpose on the plains of this earth.
He evolved to survive. He became fleet of foot with a long neck that was able to get to the often sparse grasses on the plains. The eyes of early equines were large and set wide apart to allow for greater vision while in the grazing position. The skeletal frame was designed to effortlessly carry the horse across miles and miles of ground without tiring in the pursuit of food, water, shelter, and safety. To that end, the basic equine frame is one in which the topline is level. In a grazing stance or at periods of rest, the center of gravity shifts forward, but in movement, the center of gravity shifts more toward the midline to even the distribution of weight and concussion of the forelimbs. Forelimb performance lameness as we know it in the domestic horse, including navicular, laminitis, pastern arthrosis (ringbone), and pedal osteoarthritis are largely unknown in the wild horse population despite the 15 to 20 miles the average wild horse travels in a day. As horsemen, we must ask ourselves why?
We must be careful when comparing our domestic horse to the wild horse in all ways but form to function because we are mak
ing demands on our horses that are completely unnatural. Sure, horses in the wild can perform rollbacks, spins, canter pirouettes, sliding stops, and lofty extended trots. They do not, however, perform them with a large weight in the middle of their spinal column, nor do they sustain those movements for long periods of time. Most of us in decent physical health could perform a burpee. How many of us could perform 10 of them in a row without extreme fatigue? It takes conditioning, muscle strengthening, and suppling to correctly perform athletic maneuvers without causing undue stress, strain, and wear and tear on normal joints.
Our goal as we ride and condition our horses in the hopes of developing a sound, athletic body is to create balance and suppleness through the entire frame. Like any good athletic coach will tell you, this starts with a good working knowledge of how the body is put together.
The equine spinal column is composed of three “arches” (fig. 1).
(fig.1). In the top image, you see the equine spine. The three arches of the spine are: 1. Cervical vertebrae (in blue). 2. Thoracic and lumbar vertebrae (in green and red). 3. Sacrum and caudal vertebrae of the tail (in brown and tan). In the second image, you see the long muscle of the topline—the longissimus dorsi. You can imagine if that muscle was contracted how the back would hollow as it pulls each of the points of attachment closer to each other.
Unlike the human skeleton that is designed to carry weight in a mostly upright position on a bipedal frame, the equine skeleton obviously distributes the weight along the spinal column over all four feet. As already discussed, in a grazing position, that balance shifts to carrying the weight more on the front feet, but in times of athletic movement, that weight shifts back to the “business end” of the horse, allowing for rapid acceleration and quicker turns.
In an athletic stance, you would like for all three of these arches to be evenly engaged, effectively rounding out the entire horse. In neutral, the arches form one long, low arc. It is interesting and instructive to note that the lateral mobility of the equine spine
is largely limited to the first and last arch. The lateral movement through the thoracic vertebrae is limited at best, and the loin and fused sacral vertebrae allow for virtually no lateral movement at all. The only direction the lumbar-sacral joint can move is vertically, allowing for coiling of the pelvis and flexion of the hip. Because the lumbosacral joint has dorsal (topside)/ventral (underside) flexion of only 6.5 degrees, most of the flexion in the back of the horse occurs with flexion of the hip.
Not only are we attempting to develop a frame on the horse capable of athletic movement, we also must build the muscles responsible for carrying our weight without causing injury or excessive wear and tear on the horse’s frame, as well. When the horse is first mounted, he will drop his back away from the weight of the saddle and the rider, as you might expect. The horse does this by extending his spine, contracting the longissimus dorsi. This is also the longest muscle in the horse’s body and runs from the
transverse processes of the last four cervical vertebrae along the transverse processes of the thoracic vertebrae, and it inserts on the dorsal processes of the lumbar vertebrae. This causes a “reverse arch” through the thoracic vertebrae under the saddle and a general flattening of the first and third arch, as well. Stiffening of this long muscle due to fatigue or pain impairs the ability of the horse to round underneath the saddle. Obviously, this is not ideal, and
as riders, it’s our job to help the horse learn to deal with the weight and build the muscles that will allow him to carry the weight in a balanced frame.
The muscles that are responsible for initiating coiling of the loins and the beginnings of balance through the topline are the hip flexors. They are the muscles responsible for the thrust that drives the equine body forward. When these muscles contract, they lower the croup and loin, which “loads” the hip in preparation for the thrusting phase of the movement. This spring-like action carries forward into the second and first arches like loading a spring. When the hindquarters are not brought into play first and you attempt to create an arch through the horse’s body by compressing or flexing just the head and neck, this drives the neck down into the thorax, flattens the back, and pushes the hindquarters out behind the horse.
There are several ways to help your horse begin to develop the muscles that flex the hips. Hills, going both up and down, work these muscles efficiently. Backing your horse (as long as he is correctly stepping back using diagonal pairs) will develop the muscles of the hip flexors. Lateral movements such as shoulder-in, haunches-in, and leg-yield also cause the horse to work the muscles of the hip flexors. Any movement that asks the horse to step deeper underneath himself while still maintaining propulsion will improve the strength and flexibility of these flexor muscles (fig. 2).
(fig.2). As the withers lift and rise out of the shoulders, the back is lengthened. The poll is raised and the weight shifts to the back end of the horse as the hip flexors lower the croup. Contraction of the abdominal muscles lifts the back.
The muscles that are responsible for flexing the hip and coiling the loin may not be the muscles you think of when you look at the back of your horse. The Western horse is often prized for big, beefy hip muscles that extend well beyond the point of the hip. Those are the semimembranosus and semitendinosus muscles, and they are responsible for extension of the limb and help to propel the horse forward in the stride. These are the very muscles that helped give the American Quarter Horse his name, as they are responsible for the quick burst of speed the breed is known for.
They are not, however, the muscles that coil and flex the hip. The hip flexors live deeper and include the psoas major and minor, tensor fascia latae, and gluteus superficialis. These muscles work
in opposition to the large semimembranosus and semitendinosus muscles on the back of the leg. In fact, suppleness through these muscles is as important as strength in the flexor muscles when allowing the horse to coil the loins. Some even suggest that
the long muscles of the hip are equivalent to a second topline that enables the horse to stretch forward and step underneath himself, allowing the balance of the horse to shift farther back toward the loin.
The second arch of the spine is the thoracic vertebrae and loin. We wish to develop muscles that lie below the transverse processes of the vertebrae rather than above them. So while we, as horse owners, spend a lot of time talking about developing a horse’s topline, it is not building the muscles of the topline that concerns us as much as it is making sure those muscles remain soft, supple, and flexible. While we need good muscle tone along the top of the back for strength when carrying weight, these are not the muscles that are most effective in creating an arch and loading the spring of the spine.
If you have ever seen a sway-backed horse that is also in good flesh, you will note that the dorsal processes (bony projections
at the top of the spine) are not very evident. This is because a sway back is not due to lack of muscles along the top of the spine; contraction of muscles dorsal to the transverse processes causes the spine to hollow. Horses that are worked in this hollowed frame (park horses, harness horses, and often gaited horses) will have well-developed muscle tone along the upper spine, and poor muscle tone below the spine.
In order to cause the spine to round up and load the arch, you need to work the muscles that lie below the transverse processes.
These muscles are involved, not only in elevation of the spine,
but in lateral movements as well. This is why lateral movements through the rib cage help to build strength and suppling in the muscles responsible for rounding of the spine. Bend is the key
to lateral strengthening, as well as balancing and rounding the mid-section of the horse through loading of the muscles below the spine. You need all the muscles working together to strengthen and balance the horse.
The muscle groups responsible for lifting and rounding the back are smaller than the muscle that extends the back. Like in the third arch, it is important for the muscles of opposition to remain
supple and loose in order for the smaller muscles flexing the spine to act. These muscles include the rectus abdominus, iliopsoas complex, and longus colli scalenus.
The rectus abdominus is a large thin muscle that lies along the abdominal wall and slings the abdominal contents like a hammock. It attaches at the fourth, fifth, and ninth rib, and inserts at the pubis by means of a large tendon. This muscle acts to create an arch in the back, largely by flexion at the lumbosacral joint. There- fore, when engaging the abdominal muscles, you aren’t lifting the back so much as flexing the loin, which then acts on the vertebrae of the back to arch it slightly.
If you look at the horse’s body as if it’s a suspension bridge, you can see how the first and third arch in the spine anchor the span of second arch (fig. 3 & 4).
(figs. 3 & 4). The muscles of balance that act together to raise and round the back act like a suspension bridge.
The muscles of the abdomen and back below the vertebrae help lift the back into the securing arches of the neck and loin. If either the arch in the neck or the arch in the loin is lost, the roundness in the back drops, as well. It takes each piece of the horse’s body working together to maximize the potential in all body parts. The whole horse is stronger if each of the body parts is doing its job and working in harmony with others.
Think of the tail end of the horse as the end of the bridge that has all of the supplies for building the rest of the bridge. You start there, then you create a base on the opposite side, and then you link the two sides together.
The muscles of balance that act together to raise and round the back act like a suspension bridge.
The greatest part the head and neck play in the overall balance of the horse is in shifting the weight of the horse backward, toward the second and third arch, allowing the horse’s center of gravity to shift more toward the hindquarters, thus freeing the forehand for lofty movement and lessening the concussion on the front feet and legs. Too often, people start to “balance” a horse by worrying about the “headset” before worrying about engaging the horse properly.
In order for the horse to correctly soften and arch the neck from spine to head, he must first lift the base of the neck where it meets the withers. As these vertebrae lift, you can see the engagement of the muscles just to the front of the withers and just in front of the saddle. This sets the horse up for proper head and neck carriage. If you attempt to create an arch through neck by only flexing the poll, this compresses the vertebrae, as well as causing bracing at the third and fourth vertebrae.
A properly engaged head and neck should appear larger at the base of the neck than at the mid-thoracic vertebrae. It is easy to tell if your horse has been developing the wrong neck muscles because he will bulge behind the poll. Think of the head and
neck as lifting from the chest and extending upward and then downward. Some suggest it’s the action a horse makes when he is looking into a bucket—he must first lift, then stretch, then “give” at the poll. This makes “giving” at the poll the very last action involved in the engagement of the muscles of balance and softening of the horse from tail to head.
What about the muscles at the base of the neck? Those should also be loose and stretchy, allowing for the “telescoping” of the neck. Thickening or tightening of these muscles shortens the cervical spine and creates the “ewe-necked appearance.” The muscles at the top of the neck responsible for stretch and lateral flexion are the only muscles that should enlarge in the properly worked and balanced horse. Those muscles should be toned and even from the poll to the withers.
When the poll is flexed or braced without proper engagement of the remainder of the neck, you get thickening of the rectus capitis. This becomes the widest part of the horse’s neck and is especially noticeable when viewed from the saddle.
The well-developed and balanced horse will have even muscle development through his entire upper body with soft, supple, stretchy muscles along the topline. Obviously, not every horse needs to be an elite athlete, just like not every rider is an elite athlete, but knowing which muscles are the “wrong” muscles and which are the “right” ones for balance may help you spot trouble areas in your riding and keep your horse sound and healthy well into his later years.
Read More at : Dressage the Cowboy Way – Eitan and Jenni Grimmett.
