Those who follow the path of Zen ... must develop a delicate sense of balance - a sensitivity to nuance and small degrees that deepens each step of the path. One develops this sense of balance by establishing a strong center. The samurai call it chudan - literally, middle ground."
Philip T.Sudo (Zen Guitar, 1998, 138f.)
Balance is one of the most interesting subjects in riding, because it is relevant on so many different levels. Most people think of the position of the center of gravity relative to the support base first, when they hear the word "balance". But this is only one aspect. There are other areas in which balance plays a role. There is a balance between forces, e.g. between the thrusting and carrying "forces", between extensor and flexor muscles. There is also a balance between two opposite extremes, such as firmness and flexibility, collection and extension, impulsion and relaxation, elevation and poll flexion, bending and riding on straight lines, strictness and gentleness, ambition and patience, too much and too little, too early and too late, and so on. If we look closely, we will find that the concept of balance in a wider sense pervades all areas of horsemanship.
Balance obviously has a physical dimension. It also has a psychological dimension. Both are closely linked. If the horse is psychologically unbalanced, he will not relax enough to find his physical balance. Conversely, physical unbalance can cause anxiety and emotional distress. The same principle applies to the rider. A tense, fearful, angry, or upset rider will not be able to be physically balanced in the saddle. And, on the other hand, a sense of being physically out of balance can make the rider feel out of control of the situation, which in turn creates anxiety and tension. To make matters even more intricate, we must always lead by example, because the horse tends to mirror his rider. As a rule of thumb, the horse will only be as psychologically and physically balanced as his rider.
Charles de Kunffy (The ethics and passions of dressage, Half Halt Press, Middletown, MD, 1993, 42) writes about the importance of balancing the body, mind, and soul in order to produce harmony:
"The Ancient Greeks believed the body, mind, and soul to be the three components of a person. These three facets of a rider must always be in perfect balance. The cultivation of one at the expense of the other two components will result in disharmony and discord. However, when equally cultivated and attended to, they will produce a harmonious partnership, which expresses itself in beauty."
One could further expand on this thought. Since riding is an athletic endeavor for the rider as well as the horse, the rider has to be physically in good shape: not overweight, with good stamina, muscle tone and flexibility. Again, the rider has to lead by example. We should not expect our horse to be physically in better shape than ourselves. Riding also has a very strong academic component. A serious rider has to study the technical, theoretical aspects of horsemanship, as well as the history and culture of the art of riding. Training horses is furthermore a continuous exercise of the rider's analytical abilities. We have to observe, analyze, evaluate, and draw conclusions. In other words, we have to exercise our mind and think all the time. Athletic and mental prowess have to be tempered and guided by a certain spiritual maturity and wisdom, in order not to exploit the horse's talent and good will, and in order to treat the horse with fairness. All three areas need to be developed to become a well rounded rider.
In martial arts, balance is referred to as "chudan" - middle ground, the center. It permeates the same three levels: body, mind, and spirit. Philip T.Sudo (Zen Guitar, 1998, 138f.) formulates it this way:
"To occupy chudan is to know the feeling of total balance - physical, mental, and spiritual. From chudan, our spirit is free to move forward, backward, left, right, up, or down. Whichever way we move from chudan, that in itself becomes chudan. It is an instant adjustment. ...
"Never losing the center means never losing balance. Maintaining proper balance is critical in all levels of performance. ...
"The only way to find chudan is through practice and experience. Sometimes that means crossing a line before we know where it is, but those are the risks of exploration. ...
"Those with a feeling for chudan know that the difference between balance and disproportion can be a hair's breadth. ... Know the measure of a hair's breadth; therein lies the Way."
Being centered enables the rider to blend with his horse, disappear into the horse, as it were, and to shape the gait as well as the horse's posture from the inside out. The unbalanced rider, by contrast, is stuck on top of the horse and has to try and influence the horse from the outside, which is much less effective and requires a much greater physical effort.
Physics has its own, scientific, definition of balance. So does classical horsemanship. Both concepts of balance overlap to some degree, but they are not identical. The Old Masters assumed that the untrained horse carries more weight on his forehand than on his haunches, and that one of the main training goals is to transfer the excess weight back towards the haunches, until the body mass is distributed evenly over all four legs in the Campaign School part of the training, while in Haute Ecole the haunches actually carry a larger share of the weight than the front legs. Modern physicists may argue with this traditional view, since the horse is not a solid, immobile object, but the movement of entire body with the different footfall sequences of the three gaits makes the issue of balance more complicated from a physical point of view. Luckily, as riders we don't need to be able to solve the physical equations with all their variables. Whether the traditional equestrian theory is scientifically tenable or not, it describes very accurately the feeling that the rider has on horseback. On an unbalanced horse, you feel as if you were riding down a slope. The croup feels higher, the horse feels larger behind you and smaller in front of you. The unbalanced horse will always take a faulty rein contact: either too heavy, or inverted, or coiled up behind the bit. You feel as if you were sitting on the horse's shoulders, i.e. it feels as if the center of gravity of both horse and rider were right between the horse's shoulder blades. The back usually feels hard, mostly dropped. On a balanced horse, you feel like you are sitting on a level surface. The croup is slightly lowered, the back is raised elastically, the withers are raised and the neck is stretched in an even arc. You feel as if you were sitting directly on top of the hind legs. The entire horse seems to be in front of you, while nothing seems to remain behind the saddle. For this reason, it feels to the rider as if the center of gravity were much closer to the haunches on the balanced horse than on the unbalanced one. The difference between the two is longitudinal flexion.
Most people only think of the poll, when they hear the word flexion. However, the poll is only the very last one in a long series of joints that have to participate in the longitudinal flexion to the extent that they are capable of articulating, in order to create a balanced horse. It begins with the joints of the hind legs.
Most riders emphasize the importance of the hocks, when they talk about the haunches. While the hocks are the most visible joints of the hind legs, because they are exposed to the eye, they are not really the decisive ones, as they are not surrounded by large muscle groups. The real "movers and shakers" in the haunches are the hip and stifle joints, since they are the ones that are embedded in powerful muscles. Without their active participation, the horse moves only from the hock down, which will eventually lead to a breakdown of the hocks and fetlocks. The hip and stifle joints can flex and extend with the greatest possible range of motion, if the hind legs touch down as close to the center of gravity as possible. This also gives the hind legs the necessary leverage to tuck the pelvis and lift the back.
In equestrian terms, the horse is now carrying more weight on his hind legs. The rider feels that the croup is lowering; there is a backward-downward stretch of the back muscles behind the saddle. There is also a forward stretch of the top line in front of the saddle. As the withers rise and the haunches and poll drop slightly, the rider feels as if he were sitting on top of a ball (although the poll is still the highest point). You could sum the concept of longitudinal balance up by saying that the balanced horse uses his entire body. All joints that are members of the longitudinal chain flex and extend as much as their design allows them to.
Incidentally, this implies a balance between thrusting and carrying forces of the hind legs. The unbalanced horse, on the other hand, does not use his entire body. He does not let all the joints participate in the flexion, due to an imbalance in these forces, generally in favor of the thrust, at the expense of the carriage.
In addition to longitudinal balance, there is a lateral balance as well. This could be characterized as the even distribution of the weight over the lateral pairs of legs. Alternatively, you can describe it as the balance of thrust and carriage between the left hind leg and the right hind leg. If one hind leg thrusts more than the other one, the horse is laterally unbalanced. If the horse seems to lean on one rein/shoulder more than on the other, this is another symptom of a lateral imbalance. Both are, of course, connected. Lateral balance is really just a synonym for straightness. Lateral and longitudinal balance are closely interrelated. A horse that is still crooked, i.e. laterally unbalanced, will also be more or less on the forehand, i.e. longitudinally unbalanced. You can observe time and again that a horse who is even slightly crooked, does not show optimal longitudinal flexion. He is not "through"/permeable for the aids (durchlässig). As soon as you straighten him out, the longitudinal flexion is right there.
In traditional terms, a balanced horse has to carry as much weight with his hind legs as with his front legs. He also must carry as much weight on the left side of his body as on the right side. He must furthermore carry as much as he thrusts. In all gaits and in all stride lengths (collected, working, medium, extended) thrust and carriage must be balanced. And he must thrust and carry as much with his left hind leg as with his right hind leg. As longitudinal balance is obtained through longitudinal flexion, lateral balance is obtained through lateral bending.