The Old Masters generally considered the shoulder-in to be the foundation of all other dressage movements, since it increases the horse’s shoulder freedom, the lateral and longitudinal flexion of the horse’s spine, and the flexion of the haunches. It is beneficial in so many ways and can be used to correct so many problems that some riders jokingly call it the “aspirin for the horse”.
The invention of the shoulder-in is attributed to François Robichon de la Guérinière, who is the first author to describe this movement in his 1733 book “Ecole de Cavalerie”. “This movement is developed out of the exercise of the circles on parallel tracks according to Pignatelli and of the circles on four tracks that Newcastle uses”, explains Manoel Carlos de Andrade in 1790. The circles on parallel tracks refer to a simple circle line in which the hind legs follow in the footprints of the front legs. In the circles on four tracks the inside front leg is on the smallest circle line, the outside front leg is on the next larger circle, the inside hind leg is on the second largest circle, and the outside hind leg is on the largest one. It is essentially a shoulder-in on a circle. The Duke of Newcastle had discovered that the circle on four tracks “prevents him from being entire, (that is, to refuse to turn) and renders his shoulders supple and pliant; and this is the best lesson for a young horse in the beginning, it being more difficult to work the shoulders than the croupe.”
He also found that the circle on four tracks can have the disadvantage of putting the horse on the forehand, since the leg closest to the center of the circle carries the highest share of the combined weight of horse and rider, while the leg that is farthest away carries the smallest share of the weight. The legs that are farthest away from the center of the circle have to move with the largest range of motion, since their path is larger. This means that the pair of legs that is closer to the center of the circle will tend to carry more weight, whereas the pair of legs that is farther away is suppled more by riding lateral movements on the circle.
The disadvantage of weighting the front legs more can be overcome by maintaining the same alignment of the horse’s body and changing the line of travel from a circle to a straight line. And this is exactly what De la Guérinière describes in “Ecole de Cavalerie”.
The essence of the shoulder-in is that the haunches stay on the line of travel, while the shoulders are moved slightly to the inside, the horse bends away from the direction of travel, and the inside legs cross over the outside ones. It can be ridden on straight lines (rectangles, squares, triangles) as well as on curved lines (circles, corners, serpentines, and ovals).
Much has been written about the degree of the angle that the horse’s body should form with the arena wall. The Old Masters gave two different descriptions. Borries v.Oeynhausen (1852, translation: TR) writes: “The late Stallmeister Ayrer, my revered teacher, gave as the basic position the horse’s own square. I will explain this further: Think of a horse who is halting square with all four legs vertical, his body parallel to the wall. If you draw a line that is parallel with the wall from between the hind legs to between the front legs, this will equal the length of the horse. Now draw a square based on this line, and the diagonal of this square is supposed to be the perfect position of the horse in the full fledged lateral movement.” Theodor Heinze (1889, translation: TR) says: “The air shoulder-in is determined as either a 1/16 turn or a 1/8 turn, as all leg yield exercises. Its execution as a 1/16 turn, usually called demi-shoulder-in, is practiced first, as it is the easiest one. From here, one progresses to the execution as a 1/8 turn, or entire shoulder-in.”
The consensus of the Old Masters is that the degree of the angle is directly dependent on the degree of lateral bending and collection, i.e. flexion of the haunches that the horse is capable of. This means that lower level horses who are just starting to learn the movement have to be ridden with a smaller angle, since they obviously cannot collect as much as a more advanced horse. When the angle of the horse’s body to the line of travel exceeds the degree of collection, the horse falls onto the inside shoulder, the haunches drift out, and the horse starts to counterbend. The steepest angle that a horse can sustain in high collection without losing balance, bend and alignment of hips and shoulders, as well as the connection of all four legs to the weight is generally considered to be 45 degrees, which corresponds to an alignment of the hips and shoulders in which each leg has its own line of travel
– often referred to as the four-track-shoulder-in, since an observer can see all four legs from the front or from directly behind the horse. In the descriptions above, this equates to the 1/8 of a turn and the diagonal of the square of the horse’s body length.
In the show ring, an angle of 33 degrees is required, which corresponds to an alignment in which the inside hind leg and outside front leg share a common line of travel – usually referred to as the three-track-shoulder-in, since an observer can see three legs from the front or behind.
The mildest variation of the exercise is the so-called shoulder-fore in which the outside front leg tracks in between the hind legs, so that four legs can be seen from the front or behind. The shoulder-fore is well suited to serve as an introduction for the horse to the shoulder-in in his second year of training.
When the shoulder-in is executed correctly, the weight of the horse and rider is transferred more and more towards the outside hind leg, which then becomes the more carrying one. The inside hind leg is the more reaching and thrusting one. The inside hip should lower as the inside hind leg crosses, and the shoulder should move more freely. The crossing of the inside hind leg supples the inside hip, and the lateral bend supples the rib cage.
Before the horse can successfully learn the shoulder-in, he has to be prepared by learning to bend and turn on circles of various sizes on a single track. The shoulder-in belongs into the second phase of the gymnastic training in which he learns to sidestep and bend against the direction of travel. The third stage consists of movements in which he learns to sidestep and bend into the direction of travel.
The rotation of the rider’s pelvis (outside hip a little forward, inside hip a little back) induces the horse to turn his body. The rider’s inside calf supports the engagement and crossing of the inside hind leg. The outside calf prevents the outside hind leg from falling out and can send the horse more forward, if necessary. The inside knee prevents the horse’s inside shoulder from coming in too far. The outside knee helps to bring the outside shoulder away from the track. The inner thigh supports the rib cage bend. The reins support the knees in aligning the shoulders.
In addition, the inside rein flexes the neck and poll a little to the inside, while the outside rein secures the connection between the base of the neck and the shoulders and prevents an overbending. The reins can furthermore be connected to the horse’s legs by holding any one of the legs slightly longer on the ground, which has a relaxing effect on the horse. When this rein pressure is applied against a hind leg, it is called a half halt and results in a greater flexion of the hip and hock joints of the targeted hind leg.
As far as the weight aid is concerned, some people insist that the rider should always sit on the outside seat bone, while others assert that the rider should always sit to the inside of the bend, i.e. on the inside seat bone. However, the reality of practical riding is not that cut and dried. The goal is to achieve an even loading of all four legs and at the High School level an increased weighting of the hind legs. The rider therefore has to determine which leg does not carry enough weight, which leg is overburdened and place his own weight accordingly in a way that equalizes the weight distribution, which means that there will be moments when the rider places more weight onto his outside seat bone, and there will be moments when he places more weight onto his inside seat bone.
Younger horses, who are still learning the shoulder-in, generally understand the rider’s request more readily if the weight is placed in the direction of travel, i.e. on the outside seat bone. Then the rider’s weight indicates the direction, and the inside calf asks the horse to follow the rider’s weight.
By placing his own weight onto the outside hind leg, the rider can increase the flexion of this hind leg and enhance the crossing of the inside hind leg. By placing his weight onto the inside hind leg, he can enhance the thrusting of the inside hind leg.
Sitting more on the outside hind leg can help to improve the bend through the rib cage, while sitting more on the inside hind leg can help to increase the angle of the horse’s body to the line of travel.
There are several common mistakes that can occur. As always, they relate primarily to balance, tempo, line of travel, alignment of hips and shoulders, and rein contact.
1. Loss of Tempo
If the horse slows down in the shoulder-in, it is almost always due to rider interference through stiff hips and/or stiff wrists and heavy hands. Speeding up is caused by a loss of balance: the horse falls onto the forehand and speeds up to avoid falling down. As soon as these causes are eliminated, the tempo of the original gait will be restored again as well.
2. Loss of line of travel (horse comes away from the wall)
If the horse drifts away from the wall, it is usually a reaction to the rider sitting too much to the inside. Shifting the weight more to the horse’s outside pair of legs in combination with a slight pressure of the inside leg and rein (against the side of the neck) will bring the horse back on track.
3. Loss of alignment (angle too steep, too shallow, or inconsistent)
If the haunches swing out, it is a sign that the rider’s outside leg was not placed far enough back, and is not in contact with the horse’s side. This is often accompanied by too steep an angle of the horse’s body to the track. The rider will then have to bring his outside hip a little back, frame the outside hind leg more effectively with the outside calf and the inside shoulder with the inside knee and rein. Sitting more on the outside seat bone usually helps in this situation as well.
If the shoulders cling to the wall, the rider has to sit more on the inside seat bone, bring his outside hip more forward in order to turn the horse’s body more, frame the outside shoulder more with his outside knee and rein, and engage the inside hind leg more with the inside calf. Sometimes it may be necessary also to drive the outside hind leg more forward with the outside calf and whip. These seat adjustments can be supported and enhanced by turning away from the wall or riding a volte, in order to draw the horse’s attention more to the turning aids and the framing outside aids.
If the angle is inconsistent, the rider has to balance the horse better between the inside and outside aids and coordinate the orchestra of the aids more finely.
4. Faulty rein contact (overflexion, nose-in, tilting poll)
If the horse over-bends the neck to the inside, the reason lies in an overuse of the inside rein and a lack of connection with the outside rein. This is often accompanied by a lack of muscle tone in the rider’s midsection and an over-rotation of the rider’s shoulder to the inside, while the pelvis is still facing straight ahead, so that the rider’s pelvis and shoulder are no longer connected to each other.
If the horse tilts his poll and points his nose to the outside, the reason is an insufficient connection of the outside hind leg to the ground and the body weight. In many cases, the outside hind leg is also not aligned properly, but is escaping from its weight bearing duties to the outside or out back. As soon as the outside hind leg steps down in its proper place and flexes its upper joints under the body mass, the head tilt will disappear. Stopping into the outside hind leg in the shoulder-in position, followed by a full pass or turn-on-the-forehand-in-motion away from the outside calf to engage the outside hind leg, before resuming the shoulder-in help to resolve this issue as well.
A review of the main mistakes that occur in the shoulder-in and their respective causes reveals that most of them are in fact caused by the rider’s seat and aids and must therefore be addressed by making improvements and adjustments to the seat and the coordination of the aids.
The shoulder-in is the first true dressage movement that the horse learns. It is the doorway to the so-called campaign school movements and all the airs on the ground, just as the piaffe is the doorway to the high school movements and especially the airs above the ground. The shoulder-in is so versatile and useful that De la Guérinière writes about it: “This exercise has so many benefits that I regard it as the alpha and omega of all exercises for the horse which are intended to develop complete suppleness and perfect agility in all its parts.”
READ MORE ABOUT AUTHOR: DR. THOMAS RITTER