The shoulder-in marks the stage at which the horse begins his journey into collection and self-carriage when it is correctly performed. Unfortunately, many novice riders mistake the shoulder-in with a 'head and neck-in', which locks the hindquarters and fails to achieve the very purpose of the shoulder-in: collection.
The shoulder-in is a lateral movement. Lateral movements are defined the dressage rule book of the British Horse Society as follows: 'In all lateral movements, the horse is slightly bent and moves with the forehand and the quarters on two different tracks.'
When looking up the description of the shoulder-in, a brief, yet very precise explanation was found: 'The horse is slightly bent around the inside leg of the rider. The horse's inside foreleg passes and crosses in front of the outside leg...the horse is looking away from the direction in which he is moving. Shoulder-in, if performed in the right way, with the horse slightly bent round the inside leg of the rider, and at the correct angle (although not mentioned in the rule book, it is usually agreed upon that the correct angle is approximately 30 degrees away from the track) is not only a suppling movement but also a collecting movement because the horse at every step must move his inside hind leg underneath his body and place it in front of the outside, which he is unable to do without lowering his inside hip.'
It is now summed up that the shoulder-in demands the horse to engage his hip joint, hock, and fetlock on his inside hind to remain balanced, which shifts his weight to his quarters and relieves his shoulders and forehand of the load.
Benefits of the Shoulder-in
Being one of the early 'movements' introduced to a horse, the shoulder-in teaches the horse to improve his self-carriage while suppling his joints, back, and muscles. Even if the horse is introduced to it later in his training, the shoulder-in can form the first building block to collection. To be concise, the benefits of the shoulder-in are explained below:
Deepens the hindquarters
and elevates the forehand - because the horse has to engage his hindquarters
to perform the movement, the weight is lifted off his forehand, which
supples both hindlegs and haunches.
Strengthens the horse's back - the shift of weight to the hindquarters strengthens the back and loins, giving the horse the physical capacity to achieve higher collection and perform more complex moves. Gradually, the horse will begin to develop a rounded appearance as he becomes stronger and more flexible.
Preparation for the Shoulder-in
Your horse should be allowed sufficient preparation before he is introduced to the shoulder-in. Some horses find this movement easy, but others may find it difficult. In either case, only attempt the shoulder-in when you have prepared your horse thoroughly, otherwise you may leave the horse with unhappy memories of the training session.
To begin your preparation, warm up your horse on both reins in trot and canter. You can then begin to work your horse towards collection through circles, serpentines, and frequent transitions. Serpentines improve the balance of the horse because they require him to change direction swiftly, which creates longitudinal suppleness.
While on your circles, make several transition, first from trot to canter to trot, then from walk to canter to walk. This exercise encourages the horse to shift more weight to his hindquarters and lighten the forehand. You only need 3 or 4 minutes for this exercise before you notice the difference with your horse - he will become rounder and lighter in your hand.
The next step is the spiral circle. While circling at 20m, deepen your inside seat bone a little and lightly apply your outside leg behind the girth to begin an inward spiral to a 10m circle. From the 10m circle, you may progress by spiraling outwards to the 20m circle by gently nudging with your inside leg behind the girth. At this stage, it is better to apply your inside leg by a light nudge rather than a constant squeeze. As the horse progresses, you can be more subtle with your aids and apply pressure with your inside leg on the girth.
Your horse will then step away from your inside leg to begin the outward spiral. Maintain the bend to the inside by sponging the inside rein if your horse becomes stiff and/or rushes. By stepping away from the pressure of your inside leg, your horse will be on his way to learning lateral work. This exercise can be repeated four times; twice on each rein at the walk then at the trot.
The Aids for Shoulder-in
Seat: Your weight should be on your inside seat bone and your body should very slightly be turned to the inside Be careful not to collapse at the waist.
Inside hand: Softly ask for a flexion to the inside by sponging the inside rein. Your hand should be at the wither, not away from it or crossing over it.
Outside hand: Support the horse's shoulder and indicate the direction by maintaining a quiet outside rein. Your hand should be just to the outside of the wither.
Inside leg: In the early stages, your inside leg should invite the horse to step away from it by softly nudging his side just behind the girth. When the horse become more confident, you can apply your leg on the girth with gently pressure.
Outside leg: Your outside thigh and knee should lie against the saddle (not turned outward) to support the horse's forehand.
When first attempting the shoulder-in, don't ask too much of your horse; introduce it slowly at the walk before moving on to trot. Assuming you are on the right rein at the trot, follow these simple steps:-
1 - Travel up the track in a 20m x 40m arena and ride a 10m circle at M, then at B, then at F, thinking straight and forward between each circle.
2 - At C turn right and ride up the centerline to A. At A turn right.
3 - Between A and M, make a downward transition to walk.
4 - At M, ride a 10m circle again. As you return to the track, apply the aids to the shoulder-in as described above.
5 - The moment the horse responds by taking a couple of lateral steps, reward him by walking forward into a 10m circle, then straight up the track to B.
6 - At B, repeat the process as described in step 4 and 5.
When the horse becomes more proficient, you can skip the second circle in step 5 and straighten the horse to the track. Make sure you practice on both reins, and proceed to trot only when you feel your horse is more confident. You may practice first at the rising trot, then at the sitting trot.
How Not To Do It
If your horse is not well prepared and if you are not well aware of the aids, you may result in a move that blocks all the natural beauty the shoulder-in brings out. Proper preparation is important because a horse that is not prepared may panic when asked for the shoulder-in and rush down the track with his weight onto the forehand. In these cases, the novice rider often exaggerate the use of the inside hand, dragging the horse's head and neck inwards, but failing to bring his shoulders to the inside. The result is an unhappy horse, heavy on the forehand with locked hindquarters.
your horse becomes upset, return to the preparation work before attempting
the shoulder-in again. Quite often, horses find collection coming naturally
to them after a session of shoulder-in and may perform a collected trot
beautifully the way nature intended it to be. The shoulder-in is simply
a path that we use to bring out the natural elevation and impulsion in