What is shoulder-in?
If you would have to come up with one exercise that is the core pillar of classical riding, it would probably be the shoulder-in (SI). Because it places higher demands on flexibility, mobility, strength, and shoulder control than a regular straight line or circle, it really helps to make your horse feel better over time.
To start with, let me explain to you what a shoulder-in is. It is an exercise where the entire horse is bent, from head to tail, and the shoulders are placed further into the arena or figure (like a circle) compared to the hind end. This might seem simple at first, but it can be difficult to understand the correct orientation of all the body parts involved. If the shoulders or pelvis is not in the right position, or the neck is overbent, the horse will lose balance and put more weight on their inside front leg.
Shoulder-in on a straight line
To make things a little clearer, we can identify two distinct variants of this exercise, namely a shoulder-in on a straight line and shoulder-in on a circle. Both of these variants can be made more or less sideways, but the line that the horse travels on stays the same. The straight line, from not sideways to completely sideways, can be categorized as follows:
- From completely straight
- To shoulder-fore
- To shoulder-in on three tracks
- To SI on four tracks
- And it ends up with the entire horse going completely sideways (which I sometimes refer to as two tracks)
The horse needs to rotate their shoulders into the arena, and have a slight bend throughout their body. But the pelvis still needs to be oriented into the direction of travel so that the hind legs can step straight. If we only focus on the front, and just add more inside leg, eventually the pelvis will be pointed outwards too much and the hind legs step sideways. This is by far the most made mistake in shoulder-in next to the arena wall, because it prevents the horse from going too sideways by definition. After all, the horse can’t just go through the wall! As a result your horse will have more weight on the inside shoulder and collection will become difficult.
So what if you don’t actually notice whether the horse has their pelvis in the right direction? I would really recommend you to get a friend for help or film yourself from the back when you first attempt the shoulder-in, since it will make it so much easier to notice.
Preventing your horse from falling in
In general most horses are taught steering with a very simple method. The rider points their head and shoulders in a direction, and the horse responds by moving in that direction. This means that it might take your horse some time to understand that they should move sideways.
Make sure to give them all the time they need, so that it doesn’t become a frustrating experience for either you or your horse. If your horse was taught this simple steering, they will be very likely to fall into the circle when you ask their shoulders in. You can use secondary aids such as showing a whip on the inside shoulder to ask them to not fall in, or draw the shoulders out with a shoulder target (see the previous chapter on teaching targets). You can also usa a standing exercise to make it more clear.
To begin, you want your horse to be bent in one direction, and for them to move away from your inside leg. This leg is always on the inside of the bend, so if your horse is bent to the right, you use your right leg. Ideally we would like their shoulders to stay in one place and only their hind legs to move.
To achieve this we ask with our leg and wait for a response. When you feel that they shift their weight or take one step in the right direction, we again give our marker signal and reward. Now of course the direction of the step of the hind legs here is not completely what we want in the final shoulder-in, but this exercise is about the idea of moving away from the inside leg. You don’t have to train this for a long time, just 5-10 minutes or so until they understand the idea.
Afterwards, you can go back to the shoulder-in exercise on a circle, and give your inside leg behind the girth when they fall in. When you feel they adjust even slightly on your aid, you reward. Usually this is enough to solve the issue entirely.