I thought a little more detail on performing the shoulders-in might be helpful. After all, it’s taken me since 1971 to even begin to understand it as well as the half halt. When we question why we are putting ourselves through this torture we have only to bring to mind that magical Olympic musical freestyle, or that reining horse who danced like a ballerina. When we have ridden a performance on a truly collected horse we get that silly grin and start to giggle – that’s so cool!
That springy, dancing movement is the result of your horse converting his forward movement to shifting his weight onto his springy hind legs and slowing his cadence,while exerting more effort to jump and elevate his shoulders and withers.To get this, walk your horse along a fence. Get a good energetic walk. Now, slowly turn your body away from the fence, facing inside the arena. You will turn your shoulders and also your rib cage. You and will look to the inside, even a little behind as though to see if you’re being followed. Along with your shoulders, your arms, hands and reins will come to the inside, holding the horse’s shoulders off the fence a little. This will give you the angle. The bend will come from the action of your seat bone. As you rotate, you will naturally increase weight in the inside seat bone. It may help a little more if you actually lift your outside seat bone! Finally, to keep forward movement, your thigh and calf will slide back away from the girth and press a little. Because you are pushing your own inside leg at the same time as the horse moves his inside leg, he will begin to cross over as he moves. This is the point of the shoulders in exercise, to help your horse to cross his legs and bear more weight on his hind legs. At the same time, your hands will need to squeeze ( not pull) to lift and reduce the movement of the outside shoulder. The mantra of dressage is “inside leg into outside rein!”.