If you look at this traditional drawing of the training scale, you see a nice progression of a purpose bred dressage horse from beginning through advanced. The problem is implementing this training correctly. Seriously. It looks easy peasy if you look at this progression, but how many dressage horses at any level do you see at shows, on video, or for sale that look like this? I see a lot of slightly tense horses, slightly behind the vertical, mostly leg movers instead of back movers, purpose bred, great moving dressage horses that somehow just don't look quite right instead of like this wonderful photo that is full of lightness, power, and expression.
So what is the missing element? Is it German vs. French training methods? Is it the breeding of the horse? Is it different or better tack? Why do some horses look so much closer to this ideal irrespective of breeding and some purpose bred, spectacularly moving dressage horses look not quite right? Even at the international level?
The answer my friends is the engaged hindquarters, swinging back, connected to the slightly lifted shoulders, connected to the reaching neck, at any rein length(or lack there of) or frame. A ring of muscles that lifts the forehand and lowers the quarters. Like this.
If you take that dressage bred horse at the bottom of the scale and just pull his nose in to vertical what happens as you go up the scale? You definitely have trouble with that stretchy circle competing, but more importantly that swinging back and lifted shoulders are missing. So the gaits are not as good as they should be, but still you will do well at the lower levels because your horse is a great mover. As you move up the levels, even if your horse is straight, correct collection and extension are really hard for the horse because his shoulders are slightly dropped and usually the horse is behind the vertical because he is not able to reach his neck to the contact. Everything looks a little hard and feels a little rough. And don't get me started on the lameness issues. Instead of this.
So what would happen if instead the rider focused on having a horse that could stretch out lightly to the contact all the way through the training scale? At any rein length? That my friends is where the magic happens. If the horse can stretch out slightly from seat aids in any frame, the back is always swinging, the shoulders are always lifted, and the neck is always stretched to the contact. And there is your sitting, through, light, and powerful dressage horse of any breed.
I've been amazed, after this epiphany, at how relevant this bridge of the back and shoulders is to a lot of other horse sports. The horses go in all sorts of different frames/rein lengths but the common factor is that lifted shoulder. It is the indicator of the correct biomechanics. Western, hunters, jumpers, when that shoulder lifts, the magic happens. Go check it out.