Does anyone know what muscles are built when she's held behind the vertical, and over bent?
Or are we just suggesting things because they sound like they'd work?
I'm the one that's probably going to get slammed, but what I am seeing is a gorgeous, gorgeous horse that is moving in a classically correct long and low posture and she is getting slammed for it!
Look how far she's tracking up behind. Her back is raised, the front leg is free! This is due partially to the fact that this rider DIDN'T ask for her face, and DIDN'T overbend her.
When the horse goes down into a long and low position, the nose starts to come out, as this horse here has done, to allow the base of the neck to come up, as well as the back (look at the air under her front right leg in the first pic!!). When the head is forced to be tucked or worse, over tucked, this shuts the energy from going up and out the way it is supposed to, and balls the horse up in the front. She is offering you something that is harder--by moving this way, she is lifting the base of her neck and arching the front half of her, rather then shutting down and pulling herself around on the forehand.
Working her 'overbent' works the entirely WRONG muscles. Why does a horse's nose fall on the vertical? How?
A horse's head falls on the vertical when the muscles are relaxed. The TMJ loosens, and the head virtually 'rests' on it's hinge, and what we end up seeing is a head on the vertical. When you pull a head there, usually you are just shutting down the energy and the horse will ball up in front, build incorrect neck muscle, and then pull themselves around on the forehand.
Again, I really can't stress how much I am loving your mare at the moment. The neck muscles are GORGEOUS and correct!
Anywho, if the head on the vertical is a result of relaxation and proper lift in the front... then what happens when you pull a horse's head behind the vertical and overbend them?
The horse has to tighten the TMJ to keep the head behind the vertical, as well as tighten muscles it normally only uses for chewing. When you see horses in the ring with their heads behind the vertical and they look angry, this is why! It takes tension and effort to keep the head behind the vertical. It also doesn't build any of the muscles you'd want, it shuts the horse down (as your mare is trying to tell you when you work her in side reins!). Also, if you pull the horse's head back far enough, their breathing is impaired. (Think of a hose... and then bend the hose in half. Same thing!)
I would really hate to see this horse get 'punished' whilst she's offering you something so great!
Now, before I get jumped on because I'm a 'dressage queen' and this is not a post about dressage, I ride APHA hunters and some WP. Not dressage. ;)
What I would do for the show ring:
For YOU to ride a better long and low to help bring her back up further, you need more contact with the reins. She'll start to lean into the reins and REALLY stretch, and you'll feel weight in your hands. That's the last step of long and low, which is a wonderful stretch and training tool, especially for today's Hunters/WP horses. Sit up straight! Sink your weight in your heels. :)
Otherwise, I would work on bending her. Use a fixed hand, and pull up and to the inside, making sure the bit is hitting her top lip. Fixed hand is important! When she gives to this pressure, you want to see her licking and chewing SOFTLY. This is when she releases the TMJ... and technically what you have to teach her to do is to relax and do LESS work, so that she drops her head on the vertical. Honest to god, I would only like to see her a little closer to vertical, and would love to see her nose poke out a little. I'm tired of the over bent, intimidated hunters in the ring today! (Judges will absoLUTELY pin a hunter with their nose a little poked out!)
Start the bending at the walk, and when you can get her to lick and chew, start at the trot and work on bending her back and forth softly. Don't get mad or impatient, as you're trying to teach her to relax the jaw! Keep contact with her as well, as this will help teach her that when in hunter gear and in the show ring, she has to tuck the nose!
I hope this helps, and if you need anything explained further, don't hesitate to ask. I absolutely ADORE your horse! (I actually want to use your second picture for my blog! Hehee)