Join Date: Mar 2009
Location: State College, PA
Long and low only stretches the whole topline, it doesn't really do much for impulsion of the hind end on a "green" horse. I would work on getting a nice, consistent uphill canter and then start doing shortenings and lengthenings. This will help your canter, his balance, help develop natural carriage and vertical flexion as well as help with his rushing.
The problem with horses that rush is that they only have two speeds in a gait: fast and faster. You need to add collection and extension to each gait. Starting with the trot. Open your hip angles and let your hips move with him, even pushing if you have to, when you want him to lengthen his trot. REMEMBER, don't forsake tempo and pace, you want his legs moving no faster you just want them extending longer. Work on making him fling out his legs farther not faster. That is a true lengthening.
Also, for collection you need him to slow his leg movements without slowing the tempo. You want to sit tall, close your hip angles and slow your hip movements so that he slows his legs to match your body.
When you can extend and shorten his strides on the FLAT, then you can start doing it over poles at the walk and canter. It's difficult and you will both make mistakes learning how to adjust your striding to get the perfect "takeoff" over the poles. That's why it's just poles, so if you goof up you're not crashing into a fence. When you can keep him consistent and listening to your striding changes over the poles then you can start doing small fences, grids, bounces, etc. Once he learns to respect your aids to slow or lengthen and he develops the muscle tone and muscle memory of the correct way to carry himself you will have solved the rushing problem.
Another side note is that a horse that gets rushy and doesn't have the basic flatwork foundation for stride regulation, collection and extension generally won't benefit from gridwork to slow them down per say. They will either rocket launch through the grids at 90 miles an hour just flinging out their legs or have a total mental breakdown because they don't know how to use their bodies to get through them.
You might get lucky and he might do ok in a grid but my guess is that long lines and hunter courses are your problems, and just because he can stride right through a tight grid doesn't mean he can do a nice 6 or 7 stride line on a hunter course. Since you said that you were working with a trainer and you are learning the power of finite riding as in when you ask for vertical flexion then I gave you some more advanced things to try.
The other options for rushers are to circle them around a low fence until they are relaxed, then let them take the fence. If they rush, they keep circling until they calm down and then you take the fence. The key to that exercise is that they never know if they are jumping or just doing mindless circles so there's no point in getting excited right? This exercise can get boring with a stubborn or very hot horse and it doesn't correct the underlying problem, but it does help them to mentally prepare better for a fence instead of getting overeager and charging each one. Grids have their place, but they are more for getting lazy horses to snap up their knees, actually bascule, learn to land light on their feet, etc. Hope this helps and let me know if you need any specific exercises I can give you more details.