I believe I missed something in this discussion, because I'm not exactly sure what the "cruising" exercise is, but I wanted to add a tip that works for me with horses that get quick.
I like to do a lot of small circles, so as the horse gets too fast, I put them on a small circle or figure 8. Doing a small circle forces the horse to slow down to stay balanced, but avoids me needing to use both reins, which tends to just make a quick horse brace. I also do a lot of transitions so the horse starts thinking about slowing down more often. (and the transitions also help develop the horse's balance)
I hope this is helpful, and would anyone mind explaining what the "cruising" exercise is? Thanks!
The goal of the cruising exercise is "to be able to trot and canter on a loose rein and have the horse maintain that gait and speed by himself-not any faster, and not any slower." Quote from Clinton Anderson fundamentals arena mate. The horse learns to be responsible for his own feet without the rider touching the reins. During the teaching phase of the lesson they usually start out going faster then we want them to, and the rider just needs to sit there and wait for them to slow on their own, which at some point they will drop there head and slow down, on their own. If we are constantly managing there feet they never learn to be responsible. The only time the rider would touch the reins would be if the horse breaks gait and canters at which time the rider does a one rein stop shuts the horse down and goes again at the trot. Some hotter horses may only trot for two or three strides then they break into a canter and that is fine, you one rein stop then go again, eventually they realize they will be shut down and learn to trot. It is not an exercise that you do for one day and they have it, usually it takes a good 7-10 days for them to get really confident with the exercise. Especially horses who are used to be micromanaged, they just don't know what to do and will just trot and trot in circles until they figure out they can anywhere they want, then they have fun with it.