When a horse performs a great canter lengthening, the impression he gives is more than just the technically correct lengthening of his stride and frame, stretching over his back and neck into the bridle. He also gives the impression of "breathing" through his body, channeling energy from his hindquarters up into his back and shoulders to create big, fluid strides. As he transitions from working or collected canter into the lengthening, his cadence actually slows down—because he needs more time to take each elongated stride. It speeds up again when he transitions back to working or collected canter.
Most importantly in this ideal performance of the movement, the horse shows no signs of tension. Even the slightest tightening in his body produces the opposite effect: a quicker cadence with no increase in stride length. This is the most common mistake we see in the show ring. When riders come out of the corners and "gun it," their horses hold their breaths and sprint down the arenas, without ever lengthening at all.
Although the canter lengthening is a steppingstone to the more powerful, expressive, uphill extended canter, which requires significant training to produce, you can introduce the basic concept very early in your horse's education. As soon as he understands that legs mean go and reins mean slow down, you can begin to ask him to go a little forward and back within the canter. This is an incredible everyday training tool you'll use all the way through the levels. It helps to make your horse more connected between your legs and hands and more "through" in his body, the quality I described as energy flowing forward from the hindquarters. It also keeps his mind active, making him start to ask, "What's next?"
To teach your horse to lengthen, rather than quicken, you need to master three skills. First, you need to keep him straight in his body. If he's crooked, for instance, with his haunches shifted to the inside, some of his power will be lost sideways. To maximize his power, both his hind legs need to reach directly under his body so they can push it up and forward.
The second skill you need to master is the ability to initiate the upward and downward transitions with your seat and a light leg. I'll explain how to do that in this article. It's easier than it sounds.
Finally, you need to allow your horse to relax and breathe through his back as he lengthens, so he feels free to lift up underneath you and produce bigger strides. I'll explain how to do that, too.
Read more on mastering the canter lengthening with Lauren Sammis in the September 2012 issue of Practical Horseman magazine.