Grounded in the Saddle
Part 3: One-Rein Stop
The one-rein stop is one of the most important lessons you can teach your horse; it could literally save your life some day, and his too, so take the time to practice this in all gates until it is second nature for both of you. Like the Give To The Bit exercise it helps your horse to soften and become supple. But here, from the saddle, this exercise is also your 'emergency brake' if your horse panics and wants to run - it is pretty nearly impossible for him to do so when his head is turned into his side.
At first you should work on this exercise in a controlled space if at all possible: an arena, fenced paddock, large round pen, or the like.
Ask your horse to walk and let him travel several feet before asking him to stop. Hold the reins in the center with one hand while you slide your other hand well down one rein as with the Give To The Bit exercise. Say “whoa” calmly and quietly, sit down into the saddle rocking your seat so that your seat bones push your horse into the bit, and pick up on the one rein. Keeping your hand low, pull your horse’s head around, as in lateral flexion. Your horse will come around in a circle. Sit quietly until he comes to a complete stop. Drop the rein and ask him to flex in the other direction before moving off to do it again. Practice this one-rein stop in both directions many, many times. Soon your horse will not need to walk around in a circle, but will simply stop when he hears you say “whoa”, feels your seat bones drive him up to the bit, and feels you pick up on one rein.
Once he is really good at this at the walk, try it at the trot. When you have both perfected the one-rein stop at the trot, work on it in the canter. Be sure you practice in both directions, at all three gates. Soon it will become second nature to you both, and you will be able to use it when you get into trouble. Your horse will respond immediately.