“Two Tracking” was what they used to call it. It’s the process of getting a horse to move forward while at the same time stepping a little bit sideways, leaving two lines of hoof prints in the sand. To do this the horse should be “crossing over” with both front legs and hind legs. It turns out that this movement is the foundation of “collection”. That is, the horsemanship of actually “doing something” with a horse. Now, if all you want is to be a passenger on a horse going on a scenic trail ride you can stop reading here.
If you’re still reading, I assume you’ve taken an interest in dressage, reining, working equitation, or reined cow horse competition and the like. Or maybe you use horses for ranch work. In any event, you’ve discovered that you need improved mobility in your mount in order to put him in position to do a job.Nuno Oliveira, the 20th century dressage master, said “I do nothing before I do shoulders-in”. I’ve found his approach indispensable. “Shoulders-in” is essentially “Two-tracking”. It puts the horse’s hind feet more under his body and shifts more of his weight onto them, causing him to feel springier, and to be able to move in any direction easier. It’s basically what ballet dancers and football players do.
To do shoulders in do you need three things: forward movement, body angle, and body bend. He moves forward because he has learned to do so with a squeeze of your calves, or a tap of your stick. He angles about 45° inward, with his forehand or shoulder off the fence, because you turn your shoulders, rib cage, and reins inward a little. He bends because you sit on your seat bone on the inside (arena) side. Remember how you twisted when a friend poked his finger in your ribs? Your seatbone has a similar effect on your steed.