The inside rein does not make the bend
To understand this, a basic understanding of equine anatomy is essential.
In a correctly bending horse, the inside hind leg comes under the body directly behind the inside front. This facilitates the lift of the torso – the longissimus dorsi under your saddle allow this lift, and the rib cage moves slightly away from your inside leg, expanding the outside of your horse. The under neck of your horse relaxes, and the top of their neck helps lift their shoulders. This allows your horse’s poll joint and TMJ to stay nice and loose, allowing the skull to slightly rotate with the bend of the spine in the direction of your turn. This bend is less than many are expecting when it we think of bend – your horse’s head will still be in the middle of his chest. But this full body bend will create a nice, loose but still connected feeling in your inside rein.
What is happening when your inside rein is tight, or you feel you need to use it to create bend?
Let’s start from the hind leg- the inside hind is either to the inside of the track, with the horse’s hip tipped in, or their inside hind is traveling laterally under the body toward the outside of the track. Either way, it is not under the body supporting the trunk, and cannot lift. This means the joints of the hip, stifle, hock and pastern are not flexed equally, and creates a higher hip on one side. This unevenness travels through the body, forcing the horse to compensate by supporting themselves with a shoulder and under neck. If they are falling to the inside with their shoulder, their head and neck have to counter balance, so they will look to the outside. When you pick up your inside rein to turn or create bend at this point, you only succeed at dragging the horses jaw toward the turn, but you’ve likely further locked up the poll and TMJ as the horse is out of balance. This is why the second you let go of the inside rein, the horse falls apart again.
This is the essence of back to front riding. Why isn’t my horse bending? The answer is in the work of the hind leg.