One of the most often used phrases in training horses it that the horse should move straight. It is a very important element of dressage and one of the most difficult to achieve. To create a straight horse there are some qualities that need to be developed, the first of which is suppleness and balance.
When a horse is unbalanced they use their shoulders and neck to support themselves and impulsion that is created pushes them further into the shoulder. It’s the equivalent of running downhill, the faster you go the more unbalanced you become.
Suppleness and balance are linked, the horse starts with stiffness to one side, they flex and turn more easily in one direction than the other, and good training supples the stiff side and strengthens the easy side of the horse so they become equally flexible.
Working round correct circles teaches a horse many things; they give to the rider’s inside leg, stretching the outside of their body to the outside rein giving the “inside leg to outside rein” connection. This is not a connection the rider should take; the outside rein should be soft and accept the connection when the horse seeks it.
Correctly ridden circles also start to encourage the horse to bring the inside hind leg onto a slightly shorter step, tracking in the line of the fore leg and starting to engage the hock under their body. This creates a better balance, as the horse’s weight comes out of the shoulder and then the head and neck can release and stretch forward. The shoulder becomes free from supporting the horse’s weight, the horse moves straight and this raises the wither and neck position.
Diane Followell Classical Dressage Trainer