A circle is the basic school figure both horses and riders must master if they want to compete at any level or to learn to ride confidently in an arena or outside.  Circles ridden at the walk, trot and canter helps horses develop the muscles that enable them to track correctly on any line, straight or curved.  It helps riders to coordinate their aids and communicate clearly with their horses.

The importance of circle work may be obvious to Reining and Dressage riders, since they are aware that they execute a quarter of a circle every time they come to the corner of an arena.  In fact, new maneuvers are typically taught as the horse is moving through or coming out of an arena corner before riders attempt them on a circle.

Riders first start making simple changes of direction at the walk and trot by leaving a corner and starting across an arena's diagonal.  The rider leaves the corner with the inside rein softly positioning the horse's head to the inside of the bend, the outside rein defining the size of the circle, slightly more weight on her inside seat bone, her driving inside leg at the girth and a keeping or holding outside leg a little behind the girth.

As the rider approaches the center of the arena they begin to prepare the horse for the new direction of travel by riding the horse for a few strides with even pressure in both reins, on both seat bones, and with both legs at the girth.  If the horse resists or slows down or comes above the bit or speeds up, the rider must be ready to apply the appropriate aids to correct the horse's response.  As they approach the corner diagonally opposite the one where they started, the rider repositions the horse's head slightly to the inside of what will be the new directional bend and adjusts her new inside and outside seat and leg aids.

As horse and rider progress to riding full circles wih the correct bend, changing direction through the circle becomes a good test of the rider's ability to coordinate the aids.  The rider must adjust their aids to increase the bend slightly in order to come off of the circle track and begin moving toward the center of the circle.

The leg which has been their outside "keeping" leg now comes up alongside the girth and becomes the new inside driving leg.  As the horse moves through the center of the circle, the rider uses the new inside leg to move the horse into the new outside rein and smoothly readjusts her rein and seat aids to ask the horse for a bend in the opposite direction. As the horse moves back out to circle track, the rider must adjust their leg aid pressures as the horse reaches to track to prevent him from drifting outside of it.  As the change of direction occurs, horses tend to lose forward motion, go above the bit or become crooked.

Changing direction through the circle is a more advanced exercise that riders should not attempt until they can change direction across the arena diagonal correctly.

Direction changes at the canter require changing leads.  Again, they use diagonally linked circles in arena corners to teach green horses or riders how to change direction on a straightaway before they attempt it on a full circle.

Simple changes of lead are taught first from the trot.  The rider leaves the corner in a canter and starts across the diagonal.  As they approach the middle of the arena, they ask the horse for downward transition from the canter to a few strides of trot.  Then they ask the horse to pick up the canter again on the new lead.

To do this, again, requires a change from the circle aids already described to equal rein, seat and leg pressures.  As the rider approaches the center, they use a half halt to ask the horse to trot by momentarily increasing wieght on both seat bones.  Riders "think trot" in their seat, increasing and holding pressure with both legs and holding with both reins.  As the horse picks up trot, the rider prepares for the new lead in the new direction, increasing weight on the new inside seat bone, keeping the new inside leg at the girth, sliding the new outside leg a little behind the girth, and slightly taking or resisting on the new outside rein.

Start this exercise taking as many trot steps as needed and gradually work until the rider can choose the number of trot steps the horse takes before picking up the new lead in the new direction. Again, a good beginning exercise is to move the horse away from the new inside leg into the new outside rein.  As proficiency increases, the rider can begin to connect two full circles in a figure eight, changing the canter lead through a few steps of trot where the circles overlap.

Circle work is physically challenging to joints and muscles of the horse.  The horse's age, training level and current physical condition should be considered to avoid making the horse sore.