When it comes to sharpening your horse's mental fitness and tuning him up physically, don't overlook the value of a solid, steady trot. This two-beat gait has more natural impulsion, rhythm and symmetry than the walk or canter, and you can put these qualities to good use in training. Specifically, work at the trot can help a horse with the following:
Focus. Faster than the walk but slower than the canter, the trot requires enough energy to engage a horse's mind but at a pace steady enough that both of you have time to plan several strides ahead and make adjustments as necessary. For these reasons it's a great gait for getting "in the game" mentally at the start of a ride, as well as regrouping if training difficulties leave either of you feeling a bit scattered.
Suppling. The trot is a favored gait for introducing lateral movement, such as side passes. The natural "one-two, one-two" rhythm of the trot helps discourage rushing and makes it easier to feel and correct inconsistencies in the gait. These exercises encourage self-carriage and ultimately help make a horse more flexible and balanced.
Straightness. As a sound horse trots, the diagonal pairs of legs mirror each other's movements. This dynamic naturally produces some degree of straightness, even in an inexperienced or out-of-condition horse. When a
horse becomes crooked at a lateral gait, such as the walk, returning to a trot can help straighten him quickly and relatively easily.