Before last Wednesday I had never ridden a horse at a pace -- it's not common amongst well-schooled dressage horses. The trot is a two-beat gait in which diagonal pairs of legs move together with a moment of suspension between hoof strikes. It is relatively easy to ride because the topline of the horse remains level in both planes. A posting (rising) trot is possible, and experienced riders have no trouble with a sitting trot. The pace is also a two-beat gait, but lateral pairs of legs move together so that the horse's body bobs from side-to-side with a moment of suspension between. This motion makes it impossible to rise to the gait, and uncomfortable to sit to it.
The pace is also marked by a hollow back, high head, and quite stunning speed. Many harness races are run at the pace, and the animals are bred for their natural inclination to use this rather unnatural (i.e. not often observed in the wild) gait. Tonka is not such a horse, and his propensity to move from trot-to-pace or canter-to-pace under saddle is probably due to stiffness and lack of muscle tone. It takes a lot of a conditioning for a horse to carry a rider with balance and finesse, so I have started some bending exercises to help him along. Today I was asking him to stretch his neck muscles by holding him steady while pulling his nose towards his ribs by the halter. Once he understood what I was getting at he gave me a look that said "you're one crazy monkey, you know" but he played along. What a sweetie.
45 minutes ago