The common way to teach someone about the motion of the trot is to put them on a horse and start trotting. Words of advice usually then follow like 'relax your lower back' and 'sit to the motion' which as you watch the world bounce up and down and struggle to keep your balance mean absolutely nothing to you.
It's not much fun for the horse either. Your stiffness (because you'll be tense) and subsequent bouncing in the saddle will jar the horse's back. He will tense his back to protect himself and in so doing will make his back feel even more rigid and you'll find it difficult to feel the motion underneath you and so you bounce more.
You can see it's a vicious circle and perhaps no surprise that many riders are still not comfortable in the sitting trot after years of riding. So much discomfort for the rider and horse could be avoided if you knew what to expect and how to move by correct training with an Equisimulator. Even for the more established rider who might only be able to ride once or twice a week, a 20 minute refresher before riding could make a huge difference.
The machine allows the novice to practise the movements of the lower back and pelvis first at halt, then at a slow walk speed, gradually building up to an active sitting trot. It's design not only produces an up and down motion but also replicates the left and right dip of the back produced as the horse's hind feet are brought underneath it's body. It's obviously far easier to manipulate someone's back on the ground to show them what to move than it is when they are riding around an arena 5 foot off the ground.
The equisimulator is currently being developed for retail in various designs - check Heather's site at www.enlightenedequitation.com for the latest news.