Setting the right ground pole distances can be tricky. You want to start with your horse’s typical stride and then adjust the distances depending on what you want to accomplish in terms of shortening or lengthening your horse’s stride. When integrated into your schooling sessions, working over ground poles and cavalleti will increase your horse’s strength and flexibility, improve their ability to engage their hindquarters, and make their paces more expressive. My first horse, Bogie, never had an expressive trot, but by using ground poles and later cavalleti, he developed the strength to have at least a bit of a lengthening.
So, how do you set the poles for the best effect? By measuring them. I never have a tape measure handy, so I use my feet. By “tightrope walking”, placing one foot in front of another, you can set the distances you need.
In general, the distances between trotting poles for a horse would be about 4.5 feet and canter poles would be about 9 feet. This will depend on the size/height of your horse, and also on their natural stride length. After setting up the exercise, try working through at your chosen gait to see if it feels too long or short, then adjust. As your horse becomes stronger and her stride lengthens, you’ll be able to lengthen the distance in between the poles.