Yes, trot poles are good for your horse

16 Feb 2015
Researchers from Michigan State University have shown that trot poles have multiple benefits, including activating and strengthening flexor muscles and improving visuomotor coordination.
A horse’s field vision is such that they cannot see their hooves as they cross the poles and must judge how high to lift their legs as they approach the poles.
Trot poles made the horses slow down, there was no difference in stride length, but a longer time spent in suspension, the researchers noted.
When trotting without poles, forelimbs were raised a little higher than hindlimbs but with trot poles all four legs were raised higher than normal and to an equal height.
Hip flexion was also observed, something that is not achieved by horses carrying pastern weights, the effects of which have been measured in other studies. Hip flexion is important because it determines the range of hind limb protraction and reaction during trotting.
As well as being a useful fitness and strengthening tool, trot poles could be used therapeutically to restore joint motion in horses coming back into work after an injury.
Previous studies have found that 3-4 repetitions are the optimum amount when working horses over trot poles for the first time with increases of 2 repetitions each session.
Reference
Brown, S., Stubbs, N. C., Kaiser, L. J., Lavagnino, M. and Clayton, H. M. (2015), Swing phase kinematics of horses trotting over poles. Equine Veterinary Journal, 47: 107–112. doi: 10.1111/evj.12253