Originally Posted by Rupert Pupkin

At first, I thought that your hypothesis was pretty good but the more I think about it, it really shouldn't make a difference what surface the horses are trained on. Horses usually either like a surface or they don't like a surface. They don't usually take time to adjust to a new surface. For example, you see horses run on the turf who have never had a single workout on the turf, yet these horses win all the time. It's not as if they run better in their second start on the turf. If they like it, they usally run good on it the first time. They don't need time to get used to it.

If horsess can train exclusively on the dirt and then run well when they race on the grass, I don't see why horses that train exclusively on polytrack would have a problem racing on regular dirt.