Mall,

There is no doubt that the "impact resistance" of the track will vary with the speed and force at which the horses hit the surface. The question is by how much.

For those who play golf it is very much like trying to match or "tune" a golf ball or golf club to a golfers swing. If you swing very fast you want a very stiff shaft on your club and a hard golf ball that will react to the impact more quickly. If you have a slow swing you want just the opposite. The more closely you match the frequency of the swing with the frequency of the shaft/ball the more efficient the impact and the greater the distance and the better the "feel."

The same works for the track surface. The closer it is tuned to the frequency of the impact of the hoof on the ground the more efficient the energy exchange and the faster the horse will go. Interestingly enough, I would imagine that if you could exactly tune the surface to the frequency of the horse's hoof "beat" you would not only have the fastest surface but also the safest since the impact would be in "sync" with the horses hoof and would minimize the stress at impact.

I will stop rambling but, based on this article, it does seem that the difference is significant enough that it might result in a slightly different variant for a fast horse (say a stakes sprinter) than for a slow horse (say cheap maiden claimers going 2 turns) even over exactly the same surface.

Interesting stuff.

Chris