Mall,

It has long been a belief in the UK that horses with big feet have an advantage when the ground is really heavy, usually for jump racing during the winter. The theory there is not so much the 'return of energy' but the fact that the horse's hoof doesn't sink so far into the turf. I would think that there could be two effects racing on dirt - the return of energy you refer to and the fact that there is less penetration of the surface for horses with bigger feet. Snowshoes work because they keep the wearer on top of the surface rather than letting him get bogged down in it.

Presumably a horse's weight would come into it as well so all we need now is to have each horse's weight and 'footprint' in the PPs. Something for the trackmen, Jerry?