If, for purposes of discussion, ground loss, wind, tides, etc are ignored, and it is assumed that all of races under consideration took place at the same race track, moisture content would appear to be the most important remaining factor in determining the relative speed of the track on a particular day. At this point presumably everyone agrees that it has already been proved that the absence or presence of moisture can change the speed of a track, but little if any consideration seems to have been given to the question of why, from a scientific standpoint, this is true.

According to a paper published by five impressively credentialed scientists, the reason is because of the relationships between changes in moisture content on the energy returned by the track, impact resistance of the track, and the locomotor forces exerted by the horses running on the track. In terms of the energy or force returned by the track, moreover, it isn't just the amount; it's also the timing of the return. Hence, a track which had a moisture content which resulted in a quicker return of energy would theoretically favor a faster horse, which exerts a greater pressure but which has its feet on the ground for a shorter time.

Though done for safety rather than handicapping purposes, the results of their research confirms just that. Slower horses are arbitrarily defined as those running 14.5-15.4 meters per second, while faster horses are those which go 15.5-16.5 meters per second. Both the slower and faster horses kept getting faster as moisture content increased to a certain level, at which point the speed of the faster horses levelled off and the speed of the slower horses got worse. While the researchers' definitions of "fast" vs. "slow" are different than what most handicappers would have used, there does not seem to be any obvious reason that the basic principle would not apply at faster speeds. In other words, it is at least reasonable to think that in making a variant, there are times when differentiating between fast and slow horses may be every bit as important as drawing a distinction between one and two turn races.