American Pharoah can be seen almost dancing to the post in each race, his back springing up and down so much that the jockey actually has to hold on with his feet.

bad horse---Secretariat likely would have beaten any other Triple Crown winner also. A major reason for this is, again, the way Secretariat used his back. As our analysis (“Biomechanics and Way of Going,” page 68) shows, Secretariat demonstrates a huge range of loin coiling/uncoiling, and thus of total up-anddown back flexibility.

Note that in analyzing the flexibility of the back, we are not merely talking about the horse’s appearance in the “reach” or extended phase of the gallop stride. Both the coiled or “collected” phase and the extended phase must be considered, for it is the difference between the two (which represents the total range of motion) that creates a racehorse’s power as well as his stride length.

Whereas the extended phase of American Pharoah’s stride approaches that of Secretariat, the coiling phase does not, so that while American Pharoah in his most collected phase achieves a downward pelvic slope of 32.3 degrees, Secretariat achieves 44.4 degrees. It is at the moment of strongest coiling and greatest downward pelvic slope that the first hind hoof will be placed upon the ground; both stride length and power or forward thrust evolve primarily from this hoof strike.

The far-forward placement of the first contacting hind hoof also conveys other advantages. Note that the line of overall balance (red line) in both extended and collected phases is more level in Secretariat than in American Pharoah. If the degree of slope in the red line is averaged for the two phases, American Pharoah “runs downhill” 7.55 degrees as compared to Secretariat’s 5.75 degrees. A racehorse who “runs downhill” does it for the exact reason that a reiner, a park horse or a dressage horse might: The animal is, to that degree, travelling on the forehand.

A way to confirm this is to look at the extended-phase drawings of American Pharoah and Secretariat; note that when the right forelimb in both horses is in nearly the same position, the weightbearing forelimb in American Pharoah is angled noticeably farther back, meaning that he will not be able to pick the limb up until it has passed farther backward under the body. In short, the horse on the forehand has to work harder to get his forelimbs up and out in front of him, a factor that is evident in the collectedphase image of American Pharoah.

Yet another way to “see” a horse who runs downhill is to look at the shape of his neck during the coiled phase. While Secretariat’s neck is always at least slightly arched--with the base of the neck (marked by the forward circle) always at least slightly lifted---American Pharoah’s is dropped. Horses who run on the forehand attempt to lift their chest and free their forelimbs by “horking” their heads backward and upward with each stride, just as the collected-phase image of American Pharoah shows; on film their heads appear to “nod upward,” while the superior horse “nods downward.”