ANALYSIS OF GALLOPING STYLE
Variation in the amount of “loft” during the gallop cycle achieved by American Pharoah, Justify and Secretariat is noticeable. It is not desirable for racehorses to flex the knees like show horses or jumpers; efficient galloping means that the horse must stretch the extended forelimbs straight forward. However, speed is not created by the horse’s limbs, and one who merely swings his forelimbs stiffly like a pair of broomsticks will prop along like a giraffe. A great racehorse makes his gallop stride longer by jumping up as well as forward—his stride consists of a series of arcs, as if he were attempting to clear a series of low but invisible obstacles. Unless the horse discovers the joy of expressing his prowess in this way, he cannot achieve a double-suspension gallop.
To create this comparison, I have had to dig up photos which catch the horses in the same, or very close to the same, phase of motion. The “reference limb” is the contacting hind leg; for meaningful comparison, the reference limb in both thrust and landing phases must be in close to the same position in all three horses. On this basis, I can find no evidence that American Pharoah used a double-suspension gallop; he simply does not generate enough loft. Justify generates 42 units of loft, whereas Secretariat generates a whopping 156 units in thrust phase and his lowest fore hoof is still 42 units above the ground in a landing phase photo that is actually a few frames later in the stride than that of either American Pharoah or Justify. This is the secret to Secretariat’s very long stride: It isn’t the length of his legs! Rather, Secretariat “jumps over” a higher invisible obstacle, and thus flies farther through the air during the first gallop suspension, than any other racehorse in history.