We'll take a quick tour of our understanding of this "gait," seen most often out of the starting gate, but first lets look at the related gallop. Prior to Muybridge's 1870's photographic study of equine locomotion, running horses were depicted stretch out, both hinds together behind the horse and both fore together in front of the horse, like this:
And then, of course, came Muybridge's stop motion photography study. This instantly "disproved" the common depiction, which quickly went out of fashion.
|Muybridge's The Horse in Motion, 1878|
And that was that. Right? Well...not quite. In the last decade or so, we've revisited this idea with new film technology. We need to add a few caveats. The frames above are of a mare galloping at the Palo Alto racetrack in California in 1878. The gallop exhibited by this mare is the most common way of going for horses in that gait, with the footfalls being hind, hind-opposite fore, fore, followed by a moment of suspension with all four legs curled in towards the center of the body. It is not, however, the only footfall pattern for the gallop, nor is the gallop all we see from modern racehorses.
First, let's talk about an anomalous form of the gallop whose existence is still, with todays slow motion video technology, debated. That is the double suspension gallop. In this, there are two moments of suspension, similar to a running greyhound.* The hoof-falls are hind-hind, suspension, opposite fore-fore, suspension.
|This "second suspension" is usually missing from a horse's gallop|
Secretariats immense stride is sometimes credited to his use of this gait. His winning photo from the Belmont Stakes shows him in this second suspension phase, with all feet off the ground but legs outstretched. His outside fore hangs slightly, much like the dog in the photo above. It looks so strange that I, like many, wondered if it was a glitch. Then I realized that foreleg, and the opposite hind, are still in the process of moving forward. He is on the left lead, with his left (inside) fore about to land. So I looked around to see if this glitch was repeated anywhere.
I looked at some "most obvious suspects." California Chrome. American Pharoah. Cigar. Zenyatta. All had huge closing strides– and acceleration within the gallop is where the double suspension seems to show– and none of them seem to exhibit this gait. And then I stumbled across this photo finish from the 2011 Melbourne Cup.
Red Cadeaux, the chestnut on the inside, is in almost the exact strange position that Secretariat was in at his Belmont finish. The photo IS distorted– the larger version shows one horse with a ridiculously large hock– but the distortion seems greatest the furthest from the finish line. And there are now a handful of non-finish line photos floating around of the phenomenon, like this Quarter Horse Mr Premier LV:
This photo would be the moment after the phase shown above. The left fore has just touched the ground, but both hinds are already well in the air. The double suspension gallop's effects on speed and soundness, as well as it's possible heritability, are all conjecture at this point, as is its very existence. Finding evidence of horses galloping with out fulling weighting the diagonal at the same time is easy. Evidence of a second true suspension is inconclusive. Studies are ongoing.
But wait, what about the break? Part II & III to follow.
*The greyhound, however, also tends to employ a rotary gallop, with the hind-fore pair being lateral (usually the outside pair). The double suspension gallop is sometimes called the transverse gallop; this is technically true, but the single suspension is also transverse, meaning using a diagonal rather than lateral pattern.