BILL— I remember riding in a clinic in 1973 on a little OTTB mare whom I was eventing Training Level. These days it would be a First Level test, but back then we did Training 3. Looking to the future I asked the clinician if we could work on lengthenings in the trot. She made a non-committal, disheartened response. And now I know why. The horse was simply not enough on the aids—not enough between leg and hand—not through. Real lengthenings were implausible if not impossible. Without those qualities if you got anything at all, it was likely just to be hurrying. That was also a time when meaningful warmbloods were almost nonexistent in the US, so your horse’s natural movement and cadence were not going to help you very much.
All three of the enlarged trots have several things in common. The strides must get bigger, that is, the horse must overtrack. The tempo should remain unchanged—no quickening. And the hard one for most inexperienced riders—the horse must stay on the bit: round, balanced, carrying himself, and through.
A trot lengthening is a developmental exercise which grows out of the working trot. In order to express a bigger trot, it must be preceded by a spring-coiling, energy-gathering compression. Only so much of this is possible in a working trot, especially one of a lower level horse. The “lengthening” designation recognizes this inherent limitation.
A Medium trot is done from a Collected trot where some of this compressibility and more uphill balance has been created. Because of this it will be more likely to have more lift and cadence than a simple lengthening. They are birds of a feather, however, so that if you make a good medium when a lengthening is called for, you will be rewarded, not punished.
Technically a medium trot and an extended trot are two different things, a concept which remains illusory until a horse has reached the FEI levels. If you construct a vector diagram (and for the heck of it let’s throw in passage as well) the extended trot will have maximum length and overstep with not quite as much height or suspension. The poll will not be quite as high as in a medium, and the horse’s frame will be slightly more open. A medium trot will have a bit more elevation to the steps, a higher carriage, and steps which are longer than the working gait but not as long as an extension. Just for comparison‘s sake, in a passage, the steps will be quite a bit shorter than a working or collected trot but the upward vector will be greater with the emphasis more on lift than on thrust.
Third Level is the first place that collected, medium, and extended trot are all required. With horses in the learning stage or riders who have not quite figured out how to present both bigger trots, the tactical question arises “What’s the best way to present what you’ve got to the judge?” Some riders figure that a medium is “the same as an extension but less,” so for the medium, they just don’t ask as much. This is flawed logic because if your extension isn’t all that good in the first place and you make the medium even less, you end up with two mediocre scores. Until you really know how to present them as conceptually different movements, I think it’s better to make the maximum for both, even if they end up looking exactly the same. That way you will at least get rewarded for the Medium, and the judge can figure out what to do with the score for the extension. Usually they’ll go just one mark lower.