A trot is a two-beat gait which nearly all four legged animals do. It is faster than a walk but slower than a canter. A trot may also be referred to as a jog, but only in regards to a western horse. An English-trained rider would have no idea what a jog is.
It involves diagonal pairs of legs working together: the left fore and right hind will move together and the right fore and the left hind will work together. This makes the trot very difficult to sit as the back is constantly moving in a manner that is uncomfortable to a rider. This is why a rider must either rise to the trot (otherwise referred to as posting to the trot), or sit to the trot.
Sitting to the trot is much more difficult than rising, and rising takes a good deal of muscle and coordination. When you rise to the trot you must make your body loose but not floppy; it must be able to obey the movements of the horse, and being too stiff or too weak through the body can throw the horse off balance. Pretty much only your hips move in a kind of up-down motion but also a sort of forward-backwards movement.
Timing is everything. Once you get good at the rising trot you can slow the horse down and speed him up with how fast you are moving but if you are new to this I suggest two things: get yourself an instructor and do not try to control the horse with your body for now. If you are teaching someone to rise to the trot then put them on a lunge and make sure you can control a horse on the lunge.
A quick word on lunging a horse with a rider
This is one of the most dangerous things you can do.
Horses, when being ridden or otherwise worked rely on their human for how fast they should go. When they are being lunged AND ridden at the same time things get confusing, so your commands best be very strong through the line
and the whip
to the horse. Keep them forward with the whip pointed towards their hock
, and keep them steady with constant
contact through the rein. If you do not do this the horse can trip, stumble or fall over. Horses that are being lunged can also run away and drag the lunger behind them, rear or buck wildly, tangling themselves in the lunge line and so break their legs, or flip over backwards and crush their rider. All are from true stories. Luckily, I've only experienced a few of them. If something happens like this jerk on the rein, do not give it a constant pull. Let go if you need to. A run-away horse is better than a dead human.
It is best to take the reins away from the rider. He won't be needing them. If he feels unsteady without them he shouldn't. Reins are not a lifeline but he won't like you taking them away. Tie a string loosely across the pommel so as he can hold it at the proper height. Do not allow him to hold the saddle, though. Only this string. If the rider is feeling confident or you are feeling mean, take away all handles and make him hold his hands as he normally would, or some other exercise that makes him look like an idiot but will make his balance much better, such as putting his arms out horizontally while trotting.
So, about timing. There is a thing called the diagonal and will be referred to like this:
"DO YOU THINK YOU ARE ON THE RIGHT DIAGONAL??!"
When horses are involved there is always a lot of yelling, and diagonals are the easiest thing to get wrong.
The rule is: "Up = Out" where the "out" is talking about the outside foreleg (the one on the outside of the circle, arena, or curved line that you are riding) and the "up" is telling you what you should be doing. When the outside foreleg is in front of the inside forleg, eg, you can see it from your position on the horse's back but you cannot see the inside foreleg at all, you should be rising to the step.
The reciprocal is then true: "Down = In" It means that when you can see the inside foreleg, you should be sitting down. When you are doing this, you are on the right diagonal, and you aren't messing with the horse. When you are not on the correct diagonal, things are not dandy. To fix this problem, just do a double sit or a double rise. Double sits are easier.
It is best to work out when the horse's outside leg is not visible and counting that as "one" and seeing when it is visible and counting it as "two". You then must chant to yourself "one two one two" as you sit rise sit rise.
Now, the rise is not a leap out of the saddle, and the sit is not a pile of bricks falling on the horse's back. You shouldn't rise too much, only enough that you are no longer touching the horse's back. If your stirrups are short, your "rise" should be more of a forward movement so that your groin is nearly, or exactly, over the pommel. The sit should then see you sitting back down the saddle into the seat comfortably. The rise is directly up and down.
Your general position should not change. Your thighs will move a little, as they naturally should with the hip movements you are doing, and same with your belly. But, your knees, lower legs, ankles and feet should not move. Neither should your shoulders and head. Interesting Fact The trot is the only gait in which the horse does not really need to move its head in order to keep its balance. This doesn't mean your hands can stay static, however! You should be able to give the horse a little bit of room while still maintaining the gentle contact he needs.
Sitting to the trot is difficult to learn, and can be done in many ways. I'll outline the way I was taught (read, made) to sit trot.
I was given an Arabian horse with a terrible trot. His strides were too choppy and he always seemed as though he was about to run sideways. My instructor put me on the lunge, took away my reins and stirrups and told me to trot. She made me put my arms out horizontally so that it was obvious I wasn't relying on my arms for balance, only my seat. (She was making me sit trot only to make my seat better, not to make me learn how to sit trot.) You should be relying mostly on your knees, and a little bit on your thighs, to do a sort of floppy constant half-rise. You are never out the saddle, but neither are you totally in it. Gripping too hard with your legs is a very bad thing indeed and will unbalance your horse almightily, as well as tell him to do things you don't want him to.
Do not start of a session of work with a cold horse with sit trot. Their backs won't be up to dealing with you doing that straight away. Also, posting to the trot provides more balance to the horse because just as your up coincides with their out, by going up more often you can speed them up or slow them down by posting more slowly. Young horses and horses that need the balance of posting to the trot should not be ridden in a sit trot until such a time as they are ready.
There are many different sorts of trots, ranging from the jog trot (seen only in western horses) to the racing trot (seen only racing horses). The collected trot is when the horse is collected: his hind-legs are coming under him to "carry" him forward, and his strides are short but high-stepping. The medium trot has longer strides and more impulsion. There is definite forwardness in the horse's movement. The extended trot is even more forward, has much longer strides and the horse could be seen to be running.
Some horses don't trot! There is a type of horse called the pacer, which has been trained to not trot. The pacer is a racing horse (both trotters and pacers are raced in harness) and they have traces from outside hind to outside foreleg, and a second line from the inside hind to the inside foreleg. This is so that, instead of trotting in diagonal pairs, they trot in linear pairs. This is not natural, but once trained it is very difficult to train a pacer to not pace. A pacer will not trot, and is very weird to ride.
The trot is very important. You will spend more time trotting than doing anything else. A walk is done most often in a warm up only, and a horse can't keep up a canter forever, no matter how comfortable it is to ride. Western and stock riders seem to rarely post to the trot, but their saddles are made in such a way that posting is uncomfortable for the rider, and sitting is easy.