When was the last time you had a lesson on your posting trot? Been a while, right? You probably haven't had one in quite a while because you already know how to post. In fact, you do it automatically as part of your horse's motion. I have a point to make regarding my rhetorical question (in fact I have several "points"), but as usual it will take me a while to get to them. Stay with me because you will learn that the most effective jumping position can be as effortless and automatic as the posting trot.
Three-Point and Two-Point
Let's make sure we are all using the same terminology. I plan to discuss the two positions that you need to ride eventing's jumping phases, show jumping and cross country. I refer to the first position, your show-jumping position, as a light three-point. The three points touching the saddle are your pubic bone and your two seat bones. Because your stirrups are now short enough to produce a 90-degree angle behind your knee when you are seated, you will close your hip angle slightly. I do not use a hard-and-fast rule about the location of your shoulders because your conformation has a great deal to do with the position of your upper body. For example, telling someone "keep your shoulders above your knees" will be too extreme for a rider with long thighs and a short waist. My rule of thumb is that you should have the points of your shoulders ahead of the points of your hips.
The natural shape of your spine has a slight forward curve at the waist, an arch that changes from slight to pronounced to flat, and so on, as the motion of your horse's back at walk, sitting trot, posting trot and canter dictates. When seated in your light three-point with this slight curve at your waist and with your shoulders slightly in advance of your hips, you are in the best possible position to receive the jumping motion of your horse's back and translate it into a correct two-point at the peak of the bascule. I will return to this point in a moment.
The second position, the two-point, is also called the half-seat, or galloping position. You use it in four situations: galloping, jumping, any time you want to take your weight off your horse's back (when walking up a steep slope, for example) and posting trot. I refer to this position as the two-point because you can hold yourself above your horse's back on the two inside points of your knees without other support. The two-point does not depend on your reins or stirrups for security. Note that you should maintain it by closing your legs from the large bone at the back of your knee down through your calf. Do not pinch with the bone on the inside front of your knee because this will cause your lower leg to slip back.
The Light-Bulb Moment
Are you with me so far? Good. Now let's return to my question about your posting motion--this time, however, using my terminology. In order to post, you ask your horse to trot. You are seated for one beat of your horse's two-beat motion and then rise for the other beat. In mechanical terms, you are changing from a light three-point to a two-point and back again, but posting is not something you do. Done correctly, it is something you allow your horse to do to you because the motion of his back causes you to rise from light three-point to two-point. Your seat should remain close to your horse's back. Your horse does not care if your seat bones are 1 inch above his back or 1 foot; however, he is very aware when you are too far in front of his motion or too far behind. The closer you keep your center of gravity to your horse, the more harmonious your relationship will be.
Now let me ask another question: As I describe your transition from a light three-point to a two-point and back again, am I talking about your posting motion--or your jumping motion? That's right, they are the same motion. Your jumping motion is based on the same mechanics you use to post at the trot. At this point, I hope you will feel one of the light bulbs in your chandelier turn on. One way instructors can tell if a novice class is ready for its first crossrail on calm school horses is if the students can post correctly, then hold themselves at the trot in a two-point down the long side of the arena and then smoothly resume their posting motion.
Once you understand the mechanics of your jumping position, it should improve. Jumping ahead of your horse causes many jumping mistakes. Your jumping position should be the result of your horse's jumping effort, not the cause. For obstacles up to 3-foot-6, your jumping position should be no farther out of the saddle than your normal posting motion. Done correctly, your position at the top of the arc is a response to the motion of your horse's back, rather than to you projectile-vomiting yourself up the neck of your poor, long-suffering horse.
How to Check Yourself
One of the best ways to practice your jumping position is to trot over small (2-foot-6 or less) obstacles and feel your horse's back push you into your two-point as he jumps. It will help if you put a placing pole 9 feet in front of the obstacle, which will produce two trot steps between the pole and the obstacle. Make sure you are in the seated phase of your posting for one beat between the placing pole and the obstacle. If you are posting correctly, you will feel his takeoff push you out of the saddle from a light three-point into a two-point.
To check your jumping position, the simplest strategy is to have a friend use a smartphone to take photos and videos for immediate feedback. As you critique these images, remember that when jumping obstacles 3-foot-6 or less, your body angle relative to the ground should not change. Of course, your position must react to the motion of your horse as he jumps, but that adjustment should be the opening of your elbow angle, not the closing of your hip angle.
Although you should keep your body at a consistent angle to the ground while you are jumping, that is not how you will perceive the motion. Tell yourself that you will keep your hip angle the same as you jump. (That is not exactly what happens, but that is how it feels.) If you are still leaning forward too much in the air, try this: Tell yourself there is a zip wire over the fence and there is a hook on your helmet. Keep your helmet on the zip wire throughout the process.
If your overjumping habits are so ingrained that these exercises do not work, the next exercise is to jump small obstacles without stirrups. You will be more conservative with your upper body when your balance is provided by the strength of your two-point rather than your stirrups and your horse's neck.
Between the Jumps
We have talked a great deal about your position over the obstacle. Now we need to discuss your position before and after the obstacles when on course. For show jumping, I want you to approach and depart the jumps in the first position we discussed, a light three-point. This will increase your security because you are seated. In addition, you have a wider range of expression when you are in, rather than above, the saddle: You now have your back and seat bones for aids, as well as your hands and your heels. Finally, because you are closer to your horse, you will internalize his stride better, which will improve your timing.
At cross-country speeds, on the other hand, you should gallop in a correct two-point position between obstacles. Based on science recently available to us, the correct galloping position is the two-point position I just described. It is NOT this inefficient "cruising position" that is currently being taught to unsuspecting victims. It is bad enough that we find ourselves accidentally riding in less-than-optimal positions, but to be purposely taught a position that is guaranteed to place us out of balance with our horses is truly regrettable. ("Posting" at the canter, which is closely related to the cruising position, is, of course, anathema to me.)
I want you to gallop in a two-point between cross-country obstacles. About eight to 10 strides away, transition into a light three-point and proceed to jump the obstacle. This transition consists of softly sitting down in the saddle with your shoulders in front of your hips, not sitting back with shoulders behind your hips. As described earlier, you will let your horse's back push you into a two-point as he jumps.
At some point in your development, usually at the Intermediate level and without instruction, you will begin to jump more and more of your cross-country obstacles while remaining in a two-point. This is a natural response to the increased speed of the middle and upper levels and a sign of your improving poise, confidence and balance. You will find that you instinctively return to a light three-point when you slow down for combinations, drops, etc.
It took a long time until you could post instinctively, but now you do not have to think about it. Your posting motion is a natural response to the motion of your horse's back. The next stage in your jumping education is to practice allowing the motion of your horse's back to put you into the correct two-point position at the top of the bascule. You will find that you do not have to "jump" the obstacles - your horse will do that for you.