Warming your horse’s muscles, and for that matter your own, is really important if you want to avoid injuries to your horse. You should continue your warm-up patterns for about ten minutes or until you feel that you have made progress with your transitions and your horse is relaxed and rhythmic, before you move onto other training exercises.
Exercise 2: Long & Short Reins Trot
Gait: Trot
Difficulty: 
Aim: Transitions/Consistent Rhythm
Instructions
At a letter, ride your horse forward to a working trot and as you pass a second letter, allow your reins to lengthen. Your horse should lower its head and poll in the long-rein trot while maintaining its rhythm.
Passing the fourth letter, shorten the reins and ride forward to a working trot.
Continue this exercise, changing from a working trot to a long-rein trot and back to working trot at every second letter.
You want these transitions to be smooth with your horse maintaining a consistent rhythm – no head tossing, hollow back or double tracks. Your horse’s hindquarters should keep pushing him forward.
You can either post (rising), sit the trot, or use a combination – sit a few strides then return to posting. Remember, you are trying to establish a consistent rhythm throughout the pace and the transitions.
Animation
Click on the image below to view an animated guide to this exercise.
Aids Used in this Exercise
All your aids will be given in the following order:
Prepare > Rein > Weight > Leg > Yield
NOTE: Your rein, weight and leg aids occur at almost the same time. Do not rely on your rein aids; they should be the least important aid.
Tips
Lengthen rein and long-rein does not mean loose rein, throwing the reins away or holding the reins by the buckle. Long-rein means lengthening your rein by allowing some rein to slip through your fingers. This should allow and encourage your horse to lower his head and poll, however you should still have a soft, light contact on the bit.
As you lengthen your rein, you will need to keep your horse moving forward. If your horse has a tendency to meander or become sloppy you will need to use an ‘active’ seat to keep the rhythm while you allow his neck to stretch out.
Shorten your reins by calmly drawing them through your fingers, starting with the outside rein then the inside rein. Use your seat to drive your horse’s hindquarters lightly into the bit for the working trot. Remember you do not get a horse ‘on-the-bit’ by pulling his head in with the reins, your horse should be pushing into the bit from his hindquarters.
This pattern also has corners, so you can practice your line and bend at a working trot and a long-rein trot, when you only have your seat and legs to bend your horse.
Complete an equal number of right-rein around the arena as left-rein.
Continue your warm-up patterns for about ten minutes or until you feel that you have made progress with your transitions and your horse is relaxed and rhythmic, before you move onto other training exercises.
If you find the exercise too difficult, pass three letters instead of two on the long-rein. This will give you more time to prepare for the working trot.
