When you are training your horse, in dressage or any other equestrian discipline, it is very easy to head straight to the arena every day and spend hours riding circles and figures in the belief that this is the only way your horse will learn. Trouble is, you get bored. And guess what? If you are bored, you can be sure your horse is getting bored too. But don't think you have to put your training program on hold everytime you go out on the trail.
Think about the exercises you do with your horse in the arena. You do transitions, you practice halting straight and square, you practice accuracy. Well, you can do all these things and more on the trail. Training on the trail gives you several advantages too: it gets you away from the "crutch" of the arena and makes both you and your horse think for yourselves. It's also a good way to build up fitness and stamina.
Your horse doesn't have to be at a high level of training to do this. For example, as you ride along the trail, instead of just sitting there enjoying the scenery (although there's nothing wrong with doing that sometimes too!), look ahead and pick out a tree or other landmark and use it as you use the markings in the arena. Ride straight towards it and, as you approach, prepare for a transition to halt. Once you have halted check your accuracy and straightness before asking the horse to walk on again. You can do this with transitions up and down and also transitions within gaits too. It's great for working with a horse who tends to "kick it up a notch" as you turn for home.
Practising your canter on the trail is a whole lot different to doing it in the confinement of the arena. If you are concerned your horse will take off, don't give him the chance to lose balance and get on his forehand. After a few strides, ask for a down transition, all the way to walk if you need to. Then work on something else, and try the canter again. Working like this teaches the horse to listen to you and not anticipate that a canter means a mad gallop.
If your route takes you along a stretch of road just riding along the side of the road accustoms your horse to traffic. But if there are cars parked at the side of the road, you can use them to practice side passes or leg-yielding. Approach the car and then (having made sure the coast is clear) begin to move your horse sideways till he is clear of the car. Continue walking till you are past the car and then move him sideways back to the side of the road again. You can also do this around obstacles on the trail.
Going through some woods? Take advantage of them to build your horse's suppleness. Make sure you keep an eye out for low branches as you serpentine through the trees. Do it in walk first, making a note of roots to be avoided etc. and then progress to trot if you feel it's safe. If the trees are close together, it's the equivalent of the ten meter serpentines used in dressage training. An added benefit, if you have a horse that tends to get too forward on the trail, is that the constant turning and change of direction keeps the horse focussed on you and your aids. In fact, I have to say that I utilized this technique with Annapolis, my twenty year old going on three year old, who was happy to be out and about this past weekend!
Hills can be used to strengthen your horse's hindquarters and increase his self balance. You don't have to gallop up and down, in fact walking both up and down will give your horse more of a work out. If the hill is steep, make sure you take a straight track down, or you risk your horse losing his balance and both of you sliding down the hill. If the hill is more gentle, you can trot up and down which will really test your balance.
I hope I have given you some ideas and shown you that your training program doesn't have to get put on hold every time you hit the trails. So now - get out there, ride and have fun!