In his mental development, the horse learns that if he responds correctly to a pressure we put on him, the pressure goes away. He gradually builds a vocabulary of the pressures we use to suggest the shape of his body, the direction of the next stride, the tempo of that stride, etc.
In the beginning, the trainer’s mental activity challenge is to help the horse build that vocabulary in a horse logical way that never raises the horse’s excitement level. As the horse’s vocabulary gets bigger, the trainer’s challenge is to vary the mental activity enough to keep the horse from being bored.
In his physical development, the horse needs to build the muscles that can carry him as his training progresses into the higher levels of whatever sport he’s being trained for. In the beginning, his physical conditioning needs to be made in small increments. The trainer builds bone and muscle by alternating periods of stress with periods of rest. The stress part pushes the muscle just a little bit past where it’s been before and the rest part allows the stressed muscle to heal and, in the process, become stronger.
Again, the trainer’s job is to always add physical stress just one small bite at a time so it builds the horse up without injuring him. Once he has reached the level of conditioning he needs for whatever job he’s going to do, the challenge is to keep him there. As the horse’s physical condition improves, so will his activity drive. So the trainer has to help the horse build and spend his activity drive in a cycle that works for that particular horse.
There aren’t any hard and fast rules for managing a horse’s mental and physical activity levels because every horse is going to be in a different place on a given day. You have to take into account where the horse is today mentally and physically, how he feels today mentally and physically, and where you’re still trying to go with him.
The horse’s personality is also going to be a factor. The natural "activity drive" of horses varies just like that of people. Some horses are simply more lethargic than others while some are always wired and ready to go. Some are curious about new experiences while others are more timid. Some are always friendly and looking for your company while others are more reserved and would just as soon be left alone. One horse may put in a really good workout then need a day or two of rest before he’s mentally or physically ready to put out the same effort again. Another horse might work hard in the morning and be ready to go again that afternoon.
We’ve had prospective students and parents visiting Meredith Manor who question why we keep all the horses in barns rather than running free out in pastures. The way they word the question usually implies that they believe it’s "unnatural" for horses to live in stalls. I’d be inclined to agree with them if the horses were just put into stalls and no one ever bothered with them except to throw in a little feed and water now and then. But when you are training a horse and managing his mental and physical activity levels, living in a stall or a pasture shouldn’t make any difference. You are in charge of making sure the horse has the camaraderie of other horses, sufficient mental activity to keep him stimulated but not stressed, and sufficient physical activity to produce the level of fitness he needs to work at the level you are asking of him.
Depending on the horse and the program you have him on, that may mean working him once a day, twice a day or maybe even just a few times a week. It’s going to depend on the horse’s current level of training, his current fitness level, his health, his personality, and even his age and sex. And as the horse gets fitter and more highly trained, your management responsibility gets bigger. It wouldn’t be good management, for example, to take a highly conditioned grand prix dressage horse out of his stall and turn him loose to run and buck and spend his activity drive while his muscles were still cold and tight. He’s going to tear and injure something as surely as the human sprinter who tries to run a race without warming up and stretching first.
We have one big Hanoverian here at Meredith Manor who is trained to upper level dressage and we use him for lessons all the time. When he knows he has a player on him, he goes right to work and has a good time and gives his rider all kinds of good feedback and stuff. But he has a regular nap time every day. If a student tries to bring him out and convince him it’s time to go to work when it’s his nap time, he wants no part of it. It doesn’t matter how good a rider they are, he just goes into the arena and chases the birds and ignores their aids and makes them feel like a failure. He needs his nap to rebuild both his physical and mental activity drive before he’s ready to work again. As long as everybody respects that, he gets along fine with them.
Horses don’t see the things we ask them to do as a job they’re supposed to do. They just have a feeling about it that’s its something they enjoy or don’t enjoy. Managing the horse’s mental and physical activity levels intelligently helps him enjoy what he’s doing every time you take him out.