I think as horsemen it is very common to get into this routine of releasing either physical or mental tension. You start to frame your whole training session as making the horse more relaxed or more supple. You might even use both those words together, but if you really look at what you are doing you are clearly focusing on only one.
Unfortunately, this is a very dangerous trap to fall in. And I see it with a lot of very talented horsemen. As soon as you start to think of your training as a means to release either physical or mental tension instead of both you lose the ability to truly get the relaxed, supple horse that you want. You end up pushing too hard for one or the other and in the process you build up more of the tension you are ignoring. Let me give you an example.
If you are focusing on getting your horse supple, you might do some groundwork and ask the horse to yield his haunches. The act of stepping under and across with his hind quarters will supple his body and engage his back. Say you are doing this and your horse isn’t quite suppling through his whole body. So you ask for a bit of a more exaggerated step. Sometimes that’s the right thing to do. However, if you have neglected your horse’s mental tension he might not be suppling through his whole body because he is mentally tense. Asking for an exaggerated step and then subsequently getting after him for not being able to do it will raise his mental tension and pretty soon you have a horse that is responding very nicely and is fairly supple, but is a mental trainwreck.
Similarly, if you are focusing on relaxation you might be so soft with your aids that you can never push through the physical tension. Your horse will accommodate your requests with baby steps and you will note the relaxation he maintains and feel happy. Meanwhile your horse becomes stiffer and stiffer, able to give you less and less.
Neither of these situations are good. That is why it is so important to have a balanced approach to horsemanship. For a horse to remain happy and healthy he must be free of both physical and mental tension. So often we see natural horsemanship horses wrought with physical tension and struggling to stay sound. In the contrast we often see performance horses bursting with mental tension, but able to move much better due to the suppling nature of their work. Neither of these horses are the picture of happy and healthy, yet their owners rarely see it.
The key to a balanced training program is to switch back and forth between releasing physical and mental tension. That way the horse can never build up too much tension in between you addressing it.
Another trap you have to be careful not to fall in is the assumption that certain exercises will take care of both types of tension. Although releasing physical tension can often be a means to releasing mental tension and vice versa, each time you apply pressure you have to be clear on your intent. Are you asking the horse to mentally let go or are you asking for the horse to physically let go. Once you have made that clarification in your own mind you can release at the proper time. And you can switch it up as much as you like.
For example, I might ask the horse to lower his head to release the physical tension in his neck. When he lets some of that tension go I will release. The next time I might ask him to lower his head to release his mental tension. He might drop his head easily to a light touch because he is physically supple. Instead of releasing I will hold the pressure until I see him relax into it. In this way I have used the same exercise to release both the horse’s physical and mental tension, but at separate times.
The biggest takeaway I want you to have is that you need to be very aware of where your horse is holding tension and what you are asking him to release. Asking the horse to just generally feel better isn’t effective and can often be very confusing. What you end up with is either a horse that is physically supple or mentally relaxed. Unless you carefully and continuously switch between asking for a release of physical tension and a release of mental tension you never quite get the whole package.