This is an exert from Manolo Mendez Dressage, There is s slink to a full article at the bottom.
Good Breathing Leads to Good Work.
“Riders very rarely concentrate on their breathing, and they often don’t think about how the horse is breathing, either.
The rider must learn to breathe deeply, with “softness in the air”. We must also listen to, and feel the horse’s breathing.
A young horse will often breathe too fast, because he may be a little tense about what is expected, and he is not yet completely fit. It is important to give a young horse plenty of breaks to recover his breath. It is terrible when the horse is taking stiff, frightened breaths. He cannot relax and become soft and attentive to what is being asked of him; he cannot discover enjoyment in his work.
A rider can feel the horse’s ribcage between its legs, opening and closing with each breath, feel the horse’s heart beating softly or like a hammer. Because of this we should
not tighten our girths too strongly, or for that matter the noseband or flash. We should make every effort to make the horse comfortable.
Imagine having a belt on that is very tight and having to run, do sit ups, etc..how long would you be able to keep it up?
Proper breathing encourages athleticism and mental concentration because it helps supply oxygen to the muscles and brain. All athletes work on their breathing. Don’t forget that your horse is an athlete, too. It is most
important to be soft, to be natural.
Be careful never to instill fear in the horse, so that his natural breathing will develop and he will never learn to shallow breath or simply block his breath altogether.
By encouraging the horse’s softness, and following the young horse’s natural movement, rather than enforcing unnatural movement, or stiffening or stopping the horse’s movement, we will help the horse develop his natural breathing.”
Extract From: Developing the Basics Steps by Steps
As promised, you can read the rest of this foundation article by downloading this free pdf which also includes: “Schooling: The Importance of the Long Neck”