"Unless he is standing still, then from the moment you get on him, the horse is in a rhythm – it can be regular or irregular – but everything in riding has rhythm to it. Rhythm is a very integral part of horsemanship." ~ Tad Coffin
In the sport of Eventing, ensuring that our horses are truly fit for our level of competition is one of the best ways to prevent unnecessary injuries.
Horses become incapable of learning when they go past a certain level of fear, anxiety, or stress. This means that if you keep hammering away at the horse, trying to teach them something when they are currently overwhelmed with stress, it will not work.
For the horse, the learning happens on the release of the aid. That means if you don't release the aid, the horse will not learn.
"Don't take the tempo down without revving the engine." ~ Chris Bartle