Why I Rarely (If Ever) "Flex" A Horse, Part 3: Bad Biomechanics
In the last two posts, we’ve discussed how flexing doesn’t make your horse more flexible in any good way, and isn’t necessary to produce a soft horse. Today we’re going to talk about why it should especially never be done while the horse is in motion (which I, surprisingly, see commonly in the western and modern Dressage worlds). Let’s start with vision. The horse, like most animals, relies on binocular vision to tell depth of field. His eyes do not focus as easily as ours, and he relies on moving his head backwards and forwards to pull things into focus - this is why a horse going to a tall jump will often pull his head up and back while staring at the top rail. When a horse is flexed while in motion, his functional depth perception (meaning the perception necessary to examine where he’s going) drops to almost zero. This presents a huge safety hazard as far as tripping or miscalculating foot placement.
In addition, flexing causes the horse to fall onto the forehand. When flexed, the Long muscles the pull the forelegs forwards become strained. As a result, the horse is forced to take smaller and much harder steps than he would while straight, dropping his weight onto the forehand as the hind end struggles to keep him going forwards.
Flexing during movement also creates lateral imbalance. The spinous processes that make up his withers are forced to rotate to the outside, causing his shoulder to feel as though it has fallen out from under the rider to the outside. This makes it difficult for him to turn smoothly, and places extreme wear on the forelegs. It also makes it nearly impossible for the horse to bend his thoracic spine due to the twist forcing the potential lateral movement to work against, rather than with, his musculature.
There is a common misconception that the horse must have his head turned this far to make a tight turn, but in fact their most efficient movement is just the opposite. As you can see in the second picture, a horse performing a tight rollback, or a pirouette is going to stabilize his neck and trunk in a slight bend in the direction of movement. Overbending the neck here would make the turn far more difficult for him, as he would be unable to use the “spring” of his forelegs to push him around. I hope this explains why overbending or flexing the neck in this way is not good for the horse. Id love to hear your thoughts on this topic below!