It is a common myth that a saddle must bridge to allow the horse to lift the back.
Imagine someone was standing on your back, but instead of distributing their weight evenly, they were digging in with their elbow and knees. Would you be willing to curl upwards and “lift” or would you do what any horse would do and drop/hollow your back?
The belief that a saddle must bridge to let the horse come up is nonsensical. ONLY when the back is relaxed and there isn’t excess pressure on the lumbar, shoulder, wither area, spinal nerves can the horse engage and lift.
Mechanics of the back in motion.
What goes up must come down. Imagine the immense pressure on the front and back of a bridging saddle. Now we all know the horses back doesn’t stay up. So, imagine the impact from the saddle when the back comes down as the horse moves through the gaits. That pressure will skyrocket and the horse will be less likely with each step, to come up and engage. Instead they will go around hollow with limited movement in the shoulders and hind legs out behind them to avoid the constant pressure and pain.
To add insult to injury, many saddles that bridge will also be too long and sit on the lumbar, as well as on the shoulder and along the spinal nerves.
A temporary relief.
Unfortunately horses may go “better” very briefly in this fit simply due to the over-padding of the panels which are typically too soft and cannot support the tree which ends up falling through. However, since it goes against what the horse needs based on anatomy and biomechanics, the body WILL begin to degrade. Muscles will become sore or atrophy, the horse will lose the topline, the limbs will become sore from the additional stress, kissing spine, hunters bump, and the list goes on.
This is a fashion fit, not a function fit.