Hi Dereck,
To help your horse to recover after an effort, I know three techniques.
The neck extension in step and at a trot; this exercise allows to take a breathe and to expand his back and spine.
And to go on hike with your horse for insist on a calm climate where your horse can eat grass and breathe slowly.
There is also an specific food for after an effort which provides nutriments.
I hope this helps !