My horse's chiro has suggested that I get my horse to lift his back more while undersaddle and to introduce very brief (1-2 second) periods of where he lifts up his back and holds it. The horse likes to hollow out during the warmup period and I'm trying to get him to lift up instead of hollow out.
On the ground, I know I can run something along his belly and he will lift.
Under saddle, I can use my spur to get him to lift a little, but we lose a lot of our engagement of the hind and he slows down.
Does anyone have suggestions on how I can get him to move a little more properly with lifting his back? I want to build up his back muscles. Arena or trail exercises are fine. If you have suggestions on other things to do to work up to it more, that's good too.