If you can
1. relax your upper body,
2. while moving at normal Xingyi speed, and
3. concentrate the ming jing (sharp energy) into the cestus region ending at the elbow (especially on the setup/reload phase)
... then you'll feel the really awesome internal an jing (surge energy) effect in the strike phase of Single Horse. The external mechanics are shown below. Works best if you understand and practice Double Horse first.