You can find this exercise on page 196 of the book Synergistic Golf.
Exercise Type: BIG BALL
Exercise Category: ABDOMINALS, POWER PRODUCTION, SHOULDERS
Prop forearms on ball in plank position with feet hip distance apart balancing on toes. Pike hips backward while rolling ball back toward knees to standing. Reverse and roll out over ball back to plank. Repeat 10 times keeping abdominals tight.