You can find this exercise on page 256 of the book Synergistic Golf.
Exercise Type: BIG BALL
Exercise Category: ABDOMINALS, LOW BACK, STRENGTH
Lie on your back with knees bent over big ball. Tail bone should be touching the floor and hands resting behind head. Contract your abdominals, exhale, and draw hip bones toward your ribcage slowly rolling tailbone slightly up and ball off floor. This is a very subtle movement. Focus on using your muscles to lift, not momentum. Pause at top and return to floor. Complete 15-20 repetitions.