You can find this exercise on page 259 of the book Synergistic Golf.
Exercise Type: DYNAMIC STRETCH
Exercise Category: FLEXIBILITY, SHOULDERS
Stand with feet hip distance apart, palms facing toward outer thighs. Inhale, squeeze shoulder blades together and stick out chest. Exhale, reversing the movement squeezing shoulders and chest forward and lengthening across midback. Repeat 30x with control. Arms and hands will rotate slightly around legs.