You can find this exercise on page 45 of the book Synergistic Golf.
Exercise Type: YOGA-STRETCH
Exercise Category: BACK, CHEST, FLEXIBILITY, LEGS - FEET
Begin on all fours. Even disperse weight between all fingers and palm of hand. Slowly lift knees off floor and push hips up and back to straighten legs as much as possible. Heels will be slightly off floor at all times. Lengthen through spine and stretch head and chest toward floor. Breathe and hold 10 seconds. Repeat 5 times.