You can find this exercise on page 68 of the book Synergistic Golf.
Exercise Type: PILATES
Exercise Category: ABDOMINALS
Lie on back with knees bent and feet flat on floor hip distance apart. Palms down at sides. Inhale and lift head looking between knees. Exhale and flex upperbody off floor sliding ribcage toward hips and reaching arms toward calves. Inhale pausing at top holding belly button in. Exhale as you lengthen back to floor. Repeat 10 times slowly.