You can find this exercise on page 1 of the book Synergistic Golf.
Exercise Type: DYNAMIC STRETCH
Exercise Category: FLEXIBILITY, LOW BACK, RHYTHM - TIMING
Stand with your feet firmly planted a little wider than hip distance apart and extend your arms shoulder height to your sides. Rotate 180 degrees facing behind you keeping your arms straight out at your sides and maintain weight centered between both feet. Focus on lifting through the spine and be sure to lift your trailing heel for easier rotation. Repeat 5 times each direction.