You can find this exercise on page 80 of the book Synergistic Golf.
Exercise Type: PRE-ROUND WARMUP
Exercise Category: BALANCE, FLEXIBILITY, LOW BACK, RHYTHM - TIMING
Stand with feet hip distance apart holding ends of club in both hands with arms straight in front of chest. Inhale to prepare. Exhale rotating club and upper body to the right as far as possible. Lift up on left toe to allow further rotation. Goal is to rotate club 180 degrees. Inhale return back to start position. Repeat other side. Complete 10 repetitions each side. Focus on tall spine lifting away from hips.