You can find this exercise on page 224 of the book Synergistic Golf.
Exercise Type: DYNAMIC STRETCH
Exercise Category: BALANCE, HIPS, LEGS - FEET, STRENGTH
Stand with both feet together. Reach right foot back about 3-4 feet so legs are in a staggered stance. Always keep back heel lifted and weight on toe. Weight should be centered evenly between both feet. Place hands on hips or out to sides for balance. Keep eyeline and chin lifted. Lower back knee down toward floor then push back up using the front heel and gluteal. Repeat dipping back knee down and up 10x. Switch to other side.