You can find this exercise on page 176 of the book Synergistic Golf.
Exercise Type: STRENGTH
Exercise Category: LEGS - FEET, POWER PRODUCTION, RHYTHM - TIMING, STRENGTH
Stand in static lunge position with good posture and weight evenly distributed between front foot heel and back foot toes. Use arms to help lift body upward with momentum and jump switching legs and landing with feet in opposite positions. Land lightly. Switch 20x maintaining good form with abdominals held in tightly.