You can find this exercise on page 166 of the book Synergistic Golf.
Exercise Type: DB STRENGTH
Exercise Category: HEAD - NECK, POWER PRODUCTION, SHOULDERS, STRENGTH
Stand with feet hip distance apart holding 3-5-8lb dumbbells directly in front of shoulders with palms facing inward toward each other. Inhale to prepare. Exhale alternating punches (lifts) with arms crossing over midline of body to opposite corners of room overhead. Palms slightly face downward. Complete 20 (10x each side). Focus on breathing and strong back posture throughout exercise. The heel of the punching arm may lift off floor slightly for control and power.