This exercise will strengthen your shoulders and upper back to not only help improve clubhead speed but to help prevent injury as well.

Stand with feet shoulder width apart bending slightly from the waist. Bend your arms at the elbows so that they look like the letter ‘W’.
Slowly extend your arms out at an angle so that they form the letter ‘Y’.
Return to the start position and repeat movement.
Do 8 to 10 repetitions.