We’ve always marveled at the huge shoulder turns and high hands of the longest hitting pros.
Jack Nicklaus immediately comes to mind. Dustin Johnson is a modern player who can really wind the club up on the backswing.
Scientific analysis now tells us that the further we can get the handle of the club from its initial address position, the faster we will tend to swing through the ball. We can measure this in linear inches, like if you had a measuring tape.
I define width with two criteria: one, what hour on the clock is your upper left arm segment (humerus bone), and two, how many inches off the shoulder is the clubshaft. The club must be reasonably on plane, as you can cheat by swinging too vertically.
In this photo of Jack, I’d estimate his left upper arm is at 11:00, and the clubshaft is a good 10 inches above his shoulder. This nets him about 100 degrees of shoulder turn.
Dustin Johnson goes even wider and deeper than Jack, reaching 11:45 and 12-14 inches. Some of this may be due to arm length, which if used properly, gives you a leverage advantage.
Kyle Berkshire is one of the current top long drivers in the world. He routinely swings 148 mph during competition, partially due to how far away he gets the handle of the club from its starting position. Watch:
He gets crazy wide! The commonality here is to get flexible enough to get the upper arm to 11 o’clock with at least several inches of space off the above the shoulder.
No matter where you’re at, you can improve. Believe me, I’ve seen the least flexible people around! Here is my student Marc working on his width:
While this is a giant improvement from where we started, you can see that Marc can only reach 10 o’clock with his upper left arm, and about 6 inches of space.
Marc busted his longest drive ever about 10 minutes later at 281 yards!
And here is yours truly working on mine. I can still get to 11 and 110 degrees of shoulder turn using this special surgical tubing. I simply tie it around a pole:
I can increase the stretch and force more width simply by either pushing the handle upwards, or sidestepping several inches to my right causing the tubing to stretch more.
For most golfers, increasing width on the backswing is an outstanding strategy towards building more clubhead speed as part of an overall program.