There is a lot of conflicting advice about whether the shoulders should be open, square, or even closed at impact. The real answer, like most things in golf, is “it depends.”
The key to shoulder position at impact is matching your pivot with your arm swing. What I see on a daily basis is players doing things that by themselves might not be wrong, but they don’t fit with the rest of their pattern. Even worse is someone who tries to a make change to their golf swing by adding a piece that will do more harm than good. That’s because the piece they are trying to “fix” has to match the rest of their pattern.
So where should your shoulders be at impact? It depends on the rate at which your rear arm straightens, the location of your right elbow and the speed of your arm swing. Because people tend to understand things better when they see them we will go over some examples (all examples use a right-handed golfer).
For a golfer whose left arm is deeper and more across the chest and right arm stays bent longer, the shoulders should be more open at impact. This will help the golfer’s swing move in the direction of the target.
For this golfer, the arms are moving slower, or closer to the same speed as the right shoulder. This is why their right arm stays bent longer. As the hands move closer to impact the right shoulder is also moving at a similar rate down, out and forward toward impact. This gets shoulders more open at impact.
If this golfer’s shoulders were more closed, their swing direction would be too far to the right of the target and he or she would struggle with pushes and hooks. Hunter Mahan in the video below is a good example of this sort of pattern. His right arms stays bent until well after impact, allowing/forcing him to use his body to get the club out to the ball in a way that results in a fairly neutral path.
In contrast, a golfer whose right arm straightens faster needs his shoulders more square at impact. This golfer’s arms move faster in relation to the pivot than Golfer 1, which is why the right arm straightens faster. Golfer 2’s hands are moving toward impact at a faster rate than his right shoulder is moving down, out and forward. Because of this, Golfer 2’s shoulders will be more square/less open than the shoulders of Golfer 1. This type of golfer has the club working out toward the ball due to straightening of the right arm, and will work toward the target without having the body nearly as open to the target.
The key to understanding this is that both Golfer 1 and Golfer 2 can have the same ball flight and resultant path. They just get there two different ways.
Mahan vs. Fowler at impact
Most good golfers fall somewhere between these two extremes. Poorer golfers mix and match these patterns. Most commonly, I see slicers who open their bodies too fast with a right arm that straightens too fast. This kicks the club out past the ball and causes a path that is out-to-in, which produces deflected slices and big pulls along with shots hit off the heel and shanks. You will also see some good players with a lot of “lag” who keep their right arm bent but don’t pivot enough through the ball, resulting in a path that is too in-to-out which can lead to toe shots.
When working on your impact dynamics, make sure you are adding parts that match the rest of what you’re doing. Mixing components here can lead to very poor results and frustration.