It's a long-accepted rule that on the golfer's backswing, his shoulders should turn to form a 90° angle with the target line. But without looking into a mirror, how do you know if you've reached the magic number?

Easy: Your left shoulder should be directly beneath your chin.

It's OK if your chin and shoulder touch, as long as your head is raised enough to allow the shoulders to complete the turn. In fact, if you struggle to rotate the shoulders fully, your problem may not be a lack of flexibility or technique. Try raising your chin at address – it may solve the issue.

But what about the downswing and follow-through? How do you know if you're correctly rotating the shoulders into and through the shot?

The shoulder-under-chin rule works here as well. This time, though, it's the right shoulder.

Make a slow-motion swing and stop when the right arm and club shaft are parallel to the ground (pointing toward the target) on your follow-through. Your right shoulder should be under your chin, with the shoulders again forming a 90° angle to the target line. If your chin has moved slightly left at this point, no worries. The right shoulder's rotation will naturally push it this way.

To ingrain and maintain proper shoulder rotation, practice swinging while moving the left shoulder under your chin going back, and your right shoulder under the chin swinging through. It's a simple way to boost your efficiency and power.

Shoulders under Chin for Proper Golf Swing Rotation

The golf swing is a complicated motion. There are a number of moving parts that have to work together during the swing, and the club can be swinging at speeds in excess of 100 MPH – meaning everything has to be coordinated just perfectly in order to hit a good shot. However, despite the complicated nature of the swing, it is important to simplify your swing thoughts so you aren't 'frozen' by a million different ideas running through your head. If you can focus on just one or two swing thoughts while hitting a shot, you will stand a far better chance at success.

One option for a simple swing thought is to focus on moving your shoulders under your chin. This is a great choice because it is the same thought during your backswing and your downswing. You won't have to change gears and focus on a new thought when you transition to the forward swing because this thought applies in both directions. During the backswing, you will work on moving your left s@houlder under your chin (for a right handed golfer). On the downswing, the roles are reversed and you will work on moving your right shoulder under your chin as you swing down through the shot. As long as you accomplish both of these goals successfully, you can be confident that you made a full shoulder turn.

Most golfers think of making a big shoulder turn as the key to creating power in the swing, but it is actually useful for a number of reasons. Using a full shoulder turn can help you maintain a smooth tempo, stay on balance during your swing, and strike the ball solidly – in addition to giving you the potential for power. Since you can't really see your shoulder turn while you are swinging the club, it is handy to use your chin as a 'guide' that you can monitor during the swing. It is easy to tell if your shoulder (either one) reaches the point of passing under your chin. With a little practice, you should have no trouble moving your shoulders under your chin on each and every swing that you make.

Contrary to popular belief, you don't have to possess great flexibility to make a full shoulder turn. Sure, it helps to be flexible, but there are ways to adjust your swing in order to create a big turn even if you lack the ideal flexibility in your legs and back. Spending some time on the practice range working on making a full shoulder turn will allow you to learn how to alter your body positioning in order to maximize your turn effectively. Since the shoulder turn is such an important part of the overall swing, it is worth making some modifications to your swing mechanics in order to gain rotation both in the backswing and the downswing.

All of the instruction contained below is based on a right handed golfer. If you play left handed, please reverse the directions as necessary.

Set Up for a Successful Shoulder Turn

Before you can worry about turning your shoulders under your chin during the swing, you need to first concern yourself with settling in to a quality address position. Without a proper posture at address, your attempts to turn your shoulders nicely during your swing may come up short. The position of your body at address will have a lot to do with how well you are able to rotate once the club starts in motion.

Following are a few tips that should help you build a perfect address position to promote a great shoulder turn.

• Knee flex is crucial. When taking your stance, start by establishing your lower body in an athletic position. That means your feet should be around shoulder width apart, and your knees should be flexed. It is important to flex your knees at address because you need your legs to be engaged and prepared to support the swing. A golf swing isn't just made with your arms – it is a whole-body movement. You will know that you have flexed your knees properly when the big muscles in your legs (quads and hamstrings) feel like they are being used. If you are a player who is used to standing straight up and down at address, your first order of business should be adding some knee flex to your stance.
• Flat back also important. Once your knees are flexed nicely, the next step is to make sure your back is in a flat position. Many amateur golfers hunch over the ball at address, which makes it difficult to complete a full turn. Practice taking your stance in front of a mirror so you can observe the position of your back. You want to feel like you are sticking your backside out behind you when you take your stance, as this is a good indication that you are in a flat back position.
• Head up. If you are going to be able to successfully pass your shoulders under your chin during the swing, your chin is going to have to be up and out of the way. Pushing the chin down toward the chest at address is a common mistake, but it is one that you need to be careful to avoid. Complete your posture by keeping your head up to continue the flat back position that you built in the previous step. You want to have your eyes looking down at the ball, but your head should be up to maintain quality posture.

A good posture in golf isn't any different than an athletic stance in other sports. When standing over the ball, you should feel strong and athletic rather than tight and rigid. Spend plenty of practice time working on just your posture until you are confident that you have your body in the proper position. The end goal is to be able to move both shoulders under your chin during the swing, but that isn't going to happen if you start your swing from a poor stance.

It Takes Time

One of the main goals in the golf swing is to have the club moving as fast as possible through the hitting area. That does not mean, however, that you want the club moving quickly throughout the entire swing. In fact, during the backswing and the beginning stages of the downswing, the club should be moving rather slowly. The only point during the swing where the club needs to move fast is at impact – the rest of the swing can gradually gather speed until you reach the moment of truth.
Many golfers rush through their swings, leading to an incomplete shoulder turn. When done correctly, a full shoulder turn takes time. If you are going to successfully move both of your shoulders under your chin, you are going to have to allow for enough time to let that happen. Specifically, you need to give your backswing time to turn away from the target until your left shoulder has successfully moved under your chin.

To slow down your swing enough to allow your left shoulder to clear your chin, try using the following drill during your next visit to the practice range.

• Take your pitching wedge out of the bag, and set aside five golf balls to hit during this drill.
• Find a target on the range that is somewhere in the neighborhood of 100 yards away. The target doesn't have to be exactly 100 yards – anything from 80 – 120 will work just fine.
• Place one of the five balls down in front of you and address the shot. Go through your normal pre-shot routine, and carefully aim the shot at the target you have selected.
• Once you have taken your stance, go ahead and make a swing and hit the shot to the best of your ability. At this point, you aren't going to be modifying your swing in any way. Simply do your best to hit the ball directly at the target.
• For the next shot, repeat the procedure above. This time, however, you are going to swing slower than you did on the first shot. You don't want to make any mechanical adjustments – the only change will be that you are going to make a slower swing. Watch the ball fly toward the target and note the distance of the shot as compared to the first shot you hit.
• Continue this procedure for the remaining three golf balls. On each swing, you will be trying to swing slightly slower than the previous shot. Watch each ball land so you can compare the results of all five shots.

For most golfers, this drill will lead to a surprising conclusion – the slower swings didn't actually lead to shorter shots. You probably associate swinging slower with hitting the ball a shorter distance, but that isn't necessary the case. When you make a slow swing, you give your shoulders a chance to complete the backswing, and you give your body a much better chance to stay on balance. Most likely, the longest shot you hit among this group of five was one of the slowest swings that you made.

It is important to note that 'slow' swing, in this case, is referring to the overall tempo of your swing. Obviously, if the club is moving slower through the hitting area, it isn't going to add distance to your shots. As you go through the drill, you should be trying to slow down the overall tempo of your swing, while still letting the club release aggressively through impact.
After finishing this drill, repeat the process with a couple other clubs from your bag. It shouldn't take long for you to find a tempo that will produce the best possible results from your swing. The ideal swing tempo for your swing is going to be different from other golfers, which is why this drill can be so helpful. By using five different tempos on five consecutive shots, you can directly compare the results in order to settle on a tempo that will optimize your performance.
Your tempo has a direction relation to your ability to move both shoulders under your chin during the golf swing. It isn't necessary to make a super-slow swing to get your shoulders under your chin, but you do need to allow for enough time to get into that position. Use the drill outlined above to settle on the tempo that will enable you to make a great shoulder turn.

The Risks of a Big Shoulder Turn

A big shoulder turn is a good thing for the golf swing. While that is true, making that big shoulder turn does come along with some risks that you need to consider. Many golfers have done harm to other parts of their swing while trying their hardest to make as big of a shoulder turn as possible. Getting your shoulders to pass under your chin during the swing should mean good things for your game, but only if you can avoid the following risks.

• Leaning left at the top. As you use your big shoulder turn to complete your backswing, be careful to not start leaning left with your upper body before your lower body has a chance to initiate the downswing. In an effort to turn as far as possible, you might overdo it and accidentally tilt your body toward the target. This is a problem because it will prevent your lower body from doing its job correctly as the club transitions into the downswing phase. For this reason, you should stop your shoulder turn when the left shoulder successfully moves under your chin. If you let it go on much farther than that, you are simply asking for trouble.
• Over-swinging. Balance is one of the top priorities in the golf swing, and making a shoulder turn that is too big will compromise your ability to stay balanced. Don't let that happen to you. Keep your swing under control at all times, and never feel like you are forcing yourself off balance just to make a bigger shoulder turn. The ideal goal is to make a big shoulder while staying perfectly balanced – one without the other will do you no good.
• A hook. Depending on the rest of the mechanics in your golf swing, a big shoulder turn can lead to a hook when you pull the club too far to the inside. Many players with a long swing suffer from a hook, just like many players with a short swing fight a slice. If you are hooking the ball consistently and you aren't sure why, try tightening up your backswing to see if that fixes the problem.

Make no mistake – you want to have a big shoulder turn in your swing. However, you don't want to force yourself to make sure a big turn that you do damage to other fundamentals that make your swing successful. Pay attention to your balance at all times, as lost balance is a great indication that you are overdoing your shoulder turn efforts.

Understanding the Role of Flexibility

As mentioned earlier, supreme flexibility is not essential in order to make a big shoulder turn. Even with limited flexibility, you should be able to find a way to get your shoulders to pass under your chin during the rotation of the golf swing. By simply testing your flexibility and making a few minor tweaks to your technique as necessary, you can start making a full turn during your next trip to the driving range.

To find out how your flexibility may be limiting your swing currently, try the following step by step process.

• For this drill, you don't need a golf club and you don't even need to be at the driving range. Simply find an open place to stand where you can safely make a swinging motion with your body.
• Take your stance, and hold your arms down in front of you as if you were holding a club. Interlock the pinky finger of your right hand with the pointer finger of your left hand to imitate a golf grip, and keep them connected throughout the drill.
• Start your 'swing', pretending as though you were hitting an actual golf shot. Pay attention to your left shoulder as it approaches your chin. Do not let your left heel come off of the ground during this practice swing.
• Are you able to move your left shoulder under your chin without taking your heel off the ground? If so, you are flexible enough to make a full turn without any swing modifications. If not, you will need to make a couple quick adjustments in order to complete your turn.

If you 'passed' the test above, you don't need to worry about anything else related to flexibility. As long as you can get your shoulder under your chin comfortably, you can rest assured that you are flexible enough to make a great swing. However, if you fell short of the ideal turn during that drill, you will need to decide how to adjust your stance and/or swing to accommodate your flexibility limitations.

The first option is to allow your left heel to come off the ground during the backswing. By letting your left heel come up, you will be taking some of the pressure off of your lower back during the turn. This makes it easier to finish the backswing with your left shoulder under your chin as desired. There is nothing wrong with this move, and a certain golfer named Jack Nicklaus used it to a fair amount of success during his incredible career. Give this method a try at the driving range and observe your results. If you are comfortable with this approach, spend plenty of time practicing it until you incorporate the raised left heel into your game.

Should you find that the left heel isn't the right solution for you, the next step is to try a modification to your stance. At address, turn your right foot out about 10 or 15 degrees. With your toes pointing slightly to the right (instead of straight ahead), make a few swings and check your progress by again watching for your left shoulder trying to move under your chin. Turning your right foot out to the right should have a similar effect as allowing your left heel to come off the ground. For some golfers, this technique will be more comfortable than the previous option, while accomplishing the same result.

The final method you can use to increase your turn is to straighten your right leg in the backswing. For some golfers, this move comes along with raising the left heel off the ground, but the two don't have to be connected. As the club moves through the backswing, simply allow your right knee to 'give' a little bit, so that you end up standing straighter on your right leg. This move will take some of the pressure out of your right hip, and your shoulders should be able to make a bigger turn as a result.

There is a beautiful simplicity in using your chin as a benchmark for your shoulder turn. It is easy to overcomplicate the golf swing, but there is nothing complicated about this perspective. As long as you can observe both your left and right shoulders moving under your chin during the swing, you will know that your rotation is doing its job. Golf is a rotational game, so spending the time to monitor your progress in this key area is worth the effort. Many amateur golfers try to build speed by sliding side to side, but a big shoulder turn is really the move that unlocks your hidden power. Master the ability to turn your shoulders under your chin in the golf swing and you just might be able to take your game to a new level.