Your Trail Arm is Ruining Your Golf Swing! (The 90° Rule)

If you're someone who struggles with consistency and power in your golf swing, the issue might not be your body rotation—it's your back arm. Over-swinging, especially through excessive flexing of the back arm, is a common mistake that can drastically affect your control and timing. In this post, we’ll break down the importance of keeping your back arm in check, why over-swinging is a problem, and the key drills you can use to create a more compact, controlled swing for better performance on the course.
 

The Importance of Control Over Your Back Arm

The back arm (your trail arm) plays a critical role in your golf swing. When professionals take their backswing, the angle between their upper arm and forearm remains around 90 degrees. This controlled angle allows for more stability and power as the club moves through the swing. However, many recreational golfers tend to over-flex their back arm, which gives the illusion of a longer backswing but often leads to poor mechanics, loss of control, and weak shots.

When the back arm is over-flexed, it causes the wrists to extend and the clubface to open prematurely. This leads to a lack of control over the club, and often results in a steeper downswing as golfers try to compensate. By keeping the back arm at the correct angle, you can maintain control of the club, which helps you achieve a shallower downswing and more consistent ball striking.

Why Over-Swinging Happens

One of the main reasons golfers over-swing is the misconception that they need a longer backswing to generate more power. While a long backswing might look impressive, it’s not always the key to greater distance or accuracy. For most amateur golfers, a longer backswing caused by an over-flexed back arm is often an indication of losing control of the club, rather than a genuine advantage.

If you're not in the gym every day or working with a fitness professional, an over-swing can put unnecessary strain on your body. This can make it harder to control the swing, leading to poor timing and inconsistent results. So, how do you avoid this?

How to Fix the Over-Swing and Keep Your Back Arm in Check

To get a more compact and controlled swing, it’s crucial to address the movement of the back arm. Let’s dive into a few key tips and drills that can help you manage your back arm’s flexibility, leading to better ball striking.

1. Focus on Keeping Your Back Arm at 90 Degrees

A common issue with over-swinging is the back arm flexing too much. To avoid this, focus on keeping your trail arm at about 90 degrees of flex when the club reaches parallel to the ground in your backswing. This position will allow you to maintain better control of the club while still making a full body turn.

Key Drill:

Set up and take your club back to where the club shaft is parallel to the ground.

At this point, check the angle between your forearm and upper arm. It should be close to 90 degrees.

From here, continue your swing with a focus on keeping that angle intact, avoiding excessive flexing or straightening of the arm.

2. Create Width, Not Length

The feeling you’re looking for is width in your backswing, not length. A longer backswing might look appealing, but a wider one is far more efficient. As you swing back, make sure that your trail arm moves away from your body, creating space between your arms and torso. This will keep the club on the correct path and make it easier to transition into a shallow downswing.

Key Drill:

Start your backswing and stop when your lead arm is parallel to the ground.

At this point, focus on pushing your trail elbow slightly away from your body to create more width. This feeling of “pushing away” will help you keep the arms from collapsing and improve your control.

Swing through and focus on maintaining this width as you finish the shot.

3. Maintain Proper Body Rotation

A common misconception is that an over-swing is due to a lack of body turn. However, a proper body turn can actually help you avoid over-swinging by keeping your arms in check. Focus on turning your shoulders and hips, rather than trying to force a longer backswing with your arms.

Key Drill: 

Make sure that your body rotation is happening naturally as you swing back.

Your right shoulder (for right-handed golfers) should face the target at the top of the backswing. This ensures that your arms aren’t forced to swing beyond a controlled range.

As you turn, keep your trail arm in its 90-degree flex and focus on staying wide, not long.

The Accordion Feel: Creating Space Without Overloading

One of the most effective ways to prevent over-swinging is to create a feeling of “accordion-like” pressure in your backswing. This means pushing your arms away from your body while keeping your wrists relaxed, so the swing feels dynamic but compact.

You don’t need to lock up your arm or over-extend the wrist. Instead, focus on feeling the natural hinging of your wrists while maintaining that crucial width between your trail arm and body. This is where filming your swing can be helpful—seeing the difference between what you feel and what actually happens can provide valuable insight into your swing mechanics.

Drills to Control the Back Arm Flex

Here are two simple drills to help you work on your back arm control and prevent over-swinging:

Drill 1: Back Arm Width Drill

Set up to the ball and take your backswing to where your lead arm is level with the ground.

Check the angle of your trail arm at this point; it should be around 90 degrees.

As you continue your swing, focus on creating width by pushing your trail arm slightly away from your body.

Take a few practice swings without worrying about the ball to get used to this feeling.

Drill 2: Trail Arm Control Drill

Start by taking your club back to chest height in your backswing.

As your back arm starts to flex, try to control the amount of bend by pushing your elbow away from your body to maintain width.

Keep the pressure consistent and allow your body to rotate freely without over-flexing the arm.

Conclusion: A More Compact Swing for Better Control

To fix over-swinging and improve your golf game, you need to focus on the control of your back arm. By maintaining a 90-degree angle at the top of your swing and creating width rather than length, you’ll be able to maintain better control, improve your body rotation, and set yourself up for more consistent ball striking. 

Remember, it’s not about making a longer swing, it’s about making a more efficient one. Stay mindful of your back arm’s position, and incorporate the drills mentioned above into your practice routine. With time, you’ll develop a more compact, controlled swing that leads to better performance on the course.