You can seriously improve your backswing with this drill (and do it anywhere)

The terms "extension" and "width" are popular buzzwords for describing the backswing, and they are important components to solid contact and distance. Unfortunately, they are sometimes misinterpreted, leading some players to mistakenly move the trail arm out and away from the body going back. Get wide, they might be thinking.

When you start back with the trail arm moving away from the body, it typically has the opposite effect of creating extension in your swing as you reach the top. Instead of moving on a nice, full arc (below, left), the swing often becomes cramped and narrow (below, right).

You can check if your trail arm is collapsing and getting stuck behind you by pausing at the top to take a peek or viewing your swing on video. It should be fairly easy to spot.

When you really try to stretch out your arms in the backswing, you lose the synergy between the swinging motion and your body's pivot action. You might be able to re-sync them on the way back down, but you just made your swing that much harder to repeat.

To fix this issue yourself, try this great isometric exercise that will help you link your trail arm and core together. Best part? You can practice this anywhere, even in front of your bathroom mirror.

Grab a towel and loop it around your trail elbow, then gather both ends with your lead hand (below, left). Then, get into your golf posture and mimic a backswing with your trail arm and your core moving together as you hold the towel tight. Take it to the top and note the resistance. Your trail arm should form roughly a 90-degree angle at the end of the backswing (below, right).

Now, start your downswing by pulling the towel with your lead arm while resisting with your trail side. Note how your trail elbow works down and adjacent to your body (below).

Remember how your trail elbow moves and feels as you do both parts of this drill, and then re-create those things when you go back to hitting shots. You can even rehearse this motion with a golf towel as you wait for the group in front of you to clear. Then, step up and repeat.