Left Arm Position
The golf swing in its most simple form is a circle. The radius of this circle, back and through to the finish, is defined by the length of your left arm (for a right-handed golfer). Obviously, the wider the circle, the better.
When a wide arc is established during the backswing, a golfer becomes more able to drop the arms in the correct position on the downswing, which allows the left arm to release through impact and fold correctly in the followthrough. The left-arm fold on the followthrough is key, as it keeps the club on the correct plane and the ball on the target line.
A good ballstriker creates a wide, powerful arc on the backswing by allowing the wrists to hinge naturally, which places the club on the proper plane. More importantly, they use their flexibility and upper body turn to move the club to the top without the left arm having to fold. High-handicappers tend to do the opposite. First, because of what’s likely a faulty grip, they fail to properly hinge the wrists, impeding their ability to get the club on the correct plane. Furthermore, since these golfers don’t turn as much as they should, they move the club to the top by folding the left elbow. In this position, the high-handicapper loses the swing radius established at setup and, typically, ends up coming over the top, a move that exacerbates the problem by limiting correct rotation and release of the left arm post-impact.
You don’t need to swing exactly like a Tour player to strike the ball well, but don’t do the exact opposite. Keep the left arm extended on the backswing and let it fold on the followthrough. If you’ve been struggling with a left-to-right ballflight or fat and thin shots, focus on your left arm.
Correct use of the left arm begins with the grip. Check to see that the handle lies diagonally across the fingers of your left hand, as opposed to the palm. When the grip lies correctly in your left hand, hinging the club on the backswing becomes natural. If your wrists can hinge on their own, you’ll be tricked into hinging your elbows.
Correct use of the left arm is also dictated by your shoulder turn. Good ballstrikers synchronize their arm swing with their shoulder turn. This synchronization facilitates both a solid turn and a straight left arm. High-handicappers usually stop turning their shoulders too early, but continue to let their arms swing back. The result is a shortened swing arc and a collapsed left arm.