The golf swing in its most simple form is really only a circle. The radius of that circle, back and through the swing is the lead are (left arm for a right-handed swing and right arm in a left-handed swing). Good players create a wide arc on the backswing and maintain the radius that they created at address throughout the swing. High-handicappers, on the other hand, in their attempt to create a wide arc usually over do it by over swinging and bending their lead arm at the top of the swing, which is the opposite of what they should do. Use this drill to maintain your swing plane.