The right arm's role in the back-swing is underrated and often misunderstood. In fact, many amateurs do the opposite of what they should do.
Simply put: The right arm should be on top of the left arm (1) as you start the backswing, and then it should move under the left arm (2) as you swing the club to the top.
Many amateurs fold and shorten the right arm too early as they snatch the club away. What you really want is a relatively straight right arm during the initial part of the backswing as this promotes width and good pace -- keys to hitting solid shots.
As your right arm continues toward the top of the backswing, it should start to fold and move under your left, which encourages your wrists to set and load correctly and helps your upper body to make a full coil. This combination of width and the proper body turn sets you in the ideal position for the downswing.
So remember, when it comes to the right arm, think "on top then under" as you swing back, and you'll have a great start to the whole swing.
Based at ChampionsGate near Orlando, Leadbetter runs 30 academies worldwide.