One of the most common questions golf teachers hear from students is, "What should the arms be doing during a golf swing?" It is important to understand the function of the arms in a golf swing if you want to be able to practice the correct swing. This article is written from a right-handed perspective, but left-handed golfers can use this information by simply reversing the hand indications.
On address, both arms are extended straight. Your right hand is at the bottom part of your grip on the club, and your left hand is at the top part of the grip. If the ball is too close you will be forced to bend your arms. If the balls is too far away you will be able to tell, because it will feel like you are uncomfortably reaching for the ball. Make sure you flex at the knees to bring the club behind the ball, and keep your arms extended straight.
On your back swing your left arm acts as a pushing arm and your right arm acts as the hinge that keeps the swing straight. You keep your left arm straight to get the maximum arc out of your swing. The more arc you get from your swing, the more power you will have. Allow the left arm to push the club into the back swing and keep your right arm tight to your body to keep the swing straight. If you allow your left arm to bend, you will wind up pulling the club closer to your body and reducing the speed you can generate. If you allow the right arm to drift too far from the body, the club will get away from a straight swing path and this could lead to a slice or a hook.
On your down swing the right arm becomes the power and the left arm becomes the guide. Continue to keep your left arm straight to maintain the maximum arc, and continue to keep the radius of your right arm as close to your body as possible. Your right arm will actually be pulling your club through the swing and your left arm will be guiding the club to the ball.
At contact your arms will once again be straight. Your left arm is still guiding the club through contact, and the right arm is pushing the club through the ball. As you bring the club through the ball, the right arm has gone from pulling the club through the swing to pushing the club through impact. The left arm remains straight and is still used as a guide.
The swing is not over until the club has made contact and there is a complete follow through. A complete follow through puts the club on the left shoulder with both hands still holding the grip. Always allow the club to complete the swing by ending up on the shoulder after a follow through.