Where and when your elbows pivot in your golf swing is vital to creating and maintaining a consistent swing and ball striking. Most player pivot the right or trail elbow very late in the golf swing causing a late or partial
The elbows need to have a relationship with the hip sockets. The right and left elbows should not get behind the hips at any point in the swing, until maybe relaxed finish position.
You can see in the two back swings below how better players keep from getting the right elbow behind the right hip in the back swing. This also helps get a consistent hand plane, shaft plane and club set.
The lead or left elbow proper pivot is harder to do and rarely done in armatures correctly. At impact, most amateurs have their left elbow, from the face on position, in front of the left hip. This is called the dreaded chicken wing.
The proper pivot is when the left elbow does not move past the left hip at impact. You can see from the picture below at impact both elbows are virtually right in front of the hip socket. The critical part of the left pivot is that the elbow must stop moving towards the target and pivot which allows the trail or right arm to achieve full extension and power.
Notice both elbow aligned in front of hips at impact. Also notice the left elbow pivot point is nearly over the belly button.
VJ Singh can often be seen practicing with two towels, one under each arm. The average players trying to do this will have a difficult time hitting the ball. This is because most amateurs elbows are all over the place during the swing. Go to the practice range and make small swings with your elbows staying in front of the hips and not letting the left elbow pass the left hip. Do this and you will surely improve.
This normally takes over 100-500 balls to make it a permanent part of your swing. The better you get at this the farther and more consistent you will hit the ball.
Jim Hartnett, PGA