Chicken winging is defined as a loss of extension or breakdown of the lead elbow through the impact zone. This swing fault makes it very difficult to develop speed or power and tends to put excessive force on the outside of the elbow joint.
In order to fully extend your lead arm and maintain a good width into the hitting zone several physical characteristics must be developed. First and foremost, lead arm strength and lead side shoulder flexibility are needed for a strong and fully extended lead arm at impact. If the arm is unable to rotate around the shoulder due to joint or muscular restrictions then a chicken wing will develop. Secondly, if your downswing is out of sequence and your club is travelling in an over the top, or out to in swing path, the lead arm is forced to chicken wing due to the direction of the forces that are applied upon it.