Many players who think they have an “over the top” swing are actually "casting" the club. Casting is named after a similar motion that fishermen use to fling their baited hook into the water. In some ways, “flinging” is a more descriptive term of the motion that golfers use. While the move that creates this problem is always the same, the reason for doing it varies.
Straightening the Wrists
Take your normal grip on a golf club, then lift it in front of you so your arms are parallel to the ground and the shaft is vertical. Without lifting or lowering your arms, straighten your wrists so the club shaft is parallel to the ground, in line with your arms. This is what you do when you cast the club—you uncock your wrists using your muscles. In a proper swing, you do not use the muscles in your wrists; your wrists are relaxed and merely respond to the weight of the swinging club.
Straightening Your Right Arm
If you swing right-handed and you cast the club—especially if you cast at the top of your downswing—you probably straighten your bent right arm to do it. In an effort to generate more power, many players quickly straighten their bent arm because they think they are swinging faster when they do. In reality, all they have done is uncock their wrists and lose clubhead speed. In a proper swing, you do not consciously straighten your bent arm; rather, your arm straightens as the swinging club causes your relaxed wrists to uncock.
Poor Swing Concept
In his book “Understanding the Golf Swing,” Manuel de la Torre writes that “anyone who visualizes the backswing and the return to the golf ball as having the same path will always use a casting motion.” This is because your wrists cock slowly on the way to the top of your backswing, then uncock quickly at the bottom of the downswing. If you try to duplicate the backswing motion on your way down, you will consciously straighten your arms and uncock your wrists before you reach the ball—and you will lose power.
The website GolfMedic.com states that inflexible hips can cause you to cast your club. Your lower body starts your downswing, causing your relaxed wrists and arms to start down without tensing up. If you cannot move your hips freely, you will try to make up for this absent power source by casting the club at the ball using your wrists and arms.
Golf instructors are notorious for telling their students to relax their grip, to hold the club lightly, or even to “grip the club as if you were holding a small bird.” If you grip the club tightly, you interfere with the natural uncocking motion of the swing and you will have to consciously do it yourself, which means you will cast the club. If you eliminate tight wrist and arm muscles, and if you stop consciously manipulating your wrists, you can stop casting the club.