When a golfer cocks his wrists at the top of his backswing, he needs to find a way to maintain most of that wrist cock until his hands are near the impact area. This delayed uncocking is what we call “lag.” Lag is responsible for a large part of a golfer’s power, and many players struggle with a lack of distance simply because they do not understand how lag is created.
Most players have been told to use a light grip when swinging a golf club. Some even know that this light grip is supposed to help them develop more clubhead speed, but they do not know how. You want to grip the club lightly so your wrists will remain relaxed and act as an unpowered hinge. In his book “Understanding the Golf Swing,” teacher Manuel de la Torre writes that “wrist action will be an involuntary reaction to the coiling action (backswing) and uncoiling action (forward swing) of the club." Tight wrist and forearm muscles make it difficult for the wrists to hinge properly; by keeping the wrists relaxed during the swing, they can move freely and allow the club to swing as fast as possible.
Change of Direction
If you have been fitted for clubs, you know your clubfitter spent considerable effort matching your swing to a shaft flex. During your swing, the shaft gets “loaded,” which means that it resists your swing by flexing in the opposite direction of your downswing. This power is released when the club straightens, or "unloads," at impact. This loading is accomplished by a delayed change of direction—that is, you start your downswing with your arms and body before the clubhead has finished the backswing. A good example of this is the motion you make with a flyswatter; your hand starts down while the business end of the swatter is still moving up. This action causes your wrists to cock and remain cocked until you are ready to swat the fly. The change of direction with a golf swing works the same way; it is the loading of the shaft that keeps your relaxed wrists in a cocked position until late in the swing.
One additional technique many players use to help create lag is sometimes called the “two-plane swing.” In essence, the player swings his club back on one plane then drops to a lower plane when he changes direction at the top of the swing and makes his downswing. This technique creates lag because the hands move sideways—perpendicular to the original plane—when they move to the lower plane. This eliminates much of the centrifugal force that would cause the wrists to uncock too early. This technique is most popular when using shafts that are very flexible—it was developed when hickory shafts were popular—but it can be used with any type of shaft.