Rules of THUMBS – Golf
“In the absence of any other proof,” Sir Isaac Newton said, “the thumb alone would convince me of God’s existence.” In further testament to its importance, Julius Caesar ordered the thumbs of opponents amputated so they could never again swing their weapons effectively. Both in war and golf, the one digit you want working correctly is your thumb.
Your thumb is controlled by nine individual muscles and three major hand nerves. Your target thumb (the thumb of the highest hand on your grip) plays a major role in the rotation of the clubface through impact.
In addition to its anchoring capabilities, the position of your target thumb on the club handle determines the direction in which force is applied to the shaft during your release and therefore how much the face of your clubhead will rotate through the impact.
When your thumb is on the top of the shaft at address, the pressure exerts down the middle of the club shaft, reducing clubface rotation through impact — and unless there is compensation, you’ll hit a fade or a slice. With your target thumb down the back of the shaft, the direction of the force causes your clubface to rotate aggressively through impact, imparting the characteristic spin of the draw shot.
Long or Short Thumb?
The “long thumb” position, with the top thumb fully extended along the grip, gives your clubhead the most arc by allowing you to make the largest wrist and thumb cock possible. The “short thumb” position, where the top thumb is retracted, restricts your thumb’s cocking action, producing more clubhead control but less clubhead arc and less power.
Note that cocking the wrist and cocking the thumb are related, but not identical. Your wrist can cock only about 15 degrees without bending or bowing, but your thumb can cock 90 degrees. If you cock you wrist fully, but restrict the amount of thumb cock, the shaft will appear to be less than 90 degrees even though the lead wrist is fully cocked.
This occurs in the swings of several tour players, including Steve Stricker and J.B. Holmes, prompting TV announcers to say that they are not cocking their wrists, which of course they are. Unfortunately, this mistake leads golfers to stop cocking their wrists — a recipe for a loss of power.