Golf instructor Jim Hardy has classified golf swings into two main types: one-plane swings and two-plane swings. Bob Wyatt of the United States Golf Teachers Federation notes that one of the key elements of the one-plane swing, according to Hardy, is the “upper torso rotating perpendicularly around his centralised spinal axis.” That perpendicular motion isn’t included in the two-plane swing.
One-Plane Swing Vs. Two-Plane Swing
Hardy’s distinction between a one-plane swing and a two-plane swing focuses on the golfer’s lead arm -- the left arm for a right-handed golfer. If the lead arm is parallel to an imaginary line drawn between the shoulders at the top of the backswing, the golfer is using a one-plane technique, including the perpendicular upper body turn. If the lead arm is at a more vertical angle relative to the shoulders, it’s a two-plane swing because the arm angle and shoulder angle lie in two different planes, according to Wyatt. The upper body movement will not be perpendicular to the player's spine.
Other characteristics of the one-plane swing that Wyatt highlights include a slightly increased bend from the waist, a stronger grip and a more aggressive use of the lower body in the downswing when compared to the two-plane technique. Former PGA Tour player Peter Jacobsen notes that because a player with a one-plane swing bends more from the waist he “turns the shoulders on an inclined plane and swings the arms across and around the chest,” while the two-plane swinger is more erect in the setup position and then “swings the arms in a mostly vertical manner.”
Hardy's One-Plane Keys
Hardy says the key characteristics of the one-plane swing include keeping your head “relatively still” on the backswing, swinging the club around the body, “turning your body as hard as you can” on the downswing, and attacking the ball “aggressively” with your trailing hand (the right hand, for a right-handed golfer) at impact.
Mixing One-Plane and Two-Plane Techniques
Though he distinguishes between one-plane and two-plane swings, Hardy favors neither. By employing either of the swings, he says, you should be “a pretty darn good player.” But he warns that mixing elements of both techniques within the same swing “is where golfers get into trouble.” Golf writer Stina Sternberg agrees, and further notes that the one-plane swing works best for “a fairly fit, flexible and powerful player.”