Swaying in the golf swing: sway versus slide

Sway and slide are one move, mirrored

The Titleist Performance Institute names them separately. A sway is "any excessive lower body lateral movement away from the target during your backswing that forces your weight to the outside of your trail side foot". A slide is "any excessive lower body lateral movement towards the target during your downswing".

Same axis, opposite directions, opposite halves of the swing. The word doing the work in both is excessive, since neither definition outlaws sideways movement. Going back, good players use almost none. Coming down they use several inches. Hips travelling toward the ball are a different axis, and early extension has its own guide.

What a tour backswing actually moves sideways

About 8 mmTour hip-centre shift away from the target at shaft parallel

Nick Clearwater, who runs instruction at GOLFTEC, published the figures position by position from a database of 1.5 million lessons. The measure is taken at the centre of the hips and the centre of the shoulders, and both read zero at address. By the time the shaft is parallel to the ground going back, the average tour hip centre has moved 0.3 inches away from the target. That is about eight millimetres.

Then it returns. From shaft parallel to the top, Clearwater has the hips moving about half an inch closer to the target and the shoulders 0.3 inches. Add the halves together and the hip centre ends the backswing near enough where it began.

That makes the familiar cue the problem. Telling a golfer to load into the trail leg is, in Clearwater's words, "encouraging you to sway in a manner the game's best players simply don't". Optimotion, reading Ludvig Aberg on a CBS broadcast, put him just over an inch away at the top.

The move toward the target is the one that works

≈7.5 cmHip-centre travel toward the target, top of backswing to impact

From the top to impact, the same GOLFTEC data has tour players shifting the hip centre about three inches toward the target, near enough seven and a half centimetres. That is roughly ten times the backswing figure, in about a quarter of the time. Optimotion had Aberg two inches toward the target at impact against his address position.

This direction is allowed because the bottom of the arc travels with the body it is built around. Carrying the hip centre forward carries the low point forward with it, which is the whole purpose, and the low point guide covers that relationship.

TPI's objection to a slide is amount and timing rather than direction. Its page puts the cost at the far end of the chain: a lower body that keeps going sideways cannot stabilise, and speed leaks out of the upper body through impact.

Two published sets of figures that disagree

3.9 in vs ≈0.2 inTwo published GOLFTEC figures for tour hip sway at the top

GOLFTEC also publishes the SwingTRU Motion Study, drawn from more than 13,000 golfers inside a database of over 90 million swings. It defines hip sway as "the lateral movement of the hips toward or away from the target". It puts professional golfers at 3.9 inches toward the target at the top of the backswing, and 1.6 inches at impact.

Set that beside the position-by-position figures from the same company. One has the hip centre a fraction of an inch from its starting place at the top and about three inches toward the target at impact. The other has nearly four inches at the top and under two at impact.

What no page states is the zero. A sway figure is a distance from a reference, and none says whether that reference is the address position, the ball, the lead ankle or the middle of the stance. Borrowed without it, the number will not transfer to your video.

The screen that tells a limit from a habit

TPI's Lower Quarter Rotation Test does the separating. Put all your weight on one leg, bend the other knee and rest that toe on the ground beside it, hands on your hips, then turn the pelvis as far as it will go each way. TPI looks for at least 60 degrees on both sides, and says a restriction there creates "potential for excessive lateral motion in the golf swing (sway and slide)".

Which leg is the tell. TPI's sway page lists trail hip internal rotation as the first physical cause; the slide page lists lead hip internal rotation. A trail hip that will not turn leaves the pelvis nowhere to go but sideways going back, and the lead hip sets the same trap coming down.

Restricted hips do not simply move less. Kim, You, Kwon and Yi measured thirty male professional golfers for the American Journal of Sports Medicine, split at under 20 degrees of hip internal rotation against 30 or more. The restricted group swung with significantly more lumbar flexion, axial rotation and side bending (P=.003).

On your own video, film face-on and watch the midpoint between your hip joints rather than the trail hip. A pure turn sends the trail hip away and the lead hip toward the target while that midpoint holds still, which is why the published measurements are taken at the centre. Pebble Swing reads joint angles out of the frames and the backswing-to-downswing tempo ratio out of the motion, not a sideways shift in centimetres.