[12 piece bucket]

I have still not received an informative opinion that explains the biomechanical difference between a finish swivel action and horizontal hinging - with respect to the movement of the left hand.

Consider this particular problem from this angle.

Here is photo of Kevin Na's clubhead path through the impact zone.



One can see that his splined clubhead path demonstrates that he is swinging his clubshaft on the inclined plane and that he is tracing the base of the plane line post-impact. At the same time, his clubface has rotated counterclockwise while the clubshaft is travelling on the inclined plane - and this represents his horizontal hinging action. HK states that it occurs due to rotary forces operating at left shoulder level, and one can imagine that there is a hinge joint horizontally oriented at the level of the left shoulder - as demonstrated in this TGM photo.



The effect of this hinge action is that the back of the left hand supinates slightly while it is moving up the inclined plane. Supination is a rotary motion, which means that the left hand is rotating during this horizontal hinge action phenomenon. Tiger Woods describes this "feeling" as the feeling of turning the knuckles of the left hand towards the ground after impact. He is therefore aware of a rotation of the left hand. That left hand rotation (supination) is no different to the more complete rotation (supination) that occurs fractionally later in time (during the finish swivel) as the left hand supinates more fully so that the back of the left hand lies against the inclined plane. The only difference is that the first left hand rotation (during the followthrough) primarily occurs due a rotation of the left shoulder socket left-backwards (as part of the torso pivoting action) + rotation of the left arm/forearm unit at the left shoulder socket level, while the second left hand rotation (during the finish swivel) primarily occurs due to left elbow folding and left forearm fanning combined with an active pronation of the right forearm. Although the biomechanical driving mechanisms are different, surely the left hand is rotating (supinating) throughout the followthrough and finish phases of the swing, and it is really a continuous rotary movement.

Jeff.

Jeff . . . . I haven't read all of this but the picture that you put up of Kevin Nah is MAJOR shooting the hands and arms off the torso and swinging right. He has disrupted the #3 angle and the face will rotate fast as a result.

Hinging is simply holding your left wrist vertical to one of the basic planes (Vertical Horizontal and Angled). But your hinging is going to APPEAR different for each plane angle and the amoumt of #3 Angle you set (angle between left arm and shaft).

So it's really difficult to pin point hinging without considering the plane angle and #3 angle which are related. So Horizontal Hinging is going to look MUCH DIFFERENT on the Elbow Plane than the Turned Shoulder Plane. Why? Because the more #3 angle you set the more clubhead TRAVEL you get and the less face rotation for a given amount of roll.

That being said . . . if you are swinging down on the elbow plane and then disrupt #3 (on purpose or not) you have essential SHIFTED PLANES . . . which in turn is going to impact the rate of face closure . . . Homer said that "Plane shifts are hazardous." I would venture to say that the closer to the ball you get the MORE HAZARDOUS they become.

So some people may intentionally disrupt #3 by swinging "out to right field". Others may disrupt #3 for a variety of reasons unintentionally . . . standing up or Bobbing for example. So if you don't have a centered pivot and you RAISE UP (early extension as some say) . . . Bob . . . then you will disrupt #3 and the face may not perform as predictably as you intended.

Here's two examples . . . Furyk has major whacky shifting going on EARLY but once he gets to release point his #3 angle DOES NOT CHANGE. Els on the other hand raises the hands up through the ball and the face closes much faster. Both play GREAT golf . . . but there are obvious differences in the hand paths through the ball.

Furyk . . .

Els . . .

I would say there is a difference in the Delivery Lines here . . . One is using Arc of Approach . . . the other maybe Swinging on the Angle of Approach.