[O.B.Left]

A big hello to everyone @ LBG (first post from a long-time though infrequent visitor).

The other day I got into a (non-TGM) discussion on the biomechanics of the golf swing. Part of that discussion was the 'plane' of the swing and subsequently the TGM principle) that the clubshaft is on-plane if either:
1. The butt end of the Clubshaft is pointing at the Line;
2. The length of the Clubshaft is parallel to the Line; or
3. The head end of the Clubshaft is pointing at the line.

From a biomechanics point of view we could not 'prove' (or disprove) why this is the case (as opposed to for example the opinion that the shaft is on plane when parallel to the inclined (address) plane throughout the swing). Reading through the relevant sections of TGM just now, I still can't substantiate as to WHY mr. Kelley defined being on-plane as he did.

Can anyone shed light on this? I'd very much like to know the foundation on which the TGM on-plane principle is based (preferably from either a mechanical physics or biomechanical pov).

mtr33 welcome to LBG

I only pretend to know what the heck Im talking about but:

While Homer identified the shaft as a good proxy for checking plane compliance, it is the longitudinal center of gravity , the Sweet Spot Plane that actually travels the Inclined Plane and makes contact with the ball. We dont hit the ball with the clubshaft ,hopefully. Although we have all done it on occasion. The dreaded shank.

Golf being a side on game makes the direction of force less apparent as compared to say .......darts or throwing a ball. But the physics are the same in that; the force must direct, align the c.o.g of the object/club/baseball to the target.

In regard to your question, to adopt a parallel plane method is by definition to aim the force away from the ball. It may look like a parallel plane when viewing a golfer from DTL but it isnt ideally. And any golfer who actually achieves this alignment must compensate for it or suffer the consequences. Complying with this parallel plane all the way down would see him miss the ball by an amount equal to the distance between the two parallel planes.

Another way of looking at this is to see that given any #3 Accumulator angle (the adoption of a left hand grip where the handle runs under the heel of the palm say as opposed to along the lifeline)...........that the left arm isnt on the inclined plane. Either at address or at Top. And so an actual On Plane position at Top would see an Inclined plane run from the ball to the #3 Pressure Point (its the #3 pp that is at the top of the longitudinal centre of gravity, the top end of the plumb bob that defines the sweetspot plane. The sweetspot on the clubface not being a static point but a movable point depending on where the top end of the plumb bob is. Like a balance point, a point without dimension, but I digress)...... But with the left arm above this plane!!!!

The good folks who when discussing theory, look (DTL) at the left arm as defining the inclined plane at Top have it slightly wrong. These folks include some of golfs absolute all time greats and their teachers. Its understandable, its close, it seems as if, but its not correct. However these golfers when actually playing for sure knew what it was to direct the longitudinal center of gravity, the weight in their hands, the sweetspot. And they did so with their left arms above the inclined plane that their sweetspots traveled. For full powered shots anyways, putting with the handle running along the life line would be a different story.

Regards