Up or Down ?

Let's start with something very simple, a disk, which can rotate about its axis, as shown in Fig1. Let's imagine that the clubface is at either one of the points A, B, C, or D on the disk. At point E an upward force is applied causing the disk to rotate anti-clockwise. It is evident that the upward move of E can cause various moves for the clubface. It all depends where the clubface is situated on the disk. Down, forward, up, or a mix of these. The idea I like to stress here is that the motion of the A, B, C and D depends on their position RELATIVE to E.

Fig2 shows the situation where the shoulders are kept still - only a left arm/club swing. The ball is positioned halfway between left shoulder and spine axis. The low point is below the left shoulder and the ball will be struck with a slightly descending blow.

Fig3 shows a swing where the arm/club and shoulders are swung as one unit around the spine axis. For this case the low point is directly below the spine axis and the bal will be struck slightly on the up-swing. The left shoulder goes up and the club strikes the ball on the up-swing.

This is quite interesting, even for this very simply case, no wrist hinge, a forward lean of the club shaft, and the ball is struck on the up-swing. This is not in agreement with Brian's assessment of what is happening. TGMers with their strong focus on the left shoulder joint being the swing center will be prone to make this judgement.

An TGMer viewing an image as depicted in Fig 2c, sees the forward lean of the shaft, the ball position relative to the left shoulder and concludes that the golfer is going to hit down on the ball. Caution is required however as shown above. If both shoulders and arm/club are swinging there can be actually hitting up as shown in Figs 3,4,5.

It is interesting, even for this extremely simple swing, to look at the effect of a differential angular velocity re to shoulders and arm/club. In Fig 4 we let the shoulders rotate somewhat slower than the arms/club, and in Fig 5 we have a shoulder rotating somewhat faster than the arm/club.

With the arm/club having a greater angular velocity than the shoulders the low point moves a bit away from the center towards the left shoulder, as shown in Fig 4. Below, Fig 5, the opposite takes place, the low point shifts a bit  further away from the left shoulder. The point to be retained is that the relative angular speed between shoulders and club/arm shifts the low point of the swing.