In side converstaions I've had with some of you I have detected little confusion about the positions and how you get into them, but the discussion with Jonoraises the possibility that some who are interested might not know what Bertholy advises doing.
If you understand
Keystone Position and
the Master Move and the muscle action you need to do with these, IMHO you should be able to understand the rest of the text. But to hopefully make it clearer, some more photos might help.
These two pictures are from a slow motion film of a real swing shot in at an angle that may make the annotation clearer. I have mentioned keeping the trail arm bent and that bertholy sees this as moving the forearm closer to the the upper arm. This is a 'curling' action and uses the biceps. The yellow arrow is meant to indicate the direction on force on the trail arm from this biceps curl force. Note the significant bend remaining immediately before impact. Nearly this same degree of bend is present at impact but in that frame the trail forearm is partially obscured so the annotation would not have been as clear.
These two photos are frames from the clips I provided to the DG library. Ih the first Hogan is demonstrating the motion of a swing. it is not full speed and he is not bent over to hit a ball but rather talking to the camera. After reading Bertholy and trying this it is clearer to me how this is a demonstration of the biceps curl effort of the trail arm just to hold this position. The second is a real swing. WHile you can see that his trail arm is bent at the elbow it is not as bent as in the demo. Trying the demo per Hogan and then speeding it up as you would for a real swing, the centrifugal force will pull against that biceps supplied 'curling' force. As a result your trail arm will be straighter though not completely straight at this point (and not till after impact).
This should make it clear why on occaision I've mentioned the importance of 'biceps curl' to maintain the angle and the bend in the trail arm.
With this last photo of of Sergio from the 'Master Move Examples' post, the yellow line indicates as best I can in 2D the direction of movement of Sergio's trail elbow from the top of swing. The fact that the shaft 'flattens' with this movement is an indication that the magnitude of this motion is initially larger than any lead hand motion down. Once the trail elbow is at the side or in front of the hip, the muscle force that got it there is just used to hold it there. This can be seen in the Hogan photos. This should make it clear why I've mentioned on occaision the importance of getting the elbow in close.
In addition to the elbow movement annotated, Sergio's trail forearm comes closer to his upper arm (more acute angle at the elbow) as Bertholy instructs. This component of the motion increases wrist cock and effectively begins the 'biceps curl' of the downswing.
With these photos of Hogan you have a good view of Keystone with a regular golf grip (many of the drills have a separated grip).
Hope this helps.
Peter
