[Yoda]

It doesn't just bend a bit, it bends a lot.

Okay, we're making this thing a lot harder than it is. The exercise is simplicity itself -- at least it is when demonstrated -- and I'm afraid that people now will miss the whole point.

The point of the exercise was not to be "golf-like." The point was ...

How does the right arm and elbow act -- and what muscles are involved -- when you pick something up?

So let's just forget the left arm altogether and do a new drill.

Sitting or standing or lying down, just raise your right hand above your shoulder (as if to get a teacher's attention in class). That's the way the right arm works in the golf Stroke. Without of course, the constraints imposed on it by the left arm and the Inclined Plane of motion.

The triceps straighten the arm and the deltoids lift it.

In the Golf Stroke, the Checkrein Action of the Left Arm causes the Right Elbow to bend, and this also brings the Right Biceps into play (on the Backstroke only). So, we have the triceps, biceps and deltoids all involved in an integrated way to transport the Hands -- and the Club they hold -- to the Top of the Stroke.