left arm rotation?
 

is the left arm rotation a conscious,deliberate efort?

Arm Rotation
 

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In the Backswing this is called TURN, and the Downswing ROLL. Then, there is the Swivel. These are all different things, with different identities.

TURN-- IS A PRONATION OF THE LEFT FOREARM. This can be done consciously, especially when learning. A Swinger, using Standard Wrist Action does this.

SWIVEL-- With Standard Wrist Action on the downswing, the Left ARM(Wrist) remains Turned, until the Release Swivel, which happens very quickly, takes the Flat Left Wrist into Impact.

ROLL-- IS A SUPINATION OF THE LEFT FOREARM(Flat Left Wrist). This(with Standard Wrist Action) happens after Impact. Horizontal Hinging... FEELS like a Full Roll.

All these motions can be done "consciously" until learned. With proper practice, these motions should become smooth, and more Automatic.

Swivel Action Versus Hinge Action
 

Wrist Turn (to the right) and Wrist Roll (to the left) are true rotations. They are Swivel Actions (10-18-A).

In contrast, the Wrist can remain Vertical -- perpendicular -- to one of the Three Basic Planes (of Motion), i.e., Horizontal, Angled or Vertical. While this action may appear to Turn and Roll, there is no independent rotation. This is a Hinge Action (10-10-C/D/E).

With a Swivel Action, the Turned Wrist must later be Rolled (unless a Cut Shot is being played). With a Hinge Action, it remains Vertical to its Associated Plane.

thank you for the answers

Swivel Action
 

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OK... it sounds to me like Mr. Yoda is saying that technically any actual RADIO-ULNAR activity(supination/pronation) of the left arm, whether conscious or automatic, is actually termed SWIVEL ACTION. So with Standard Wrist Action, which usually is used with SWINGING, there is a TAKEAWAY SWIVEL(pronation), a RELEASE SWIVEL into the IMPACT CONDITION( where there is a FLAT LEFT WRIST, and very slightly OPEN CLUBFACE). With the RELEASE SWIVEL, the RADIO-ULNAR ACTIVITITY is in the opposite direction as with the TAKEAWAY SWIVEL. Finally... there is the FINISH SWIVEL, where there is additional RADIO-ULNAR ACTIVITY, and probably some left SHOULDER JOINT ROTATION, as well as PRONATION of the RIGHT FOREARM, to keep the shaft on plane at this stage.

With SINGLE WRIST ACTION, which usually is used with HITTING, but can be used with SWINGING, this is a little different. In the TAKWAWAY there is a LEFT WRIST COCK, but not a TURN. So there is no TAKEAWAY SWIVEL here. On the Downswing, "Normally" there is no RELEASE SWIVEL with SINGLE WRIST ACTION. The "Clubhead Fix alignment remains undisturbed." Some Hitters use the Finish Swivel, and some do not.

Now... Hinge Action is a different thing.

Muscle Madness And Hinge Action
 

Lagster,

I am no biomechanic, but I really don't think that is the case.

The Horizontal Hinge Action is actually the natural product of the Body Rotation and the Arm Swing. To the extent the Left Wrist remains Vertical to the ground, i.e., the horizontal plane, then we have a Hinge Action, not a Swivel Action.

And the natural Arm Swing will -- I think :confused1 -- produce the muscular activity you have described.

Left Arm
 

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This was jerry1967's original question. I think the LEFT ARM ROTATION, in certain cases CAN be a conscious thing, especially if the player is not automatically doing what he should.

What do you think?

Wouldn't it be more important to let the Hands function and allow the left arm to move accordingly?

Hands
 

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Yes!!!!!!!!!

This topic is more complex than it looks. One factor we have not discussed with this is GRIP TYPE. With a 10-2-F Grip, for example, both hands are already Turned. There is "no Turn or Roll." Employ the 10-2-B Strong Single Action, and use Standard Wrist Action, and there is a Turn and Roll.