Forearm rotation in the downswing

[imperfectgolfer]

See this 3jack forum thread.

richie3jack.proboards.com/index.cgi?board=general&action=display&thread=3657&page=1

The question is whether one needs to rotate the left arm/forearm counterclockwise in the downswing.

Tapio responded by producing this video to explain that one doesn't need to rotate (supinate) the left forearm between P5.5 and P7.





I think that he is wrong in his video-explanation.

Note that Tapio uses a neutral left hand grip, which means that the back of his FLW must face the target at impact.

Here is Tapio demonstrating his shallow clubshaft angle at P5.5.



He states that he simply rotates his body/arms/club as a single unit ("whole system") from that position into impact without rotating (supinating) his left forearm. I think that he is wrong and that he is not doing what he claims that he is doing.

Look at the back of his FLW in that image - it is parallel to a shallow inclined plane. How did he get it to rotate flat onto the inclined plane during his backswing action if he didn't rotate his upper torso 90+ degrees from his address position? He must have rotated his left arm/forearm more than he rotated his upper torso (left shoulder socket). He therefore has to reverse the process in the downswing to get the back of his FLW to face the target at impact.

I think that the only golfers who don't have to rotate their left forearm in the backswing (pronation) and therefore downswing (supination) are golfers who use an ultra-strong left hand grip (eg. Dominic Mazza).

Try a simple experiment - adopt a neutral left hand grip (GFLW) with your left arm straight-in-line with your left shoulder socket - as I demonstrate in this next photo.



Now try and get to the P2.5/P5.5 position with the back of your GFLW parallel to a shallow inclined plane (as Tapio demonstrates in that capture image) - but do not allow your upper torso to rotate >45-60 degrees during that process. I believe that it is biomechanically impossible to achieve that goal of laying the GFLW flat onto the surface of the inclined plane (parallel to the surface of the inclined plane) if you do not pronate your left forearm.

Jeff.

[natep]

I saw a slow motion Hunter Mahan dtl video on a bigscreen tv a while back and I'm 99% sure he gets to impact with zero supination from the start of the downswing to impact. He's the only person I've ever seen who had that look.

[imperfectgolfer]

I am >99% sure that Mahan supinates his left forearm during his release of PA#3, which happens between P6.5 and impact.

Here is a face-on video.



Here are capture images.



Image 1 is at address - note that his left antecubital fossa faces away from the target and his left forearm is significantly pronated, and that results in a relatively strong left hand grip (3-knuckle grip). Note how much of the logo of his glove that you can see.

Image 2 shows him at P1.5 - note that the back of his left hand (logo) and left lower forearm (watchface area) is now parallel to the ball-target line and that is partly due to a small amount of left forearm pronation. That rotary left forearm motion has to be reversed during his downswing to get his clubface to be square at impact.

Image 3 shows him at P6.5 - note that the back of his left hand (glove logo) and lower left forearm is parallel to the ball-target line and his clubface is slightly open to the clubhead arc (similar to image 2).

Image 4 shows him at impact - note how much he rotated the back of his left hand (glove logo) and left lower forearm - and that is partly due to left forearm supination (representing the release of PA#3).

I think that the only golfers who do not supinate their left forearm in their downswing are golfers who do not use PA#3 release in their late downswing action.

Jeff.

[natep]

I cant see his elbow at all in any of those pictures......so how can you know that his forearm is supinating when you have nothing to compare it against? The video I saw was from dtl and it appeared that the whole left arm turned together with no rotation of the forearm between the elbow and the wrist for the entire downswing.

it was a driver swing fwiw. Maybe I can find it.

[natep]

This view isnt great, but its similar to what i saw. If theres supination before impact it doesnt look like much, look at how fast the clubhead reappears on the left side of his body, how low it is and look at the face. You need a ton of range remaining for forearm rotation to get from impact to that position with a driver. This video looks like the majority of supination occurs just after impact, resulting in the quick, low left exit of the clubhead. I think Mahan is the only person I've seen who appears to delay supination to this extent.

[imperfectgolfer]

Natep wrote-: "If there's supination before impact it doesnt look like much, look at how fast the clubhead reappears on the left side of his body, how low it is and look at the face. You need a ton of range remaining for forearm rotation to get from impact to that position with a driver. This video looks like the majority of supination occurs just after impact, resulting in the quick, low left exit of the clubhead."

I have bold-highlighted part of Natep's comments. I agree with his bold-highlighted comments, which must apply to any golfer who has a relatively strong left hand grip at address - the amount of left forearm supination pre-impact must be small because he must only get back to his address position of a considerable magnitude of internal rotation of the left humerus and a considerable degree of left forearm pronation (which are responsible for his strong left hand grip) if he wants to have a square clubface at impact. There is much more counterclockwise rotation of his left forearm happening after impact - which is happening due to three biomechanical phenomena - i) continued rotary movement of the left shoulder socket inside left; ii) a small amount of external rotation of his left humerus and iii) a small amount of left forearm supination. I think that biomechanical phenomenon i) is responsible for most of the rotation of his left hand/club because he uses a CP-arm release action.

I don't think that left forearm supination is responsible for the low-left exit of the clubhead. I think that it is due to his use of a CP-arm release action and the fact that the clubshaft is on a shallow plane in the impact zone. Left forearm supination primarily rotates the clubshaft around its longitudinal axis when the clubshaft becomes more straight-in-line with the left arm at low point.

Jeff.