Dr Mann
I have some emails from Jon Sinclair that I'd like to share with you as I am having a problem understanding (whereas you might make more sense of them). It is with regard the following section on your website.
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Here are comparable images of Jon Rahm's address and impact alignments that will allow one to assess how much more his left forearm is supinated at impact compared to address.
I have drawn a red line over his left lower radial bone just above the level of his left wrist crease.
Image 1 is address. Note that he has a weak left hand grip. Note that one can partially see his left antecubital fossa and that means that his left humerus is not significantly internally rotated at address - as would be seen in golfers who adopt a moderately strong left hand grip (like Dustin Johnson and Keegan Bradley) or golfers who adopt a very strong left hand grip (like Daniel Berger and Jamie Sadlowski). Note that his left lower radial bone is rotated slightly clockwise relative to his left antecubital fossa, which means that he has a very small degree of left forearm pronation at address.
Image 2 is at impact. Note that his left antecubital fossa is facing away from the target due to the fact that his left humerus is internally rotated at impact. Note that his left lower radial bone is rotated counterclockwise a lot more relative to his left antecubital fossa, which means that his left forearm is significantly less pronated (compared to its address alignment).
These comparative images demonstrate that Jon Rahm has to use a lot of left forearm supination in his mid-late downswing in order to get a square clubface at impact. In fact, the total amount of left forearm supination required is greater than the amount that would be required by a golfer who adopts a similarly weak left hand grip, but who doesn't come into impact with a markedly bowed left wrist. The fact that Jon Rahm probably used an element of twistaway in his mid-downswing, that was combined with the use of an "early left forearm supination + increased left wrist palmar flexion" maneuver, does not alter the fact that he still needs to use more left forearm supination than usual (for a golfer who adopts a weak left hand grip) and that he still needs to use a rapid left forearm supination action (PA#3 release action) in his later downswing in order to square the clubface by impact.
Scientifically valid "3D-evidence" that Jon Rahm is rapidly supinating his left forearm during his later downswing can be derived from studying his 3-D graph.
The vertical black lines show his address position (Adr), end backswing position (Top) and impact position (Imp).
The blue graph represents his left forearm pronation-supination graph, and pronation is below the zero horizontal back line and supination is above the zero horizontal black line.
Note that his left forearm is slightly pronated at address. Note that his left forearm pronates a lot more during his backswing action. Note that his left forearm does not move in the direction of left forearm supination in his early downswing and it actually becomes fractionally more pronated (as he shallows his clubshaft to a shallower plane) - see faint red block area painted over the blue graph. Note that his left forearm moves fractionally in the direction of left forearm supination just before his club start to release (start of the rise of the red graph that represents left wrist radial => ulnar deviation) and that likely reflects his "early left forearm supination manuver" that starts to happen between P5 and P5.5 - see faint green block area painted over the blue graph. Then, note how rapidly his left forearm moves in a supinatory direction in his late downswing and that represents his release of PA#3.
Note that his blue graph is just below the zero horizontal black line at impact, and that he is significantly less pronated at impact than he was at address,
which means that he had to use more left forearm supinatory motion in his late downswing's PA#3 release action (than expected) in order to get a square clubface by impact, and that is due to the fact that he uses a bowed left wrist technique.----------------------------
Email responses from Jon Sinclair
The first email was in response to my question whether he had any TPI graph information showing more lead arm rotation for golfers with bowed wrists into impact than at address (for DJ, Jon Rahm, Jordan Spieth).
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"The wrist are very complexed. You have to look at both to really determine how the club is being manipulated. I only have one of these players on 3D.
First of all a position in and of itself neither opens or closes the club face. So these players having flexed lead wrist does not mean they have closed the club. The grip has a lot to do with what is happening as well.
As a very general rule a player with a lot of flexion in their wrist at the top will actually start closing the club face later than one with a lot of extension. I am talking about world class players here. After club transition flexed players will tend to move toward extension a bit before going hard back to flexion.
I cannot think of a player off the top of my head that does not have less supination at impact than when they started. This is a tricky measurement though. AMM does not do the shoulder girdles so that can alter it some.
Moving toward flexion closes the club face at the top but then acts as an opens it at impact. Pronation/Supination takes the in and out of plane until you get more ulnar deviation then lead supination/trail pronation closes it.
I would need to do a complete study but I would doubt highly that there is less or more forearm movement in a flexed wrist over a extended one. If you are talking about higher or lower ROC I would also say that is a myth. It is what people want to believe. It fits nicely with a narrative.
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Jon Sinclairs reply when I sent him Jon Rahms graph from your website that seems to show less pronation at impact vs address
"Thanks for this graph. I did not have this one.
This is a typical graph I would see with a player with a weak grip. John has more pronation than when he started which is the same as saying less supination. Same direction on graph. I more proper way to say it would be “I can’t think of a player that does not measure more negative than when they started. Does this make more sense?
John has what I would consider a normal motion of flexion for a player that is in so much flexion at the top. He is also a extreme outlier when it comes to flexion at the top. You can see it is as I predicted. He moves more toward extension after transition before he goes back quickly toward flexion. As I always say it is the motion not the position. This is a good motion with a extreme position.
I would say he closes the club face later than someone that is in extension at the top. This I believe is because flexed player go back to rad extension and extended players have no need to. I would really need to see more graphs to be sure but I am confident in saying that. I would restate as well that there is absolutely no evidence that shows he would be able to square the club better by doing this then someone in extension. I would also say that I have seen no evidence yet that tells be he would have a lower rate of closer with this position. I would teach this with a player with a short backswing for sure!
I attached a picture with some notes.
Thanks!
Jon
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My Queries/Questions
1. Jon Sinclairs comments in first email response says
"Moving toward flexion closes the club face at the top but then acts as an opens it at impact"
"So these players having flexed lead wrist does not mean they have closed the club"
Doesn't this support your own statement that bowing the wrist opens the clubface coming into impact?
2. Your pictures showing lead arm supination from address to impact for Jon Rahm doesn't seem to tally with the 'magnified' JPEG image that Jon Sinclair emailed to me (shown above although I'm unsure how to make that picture bigger in this post) . The above jpeg shows MORE pronation at impact vs address which doesn't make sense to me because the Jon Rahm images clearly show less pronation at impact.
Further , Jon Sinclair says the following: " I would doubt highly that there is less or more forearm movement in a flexed wrist over a extended one."
Could this difference between the images and 3D Graph be explained by the way 3D AMM measures supination and pronation (see Tyler Ferrells video below)? You use the antecubital fossa as a point of reference whereas TF seems to show a different method where supination/pronation of the wrist is compared to its alignment with the elbow (or will there no real difference in the methods used)?
3. What does Jon Sinclair mean when he says "AMM does not do the shoulder girdles so that can alter it some." ? How can shoulder girdle movement affect supination/pronation measurements?
4. I don't understand these comments below and wondering whether you have a clue?
"As a very general rule a player with a lot of flexion in their wrist at the top will actually start closing the club face later than one with a lot of extension. I am talking about world class players here. After club transition flexed players will tend to move toward extension a bit before going hard back to flexion."
"John has what I would consider a normal motion of flexion for a player that is in so much flexion at the top. He is also a extreme outlier when it comes to flexion at the top. You can see it is as I predicted. He moves more toward extension after transition before he goes back quickly toward flexion. As I always say it is the motion not the position. This is a good motion with a extreme position.
I would say he closes the club face later than someone that is in extension at the top. This I believe is because flexed player go back to rad extension and extended players have no need to"
DB
Addendum: I think I now understand why a flexed wrist will start closing the clubface later.That is because the clubshaft is angled back more from the target line and therefore needs to close later with more supination to square the clubface without causing too much shaft lean at impact (hope I've got this correct!).