Andy Plummer on Abduction and Adduction

[iacas]

I like discussing the golf swing. Whether you call it "swing theory" or what, I like to talk about things that can expand the potential for what I know and understand. As a scientist, I like being shown that I'm wrong, too, because as I've said a bunch of times… "you're wrong and here's why" is an instant opportunity to upgrade my knowledge.

I also like to help golfers, and one of the things I'm most glad to have moved away from from 15 years ago was the "Hands In" idea from S&T. Jim Waldron is often credited (probably rightly so) with explaining why so many Tour players and good players talk about "keeping their hands in front of themselves" while it appears that they're moving their arms around their bodies. From over 30 years ago:

I've also got videos like… this (Instagram link here😞

I'm happy to say that I've become friends with Shaun and Mike at Athletic Motion Golf (AMG), too. I tend to get along with other smart folks who measure things, who look critically at information, who don't assume that what they thought 20 years ago holds true today. I get along with folks who look for chances to instantly upgrade their knowledge.

Andy Plummer remains one of the people who does not look for these opportunities. He didn't care in early 2013 when we had evidence that the information in their S&T 2.0 DVDs was bogus, and they seemingly don't care now. They've been attacking (it's their favorite pastime) AMG in particular for the better part of a year now. There have been a few shots back at them from AMG (like… this), no doubt. But as is typical of the AMG fellas, it's with measured data.

Well, recently, Andy took yet another shot at AMG: https://www.instagram.com/p/DZfHe0DuPXC/.

Andy demonstrates that true power in the golf swing comes from doing stuff like this:

Andy claims that the idea that the arms mostly lift and lower, while the body turns, is bogus. What golfers should be doing is using "angular velocity" to abduct and adduct their shoulders to move the club fast like this (above). Then he makes a ridiculous example of what AMG supposedly teaches, but misses by a mile.

Now, it doesn't take a biomechanist to know that you can't possibly swing as Andy demonstrates. His right arm is so far around and behind him that his left arm would have to grow several feet to reach the grip of the club (or alignment stick), and a follow-through with the right arm position like that would be absolutely silly. But, it's a demonstration, so let's not read too much into it.

However, I find ideas like this dangerous. Again, I like to help golfers, and in my opinion, the idea that you should abduct and adduct your arms a lot is a dangerous one. There's some adduction and abduction going on, but… it's not much.

Anyway, this statement was posted:

130 degrees of dynamic range of horizontal abduction and adduction is quite the claim! I posted some comments to Andy and others, and was issued a challenge:

Well, okay then.

Here's Bryson's lead shoulder adduction:

This measures the angle between the "virtual spine," the left shoulder, and the elbow. Bryson has a 97.34° "adduction angle" at P1, a 62.53° angle at P4, and returns to an 89.21° angle at impact. Rounding, that's a change of 34° from address to the top, and then a change (back toward the angle at address) of about 26° from the top to impact.

If we want to worry about only horizontal abduction and adduction (where D = adduction and B = abduction):

Left shoulder: 8.33° D, 38.74° D, 14.67° D

Right shoulder: 1.03° D, 55.75° B, 14.04° B

If we call moving the arms farther around you as negative, those are changes of -30.41° from P1 to P4 for the left shoulder and +24.07° from P4 to P7 for the left shoulder and -56.78° and +41.71° for the right shoulder.

I have no idea on earth where he gets 130°. From the last frame of Bryson's swing where he's at 126.98°? But the lowest that number gets is 62.53°, for a range of 64.45, or less than half of the 130° claimed (plus it includes part of the swing, post-impact, that has no bearing on what the ball does).

For good measure, another pretty good player:

Left: 22.55° D ➡️ 33.35° D (∆ 10.8°) ➡️ 17.36° D (∆ 15.99° from P4, 5.19° from P1)

Right: 15.03° D ➡️ 24.29° B (∆ 39.32°) ➡️ 1.93° D (∆ 26.22° from P4, 13.1° from P1)

Of the biomechanists and experienced 3D users (on any platform), none of them have seen anything like 130° of dynamic adduction/abduction from a good player P1 to P7. And, like my little joke above, even if you go to the end of the swing, you rarely get much more than a little over halfway there. Maybe Andy is adding them? He does say in the video "and then add it to that with the lead arm." (I think that's what he says, but this isn't an additive type system.)

I regularly coach golfers out of positions with a lot of adduction and abduction. I regularly work golfers away from moving their arms around their bodies. Even my juniors (the ones who have paid attention anyway! 🤣) can recite "arms = up/down, body = around."

Like this:

So, I don't know where this leaves us. Andy claims to have seen something on GEARS that shows 130° of dynamic adduction/abduction. I'm open to being wrong, but… I don't think I am here on this one.

And, until that comes to be, I will continue to stand up for what I think is the best information, and do my best to work with golfers toward simpler, easier moves that don't get them stuck. Simpler, easier moves like the moves Tour players and great players tend to make, not complicated, difficult moves.

Shaun and Mike said it in a video once where they demonstrated that the average Tour player adducts their lead arm 20° across their chest from the top to impact (P4 to P7), while the amateur often tries to go 40°. They said something like "the amateur is trying to move their arm TWICE the distance in the same amount of time as the professional athlete." Yep. The swings of great players are often easier and simpler. They are not abducting and adducting their arms much in comparison to average golfers.

As a smart man once said: "Why would you teach something (abduction in this case) that bad golfers already do?"

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On a related note… the S&T crowd continues to be… well, who they've been as long as I've known them. Take this comment for example:

I mean…

I would think that this is pretty self-explanatory, but then again… I didn't think it needed explaining to begin with.

P.S. As I was finishing up this article, another biomechanist replied with something so simple I hadn't even thought of it as I had immediately jumped into looking at the actual measurements: "90 doesn’t even seem physically possible.“

No, sir. It doesn't.

[iacas]

I have an update…

I don't have much of a response, because the fact that they would ADD the numbers for the lead and trail shoulder together… I mean, wow. I was giving them too much credit. Nobody would think to assume they were doing THAT. That's beyond comical.

One of the biomechanists I talked to put it this way: "So if I squatted down and went from 180 to 90 deg knee angle, then I would say 180 deg range of motion because I have two knees?"

I'd type more (maybe), but honestly, I'm laughing a bit too hard. 🤣

Update: Mini Manavian blocked me on Instagram, so I cannot see his post showing Bryson with about 50° of range of motion (with a driver) from P4 to P7, and 75° only if you go out to the mid-follow-through. What a terrible loss for me. 😉 

[BrooksButlerHays]

Do you know how Manavian is measuring his shoulder adduction-abduction that purports to demonstrate 50 degrees or motion in Bryson's downswing? I know the broader biomechanics research/scientific literature on this suggests shoulder adduction-abduction is only a modest contributor of force generation in the downswing, so I'm definitely not convinced by anything he's arguing, I'm just curious how different people can be claiming to use ostensibly the same "data" to tell a much different story.

[saevel25]

30 minutes ago, iacas said:

I don't have much of a response, because the fact that they would ADD the numbers for the lead and trail shoulder together… I mean, wow. I was giving them too much credit. Nobody would think to assume they were doing THAT. That's beyond comical.

That makes no sense at all. 

1 hour ago, iacas said:

Update: Mini Manavian blocked me on Instagram, so I cannot see his post showing Bryson with about 50° of range of motion (with a driver) from P4 to P7, and 75° only if you go out to the mid-follow-through. What a terrible loss for me. 😉 

so, I watched that Instagram. Here is a summary... 

Bryson....
Address: Trail Shoulder 0 degrees adduction.
P4: Trail Shoulder 65-deg abduction.
Impact: Right shoulder 15-deg abduction.
P9: 10 degrees adduction.

Rory...
Address: Trail Shoulder 16 degrees adduction.
P4: Trail Shoulder 26 degrees abduction.
Impact: Right shoulder 0 degrees abduction. 
P9: 18 degrees of adduction. 

DJ...
Address: Trail Shoulder 4 degrees adduction.
P4: Trail Shoulder 42 degrees abduction.
Impact: Right shoulder 2 degrees abduction. 
P9: 15 degrees of adduction. 

Their point is that arm doesn't stay on the trail side. That the arms have to get across the chest from P4 to P9. I mean they do. What matters is the rate of which it happens relative to the position of the swing. The trail shoulder at P9 is not abducted a lot. The range of that total abduction movement is like 40 to 70 degrees. Bryson might be an outlier. Rory might be an outlier as well. 

A couple of points. 

1. None of them had any adduction at impact. So, this tells me the trail arms stays on the trail side of the body at impact. Is it moving towards lead shoulder, yes. It doesn't happen till post impact. The right side of the body is moving towards the target, so the arms don't have to as much as people think. 

2. Trail shoulder adduction from Impact to P9 is 18 to 25 degrees. 

3. P9 adduction of the trail shoulder is only about 2 to 12 degrees more adducted than at address. The arms/hands stay in front of the chest a long-time post impact. If Rory, from his address position just rotated his body towards the target and raised up his arms so he is at P9. He basically didn't have to move his trail arm further across his chest than where he started at address. Visualize that for a bit. I bet for people who tend to stall and drag their arms across their body to hit the ball, that would emphasize how much the arms stay in front of the body and how much you have to turn. 

 

 

 

 

 

 

[iacas]

37 minutes ago, BrooksButlerHays said:

Do you know how Manavian is measuring his shoulder adduction-abduction that purports to demonstrate 50 degrees or motion in Bryson's downswing?

He's using a driver swing, while I used the iron swing. Bryson goes from about 65° B to 15° B, hence the 50°.

37 minutes ago, BrooksButlerHays said:

I know the broader biomechanics research/scientific literature on this suggests shoulder adduction-abduction is only a modest contributor of force generation in the downswing, so I'm definitely not convinced by anything he's arguing, I'm just curious how different people can be claiming to use ostensibly the same "data" to tell a much different story.

If you bend your right elbow, you're going to pull your hands across your chest some. Conversely, if you abduct your right arm and hold onto a grip with your left arm, you can see how extending the right elbow as we do in the golf swing during the downswing will "pull" the right shoulder/humerus forward (adducting it, as going from 65° to 15° of abduction is). Even people who pull their right shoulder WAY too far around them eventually get it "back in front" when their right arm/elbow extends.

So, such a motion shows up as shoulder adduction even though the movement that causes it is just widening the trail elbow. The left hand on the grip almost "pulls" the hands forward as the left arm can't stretch much (there's some shoulder protraction, but that's almost maxed out at P4).

1 minute ago, saevel25 said:

so, I watched that Instagram. Here is a summary... 

Oh, I downloaded it and watched it (and commented there) before he blocked me. It's what led to him posting the comment in the "update" above. 😄 

2 minutes ago, saevel25 said:

Bryson…
Address: Trail Shoulder 0 degrees adduction.
P4: Trail Shoulder 65-deg abduction.
Impact: Right shoulder 15-deg abduction.
P9: 10 degrees adduction.

Single shoulder range of 75°, and that's going out well into the follow-through. 50° Max range up to impact.

2 minutes ago, saevel25 said:

Rory...
Address: Trail Shoulder 16 degrees adduction.
P4: Trail Shoulder 26 degrees abduction.
Impact: Right shoulder 0 degrees abduction. 
P9: 18 degrees of adduction. 

DJ...
Address: Trail Shoulder 4 degrees adduction.
P4: Trail Shoulder 42 degrees abduction.
Impact: Right shoulder 2 degrees abduction. 
P9: 15 degrees of adduction. 

Manavian's video is bad. He keeps saying "midline" which is just a horrible way to look at it. He also kept saying that the club was moving that amount — also wrong.

Adding left and right together is really freaking dumb. Another golf instructor said "That's like saying the player has 100 degrees of knee bend (adding left knee bend to right knee bend) 🤦‍♂️" (similar to what the biomechanist said about squatting).

Also, see my post above about elbow bend. That's why Plummer’s alignment stick demo is so intellectually dishonest. A golfer can't get anywhere near that position on the left with his left hand on the alignment stick (quoted below).

14 hours ago, iacas said:

 

[saevel25]

17 minutes ago, iacas said:

Manavian's video is bad. He keeps saying "midline" which is just a horrible way to look at it. He also kept saying that the club was moving that amount — also wrong.

No one should measure a joint mobility away from that joint. If you go to physical therapy, they are not measuring your knee mobility based on your midline. It is based at the joint. Shoulder mobility should be measured in reference to the shoulder joint. 

[iacas]

3 hours ago, saevel25 said:

No one should measure a joint mobility away from that joint. If you go to physical therapy, they are not measuring your knee mobility based on your midline. It is based at the joint. Shoulder mobility should be measured in reference to the shoulder joint. 

He's not and GEARS doesn't really measure toward your midline. It's measured at the joint. That's not why his use of "midline" is bad (part of the reason is that your "midline" is twisted, the top of your sternum can be pointed at a different place than the belt buckle, and your shoulders protract and retract, too.

I think he's just trying to use midline to say which way the arm is moving. But they have terms for that — adduction and abduction — so whatever.

[iacas]

Athletic Motion Golf (@athletic_motion_golf) • Instagram reel

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39 likes, 7 comments - athletic_motion_golf on June 15, 2026: "It’s worth understanding the full picture so you can make the best decisions for your swing 👊🙂".

Well worth clicking through to watch that video on Instagram.