External Rotation in the Downswing (AMG Shallowing Video)

[iacas]

Time-linked (9:23):

They say that "none of their players externally rotate in the downswing." Specifically, Mike Granato says "none of those five players or any of the other Tour winners we have data on externally rotate their trail shoulders in the downswing. We've yet to find a single one who does." They go on to say it's "not something we recommend."

So finally, how is Mike Granato defining "in the downswing"?

• None of the lines in the Kwon graph show the player going more external (absolute) than their most external (absolute) point in the backswing.
• None of the lines in the Kwon graph end the downswing (BI) more external (absolute) than at the top of the backswing (TB).

This graph begs to differ:

"Rotation" (internal or external) here is defined as: the internal or external rotation is the axial movement of the upper arm compared to the thorax plane. This is a shoulder movement.

I tried to discuss this more in Golf Biomechanists, but a bigger discussion is occurring here:

Golf Teaching Professionals | Facebook

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The purpose of the group is to host discussions about the golf teaching industry. In my mind there is no better way for someone to improve at the game than with excellent coaching, so I want to help...

I'll post a few relevant or good quotes.

Tyler Ferrell: "Here are graphs from a Golf Biodynamics system (Dr. Rob Neal) and a graph from AMM/TPI 3D. Both are of Grant Waite captured at different times. One is a 6 iron and one is a driver. Both systems show an external rotation of the trail shoulder during transition (keep in mind that they define top of swing differently, so the timing is different). The owners of both of these data sets claimed that these are typical patterns of the pros that they’ve collected. Not all externally rotate significantly, some flat line before moving into internal rotation, but only steeper arm motion golfers demonstrated internal rotation during the initial transition. … Here’s also a data set from Dr. Kwon’s database of 85 elite golfers, showing external rotation in transition as well."

Tyler (cont.): "Collectively, we have 3 other systems showing external rotation in transition (with actual data) as opposed to just a verbal description assuring us that all golfers go into internal rotation. Perhaps when Mike said in the video that they haven’t measured everyone, what might be more accurate is stating that systems can measure things differently and maybe our data is different than some other systems."

Tyler (cont.): "I’ve seen many wrist/forearm graphs and almost every tour golfer I’ve seen pronates in transition. Here’s a graph of Grant Waite and Henrik Stenson showing how the trail arm pronates (not supinates) during transition. This too is the normal pattern of the data that I’ve seen related to arm motion during transition. Because supination is relative to the elbow, and influenced by the shoulder movements, I typically saw golfers with supination having much steeper swings than those who had pronation. Dr. Rob Neal said his data showed the same pattern."

Jon Sinclair: "I will have you look at Dr. Kwon’s Measurements. I have been there and studied in detail his care and techniques on measurements. His measurement on this is as good as it gets from all I have witnessed so far. Even AMM is showing motion that is matching his data so there is two systems saying elite players indeed do externally rotate their trail shoulder on the downswing. I should have added GBD as the 3rd system saying this. They state that no players they have measured externally rotates in the downswing. Since the Gears program is not reporting this how was it being measured?. It is possible they have written their own calculations. I do not know."

Jon Sinclair (another comment): "Actually as it turns out GEARS does not report this in their software. If it is being measured it must be a calculation that AMG is doing on their own."

Michael Neff (GEARS founder): "GEARS does NOT REPORT shoulder range of motion. The AMG boys are using thier own calculations on this specific segment. … 1. GEARS does not report shoulder rotation in our user interface BUT our clients can export data and get it. 2. We use Phil Cheetham’s algorithm for our thorax and pelvis stuff and it is GLOBAL. 3. Most tour players go external on the backswing and minimal if any on the downswing (depending on your reference frame). 4. It's plausible lowering kills external and the wrist can bend without external. 5. Measuring the shoulder is very hard because of the challenge with the scapula, muscle and facia. Especially when the elbow gets over the shoulder. 5. Most agree thay there is minimal external if any on the downswing and that teaching excessive external can really cause problem. Which is really the main story they are trying to say."

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Presented for discussion.

[mvmac]

4 hours ago, iacas said:

Tyler (cont.): "I’ve seen many wrist/forearm graphs and almost every tour golfer I’ve seen pronates in transition. Here’s a graph of Grant Waite and Henrik Stenson showing how the trail arm pronates (not supinates) during transition. This too is the normal pattern of the data that I’ve seen related to arm motion during transition. Because supination is relative to the elbow, and influenced by the shoulder movements, I typically saw golfers with supination having much steeper swings than those who had pronation. Dr. Rob Neal said his data showed the same pattern."

Good discussion. Yes, I've seen Scott Cowx and Rob Houlding talk about these kind of moves. The elbows move a little closer together as the right forearm pronates and shoulder goes external (or holds external), left wrist flattens or moves towards flexion and left shoulder sits down.

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@iacas with the AMG video, what did you think about the way they described the right arm on the downswing? How it basically just bend up and down. I would have guessed there might have been more adduction on the downswing.

[iacas]

On 1/22/2023 at 2:24 AM, mvmac said:

The elbows move a little closer together as the right forearm pronates and shoulder goes external (or holds external), left wrist flattens or moves towards flexion and left shoulder sits down.

Yeah. Can I ask for clarification on "holds external?" Kwon's chart doesn't show the shoulder ever getting actually external, and none are more external than they were at the start.

On 1/22/2023 at 2:24 AM, mvmac said:

@iacas with the AMG video, what did you think about the way they described the right arm on the downswing? How it basically just bend up and down. I would have guessed there might have been more adduction on the downswing.

They said it adducts slightly IIRC. 10°, just watched that part again. I think that's a reasonable guess. Maybe 15° wouldn't have surprised me. 20° probably would have made me look at few swings myself.

Then again, most of their players… aren't abducting it much during the backswing, either.

[mvmac]

On 1/24/2023 at 4:02 PM, iacas said:

Can I ask for clarification on "holds external?" Kwon's chart doesn't show the shoulder ever getting actually external, and none are more external than they were at the start.

"Hold" is my lingo. Almost like if you had your hand on a wall at 4, then kept it on the wall as you went to 5. Elbow is working a tiny bit under. That's how they would demonstrate.

Ok, yes I can see that with the chart.