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Let's Remember… It's not ALL about the Vertical GRFs


iacas
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Four or five years ago, when Dave and I first began working together, I bought two bathroom scales and we began to mess around with the ideas and concepts of weight, pressure, and force. Where is it during the golf swing, where is it going, how is extra force generated, etc.

We were some of the first people to use SwingCatalyst's force plates to measure what is now called "GRF" or "Ground Reaction Forces." We have, in a small way, led the charge in understanding this from the get-go.

But, lately, the attitude we "sense" in the golf industry is that it's starting to get over-blown. It's the "hot new thing" for many people. There are certifications being created just based on understanding GRF. While we think it's important… we also want to remind everyone that it's not all there is to generating speed in a golf swing. There's not only rotational speed (torque generated horizontally, or nearly perpendicular to GRF-related torque, though the friction in your feet do help to resist twisting the opposite direction) and there's also simple, pure arm speed, wrist release speed, etc.

This video is intended to highlight that, while GRF are important (and we certainly aren't saying that Dave is not "using the ground" at all here, but it's greatly minimized and almost limited to purely rotational friction), there's more to generating speed than GRF.

Watch, and enjoy…

Thanks.

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Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

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Great myth-buster!! Do you think the loss of speed with the fully seated hit vs. the half seat is simply because of loss of further rotational range of the torso, yes?

Vishal S.

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Great myth-buster!! Do you think the loss of speed with the fully seated hit vs. the half seat is simply because of loss of further rotational range of the torso, yes?


Some of the loss of speed is due to that. Some of the loss of speed is also likely due to the loss of vertical GRF.

Again, though hardly a true "scientific" test, it is fairly illustrative…

Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

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I'm impressed by how solid he hit that second shot. I've tried the shot where you hit off your knees before, so somewhat similar to this, and it's hard to connect solidly swinging like that!

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I am a player hits an average drive of about 290 and carries a 5 iron about 200 and I've always been one to use more rotational speed than speed from the ground. I'm glad that someone now knows that this is not the only way to generate power. When you use the ground mainly, people tend to sink down in their swing and this can cause some issues. Speed due to rotation does not require as much timing as from the ground. I like this ideology a lot. Thanks for starting the thread!

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Can a golfer tap out their maximum rotational force without using the ground?  Then create additional power by using the ground? I think it's all important and needs to be understood better by all coaches.

Without the ground you get nearly zero force. Try punching someone in space, or while skydiving in freefall. It's not very effective. You use the ground to essentially hold your lower body stable giving you a platform to rotate against. If you meant can people max out their rotational forces without using GRF, I would imagine it's possible.

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Can a golfer tap out their maximum rotational force without using the ground?

No. But they can create a LOT of force.

GRFs are primarily concerned with the vertical forces generated. For example, in this image ( from this video ):


Now, in this, I've VERY quickly drawn in the COM (center of mass, red circle), the combined GRF (green arrow), and the moment arm (blue line). The torque is shown as purple arrows. The moment arm is like a wrench. You can generate torque in two ways: 1) by having a longer wrench (directing your force away from the COM to create a larger moment arm), or 2) by pushing harder (i.e. the size of the green line).

Unfortunately, these are mainly what I'll call now "vertical rotation" components. The help the body to spin (though the body doesn't spin purely vertically either). They do little to help the arms simply swing down, the wrists to "throw" the clubhead , etc.

Consider how these lines would be drawn if we had a photo from face-on of Dave sitting in the chair: the COM would be low, the green arrow would be very, very, very short, and it wouldn't be oriented very much at all in front of the COM - the moment arm would be tiny. And yet, Dave is able to generate 70% of the speed essentially from just his arms (and his wrist).

(BTW, I probably drew the COM a little too far to the right in the images above. This shortens the moment arm a little.)

Then create additional power by using the ground?

Yes. Every golfer will be different, but let's imagine Dave can generate 70% of his speed from using his arms (this is a VERY rough approximation, and it's more of just spitballing numbers right now, so don't take it as gospel at all); you might find that he can generate 22% of his speed by rotating his shoulders and hips (which would result in shear forces during the downswing, which prevent his lower body from trying to twist the opposite direction of his upper body - that's why a golfer's right foot sometimes slips out "backward" or behind them on hardpan or wet conditions). Maybe 8% speed would be generated from pure GRF - lots of "extension" and "jumping" and really trying to make that green arrow point forward of the COM and have it be large in magnitude.

Without the ground you get nearly zero force.

That's not really true if "force" means clubhead speed. Without the ground you get no GROUND reaction forces, yes, but you can still generate clubhead speed:

Still swinging the clubhead pretty fast there…

Now, is Dave still using the ground to provide friction when he's sitting in the chair? Absolutely. But how much do you think his swing speed would have been if Dave had been seated in a chair on a frictionless (picture a perfectly smooth sheet of ice, perhaps)? Not a lot less. Just enough to offset the motion of his arms and the clubhead. And remember, the body weighs a fair amount more than the arms and the clubhead… :D

Try punching someone in space, or while skydiving in freefall. It's not very effective.

It would still hurts. Your arm is again a small portion of your body. If you can punch at 50 MPH on earth, you could probably punch at 47 MPH in mid-air. In such a scenario, your BODY is essentially the platform. Your COM will seek to maintain the same position, so if you move your arm out a little bit, it'll shift the COM, what, an inch? Maybe less? So your body moves back an inch (or less).

If you meant can people max out their rotational forces without using GRF, I would imagine it's possible.

I don't know what that means. The frictional (anti-rotation) forces still matter, of course. If you try to "max out" your rotational forces standing on a sheet of ice it won't end well for you… :) But the GRF we're talking about, and which is all the rage lately, is illustrated by the red circle, blue arm and green and purple arrows in the image above.

Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

Check Out: New Topics | TST Blog | Golf Terms | Instructional Content | Analyzr | LSW | Instructional Droplets

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Without the ground you get nearly zero force. Try punching someone in space, or while skydiving in freefall. It's not very effective. You use the ground to essentially hold your lower body stable giving you a platform to rotate against.

If you meant can people max out their rotational forces without using GRF, I would imagine it's possible.

JAB. Pure muscular force. They develop it using a speed bag. A seasoned boxer can knock you out cold sitting on a bar stool.

Vishal S.

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Found this thread interesting. Reminded me about something I noticed the other day. I saw a golf magazine with a Rory McIlroy ad promoting new Vapor Clubs and was struck by two things - 1: Rory's forearms are :censored: jacked (that's not the main point here), 2: He had a tremendous amount of WRIST cock (the picture showed him at the top of his backswing with a driver).

FWIW, and maybe the moderators could comment on this post to make a professional statement out of it, I think that proper wrist cock and release of the wrist angle might be a big contributor to swing speed. I've only gone to the range a couple of times, and not played, since thinking about this, but I was trying to think about this "swing thought" while practicing and it seemed to do two things - 1: increase the distance my ball travelled by enough to notice (maybe 10 yards per iron), 2: make it feel like I wasn't struggling so hard to hit it farther.

I always remembered an old baseball coach of mine saying that this power hitter we were facing had "great wrists," so I ask - Am I on the right track here, or totally off-base?

BTW - mostly through Lowest Score Wins. I'll be posting a review here. Big fan of the separation value concept. Thanks

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FWIW, and maybe the moderators could comment on this post to make a professional statement out of it, I think that proper wrist cock and release of the wrist angle might be a big contributor to swing speed. I've only gone to the range a couple of times, and not played, since thinking about this, but I was trying to think about this "swing thought" while practicing and it seemed to do two things - 1: increase the distance my ball travelled by enough to notice (maybe 10 yards per iron), 2: make it feel like I wasn't struggling so hard to hit it farther.

I always remembered an old baseball coach of mine saying that this power hitter we were facing had "great wrists," so I ask - Am I on the right track here, or totally off-base?

Yes, the wrists alone can generate some speed. If you did nothing but hinge your wrists back and then unhinge them, you could generate non-negligible clubhead speed.

Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

Check Out: New Topics | TST Blog | Golf Terms | Instructional Content | Analyzr | LSW | Instructional Droplets

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  • 3 weeks later...
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Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

Check Out: New Topics | TST Blog | Golf Terms | Instructional Content | Analyzr | LSW | Instructional Droplets

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[URL=http://thesandtrap.com/content/type/61/id/116153/] [/URL]

Well that was certainly convenient of you guys to both have your magnetic hover suits at the cleaners ;-) I doubt the results will be much different in a swivel chair or dangling from a rope. Muscles generate power. It's kind of what they do.

Bill

“By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.” - Confucius

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Well that was certainly convenient of you guys to both have your magnetic hover suits at the cleaners

I doubt the results will be much different in a swivel chair or dangling from a rope. Muscles generate power. It's kind of what they do.


Yes.

Erik J. Barzeski —  I knock a ball. It goes in a gopher hole. 🏌🏼‍♂️
Director of Instruction Golf Evolution • Owner, The Sand Trap .com • AuthorLowest Score Wins
Golf Digest "Best Young Teachers in America" 2016-17 & "Best in State" 2017-20 • WNY Section PGA Teacher of the Year 2019 :edel: :true_linkswear:

Check Out: New Topics | TST Blog | Golf Terms | Instructional Content | Analyzr | LSW | Instructional Droplets

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:doh:

Muscles generate power. It's kind of what they do.

If only common sense was common in the golf business.

Mike McLoughlin

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  • 3 weeks later...
Note: This thread is 3268 days old. We appreciate that you found this thread instead of starting a new one, but if you plan to post here please make sure it's still relevant. If not, please start a new topic. Thank you!

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