Who Pushes Off With Their Trail Leg?

[saevel25]

1 minute ago, hoselpalooza said:

just so we're clear, you're saying that the PhD director of research at swing catalyst is wrong about this?

do you want me to toss out more data published by other PhD's which supports the fact that golfers, to some extent, push off of their right side? 

Yes, PHD doesn’t mean they are 100% correct. There have been plenty of PHD’s in the history of PHD’s who are wrong. 

Sure, go ahead. I’ve got time to burn reading.

 

[phillyk]

31 minutes ago, hoselpalooza said:

@iacas, you might want to re-up on your swing catalyst certification.

 

 

source: https://carolinas.pga.com/wp-content/uploads/sites/3/2019/03/Dr.-Scott-Lynn-PhD-Swing-Catalyst.pdf

 

Here's a golf swing with no GRF.  The only thing missing in this swing is friction with the ground, aka GRF.  His torso swings one way, his legs move the other.  Put something, like ground, to stop the legs, and he has a normal golf swing. Your torso muscles moving are the original force, which translates through the legs and into the ground to create the opposite force.

[iacas]

Great post @phillyk that will go under-rated. Talked with Chris about this topic briefly today, oddly.

[boogielicious]

5 hours ago, hoselpalooza said:

 because I DON’T know, physics

Fixed that for ya! 

I do however. I didn’t just google the word  “Physics” on the internet or pull up random YouTube videos and completely misunderstand them as you did. 

For someone who is not brave enough to post your own handicap, you sure seem to know more about the golf swing than anyone ever. Must be wonderful to be you.

Again, your schtick is getting really old.

[chspeed]

11 hours ago, boogielicious said:

But as you can see in the video, as soon as I begin the downswing, my right knee bends

Just to be fair, in that picture, you're right knee cannot extend, because it's almost completely straight by the end of the backswing. In other words, it would be impossible for you to push off with any significant force. 🤔

Edited June 9, 2019 by chspeed

[Vinsk]

5 hours ago, hoselpalooza said:

Imagine trying to throw a baseball, or swing a golf club, while standing on ice.

 No, imagine doing those maneuvers with your trail foot on ice. Or...as @DrMJG posted, a guy with no trail leg at all.

Edited June 9, 2019 by Vinsk

[chspeed]

On 6/8/2019 at 8:21 AM, iacas said:

for my daughter's tournament

Good luck to your daughter!

[boogielicious]

1 hour ago, chspeed said:

Just to be fair, in that picture, you're right knee cannot extend, because it's almost completely straight by the end of the backswing. In other words, it would be impossible for you to push off with any significant force. 🤔

But it is not fully extended. Most PGA pros straighten their rear leg in the backswing and immediately start bending it at the start of the downswing. This action indicates they aren’t pushing off. This has been said many times in the posts above. To push off, you have to extend the leg. 

[saevel25]

7 minutes ago, boogielicious said:

This action indicates they aren’t pushing off. This has been said many times in the posts above. To push off, you have to extend the leg. 

Yep, those who have supported the push off opinion have not have any response to that point. 

 

[ncates00]

6 minutes ago, saevel25 said:

Yep, those who have supported the push off opinion have not have any response to that point. 

 

Further, wouldn't we see a spike (whether steady or explosive) in pressure on a GRF plate under the trail foot if this were true?  The golf swing is not a lateral "juke" like in football or basketball; in such a move, we would see a push-off.

[iacas]

1 hour ago, chspeed said:

Good luck to your daughter!

She played well. I popped on long enough to see @phillyk's post above, add that comment, and get a notification that @hoselpalooza had been given a mild warning once again. I just got home, mowed the lawn and am sitting down to catch up on email, etc.

She played well today. Finished on 18 with a tap-in eagle and shot the fourth lowest score of the day (rounds 1-3 were all just one stroke better).

1 minute ago, ncates00 said:

Further, wouldn't we see a spike (whether steady or explosive) in pressure on a GRF plate under the trail foot if this were true?  The golf swing is not a lateral "juke" like in football or basketball; in such a move, we would see a push-off.

Saw that reply as I was typing mine up, and yes, we would.

[ncates00]

13 minutes ago, iacas said:

She played well today. Finished on 18 with a tap-in eagle and shot the fourth lowest score of the day (rounds 1-3 were all just one stroke better).

Awesome!  Nice playing!  I hope to enjoy watching my little ones enjoy the game as well (mine are 4 and 2).

[iacas]

As predicted, I put up a post with a reasonably good density, and a good amount of good information, and @hoselpalooza acted like it doesn't exist, completely ignoring it.

Go figure.

While out following my daughter today, I talked with three people, all of whom know more than me about this (though I'm pretty well versed in this stuff, partly from having spent a good amount of time talking with and working with people like or exactly like the people I talked to today). Two are Ph.Ds in biomechanists and have pressure plate systems, and 3D systems, that make SwingCatalyst and GEARS look like McDonald's Happy Meal toys.

7 hours ago, hoselpalooza said:

literally everyone pushes off to the right to some extent

Pretty sure you meant "to the left," and even then, I have two comments:

• It's generally wise to say "target-ward" or "trail leg" or things like that, so as not to exclude lefties.
• Just saying "this is true" repeatedly does not make it true.

7 hours ago, hoselpalooza said:

"With sufficient traction between the golfer's feet and the surface, the horizontal force allows the golfer to push in one direction to move in the opposite direction (for example pushing to the right to move the body mass to the left at the beginning of the downswing for a right-handed golfer)."
https://www.swingcatalyst.com/learning-center/articles/ground-reaction-force

You have to be careful when reading articles that try to take a "Science for everyone!" type approach. They cut a lot of corners. It starts off with "By definition, force is the result of mass multiplied by acceleration." Uhh, no, that's not the "definition" of force. I can apply a force without anything accelerating. Two magnets being held together (or separated by a barrier, etc.) aren't accelerating. They're not moving. I can push against a wall, and accelerate nothing. Yet forces exist.

That said…

Your bold phrase doesn't say anything about the trail leg doing this pushing. The simple truth is, this small (and it's pretty small) shear (horizontal) force is simply a matter of the core pushing your hips left and the hips turning. In fact, you see pretty much exactly the same forces if you replace the trail leg with an inert object like… an aluminum pole attached to a prosthetic "foot."

How do we know this? Because PhDs have done just this. And they get virtually identical results.

7 hours ago, hoselpalooza said:

6:55
demonstrates pushing off of trail foot to shift COP/COM forward

Problem for you: he doesn't ever say it's the "trail foot" that does this. Replace the trail leg with a pole, push your hips forward with the core muscles, and voilà, you get nearly the same sort of forces registering (actually I've seen them be higher, because the pole, unlike a trail knee, doesn't gain flexion, which helps decrease the forces being put "into the ground").

This, like almost everything, will likely go over your head. And that's fine; you're not going to admit any wrong here. But someone else reading this in the future will perhaps gain something from it. To that person, I have this to say: there's more to it than I'm even typing out here. I'm not keen on wasting a lot of time typing up a response @hoselpalooza will likely mostly ignore, or will quote a fraction of. If you're truly interested, some of these points should serve as good jumping off points. They're not intended to be "100% complete."

7 hours ago, hoselpalooza said:

8:24
demonstrates how kevin chappell pushes off with the trail foot at the top of the backswing to shift COP/COM forward

You're hearing what you want to hear. Not once does he say "with the trail foot." The force in the trail foot is a resultant force - again, a pole would transmit a force to the ground (occasionally better than a re-flexing trail leg).

7 hours ago, hoselpalooza said:

- numerous tour-level pros and instructors mention the trail leg push off, many likening it to throwing a baseball.

We're not talking about baseball, but again, much of what I've read about baseball suggests that you don't "push off" in pitching, either. And feel ain't real. And none of these have said "the trail foot."

7 hours ago, hoselpalooza said:

- sean foley, who uses swing catalyst and whose work with justin rose has been referenced by dr. lynn in certification courses, describes the push off as a "key source of power", and uses throwing a baseball as an analogy. https://www.youtube.com/watch?v=VWmUOyVa5hA

Video discussed already. @saevel25 discussed it above, and Sean's exact words are "driving from this right glute and right hip." Neither of those are "the leg" and they sure as hell aren't "the foot." He later says "driving through with "the pelvis" which is also not a part of the leg or foot.

You know what I said before about your own videos, your own evidence, showing the opposite of what you think? Hmmmm.

7 hours ago, hoselpalooza said:

- every single baseball pitcher pushes off of the mound because of physics.

Saying something is true doesn't make it true. And once again, this isn't a baseball forum. And once again again, most of what I've seen says that you're not right about baseball, either.

7 hours ago, hoselpalooza said:

- and lastly, the research director for swing catalyst clearly demonstrates/explains how some elite golfers, kevin chappell in this case, push off of the ground with their trail foot

He doesn't say "with [his/the/their/etc.] [trail/back/rear/etc.] foot" at all. He doesn't even say "leg."

7 hours ago, hoselpalooza said:

i really should have phrased this differently. it's physically impossible to move the COP/COM toward the target without pushing off with the trail foot near the top of the backswing.

Incorrect in so many ways. Heck, one of the least ways in which it's wrong is that you keep adding "with the trail foot."

6 hours ago, hoselpalooza said:

I'm sorry, but where does any of that say "trail foot" or even "trail leg"?

Furthermore, "golf swings" would not be impossible without them. Chris made a "golf swing" without any GRF in the video of him jumping from the high dive. It wasn't a good golf swing, or at least wasn't a powerful one. But it was "a golf swing."

6 hours ago, hoselpalooza said:

https://carolinas.pga.com/wp-content/uploads/sites/3/2019/03/Dr.-Scott-Lynn-PhD-Swing-Catalyst.pdf

Nothing in there says "trail foot" or really even "trail leg" wrt "pushing."

BTW, here's a problem you won't be able to address, and which speaks to my previous explanations:

Look at that - right/left force switches midway through the backswing and actually reaches a peak before the start of the downswing.

What you seem to be missing is that this force is simply helping to slow the rotation of the body during the backswing. Let's call it a "negative" force being applied, which helps the golfer begin to turn back. If that force continues to exist, the golfer will continue to keep turning at an accelerated rate. The golfer, though, must slow down (in order to eventually reverse) the direction of rotation. So that's why we see the "positive" (rightward, or forward) force being applied during the backswing.

A second problem you won't be able to explain: a golfer is still sending the "body" forward here, and yet… look at that vector beneath the trail foot?!?! It's pointing backward. Why? Because, again, the GRF vectors are reactionary forces. The right foot is banking and trying to slide forward a bit, so the force (friction) is opposing it slightly.

The overall GRF is backward at this point, too, which helps to slow the golfer down (at this point the arms and hands start to slow down, which is how the shaft kicks out to deliver the clubhead to the ball and "release" the "lag").

6 hours ago, saevel25 said:

You have never addressed the fact that golfers gain flexion in their right knee in transition. This alone shows that they are not pushing off.

He likely never will. He sees what he wants to see in things, even when nobody says the word "foot" or "leg."

6 hours ago, hoselpalooza said:

do you want me to toss out more data published by other PhD's which supports the fact that golfers, to some extent, push off of their right side? 

Nobody here is going to deny that there isn't a little bit of force "backward" to help the golfer move forward. We've all seen that the vectors will point slightly forward throughout the early part of the downswing.

What you've never shown is that the "trail foot" or "trail leg" is responsible, actively responsible, for these vectors. Hell, the arrow in the FRONT foot points forward, too, and that foot isn't "pushing" forward.

Muscle activation studies say otherwise. Physics explains otherwise. The fact that the trail knee re-flexes says otherwise.

You've not got a (trail) leg to stand on here, @hoselpalooza.

---

BTW, new rule, as I despise talking about stuff with people who won't even share their identity. Add a signature with your identity - we don't need your SSN or your street address, your cell phone #, nothing like that - so we can address you by your name. And remember, this is golf, so we expect you to be honest. No name, no identity: no more conversation here. Though, to be fair, this conversation is just about over anyway. You've not presented anything to support your claims. You twist the words of people you cite, rely on "feels" of others, and read what you want to read on screens where "foot" or "leg" don't even appear. You don't address the points brought up against you. You're trolling, pure and simple.

[Piz]

Baseball pitchers do not "push" off the mound.  They step in the direction of the plate and, as I said before, some of them (or their coaches) describe that as a "push".  It doesn't matter, at the end of the day, how an individual accounts for physical sensations.  If player A likes to think one way and player B prefers another image...fine...let's move on and talk about something important.  Sometimes, in coaching, you have to let Dumbo (or his dad) keep the feather.

[iacas]

Let's stick to golf, as noted a few times before. Thank you.

[hoselpalooza]

@iacas, i thought it was clear that dr. lynn was talking about the trail foot. isn't that what he's demonstrating with kevin chappell's swing here?

though perhaps it would be better to refer to his published research which clearly mentions the trail foot:

Quote

 

"The TF ML force PC3 demonstrates that the Collegiate golfers create forward momentum through a large positive ML force (directed toward the target) during the early part of the downswing that subsequently needs to be stopped by negative ML force (directed away from the target) before ball contact (Figure 1e)."

TF = trail foot
ML = medial-lateral

source: Lynn, S. K., Noffal, G. J., F.W. Wu, W., & Vandervoort, A. A. (2012). Using Principal Components Analysis to Determine Differences in 3D Loading Patterns Between Beginner and Collegiate Level Golfers. International Journal of Golf Science, 1(1), 25–41. doi:10.1123/ijgs.1.1.25

 

now that we've established "trail foot" is in play feel free to review what i've previously posted with an open mind. and for others following along, i think this is a pretty good overview of the forces involved that originate from the feet: https://www.youtube.com/watch?v=raaEMTKmNUU#t=1m43s

On 6/9/2019 at 10:23 PM, iacas said:

Pretty sure you meant "to the left," and even then, I have two comments

no, i meant right. and obviously i agree with your feedback about using trail/lead instead.

below is more info to support what i was talking about (from the swing catalyst 3d motion plate data guide). remember, we've already established the use of "trail foot" in the published literature as a source of GRF to create forward momentum so it should be clear by now i'm not "twisting" others' words or whatever you said:

Quote

 

"TIMING OF MAXIMUM HORIZONTAL FORCE TOWARD THE RIGHT

Due to the traction that is present between the golfer and the surface, pushing to the right causes movement to the left. The timing of maximum horizontal force toward the right typically marks the beginning of the pressure shift from trail foot to lead foot."

https://support.swingcatalyst.com/hc/en-us/article_attachments/208468788/Data_Guide_3D_Motion_Plate_2015_-_email.pdf

 

here's a good video demonstrating this:

Quote

"see how easy it is for me to make a linear pressure trace. i'm pushin' with my right foot, lettin' weight off my left heel..."

i cited dr. lynn's work earlier because swing catalyst is relevant here, but i could also cite research from kevin ball, russell best, and many others who talk about trail foot/leg/whatever GRF in the golf swing. or if you have some way to disprove trail foot/whatever push off with peer-reviewed, published research, i suggest you provide it. 

the videos @billchao and @saevel25 shared don't disprove anything, either. i thought the focus was supposed to be on elite golfers? and similarly the video @phillyk shared with chris como jumping off of a diving board does nothing to prove the absence of trail foot/leg GRF in the golf swing; it's a joke.

Edited June 12, 2019 by iacas
removed baseball and OT crap

[iacas]

5 hours ago, hoselpalooza said:

@iacas, i thought it was clear that dr. lynn was talking about the trail foot. isn't that what he's demonstrating with kevin chappell's swing here?

It's not clear to those who know what they're talking about because Chappell doesn't push off with the trail foot.

You're seeing the results of what the body has done during that phase of the swing being transmitted through the trail foot because it's the only thing touching the ground.

As I previously said, a prosthetic foot attached to an aluminum pole generates similar forces and torques. And in the words of Chris… "just because the total HRT is targetward doesn’t mean you are pushing."

5 hours ago, hoselpalooza said:

now that we've established "trail foot" is in play

We have not. It's simply the point of contact with the ground… a very simple point you're failing completely to understand. A peg leg transmits similar force.

You've not demonstrated at all that the trail leg or trail foot actively pushes.

5 hours ago, hoselpalooza said:

now that we've established "trail foot" is in play feel free to review what i've previously posted with an open mind. and for others following along, i think this is a pretty good overview of the forces involved that originate from the feet: https://www.youtube.com/watch?v=raaEMTKmNUU#t=1m43s

That doesn't demonstrate that anything originates through the feet. You're confusing the fact that the feet are the only points in contact with the ground with what they're actively "doing."

5 hours ago, hoselpalooza said:

below is more info to support what i was talking about (from the swing catalyst 3d motion plate data guide). remember, we've already established the use of "trail foot" in the published literature as a source of GRF to create forward momentum so it should be clear by now i'm not "twisting" others' words or whatever you said:

That has not been established at all. Once again, it's simply the point in contact with the ground.

If I put a pole on the ground and then drive a hammer into the other end of the pole, the force plate will register the points where the pole contacts the force plate as the "source" or "location" of that pressure… despite the fact that the actual force came from the hammer. You're confusing the pole with the hammer.

5 hours ago, hoselpalooza said:

i cited dr. lynn's work earlier because swing catalyst is relevant here, but i could also cite research from kevin ball, russell best, and many others who talk about trail foot/leg/whatever GRF in the golf swing. or if you have some way to disprove trail foot/whatever push off with peer-reviewed, published research, i suggest you provide it.

I don't have to, because none of the work you've cited proves your claim. You're confusing the pole for the hammer.

Furthermore, the backward-directed shear force generated is very, very small. Why? Because the foot is quickly unweighted. The core drives the center of the body forward (the pelvis), which results in a small reverse push and thus a small force.

You've not proven a darn things, except that you still don't understand how to read a pressure trace or interpret a scientific paper.

5 hours ago, hoselpalooza said:

the videos @billchao and @saevel25 shared don't disprove anything, either. i thought the focus was supposed to be on elite golfers? and similarly the video @phillyk shared with chris como jumping off of a diving board does nothing to prove the absence of trail foot/leg GRF in the golf swing; it's a joke.

You said (or posted a presentation that said) players can't make a "golf swing" without GRF. The video demonstrates that you can.

Here's the final challenge for you, or anyone else out there:

• Stand with your feet as wide apart as they are in a golf swing or a bit wider.
• Doing nothing with your trail leg at all, slide your hips forward and drag your foot a few inches.

Now, were you on a force plate, you'd see a little force exhibited through the right foot, which @hoselpalooza seems to believe means that the right foot is actively pushing off. It's not - it's just that the force is transmitted through the foot as the sole point of contact with the ground. You could replace your entire trail leg with an aluminum pole and a prosthetic foot and you'd see the same thing.

Furthermore, while you were sliding the foot forward, you'd see a force registered as a shear (horizontal) force pushing back, even though your foot is moving forward. That makes sense, too, and likewise does not mean your foot is actively pushing backward - it's actually pushing forward as it slides, and the friction pushes back.

---

Throughout this discussion we've laid out several points, and @hoselpalooza simply replies with the same old misunderstandings of videos and PDFs. He's confused the fact that, again, the feet are the only points of contact and that forces are registered as coming "through" them rather than understanding what the trail foot or leg are actually doing. They're not actually contributing to the relatively small forward tilt of the rear GRF "arrow." The fact that an aluminum pole attached at the hip with a prosthetic foot on the end generates a similar trace/pressure reading is proof enough - the trail hip, pulled forward by the core as it lowers and travels forward, creates the GRF as measured at the foot (as the point of contact).

---

On 6/9/2019 at 10:23 PM, iacas said:

BTW, new rule, as I despise talking about stuff with people who won't even share their identity. Add a signature with your identity - we don't need your SSN or your street address, your cell phone #, nothing like that - so we can address you by your name. And remember, this is golf, so we expect you to be honest. No name, no identity: no more conversation here. Though, to be fair, this conversation is just about over anyway. You've not presented anything to support your claims. You twist the words of people you cite, rely on "feels" of others, and read what you want to read on screens where "foot" or "leg" don't even appear. You don't address the points brought up against you. You're trolling, pure and simple.

BTW, this is still in effect. Man up.

[mvmac]

Great post @iacas

Just filmed this to show what a "push" would be.