Jim McLean's 6 degree-of-freedom 3D report and other pevis/hips commentary

[Brian Manzella]

 

[lia41985]

Looks like club, hand, shoulder accelerated more in the bottom swing capture.

What does that say about the sequence of accelerations/decelerations/negative accelerations/etc.?

I know what it doesn't say.

Proximal-to-distal...

Ah, complexity.

 

[lia41985]

Brian,

Should I let you or do you want me to explain the "peakiness" of the lines in the second capture?

By the way, Trackman/Flightscope numbers for these swings?

Actually, I want Flightscope so I can get a read out on acceleration profiles.

MikeG! Can you donate? Uh ha

 

[spktho]

I don't quite know what you're saying here, Lia. As I understand it, for swing sequencing, it's not the "accelerated more" segments that matter so much. It's about when (time) in the swing sequence each segment had peak velocity.

 

[lia41985]

Yes, sir. There's a summing principle in that "something" is being done to get speed "out to the club." However, the something that is being proffered in this particular sample is that there's a particular sequencing of body parts. Kinematic sequence theory operates on the level of proximal/distal sequencing. It's a theory. In reality it's not that simple. Science has its shortcomings. It's not perfect. We'll keep learning. That's life.

 

[lia41985]

The shoulder issue we first noted when MATT sequences were posted...

It remains the elephant in the room...

All these images and lines aren't illuminating.

We used to draw lines on video and then laugh at the impracticality.

Now it seems we just went round a cul de sac, in reality.

 

[Matt Bryda]

What about the pelvis max speed and when it had this max speed compared
to the first swing?
Maybe the pelvis was better able to assist the other segments in the second swing.

 

[dschultz6072]

I see a clubhead that hits max speed before impact, then slows down and slightly accelerates again at impact.

My eyes! The goggles do nothing!

 

[natep]

Yes, sir. There's a summing principle in that "something" is being done to get speed "out to the club." However, the something that is being proffered in this particular sample is that there's a particular sequencing of body parts. Kinematic sequence theory operates on the level of proximal/distal sequencing. It's a theory. In reality it's not that simple. Science has its shortcomings. It's not perfect. We'll keep learning. That's life.

Oh really?

 

[lia41985]

Oh really?

Three-dimensional kinematic analysis of the golf swing using instantaneous screw axis theory, Part 2: golf swing kinematic sequence - Springer

Results indicate that the kinematic sequence of 2 of the 5 subjects analyzed supports the summation of speeds principle, where the sequence in which the maximum angular velocity about the pelvis, shoulders and left arm occurred, for one subject, at 68.2 ± 3.2, 72.8 ± 1.7 and 100 ± 0.0% of the downswing.

2 of the 5

Uh ha

 

[natep]

So what is your point exactly?

That not every swing in the world has optimal sequencing?

We already know that. Here's a TPI graph from ten years ago:

Lots of people accelerate their hips into impact. They're just not very good.

 

[lia41985]

So there are guys like Dustin Johnson, 4 other Taylor Made/MATT pros, and Jim McLean, who's shoulders don't operate according to the theoretical framework and you don't have a problem with the theory. Ok. I'd like to see it refined if not discarded.

Don't talk hips when the pelvis is being measured.

 

[lia41985]

Write this down:

It's not the intention to decelerate the prior segment.

It's the intention to accelerate the heck out of the next segment.

 

[natep]

I would generally agree, although intention is a tricky thing and everyone will be different, there probably are people who need to try to slow some things down.

I'm trying to find the DJ video, etc., so I can respond to your last post.

 

[lia41985]

I love how I can say that and we can come to an amicable disagreement.

Yet there are still people who think I couldn't appreciate something like "tear the cover off that mofo."

I'm different, I guess.

 

[birly-shirly]

So there are guys like [...] Jim McLean, who's shoulders don't operate according to the theoretical framework [...]

I'm struggling here. Is that what both those graphs show? Or just the first one?

 

[natep]

I can't find the DJ video. As I remember it the torso numbers fluctuated all over the place on the downswing.

Because the shoulder sockets can adduct and abduct independently of each other, this can be an issue if the shoulders are used for the torso measurements. It's a different situation than the hip sockets, which cannot move independent of one another.

The creator of the MATT system also said he thought it the torso numbers were probably an anomaly, IIRC.

IMO, this is not enough to debunk proximal to distal sequencing in elite swings.

 

[lia41985]

I can't find the DJ video. As I remember it the torso numbers fluctuated all over the place on the downswing.

Because the shoulder sockets can adduct and abduct independently of each other, this can be an issue if the shoulders are used for the torso measurements. It's a different situation than the hip sockets, which cannot move independent of one another.

The creator of the MATT system also said he thought it the torso numbers were probably an anomaly, IIRC.

IMO, this is not enough to debunk proximal to distal sequencing in elite swings.

I disagree with this entire post.

 

[spktho]

The shoulder issue we first noted when MATT sequences were posted...

It remains the elephant in the room...

I'm still not sure what you are asking. Are referencing the shoulder's line increasing above the other lines from approximately 1.85sec. to about 1.92sec.? If so, another possible explanation (besides the shoulder's independent motions that you have already dismissed) is the "slack" being taken out of the left arm/torso connection. The shoulders want to "go" with the hips as they accelerate just due to muscular connections. But, the arms and club are still back behind the golfer and there is slack between the left arm and torso. So the shoulders show a sort of pre-peak, then get slowed by the arms and club being pulled as that slack is taken out.

If you look at the Mclean graph this correlates pretty well with the left arm acceleration (greater positive slope) from about 1.90 sec. to 1.94 sec. From this time period the shoulder slope is leveling as the arm slope is increasing pretty dramatically.

 

[natep]

I've been reading through every academic journal I can find on my school's journal database researching kinematic sequencing. There have been countless studies done on basically every athletic motion you can think of. Not once yet have I come across a study that debunks proximal to distal sequencing as being optimal. They all confirm it.