Some scientific analysis of Mao's 3A

[silverlake22]

As far as 2A is concerned, I believe Mao does TRUE 2A as well as Yuna.

They just do in different style. Mao hops high while Yuna throws herself in the air using the speed.

Yes, I believe that this is considered not the best technique for a 2a, and that's why some have issues with Yuna's 2a. In reality, I think someone thought I was a Yuna-bot (which I'm not - I like other skater's too) and wanted to point out a flaw in her skating, which I can understand now, but I still think her 2a is fine. I like it when she does it on the ground :agree:

 

[gfskater]

I remember seeing a video of a coach explaining that a jump can be:

1. Almost but not clearly backward on takeoff.
2. Up to 1/4 revolution cheated on the landing

and not be downgraded.

He then said that this means a singe jump can be a little more than 1/4 turn in the air and be legal! This makes sense to me.

This means a double can be a little more than 1-1/4 rotations and a triple a little more than 2-1/4 rotation and not be downgraded.

So a triple axel can be a tad more than 2.75 rotations and not be downgraded right?

 

[silverlake22]

I remember seeing a video of a coach explaining that a jump can be:

1. Almost but not clearly backward on takeoff.
2. Up to 1/4 revolution cheated on the landing

and not be downgraded.

He then said that this means a singe jump can be a little more than 1/4 turn in the air and be legal! This makes sense to me.

This means a double can be a little more than 1-1/4 rotations and a triple a little more than 2-1/4 rotation and not be downgraded.

So a triple axel can be a tad more than 2.75 rotations and not be downgraded right?

I believe so. It must mean that at Nationals Mao cheated it just more than is allowed without a downgrade, but I can't really tell from the video, it looked pretty good to me.

 

[Iscariot]

Did Chin ever attempt it in competition? Or are you going off a practice video. I know there are practice videos of Kristi Yamaguchi falling on it as well, surely underrotated.



Ludmila Nelidina at 2002? Skate America -- same time Nakano first landed it internationally.

Others I know of who attempted but weren't successful include
Yoshie Onda -- stood up on it, cheated, at least once at one of the European fall competitions ca. 2001 or 2002
Lisa Sargent at Canadian Nationals at least once in the early 1990s
Angela Derochie in the late 90s, possibly at Canadian events and I know she tried in the short program at I think 1998 Cup of Russia -- underrotated and fell, and judging from her scores it seemed at least some of the judges counted it as a failed double axel which then gave her no credit for her successful double axel later in the program



Meissner hasn't officially retired but she has been injured and isn't competing this season. We might see her in competition again, but I don't think we'll see her attempt 3A again.

Bulanhagui competes as a senior within the US and is now in her last year of junior eligibility internationally.

Here you have it Chin 3A
http://www.youtube.com/watch?v=GE9pApU53W0

I dont agree with miessner having the same high in the jump as mao, i think she was in the rank of yukari nakano, quite low but rotating quickly

 

[hellcat]

I believe so. It must mean that at Nationals Mao cheated it just more than is allowed without a downgrade, but I can't really tell from the video, it looked pretty good to me.

I thought she had some issues with the 2nd and/or 3rd 2Lo in general with combo. They look severely UR.

If any, I think it could be that pre-grinding/scratching-ice can be considered pre-rotation or not. I do not know the answer.

But if it is considered pre-rotation, her 3A looks OK to me.

 

[sleepymom]

I think it would have been better with higher qaulity video.

Try this one. Not sure this link will work.. let me try this anyway.

3A

I'm sorry if I'm late, but this is wonderful resolution. On this one, I can say she's pre-rotating about 1/4 turn, but short on more than 1/4 turn on landing. So.. by the ISU rule, this one would have been downgraded, I guess.

 

[Basics]

I'm sorry if I'm late, but this is wonderful resolution. On this one, I can say she's pre-rotating about 1/4 turn, but short on more than 1/4 turn on landing. So.. by the ISU rule, this one would have been downgraded, I guess.

yes, good point!

If you call that about 1/4 turn pre-rotation, then it's more than 1/4 turn short on landing.
If you call that less than 1/4 turn short on landing, then she must had pre-rotated about a half turn. get it?

I'm not sure if that 3A should've been downgraded though. that one looks on the borderline. so it's up to individual techies to decide?

 

[sleepymom]

I remember seeing a video of a coach explaining that a jump can be:

1. Almost but not clearly backward on takeoff.
2. Up to 1/4 revolution cheated on the landing

and not be downgraded.

He then said that this means a singe jump can be a little more than 1/4 turn in the air and be legal! This makes sense to me.

This means a double can be a little more than 1-1/4 rotations and a triple a little more than 2-1/4 rotation and not be downgraded.

So a triple axel can be a tad more than 2.75 rotations and not be downgraded right?

While this is true, the danger of this approach is that you are on the mercy of technical caller of the day. And from what I understand, if you pre-rotate too much then you wouldn't cover much distance on the ice - because your speed is not converted to jump force enough - so probably not good GOE, unless you have really good power in your leg to jump high. Am I getting it right?

 

[sleepymom]

yes, good point!

If you call that about 1/4 turn pre-rotation, then it's more than 1/4 turn short on landing.
If you call that less than 1/4 turn short on landing, then she must had pre-rotated about a half turn. get it?

I'm not sure if that 3A should've been downgraded though. that one looks on the borderline. so it's up to individual techies to decide?

Hm.. I thought the turn is to be counted using the direction of the skater? In this case I thought it's 45 degree to the left, by the original incoming direction and counted that way.

Yeah, on 2nd viewing, that seems to be borderline.

 

[silverlake22]

Hm.. I thought the turn is to be counted using the direction of the skater? In this case I thought it's 45 degree to the left, by the original incoming direction and counted that way.

Yeah, on 2nd viewing, that seems to be borderline.

I can see it now, but this does not bode well for Mao. If a borderline rotated 3a got a UR call at JAPANESE NATS it means that her 3a's will have to be nearly perfect at the Olympics to get credit, which is going to be tough. I just hope she does a good short there, Mao always seems to be able to pull out a decent to great LP but often makes mistakes in the SP. If she makes mistakes in the SP, Yuna if she performs as usual could have over a 15 point lead which would allow her to do less in the LP and still win. Mao on the other hand would really need both 3a's in the LP if she has to make up for mistakes in the SP.

 

[Phoenix347]

I think it would have been better with higher qaulity video.

Try this one. Not sure this link will work.. let me try this anyway.

3A

From watching the shockwave video:

1) It looks like she's definitely jumping more than 10 inches off the ground.

2) To me the landing looks less than 1/4 turn cheated.

3) 3A looks okay to me.

 

[miki88]

I can see it now, but this does not bode well for Mao. If a borderline rotated 3a got a UR call at JAPANESE NATS it means that her 3a's will have to be nearly perfect at the Olympics to get credit, which is going to be tough. I just hope she does a good short there, Mao always seems to be able to pull out a decent to great LP but often makes mistakes in the SP. If she makes mistakes in the SP, Yuna if she performs as usual could have over a 15 point lead which would allow her to do less in the LP and still win. Mao on the other hand would really need both 3a's in the LP if she has to make up for mistakes in the SP.

True. If only she substituted another type of jump for the 3A in the short. I think attempting 2 3As in the LP is enough.

 

[sleepymom]

I can see it now, but this does not bode well for Mao. If a borderline rotated 3a got a UR call at JAPANESE NATS it means that her 3a's will have to be nearly perfect at the Olympics to get credit, which is going to be tough. I just hope she does a good short there, Mao always seems to be able to pull out a decent to great LP but often makes mistakes in the SP. If she makes mistakes in the SP, Yuna if she performs as usual could have over a 15 point lead which would allow her to do less in the LP and still win. Mao on the other hand would really need both 3a's in the LP if she has to make up for mistakes in the SP.

From the costume, I think this is LP. If I remember correctly, LP 3A was ratified - all her triples in LP was ratified, it's 2toe and 2loop that was the issue.

 

[Basics]

From the costume, I think this is LP. If I remember correctly, LP 3A was ratified - all her triples in LP was ratified, it's 2toe and 2loop that was the issue.

you are right. The one in SP was downgraded. I don't understand why they marked it though because it looked just like the one in LP.

Looking at her LP protocal, it's really interesting how almost every single one of her double jumps were marked while all other her triples were ratified.

 

[silverlake22]

True. If only she substituted another type of jump for the 3A in the short. I think attempting 2 3As in the LP is enough.

Yeah I agree, her LP is already risky and technically difficult enough as is. Because Mao doesn't have a 3lutz though it would mean she would have to switch to a 3lo in the SP. A 3lo-2t, 3f, and 2a is not a super technically difficult program so she might be better off with the 3a, if she can land it.

 

[steyn]

Seems like a good summary of things.

The point about CM is well taken, however, if the body only rotates around the center of mass it will not affect it's motion in the air. Things like tucking the legs or bending the body slightly will. But most of the mass of the skater is in the torso, so motions of the arms and legs will have only a small impact on the location of the CM.

Still, this is a limitation, that the time measured from the moment the skater leaves the ice to the moment of the landing is not exactly the time the CM is on it's ballistic trajectory. This time that determines how fast the skater has to rotate to get around, but there may be a small error introduced in determining the height of the jump from just that time, or not. But I think this is at worst case a small error (one could adjust for in a careful analysis), and it does not prevent a meaningful comparison of different skaters and jumps if the time is measured in a consistent way.

I know your point. What I meant was that the height people usually see on the video might not be the real height of the center of gravity. For example tilting the body by, say, 15 degree would result in the error about 1-cos(pi/12) ~ (1/16)/2 ~ 1/30 which is about 1 inch. More significant error will come from the angle that the skate makes with the leg on the air after jumping. I guess this will make about 3-4 inches. This kind of small errors can eventually be added to about 5 inches higher height.

A bigger uncertainty is that if the video has a 15 frame per second rate (as some posted videos do), then there could be up to a 67 msec error in the measurement of the time the feet are off the ice.

That's right. So experts use cameras with higher frame rate as you wrote somewhere.

I understand the point of the article (low and fast vs high and slower) but I don't believe there are TWO types of jupmers. I believe there is a continuim from low and fast to high and slower. I believe Mao is above the middle range. Low being say 5 inches and high being 36 inches. She definaltly does her 3A in a range from 18 - 26 inches. I have seen her do them several dozen times ten feet in fromt of me. If you by the practice pass for events you can stand by the boards and watch her (and others) jump. It is actually better than attending the competition.

When it is said there are two types of jumpers, it means that the distribution has two local maxima, not like the normal distribution with one maximum. Of course there will be a continuum connecting the two maxima. What the japanese professor said is that Mao belongs to the second maximum not to the middle. Whether you believe it or not, this is the research result of scientific measurement with high-tech facilities by a world-class expert in this field.

 

[gsrossano]

When it is said there are two types of jumpers, it means that the distribution has two local maxima, not like the normal distribution with one maximum. Of course there will be a continuum connecting the two maxima. What the japanese professor said is that Mao belongs to the second maximum not to the middle. Whether you believe it or not, this is the research result of scientific measurement with high-tech facilities by a world-class expert in this field.

Maybe. The popularized article of his work seems to imply it is a bimodal distribution, but then the few examples given don't illustrate the point. The skaters discussed there and in this thread all seem to rotate at more or less the same rate 4.5 - 5 rps. Most of the non-elite skaters I measure rotate at 4-5 rps and are 0.5-0.6 seconds in the air. A bimodal distribution is not obvious to me, but I admit I haven't dug that deep into it, that I might not have overlooked it.

But until I see/have some data that shows a bimodal distribution, in my mind it is an open question I would like to know more about. To prove it is a bimodal distribution one would have to show histograms of jump heights and rotation speeds for many skaters doing the same jumps that show two statistically significant bumps. At least that is how I would approach it for starters.

The problem with this area of research is that very little sees the light of day for the general public and reaches the skaters and coaches in a form that is of practical use to them. And what does come out in generalized articles is so incomplete, simplified, or garbbled one has to wonder what the original researcher really has for data or thinks.

 

[SkatingAnalyst]

Facts

It is a fact...
If you skid between 1/4 -1/2 turn, it is impossible not to pre-rotate your body.
Try yourself with bare feet...

and...

There is NO Rules stating up to 3/8-skid is acceptable to judges & specialists.
Also...There is NO Rules only 1/2 turn cheat is un-acceptable.
It just uses the word "CLEAR"... rather ambiguosly.
Remember... Axel is a forward take-off jump. Anything more than 1/4 turn is
backward.

Also, we must realize 3A is supposed to be 3 1/2-turn jump.
When you consider a TRUE 3Lutz has 2 3/4 - 3 revolutions...
Acceptable 3Axels should have at least 3 full revolutions considering 1/4 turn-
skid necessary for turning-momentum.

Why judges have to reward HUGE 8 POINTS for a cheated 3Axel that has
same 3 or less revolutions as 3Lutz which is worth only...paltry 6 points.

 

[Basics]

It is a fact...
If you skid between 1/4 -1/2 turn, it is impossible not to pre-rotate your body.
Try yourself with bare feet...

and...

There is NO Rules stating up to 3/8-skid is acceptable to judges & specialists.
Also...There is NO Rules only 1/2 turn cheat is un-acceptable.
It just uses the word "CLEAR"... rather ambiguosly.
Remember... Axel is a forward take-off jump. Anything more than 1/4 turn is
backward.

Also, we must realize 3A is supposed to be 3 1/2-turn jump.
When you consider a TRUE 3Lutz has 2 3/4 - 3 revolutions...
Acceptable 3Axels should have at least 3 full revolutions considering 1/4 turn-
skid necessary for turning-momentum.

Why judges have to reward HUGE 8 POINTS for a cheated 3Axel that has
same 3 or less revolutions as 3Lutz which is worth only...paltry 6 points.

well said.

 

[gsrossano]

It is a fact...
If you skid between 1/4 -1/2 turn, it is impossible not to pre-rotate your body.
Try yourself with bare feet...

Bare feet is not the best example, since the friction of your foot on the floor is not the same as the motion of the blade on the ice. But I agree that once a skid is more than 1/4 turn the upper body will begin to follow the foot around to some extent (maybe even a lot sometimes). And the bigger the rotation in the skid, the more the upper body will follow.

There is NO Rules stating up to 3/8-skid is acceptable to judges & specialists.
Also...There is NO Rules only 1/2 turn cheat is un-acceptable.
It just uses the word "CLEAR"... rather ambiguosly.
Remember... Axel is a forward take-off jump. Anything more than 1/4 turn is
backward.

U.S. judges tend to be picky about the skid and the cheat, and reduce jumps with those. Even if a jump is not downgraded, I think most U.S. judges would give a reduction for a cheat less than 1/4. (Though if somethng else is a positive aspect, the GoE might not necessarily be negative.) For judges elsewhere, I can't say. My observations is specialists tend to be more willing to cal the pre-rotation on toe loop (aka the toe-axel) than on an Axel.