Tuesday, March 06, 2007

It's All About the Sweet Spot (and some symmetry)


My last competition in my pre-Vicious Momma days. I was 27 and got pregnant with my first child about a month later. The top right photo is a "flying camel" in midair. Below that is a split jump, and the other two are just interpretive moves to the music ("I Need A Man" by the Eurythmics, lol). For comparative purposes here is a photo of Dick Button midair in a flying camel. You can see the difference between an Olympic champion and a recreational skater:




I haven't read any of the articles found on Google about this because I just want to say what I'm thinking about it first. And I'm sure some of those other articles are much more technically adept.

Figure skating could be a kind of real life analogy to some of the problems of theoretical physics. What I mean is that advanced skating requires probably as many considerations to successfully execute a trick as it takes calculations to get to a final answer.


(slightly exaggerated "hollow")

The blade is concave along the bottom (the "hollow") such that there are two sharp edges, and the blade is also not flat longways.



It is slightly curved, sometimes referred to as the "blade rocker." When learning to skate you learn the "sweet spots" on the blade that make jumping and spinning easier and more 'efficient'.



If I were a real physicist I might know how to calculate the speed and curvature of the blade and so on to describe the various jumps and to explain why the "sweet spots" make them easier, but this is one situation where being able to make the calculations on paper doesn't necessarily help you execute the tricks on ice. It is a much more intuitive process that allows you to feel the sweet spots.

Back in the "old" days we still did compulsory figures, or "figure eights." These exercises were ultimately intended to teach and train skaters how to 'finesse' their blades and bodies to perform precision turns and tracings on the ice. We learned how to make slight adjustments in our posture, shoulders, hips, arms, legs, heads, feet, and even toes so that the blades moved through turns in the most "perfect" ways. For example, a "3 turn" when done just right should leave a tracing a like this (below), note the gap at the top which shows the shift from one edge to the other while changing direction (forward to backward or backward to forward).

Another example is a "bracket," a more advanced turn which done right looks like this (above), notice the "rabbit ears" which indicate the change from one edge to the other while also changing directions.

And yet two other advanced turns are the "counter" and the "rocker" which are closely related to the three turn and bracket but in instead of changing edges you change "lobes" on the figure eight and direction but stay on the same edge.



In order to perform these turns and to 'retrace' them we had to learn the sweet spot on the blade and learn how to repeat all the factors that created it. Incidentally, figures blades don't have the bottom toe pick like freestyle blades, and that increases the "rocker" length and how much you can manipulate the blade. This took hours of practice, but I always loved doing figures because it appealed to my detail and perfectionist nature.

Also, perfectly executed turns are supposed to be symmetical. In fact, skating is where I first heard the word "symmetry." I won't tell you how many drawings it took to get close enough to symmetrical in the above illustrations, but it was more than I planned on. If it is hard to draw a nice 3 turn on paper, then just imagine how hard it is to do it with your feet and a blade on the ice!

Most of my skating teachers didn't pay any attention to the tracings of jumps and spins, but I was lucky enough that my last teacher used these tracings as a tool to evaluate jumping and spinning technique. All skaters should learn such things! We referred to this as "physics" of skating, but I really don't know if that is an accurate description. However, it most certainly helped my technique to "read" the tracings and therefore see how the errors in them tranlated into errors in my body position, etc. If your tracings are correct then your trick (jump or spin) will most likely succeed and be good.

There are many skaters at the highest competitive levels who could really benefit from this kind of instruction. Maybe these days it is more common than when I was growing up. I don't know. But I sure do see some very sloppy technique on TV that is most likely a symptom of focusing on the wrong body parts, instead of the feet which are the ones closest to the ice. The best skating is in the feet. Chances are if your feet are doing the right thing the rest of your body will follow, though there are some exceptions and you can't exactly separate the feet and the body and how they interact.

Anyway, skating is probably one of the most beautiful, and technically complex, expressions of the laws of physics in motion. I wish I was clever and smart enough to make deeper analogies about it.

15 comments:

Rae Ann said...

Is it just me or are those drawings of the turns not rather suggestive? Wow, I just noticed that.

Bee said...

Hi RaeAnn,

what an interesting post! I didn't know you skate yourself, how amazing. And thanks for the photos :-)

I have a question for the expert: A friend insisted I have to read Michael Ondaatje's 'In the skin of a lion' (apparently you aren't allowed to live in Ontario without knowing it). I'm trying my best. Now this takes place sometime around 1915 in Toronto and on every page there's some mentioning of ice and snow. At one point he writes:

[...] they emerge to skate along the like of river, on homemade skates, the blades made of old knives.

Did people really do that? Make skates out of old knives?

Best,

B.

Bee said...

PS: Maybe some arrows would be helpful on the drawings? It's not so really clear to me how that would look dynamically.

Bee said...

oops, typo: it should have been 'the line of river', sorry.

Rae Ann said...

Hi Bee!

Thanks! But I haven't put foot to ice in 10 years. Ack! I should start going again and take the kids.

Yes, people did actually strap knives, or whatever kinds of metal blades they could use, to make skates. "Real" skating blades were probably prohibitively expensive for most people back then.

And you're right! I should put arrows on the drawings. I'll try to get that done soon.

Bee said...

Ack! I should start going again and take the kids.

And take a DigiCam! I remember my mum went ice skating with my younger brother and me, it was a lot of fun (my brother hated it though).

I haven't been ice skating since, don't know, 1999 or so. But since I moved here I actually thought I should give it a try. I go running on the indoor track, and the track build around an ice-skating arena. Ice skating is just so elegant in the motions.

That is interesting how people made blades, thanks!

nige said...

Hi Rae Ann,

It's very pretty with bare knees and long hair, but it's not too suggestive of anything sinful, don't worry! ;-)

nige said...

Sorry I misread your first comment and thought you were referring to turns in the photos as suggestive. I now see you just mean the drawings. I think they are just suggestive of the blades on ice skates. Don't let your imagination run away too much...

dhammett said...

Nonsense. Let your imagination run. Mine has, and boy was it fun. ;-)

dhammett said...

Seriously, thanks for the post. I didn't know about the concave shape of the blades. I'm no skater, but I've done it recreationally a handful of times. It always seemed the blades on my skates were flat. But, then, I know that rental skates are dull so those of us who don't know what we're doing don't hurt ourselves.

rafa said...

Dear Rae Ann

I do skyiing. I once thought being expert on skyiing would make skating on blades easy. Wrong. I made an absolute fool of myself. I know the laws of physics governing both sports are the same but, believe me, it was a spectacular failure. Maybe Bee can find out if skating requires SUSY o some below the Planck scale requirement that I missed!

:-)

best

Bee said...

Hi rafa,

yes, I am sure skating goes much smoother with a superpartner :-)

B.

Rae Ann said...

Hi Bee, that's really cool about the indoor track around the ice rink. When I was training near Atlanta as a young teen the rink was in the middle of a (largely deserted) mall. You should try skating again!

nige, thanks, but sometimes I just can't keep my mind from wandering so much. lol

dh, thanks, and yeah, rental skates are usually crap. They do keep the blades dull for "safety" but it's not at all helpful for actually skating. One reason I've not gone in so long is because my own skates are too small now. Unfortunately, that was a side-effect of having three babies. The ligaments in a woman's body loosen in pregnancy, and it's common for their feet to "grow" a little. Mine increased a half size which is enough to make the skates too tight. I can't bear the thought of wearing rentals. I guess I could buy some "cheap" skates, but that would be really weird after so many years of having good ones. Excuses, excuses. ;-)

rafa, skiing is fun too. I went many years ago and did okay. Most of your skating troubles can be attributed to the bad rental skates. But yeah, Bee is right that with a partner (super or otherwise) is can be a little easier and definitely more fun. By the way, have you been to your Tennessee Three show? If so I hope you enjoyed it.

rafa said...

Dear Rae Ann

Re: Tennesse Three. Tomorrow night (Tuesday).

Re: Skating

And as you cross the circle line, the ice-wall creaks behind ---
Youre a rabbit on the run.
And the silver splinters fly in the corner of your eye ---
Shining in the setting sun.
Well, do you ever get the feeling that the storys
Too damn real and in the present tense?
Or that everybodys on the stage, and it seems like
Youre the only person sitting in the audience?

Skating away on the thin ice of the new day.

SKATING AWAY (Jethro Tull). I always loved this song. Despite my poor skating (or inadequate super-partners)

;-)

Rae Ann said...

rafa, enjoy the TN Three show! Will you get to enjoy some TN whiskey before, during, and/or after the show too? ;-)

That's a great song! You always introduce me to new things. Thanks for that.