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#11
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looking for better technique isn't worth it
Ken Roberts wrote: Zeke wrote You seem to be assuming that the only purpose for nordic skiing is going fast. This just isn't true. You're right to call me on that -- thanks Zeke. I should have been more clear at the start that I was talking about the goal of speed. I basically agree with you, but when you start saying stuff like this . . . ... racing is just one minor aspect. Whoa!?! Watch out for lightning bolts from above. do it as gracefully and with as good technique as possible. An unexamined assumption is that the technique which is best for speed is also going to look and/or feel graceful. Ken As you say, skiing is a very complicated set of variables, so analysis is quite difficult. But your observations about what looks good and/or feels graceful reminds me of when I try to keep up with some of the old timers at the speed-skating track. Guys 70+ years old that wouldn't stand a chance against me on a bike or skis, or any other sport you could think of. But put them on speed-skates with 60 years of practice and near-perfect technique, and I'm left huffing and puffing. With skiing, I'd say that the weaker your are, the more technique can help your absolute performance. As you get stonger (higher sustainable power) inefficiencies in technique become less apparent, til you get to the elite level where it seems to not really make a difference. My $.02. Joseph |
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#12
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looking for better technique isn't worth it
Bob wrote
Ken Roberts wrote: An unexamined assumption is that the technique which is best for speed is also going to look and/or feel graceful. For me, this is not unexamined ... at a clinic ... clearly demonstrated techniques that really looked good, but were all wrong. All wrong for the goal of speed. All right for the important goal of "looking good" -- or the even more important goal of "not looking stupid". My analysis of the physics is there's not much in the formulas for power and speed in cross-country skiing which favors "grace" or smoothness -- except that (especially in skating) smashing the ski down into the snow produces more resistance to sliding, so there's some benefit to setting the ski down smoothly. And there are some aspects of the physics of power which favor explosiveness over smoothness in some other aspects of XC ski motions, especially Classic. It is easy to wring the life out of a sport with training, racing and constantly analyzing (and second guessing) every aspect of it I find that my training program always falls apart once I get on snow. The wonderful environment and playing with the feel of the ski going thru snow, the challenge of being back on my favorite hills -- seem to shut off my mind from remembering about disciplined training. Analyzing doesn't seem to get in my way of enjoying the environment and the feel. Completely different part of my brain than enjoying the snow, so the two can co-exist without interfering too much with each other -- I can switch focus back and forth between them. Skiing with other people is a much bigger disruption of other aspects of skiing -- a disruption that I usually enjoy. Ken |
#13
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looking for better technique isn't worth it
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#14
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looking for better technique isn't worth it
john / jgs wrote
As for speed and technique - I think proper skiing is removing everything that is wrong. That strategy is either helpful or unhelpful for speed -- or some mix of those. Even if one person finds that strategy convincing, how would the rest of be able to decide if or which parts of it are helpful? My survey of the last 20 years of scientific study of seated bicycle pedaling led me to these conclusions: * All simple rational rules about pedaling technique are wrong. * Pedaling a bicycle already requires such complicated muscular coordination that the safest technique strategy for most of us is: Get your bicycle fitted properly -- then leave managing the coordination to the special-purpose neuro-muscular control supercomputer in your unconscious brain. Unless you have an expert coach, most attempts to apply conscious rational understanding to modify pedaling technique are more likely to reduce long-term power than to increase it. If the first conclusion if true for seated pedaling, how much more so for coordination way more complicated moves like XC skiing with poles. Ken |
#15
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looking for better technique isn't worth it
Camilo wrote:
Maybe not perfect by (insert your favorite standard here), maybe not what a good instrucor would be teaching as an ideal to shoot for, but none of them are truely "poor" by any means. The differences between "perfect technique" and the poorest world cup technique is very much on the margins. Just mho, of course. I've seen fast local skiers with what one might consider awful technique. Huge engines with beginner level technique. But that's not the world cup and they couldn't begin to compete with equally fit world cup type skiers who all have the engine and very good technique. I think I agree with you. I've thought of it this way: Imagine that you are looking at a field of top-notch ski racers and you have a perfect scoring system for "technique" and a perfect scoring system for the skier's "engines," with each skier rated from 1 to 10 on each, so the best possible score, perfect technique + best engine in the field, gets 20 points. Then suppose that you are magically given, say, 16 points to use any way you want to create your own personal blend of technique + engine. I would "spend" 10 points on engine and 6 on technique, guessing (I have no way to prove it) that it would give a bigger payoff in speed than any other combination. Which isn't to say that you could get away with lousy technique, but once you get past a certain level of skill, I would guess that the engine is the bigger factor. Johann Muehlegg was only a top 20 skier and admitted his technique wasn't much - then he doped his engine in 2002 and blew everyone off the track. Russ |
#16
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looking for better technique isn't worth it
Russ wrote
Julia Tchepalova and Marit Bjoergen in ... Oberstdorf World Cup Women's Relay you'll see a good example of two different styles that have both produced gold medals, So we've got lots of evidence that there's no single known answer to technique for speed. Or at least that only one or two have found it -- and that's why the others are different. Actually I think there are some important moves and aspects of technique that most of the World Cup winners have in common -- but they're not the obvious things we tend to notice. I would be very interested in someone asking questions about the most efficient, not necessarily the fastest, ways to ski. Some of these other questions might be easier to analyze than the goal of "optimal speed". (see more below on why speed is so tricky) And more likely to be able to reliably find an instructor who could reliably help achieve the goal (though likely only thru multiple stages of development in a sequence of lessons). "Efficient" is a tricky goal for technique, because to be helpful it must be very carefully defined. Which most people using the word people don't do. Need to get clear and explicit about: Efficent use of which limited resource? (oxygen? fuel? lactate threshold? etc?) to achieve specifically what objective (distance? hill-climb? speed? both?) -- you're going to get a different answer about technique depending on what definition you choose. I suspect what lots of people want in ski-skating technique is: How to ski their favorite loop which has two big hills and five little hills -- without needing to stop for rest at the top of some hills, and not feel like they need a half-hour break from skiing after finishing. (Actually I think learning the technique for that is straightforward, but lots of people aren't satisfied with it -- because they have a second goal they didn't mention. Or a third.) _________________________________ Speed is a tricky goal: I'm thinking that finding the optimal technique for power + speed is one of the trickiest biomechanical optimization problems. Because physical power (the kind measured in Watts) is: Power = Force * Distance / Time (where each term must be defined very carefully for each muscle move which is getting utilized and coordinated in the overall motion technique.) Turns out that there's all kinds of trade-offs between each pair of those terms -- e.g. Distance versus Time; or muscle Force versus muscle Speed (where Speed = Distance / Time). And often conflicts between Force for one move versus Force for another (in skiing this arises especially for a muscle adding its own Work versus transmitting the Work from another muscle move, where Work = Force * Distance). So even if it's obvious how some new move adds positive work, it's much harder to demonstrate that the positive outweighs the negative side-effects from trade-offs and conflicts in the Power formula. I can look at a video clip of elite racer Carl Swenson skating up a hill, and explain how every move _should_ add propulsive work (or else recover some parts into position where they next soon will add propulsive work) -- and some of his moves are obscure and clever. What I cannot do is demonstrate that each attempted propulsive move actually adds more work than it costs in side-effects. Ken |
#17
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looking for better technique isn't worth it
Camilo wrote
I think that what people claim to be " poor technique" on the part of world class skiers are actually very minor faults. I agree, and I'd go further to say: Since nobody has anything remotely close to a complete model of what the muscles of any elite racer are actually doing while ski-skating with poles, nobody could have sound argument in physics or biomechanics for supporting most claimed instances of even "very minor" faults in the technique of an elite racer. My experience is that most of the time when somebody claims to have found a flaw in a winning racer's technique, it shows only that somebody doesn't really understand physics -- Not surprising, since the physics of XC skiing is rather complicated. Ken |
#18
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what does work (was looking for better technique isn't worth it)
Finished my warmup, came to the bottom of my regular hill workout road. Guy
on a racing bike starts up climbing it. I click my timer and take off after him. No poles, just my skates. Top of the first steep section and to my surprise I'm not losing ground, like 8 meters behind. Grade eases to 8% for a while, I start gaining a couple of meters, I'm thinking it would fun to try to tap him on the shoulder -- but tell myself to hold back. Into the steep stuff again and I'm gaining a little -- then I sprint for the street sign at the top. He hears me coming and picks it up too and beats me by 2 meters. I didn't get to touch him, but I did take 20 seconds of my previous personal best for the hill. It was great luck with timing, because I almost never see anybody else climbing that hill, whether bike or rollerskis or skates. It was amazing to find a bike rider at my perfect "challenge" pace right there in front of me. cyclo-pacing -- that's my new workout secret. People who say they can't get a good workout on smooth pavement just haven't found the right bike rider to chase. (assuming you have the control and braking ability to handle what might happen at higher speeds). Ken |
#19
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what does work (was looking for better technique isn't worth it)
cyclo-pacing -- that's my new workout secret. People who say they can't get a good workout on smooth pavement just haven't found the right bike rider to chase. (assuming you have the control and braking ability to handle what might happen at higher speeds). Ken I do that to cyclists, too, they get really nervious. the steeper the hill, the less advantage gearing has over direct power transfer (like skiing or walking). One can't ride a bike on a hill steeper tha 45 degrees, but walking up that is just fine. Skating is still not the most efficient way of power transfer, since there is a sinus of an angle involved. Which probably explains that skating does not beat classic up really steep hills (assuming perfect grip) |
#20
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Power transfer efficiency in skating
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