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

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

wrote:
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

I think "it seems to not really make a difference" implies that they
actually ski poorly and that doesn't make a difference. I think that
what people claim to be " poor technique" on the part of world class
skiers are actually very minor faults. I think they all have what
would be considered very good or excellent technique by any reasonable
standard - understanding that standards are variable and are somewhat
opinions on what's best, not tested and true by scientific methods.

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.

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

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

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

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

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

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)

wrote
I do that to cyclists, too, they get really nervious.

It was funny, he had to know I was there -- hearing the sound of my
breathing and my wheels hitting the pavement -- but he never looked back at
me once. But then when I closed in on him coming to the sign at the top, he
speeded up just enough to hold me off.

Skating is still not the most efficient way of power transfer,
since there is a sinus of an angle involved.

Actually I think the power transfer of the skating leg-push is much more
"efficient" than that, for two reasons:

(a) The ratio of propulsive Power transfer is different from the ratio of
propulsive Force transfer.

If it is true that the skating ski perfectly waxed with zero sliding
resistance only will directly transmit only a percentage of the leg-push
Force into pushing backward against the ground -- and that's the portion
that immediately supplies the force which keeps the skier moving forward
against air resistance and gravity. The proportion of the backward-push
component is the sine of the ski's "aiming" angle (how far the ski's gliding
direction deviates from the overall average direction of the forward motion
of the skier's mass). There's also a portion of leg-push Force which goes
into a sideways-push component (which does not directly help the skier's
forward motion) and that proportion is given by the cosine of the ski's
"aiming" angle.

Power is split into backward and sidways components with different
proportions than Force. That's because Power = Force * Velocity, and the
forward component of the velocity of the ski is different from the sideways
component of velocity. When the skier is moving fast on gentle terrain, the
ski's "aiming" angle is small, and the forward component is much larger than
the sideways component of Velocity. So even though the backward component of
Force is much smaller than the sideways component, the backward component of
Power is larger than the sideways component of Power, and a much larger
percentage of leg-push power than the sine of the ski's aiming angle.

(b) Delayed power transfer. The power component in the sideways direction is
not lost. By pushing sideways outward against the ground, it first slows the
sideways motion of the skier's body mass to a stop, then sends it back
toward the other side, where it's kinetic energy is available to add force
and power to the next leg-push push on the other ski. Of course there's
some inefficiency in this, but "reflecting" the power to the other side does
"recover" some of the sideways power convert it it into forward-propulsion
power.

Which probably explains that skating does
not beat classic up really steep hills (assuming perfect grip)

But it's astonishing how really steep the hill has to be before elite
Classic technique is faster than elite Skating technique.

Actually I think the reason is not power transfer efficiency. Because in the
limit of hill-steepness and slow speed, skating approaches classic
herringbone. So then we get to the question of why Classic striding with
feet aimed straight up the hill (assuming perfect grip) is faster than
Classic herringbone with feet angled out to the side. My answer: (a) more
muscle mass engaged; (b) muscles better positioned to leverage their
bone-attachment and joint-routing geometry.

"Efficiency" is typically not a very important explanatory factor for why
one human propulsion technique is faster than another. That's what I've
found in my analysis. Typically some other differentiating factor turns out
to be much bigger than "efficiency".

Ken