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video analysis of my ski technique -- less expensive



 
 
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  #1  
Old November 3rd 03, 11:45 AM
Ken Roberts
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Default video analysis of my ski technique -- less expensive

I've just started capturing my own amateur ski technique on digital video --
but without buying a digital video camera.

Turns out that lots of not-terribly-expensive digital _photo_ cameras will
capture a 15-second movie clip. I think that's plenty for analyzing my
progress in learning ski technique -- if it's the right 15 seconds.

Over the weekend Sharon shot 24 different clips of me trying ski on dryland,
both side and front views. I've put some of those clips up on the web at
http://roberts-1.com/t/xc034/dry/p1

My photo camera uses Apple Quicktime movie format, so I had to first
download the Quicktime Player (see that page for a link to it)

Now I;ve found out that I like the Quicktime player for analysis, because it
gives me easy control of frame-by-frame advance (and reverse), so I can
check body position and timing synchronization at various points in the
stroke cycle.

I'm just getting started on digital video, so I'd be glad for suggestions
about using it with skiing.

Ken


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  #2  
Old November 3rd 03, 02:17 PM
Joe K.
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Default video analysis of my ski technique -- less expensive

Ken,

You've done a great job as usual! IMO the video quality and duration seem
just right for evaluating technique. Nice choice of skis as well!

Concerning your V2 I noticed a similar lack of follow through with your
poles that I and the people I ski with have when on pavement, with the
exception of Vince of course. I'm aware of it and have tried to make
corrections but to no avail. For some reason it disappears when on snow.
Just can't figure it!


--
Thanks,
___o
_\ _
(*)`(*)


Joe Korzenecki



"Ken Roberts" wrote in message
...
I've just started capturing my own amateur ski technique on digital

video --
but without buying a digital video camera.

Turns out that lots of not-terribly-expensive digital _photo_ cameras will
capture a 15-second movie clip. I think that's plenty for analyzing my
progress in learning ski technique -- if it's the right 15 seconds.

Over the weekend Sharon shot 24 different clips of me trying ski on

dryland,
both side and front views. I've put some of those clips up on the web at
http://roberts-1.com/t/xc034/dry/p1

My photo camera uses Apple Quicktime movie format, so I had to first
download the Quicktime Player (see that page for a link to it)

Now I;ve found out that I like the Quicktime player for analysis, because

it
gives me easy control of frame-by-frame advance (and reverse), so I can
check body position and timing synchronization at various points in the
stroke cycle.

I'm just getting started on digital video, so I'd be glad for suggestions
about using it with skiing.

Ken




  #3  
Old November 3rd 03, 08:14 PM
Terje Henriksen
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Default video analysis of my ski technique -- less expensive


"Joe K." skrev i melding
...
Ken,

You've done a great job as usual! IMO the video quality and duration seem
just right for evaluating technique. Nice choice of skis as well!

Concerning your V2 I noticed a similar lack of follow through with your
poles that I and the people I ski with have when on pavement, with the
exception of Vince of course. I'm aware of it and have tried to make
corrections but to no avail. For some reason it disappears when on snow.
Just can't figure it!


It seems to me that he needs to put down the ski before he starts pushing, a
common failure.

When I am skating, I think of an imaginary line along the road, beneath my
body, and I always try to place my feet on that line before I start pushing
or kicking. When I succed in doing this, skating is swinging like dixieland
music.


--
Terje Henriksen
Kirkenes


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  #4  
Old November 3rd 03, 11:49 PM
Ken Roberts
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Default video analysis of my ski technique -- less expensive

Joe -

Lack of follow-thru with poles:
I've nearly given up on that too. My interpretation is that on most
pavement the pole tips just don't grip reliably beyond a certain angle to
the rear -- no matter how much I sharpen the tips. I even try to get around
this by applying additional down-pressure on the pole tip by pressing with
the heel of my hand.

But there's long-running (at least back to Endestad and Teaford 1987) school
of thought that "full" follow-thru in poling is not a good idea anyway for
skating. My interpretation of that is in the far rear-ward angle, the pole
is in a "low gear" configuration -- so it doesn't deliver power effectively
at high skating speeds. Better to focus my effort on the "high gear"
configuration when the pole is at a forward angle near my boot -- the big
initial crunch.

Jenex 6400 rollerskis:
I'm liking them a lot for these reasons:
-- two wheels at each end makes it much more stable for rolling over a rut
(because as JanneG pointed out, one wheel cannot drop into the rut if its
partner wheel right next to it is still rolling on the main pavement
surface.)

-- I like the hard narrow wheels for training muscle speed, turnover
frequency, and correct neuro-muscular rate.

-- I like having the speed reducer as an option for training strength and
peak force, and for feeling more comfortable on some downhills.

-- I can also change the resistance range _without_ the speed reducer -- by
swapping in different kinds of 80 mm wheels that I can get from an inline
skate shop. Like harder faster wheels for super-speed training. Or the K2
Continental rubber wheels for wet days or strength-force workouts. (Now if
only Jenex would space the twinned axles just 20 mm further apart, we could
swap in 84 mm or 100 mm inline wheels, for an even smoother ride).

I tried the Marwe 610 recently and liked that too -- especially for its
larger wheels (around 100 mm) -- had a long and glorious October morning on
them at River Rd including the section north of 116. Ed warned me that the
bigger wheels might have a learning curve. Yeah, for me about two minutes
(Despite the bigger wheels, I bet the actual height of the sole of my foot
is still lower to the ground than on inline skates)

But while the Marwe 610 offered a nice snow _imitation_ feel, I want my
dryland training to be more than just imitation. I also want
_exaggeration_ -- to expose my muscles to training stresses and situations
that are more effective for producing some adaptation responses, than mere
imitation. And for experimenting with new techniques, feeling safe is
important for me -- nice to know that speed reducer lever is right down
there.

Ken


  #5  
Old November 5th 03, 12:05 PM
Ken Roberts
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Default video analysis of my ski technique -- less expensive

Terje Henriksen wrote
When I am skating, I think of an imaginary line
along the road, beneath my body, and I always
try to place my feet on that line before I start pushing.


Thanks for that observation, Terje. Now when I go back and look at my V1
video more closely, I see that I'm starting my leg-push with the ski already
outside the range of my shoulders.

When I compare with the World Cup videos, I see them starting with the ski
within the range of their shoulders. So maybe I've been leaving out the
first part of the push.

An interesting question is the right way to fix this: Land the ski down
more under my shoulder -- or move my shoulder more over the ski?

Ken

P.S. It's odd to see myself with this problem, because on inline skates I
love setting my skate down on the _other_ side underneath my body -- across
the center-line -- and starting the push from my outside edge. Or even more
radical crossing of the center-line, with double-push. Skating like that on
inlines is beyond dixieland music.


  #6  
Old November 5th 03, 01:25 PM
Rob Bradlee
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Default video analysis of my ski technique -- less expensive


An interesting question is the right way to fix this: Land the ski
down
more under my shoulder -- or move my shoulder more over the ski?


I vote for moving the upper body with the foot under it.



=====
Rob Bradlee
Java, C++, Perl, XML, OOAD, Linux, and Unix Training




  #7  
Old November 5th 03, 01:38 PM
Terje Henriksen
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Default video analysis of my ski technique -- less expensive


"Ken Roberts" skrev i melding
...
Terje Henriksen wrote
When I am skating, I think of an imaginary line
along the road, beneath my body, and I always
try to place my feet on that line before I start pushing.


Thanks for that observation, Terje. Now when I go back and look at my V1
video more closely, I see that I'm starting my leg-push with the ski

already
outside the range of my shoulders.

When I compare with the World Cup videos, I see them starting with the ski
within the range of their shoulders. So maybe I've been leaving out the
first part of the push.


Yes, you are missing an important part of the push. According to
speed-skating trainers, the most important and effective part of the push is
when you shift the weight from the outside of the ski to the inside.
Speed-skaters are the best skaters, so I believe one can learn most of them.
They have hundred years of experience.

An interesting question is the right way to fix this: Land the ski down
more under my shoulder -- or move my shoulder more over the ski?


Land the ski under the center of your body; that's my suggestion; you're
body should not move. If you do it right, it is like dancing.

Ken

P.S. It's odd to see myself with this problem, because on inline skates I
love setting my skate down on the _other_ side underneath my body --

across
the center-line -- and starting the push from my outside edge. Or even

more
radical crossing of the center-line, with double-push. Skating like that

on
inlines is beyond dixieland music.


Try skiing the same way. I think the most important thing in skating is
where you put down your ski.


--
Terje Henriksen
Kirkenes


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  #8  
Old November 5th 03, 04:41 PM
Marsh Jones
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Default video analysis of my ski technique -- less expensive

Terje Henriksen wrote:
"Ken Roberts" skrev i melding


Try skiing the same way. I think the most important thing in skating is
where you put down your ski.


'Dorothys' (Wizard of Oz - click your heels 3 times and ...)

This is a drill I use teaching kids to skate - to bring their heels all
the way in and touch boots before they set the new ski down. Without
telling them what we are accomplishing, they learn to set a flat ski (or
slightly outside edged if lucky).
I've noticed that if I'm tired and sloppy, I can really tell it in my
V2-I tend to overcommit and wind up hanging on the outside edge. Either
a hop or extra pole will bring me back, but it costs a lot more in terms
of extra effort.

Marsh

  #9  
Old November 5th 03, 06:05 PM
Ken Roberts
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Default shoulder swing in skating (was video analysis of my ski technique)

Terje Henriksen wrote
Land the ski under the center of your body;
that's my suggestion; your body should not move.


My observation from videos of inline speedskaters is that they _do_ move
their upper body. The big swing of the shoulders is obvious in any of the
inline videos listed on
http://roberts-1.com/xcski/skate/resources/video

I'm also looking at a Rollerski race video clip listed on that page -- which
clearly shows the race leader swinging his shoulders from side-to-side.
Outrageously enormously swinging -- to move his upper body over the
rollerski he is pushing on. The guys behind him are swinging their
shoulders too. Thanks to JanneG for making it available.

What about snow skiing? I'm seeing a side-to-side _shoulder_ move in those
videos too.

Especially in the middle V1 section of Thomas Aalsgard:
http://avari182.mt.luth.se/Technic/Alsgard1.mpg
Looks to me like his shoulders move side-to-side about twice as far as his
hips. Aalsgard is not just landing his ski further under his hips. He's
also shifting his shoulders out sideways further over the pushing ski.
(Vordenberg may allow for a "little loop" of the head in his "new skate"
debate with Borowski, but looks to me like Aalsgard has been winning for
years with a _big_ loop head motion).

I was surprised by the video of Carl Swenson.
http://avari182.mt.luth.se/Technic/swenson1.mpg
I figured with the American "new skate" coaching, he would have eliminated
the "extra" sideways motion of the shoulders. But then in the middle
section of his video I saw the same thing: Swenson's shoulders move
side-to-side about twice as far as his hips.

So now I've started adding the shoulder swing to my V1 skate (offset,
paddle-dance). So far it feels strong, it gets me started pushing from more
underneath, then adds to the force of the whole push.

And it's fun -- the next phase of my ski dance.

Ken


  #10  
Old November 6th 03, 12:46 AM
Serge
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Default shoulder swing in skating (was video analysis of my ski technique)

Thanks for videos.

The leading guy on rollerski video is doing Double Push on skis.
It is slight, not as pronounced as on skates, but it is DP!

Rollerskiing is clearly becoming independent sport with the
technique advancement not applicable to snow.
 




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