From: mmwang@adobe.com (Michael Wang)
Newsgroups: rec.skate
Subject: Re: questions on skating technique
Keywords: skating, stroking, technique
Date: 8 Oct 92 20:16:14 GMT
Organization: Adobe Systems Incorporated

In article <ld7b88INNldv@news.bbn.com> ado@bbn.com (Buz Owen) writes:
>I have a couple of questions on technique: clearly they apply to more
>than just speedskating, but I expect that it is in speedskating, ice
>or other, that these things are given the most attention...
>
>I have often read on this list, and elsewhere, the following two bits
>of advice:
>
>   a) when stroking, push directly to the side, not back and to the
>      side, and
>
>   b) place your foot directly under you, or even a little beyond
>      that, when starting a new stroke.
>
>I try to do these things (blading), sometimes manage to, and can see
>that they do produce a reasonable stroke, but would anybody care to
>offer explanations as to why they are good technique?
>
>On point a, I don't see that there would be any loss of efficiency if
>the push was angled somethat back.  The sideways component of your
>push works against the angle of the blade to produce a forward force,
>and the backward component of your push should produce forward force
>directly.  I have also noticed that it is possible to skate with your
>stroke going somewhat forward of your body -- sometimes you will see
>people do it when skating casually, for example.
>
>On point b, if you place your foot across the center line of your
>body, don't you immediately start to fall a bit to the (wrong) side,
>and then just have to do something to stop it?  Why would this be a
>good idea?

Good questions. I'm not sure I understand all this fully myself, but
here is how I would answer them.


Question A

It is true that you aren't actually pushing off directly perpendicular
to your support leg, but why not push off more towards the back?
Shouldn't that give a larger force component in the direction of
travel? Well, yes and no. 

Picture yourself in a T-stop position. For me that would be right leg
forward and left leg in back with my left foot pointing almost
perpendicular to my right foot. If I push off with my left leg, more
or less straight back, I can propel myself forward. And I can continue
to do this for a while (balance on right leg, push off towards back
with left leg). The problem is, once I start picking up speed, I have
to keep thrusting my leg back faster and faster to keep accelerating.
Eventually I'll reach a speed where pushing back will no longer
accelerate me because I can't thrust me leg fast enough. Anybody who
has ridden a skateboard will recognize this phenomenon.

So not only does pushing back form a barrier in terms of how fast you
can get going, it also tends to be a very anaerboic activity and you
can tell because your pushing leg will get tired very quickly. Also
note that the speed at which I thrust my leg back is independent from
the amount of strength I put into each stroke. If my thrusting speed
can keep up with my forward motion, then the more strength I put into
the stroke the faster I will accelerate. If I can't thrust fast
enough, then I doesn't matter have much strength I put into the
stroke, I'm not going to accelerate.

Now think about what happens if you push off more towards the side.
I'm not sure how to draw the force diagram, but if you picture
yourself doing this, you will realize your "thrust" speed can be
slower for a given amount of forward speed than when you where pushing
straight back. However, because of the angle, the strength of the
stroke will need to be greater compared to pushing straight back if
you want to achieve the same amount of acceleration. But that is okay
since it is easier on the legs to be pushing off at a slower speed but
putting more strength into each stroke. So you can actually go faster
for longer periods by doing this.

So extending this idea further, pushing off even closer to the
perpendicular allows you to have a long, slow, but very powerful
stride, which is actually more efficient compared to pushing off
straight back where you would have a short, fast, and relatively weak
stride.


Question B

Where you place your foot on recovery has mostly to do with stride
length. The farther in you can place your foot, the longer the stride
with your other leg. You are right in noticing that by placing your
foot on the centerline you have a tendancy to fall to the side. I.e.
If your right leg is support leg, and you bring your left leg back and
place your left foot on centerline, you may feel unstable and want to
fall to the left. But that is good because you can let gravity give
you a little extra "push" even before you start to push off with your
other leg. To picture this, imagine yourself standing on some ice with
just your socks (very thick ones!) on. Lift up your left leg and hold
it next to your right foot. Now tilt over to your left and a little
bit forward. As you tip over, at some point your instinct will be to
plant your left foot down to support yourself. When you do so, you
will actually slide a bit to the side and a bit forward because
gravity is helping accelerate you in that direction.

So as Phil has mentioned here before, all the really good skaters will
"fall" from side to side when speed skating to give them an extra bit
of acceleration. Since you don't need to expend any effort on your
part to fall like that (once you have mastered the technique), you are
in effect gaining this extra boost for "free".


-- 
Michael Wang
mmwang@mv.us.adobe.com