Saturday, April 20, 2013

Forward Eights

I started out skating wanting to do figures. For those of you who are too young to know what 'figures' was, it was a form of structured skating often known as 'compulsory figures.' These were skated in competition until 1990. In the last couple of years the basic figures, the forward 8s and the backwards 8s have been introduced into Moves. So while these may seem 'antique', there's still a reason to learn them. Recently, I began to do the forward eights successfully, consistently.

Here's what a basic figure 8 looks like.

Text for this diagram
Some people are able to do these right away, and others have to work on them. I was the 'work on them' type. Up until recently, even though I have a good push (the "strike") and nice upper body position,  I couldn't complete the figure without giving myself a toepick boost to make it past the last couple of feet. Now I can. Here's how.

So you start a figure 8 in the center where the two circles intersect. On the diagram above, this is position 6. The figure above is pushing with the left foot onto the right outside edge (position 1). This part is easy, just remember to face out of the circle and keep you trailing shoulder pushed back to keep your back against the circle (arcane skating talk there).  Your free foot should be tucked to the heel of the skating foot.

As you approach the halfway point of the circle you must bend deeper in the knee and bring the free food smoothly in the front of the skating foot. This will give impetus to your power.

Use the free foot in front to guide you to the center of the figure,  when you are at the 3/4 point of the figure switch your arms.

As you get to the center of the figure you will step down onto the free foot, and do the other circle with the new skating foot.

I am now going to talk physics (mechanics) which I haven't thought about for 30 years. So I could be wrong.

The curvature of the blade and the  twist in our body, makes us skate on a curve. As we skate on a curve vector forces come into play. I will now simplify them down to two.

First the radial vector that points to the center of the circle.

Second, the downward vector that is a combination of gravity and our acceleration over the ice.

If you take the cross product of these two vectors, you will get the vector for your forward motion (right hand rule).

When you bend deeper in the knee at the halfway point, two things happen. First when you drop deeper in the knee, you briefly change the load into the ice, altering the vector due to your acceleration, and  you shift back on the rocker, which also affects the acceleration by changing the load. This is very brief so you generate a pulse into the system, which kicks up your power. Finally, bringing the free foot forward also subtly affects the load as well.

Properly done, this is all smooth, and doesn't look like anything much is happening, but it's a 'stroke less stroke'. You get a tiny push of power, just enough to move you across the ice without putting your free foot down.

And now I can do 8's successfully, because I have new knees and can get that kneebend at the halfway point!

Yeah, angular momentum is in there someplace,
I'm just not touching anything with a theta angle in it.
That's real physics.


  1. Thanks for this wonderful post - the detail is terrific and inspiring. I will do this in my head because that's all I can do at the moment - had knee surgery for a torn meniscus (actually 2 tears on the right knee) this past Thursday. But I will work on this in 5 1/2 weeks (started the countdown already) when I can get back on the ice.

    Your posts are always enjoyable - this one is educational too!

  2. I love figures! I am glad there are still pople in ice who want to do them. If you think the eights are fun wait till you get to enjoy the wonders of paragraphs.