Running article with lots of applicability to x-c skiing

http://www.mastersathletics.info/ind...ing&Itemid=129

The first thing that came to mind while reading it was how we were
taught about "kicking back" years ago (some still teach it), but the
article goes well beyond that to the physics and biomechanics of how we
move and where speed comes from - and the illusion of video.

Gene

wrote:
http://www.mastersathletics.info/ind...ing&Itemid=129

The first thing that came to mind while reading it was how we were
taught about "kicking back" years ago (some still teach it), but the
article goes well beyond that to the physics and biomechanics of how we
move and where speed comes from - and the illusion of video.

Very interesting, but wrong in at least one aspect:

They imply very strongly that a body moving (parallel to the ground!) at
higher speed will strike the ground with more force than a slower one.

Other than that, the main thing I got out of it was the reference to the
paper which predicted running times over a large distance range, based
on just two measurements, and that this should be used to dictate how
many sprint repetitions to perform while training.

Terje

--
- Terje.Mathisen at tmsw.no
"almost all programming can be viewed as an exercise in caching"

On Fri, 11 Feb 2011 07:40:47 +0100
Terje Mathisen "terje.mathisen at tmsw.no" wrote:

wrote:
http://www.mastersathletics.info/ind...ing&Itemid=129

Very interesting, but wrong in at least one aspect:

They imply very strongly that a body moving (parallel to the ground!)
at higher speed will strike the ground with more force than a slower
one.

Physics is not my field. As I read the article - and I've copied two
relevant passages below - it would seem its key claim is that greater
speed largely comes from greater isometric force support against the
ground, leading to more stored elastic energy released with each push
off. It looks to me like the word "support" is key to the point. That
is, is the writer actually saying that faster runners strike with more
force, or that the same force against the ground has different results
depending on the runner's plyometric strength (and conditioning)? It's
not real clearly written in that regard.


"Faster runners have “quick feet� because they create more elastic
energy and have greater mass-specific force support against the ground.
Mass-specific force is the amount of isometric force applied to the
ground to offset the effects of gravity. Greater amounts of
mass-specific force = shorter ground contact time = faster running."

"The speed of the athlete is dictated to a large extent by the amount
of stored elastic energy that is released."

Gene