see also: Back Lift move for
extra grip
Some people say that committed body weight is not enough for good grip
friction in Classic striding -- that I need to supplement it with some extra
down-force.
(e.g. "Why do you think they call it kick?" :: "Drive the knee
down" ::
"Drive the heel down and back".)
Yes, applying extra down-force in the kick does give better grip, which
then lets
me kick with greater forward-force.
But there is a "side effect" to using extra down-force:
The center-of-mass of my body starts moving up.
And this has some interesting further impacts.
I think the sequence goes like this:
1a - Applying extra down-force during the kick to increases grip friction.
We can call this the "launching" down-force. (Positive A)
1b - But it also makes my center-of-mass move upward.
1c - This required real extra work from my leg muscles. (Negative A)
2a - As my body rises after the kick, there is reduced down-force on my
glide ski, so it slides better (Positive B)
2b - Then gravity slows and stops my rise, and makes my body sink back down
again. I must wait for this before I can get good grip for the next kick.
(Negative B)
3a - I need to push up to slow and stop my body's fall. This requires real
extra work from my leg muscles (Negative C)
3b - My center-of-mass coming down on the ski produces "landing" down-force.
If I'm taking a long glide, then this likely hits during the glide phase.
So there is increased down-force on my glide ski, so it slides slower.
(Negative D)
Conclusion:
So I got more grip friction, but I paid double for it in leg-force work.
Seeing the second "landing" down-force slow down my glide adds "insult".
But there is another way to use up-down motion for extra grip which
does not have this double cost -- see
Back Lift move for extra grip
One big advantage of the "hill-bound" striding technique for steep hills is
that it helps both the "launching" down-force and the "landing" down-force
fall into the kick phase. I still pay twice, but I also get twice the
benefit in increased grip-friction. See the Steep
Uphill is Different "secret".
see Discussion
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