summary of results
Number of muscle moves, using poling:
(a.k.a. "offset",
"paddle-dance")
major move "functions"
special offset poling for V1 skate
??
special recovery-side arm recovery path for V1 skate
(small contribution)
arm-behind-outward
(small contribution)
arm-side-swing (inward)
sub-moves + "articulations"
special offset poling for V1 skate
poling direct push
poling arm recovery
sideways inward-outward path, timed to
generate positive reactive side-force in both directions.
-
(small contribution)
accelerate recovery-side arm more outward while weight is still on
the poling-side ski. (lateral shoulder rotation)
-
(small contribution)
decelerate and stop recovery-side arm's outward motion after weight
has been transferred to the recovery-side ski. (medial shoulder
rotation)
remove some no-poling-skating Upper Body side-swing moves
because some are in conflict with Poling moves
-
arm side-swing inward from shoulder
-
arm side-swing outward from shoulder
-
(small contribution) forearm side-swing inward from elbow
-
(small contribution) forearm side-swing outward from elbow
remove some no-poling-skating Upper Body up-down moves
because some are in conflict or redundant with Poling moves
de-synchronization of timing among moves
My analysis of the stroke-cycle shows these points where the amount of propulsive work is
impacted by the accuracy of de-synchronization:
-
0.5 for Starting the phase 1 leg-sweep-outward move
early, perhaps overlapping with phase 3 of the previous push by the
other leg. Then starting the leg-radial-press move later, but with
some overlap between the two different kinds of pushing motions by the
same leg.
. . . so that their highest sideways speed will be
attained as weight is transferred from one foot to the other, and their
deceleration and stopping will occur during the main push of the next leg on
the other side. The temptation is synchronize the start of the side-swing
moves with the start of the main leg-push move -- but then the deceleration
occurs mostly while the weight is on the same foot whose push is still aimed
toward the same side -- so the resulting reactive side-force yields negative
work which roughly cancels the earlier positive propulsive work.
Actually this is not de-synchronization of
timing, but the feeling of moving linked body parts in opposite directions
is surely is strange for most skaters -- and the concept is
counter-intuitive for many coaches (as of 2006). There is no
de-synchronization of timing, because for maximum propulsive work, the
timing of the starting and stopping of the pelvis-twist move can be
simultaneous with the starting and stopping of the main leg-push.
Actually in videos of elite-racer technique
the spine-torso moves start before the pole-tips reach the
ground, and before the poling-side leg-push begins. And sometimes
perhaps the pole-push starts just a little bit before the leg-push.
Note that there would be additional reactive side-force
work if the inward move were delayed so that Stopping occured mostly
after the poling-side leg is set down on the ground. But most eliter
racer videos do not show this timing, which suggests that it's more
important to get the next pole-push started early.
calculate entire-body complexity
Results from ski-skating with no Poling:
Impact of upper body and poling moves:
-
add func= 1, artic= 1 for special V1 "offset" poling
-
add func= 1, artic= 1 (range 0 to 2)
for propulsive pole-recovery path special for "offset" poling.
-
subtract func= 1, artic= 3 (range 2 to 4) for
skating Upper Body side-swing moves in conflict.
-
subtract func= 0-1, artic= 1 (range 0 to 2) for
skating Upper Body side-swing moves in conflict.
Total propulsive moves available from entire body:
(a.k.a. "1-skate",
"double-dance")
major move "functions"
in addition to the upper-body pole-push moves:
to build gravitational potential energy
sub-moves + "articulations"
build gravitational potential energy
Leg+Hip moves during the pole-push. By vertically raising the mass of the legs, more
weight is kept on the poles as the hips drop, and less weight on the
feet, which means more force transmitted propulsively to the ground
through the pole-tips.
remove some no-poling-skating Upper Body side-swing moves
because some are in conflict with Poling moves
-
arm side-swing inward from shoulder
-
arm side-swing outward from shoulder
-
(small contribution) forearm side-swing inward from elbow
-
(small contribution) forearm side-swing outward from elbow
remove some no-poling-skating Upper Body up-down moves
because some are in conflict or redundant with Poling moves
de-synchronization of timing among moves
My analysis of the stroke-cycle shows these points where the amount of propulsive work is
impacted by the accuracy of de-synchronization:
-
0.5 for Starting the phase 1 leg-sweep-outward move
early, somewhere in the main part of the pole-push. Then starting the leg-radial-press move later, but with
some overlap between the two different kinds of pushing motions by the
same leg.
I'm not sure if V2 skate by elite racers shows
the overlap between the later part of phase 3 of the previous leg and
initial part of the phase 1 leg-sweep-outward move which is typically
seen in other skating modes -- because of the intervention in V2 of the
preparation for and start of the pole-push.
Typically in elite racer videos from actual
races there is an overlap of the two feet on the ground at the same
time, with the previous leg in phase 3. Instead it looks more like an
overlap of using the next leg to raise the hips vertically to build
gravitational potential energy for the pole-push.
. . . so that their highest sideways speed will be
attained as weight is transferred from one foot to the other, and their
deceleration and stopping will occur after weight has been transferred to
the next leg on the other side.
Perhaps this delay is easier in V2 skate,
because the upper body is "anchored" by its pushing on the poles, which
helps keep it "centered" until the pole-push is mostly over. Which could
lead to a different temptation: to forget to make the
spine-torso-side-swing move at all.
Actually in videos of elite-racer technique
the spine-bend-forward move starts before the pole-tips reach the
ground.
calculate entire-body complexity
Results from ski-skating with no Poling:
Impact of upper body and poling moves:
add func= 1, artic= 2 for special V2 poling subtract func= 1, artic= 3 (range 2 to 4) for
skating Upper Body side-swing moves in conflict.
-
subtract func= 0-1, artic= 1 (range 0 to 2) for
skating Upper Body side-swing moves in conflict.
Total propulsive moves available from entire body:
(a.k.a.
"kick-and-glide", "diagonal stride")
Using ski poles to help push adds more muscle functions
to the no-poles list
further above:
major move "functions"
sub-moves + "articulations"
poling direct push
abdominal crunch:
arm-push:
-
scapula-adduction -- drive down and back thru shoulder
-
elbow-extension
-
internal-shoulder-rotation
-
(perhaps) muscles to drive down through
thru wrist
build gravitational potential energy
by vertically raising the mass of the
torso+shoulders+head, which will help drive the next poling push.
-
lower back-extension
-
upper back-extension
remove some no-poling-skating Upper Body
forward-backward moves
because some are in conflict or redundant with Poling moves
But perhaps should not remove the moves
for the forward arm-swing, which generates reactive forward-force.
de-synchronization of timing among moves
My analysis of the stroke-cycle shows these points where the amount of propulsive work is
impacted by the accuracy of de-synchronization:
In striding on skis, this is somewhat after
the next foot sets down onto the ground. For maximum work,
hold the leg extended out behind after it lifts off the ground, while
the next foot sets down and starts gliding. Don't let it start drifting
down and forward too early, before the pole-push starts.
This timing would result in maximum
(non-self-cancelling) propulsive work from reactive forward-backward
force from the arm-swing-backward move -- reactive force transmitted
through the foot and the ski into the ground.
The problem with this timing for the Stop is
that it interferes with getting maximum
(non-reactive-force) propulsive work from the pole-push move directly
through the pole-tip into the ground. So for many skiers in many situations it
is better to continue the backward motion a little after the
pushing foot comes up off the ground -- one of the compromise trade-offs
of Classic striding. But as long as much of the deceleration
takes place while the foot is still pushing against the ground, then
much of the positive propulsive benefit from reactive force is also
gained.
Typically if the pole-push is started early
before the leg-push, and the pole is pushed with strong force, then as a
matter of course much of the stopping will have occurred before the
pushing foot comes off the ground -- so the attention to coordinating
the timing of the pole-push should go on the Start of the move.
Even without the early timing of the Stop, the
de-synchronization of Start timing is still useful for avoiding a
negative impact of reactive forward-backward force on propulsive work.
This early timing of the Start is also important for getting maximum
grip-friction for the striding leg-push: so that the pushing of the pole
tip downward against the ground does not reduce the grip-force. [
see more on this offset pole timing "secret" ]
The easier timing to learn is to synchronize the
starting and
stopping of the arm-pole-push-back move with the starting and stopping of the opposite
leg (following the old advice to synchronize the arm moves with the
opposite-side leg). But that easy timing does not generate any
propulsive work from the arm-swing-backward move (and is also bad for
grip-friction)
calculate entire-body complexity
Results from classic striding with no Poling:
Impact of upper body and poling moves:
-
add func= 2, artic= 5 for poling direct push
-
add func= 1, artic= 2 for build gravitational energy
-
subtract func=0-1, artic= 0.5 (range 0-1) for Upper Body
forward-backward moves redundant.
Total propulsive moves available from entire body:
major move "functions"
during pole-push:
during recovery:
sub-moves + "articulations"
poling direct push
arm + shoulder push on poles:
-
drive-down-and-back thru shoulder
-
elbow-extension
-
internal-shoulder-rotation
-
(perhaps) muscles to drive down through thru wrist
crunch abdomen and legs down + back:
legs forward-backward
(with timing for
reactive backward-force)
build gravitational potential energy
during the pole-push:
By vertically raising the mass of the legs, more
weight is kept on the poles as the hips drop, and less weight on the
feet, which means more force transmitted propulsively to the ground
through the pole-tips.
during the recovery for the next pole-push
de-synchronization of timing among moves
My analysis of the stroke-cycle shows these points where the amount of propulsive work is
impacted by the accuracy of de-synchronization:
-
0.5 for transition from spine-bend-forward move
early in the pole-push to later focus on arm-pole-push-backward
move.
-
1 for Hold back the Start of knee-extension move
(to thrush the feet forward) until later in the pole-push, then move
very quickly, so the maximum speed of the move is attained at the
instant the pole tips come up off the ground, and all the
deceleration occurs while the pole tips are up in the air.
The amount of the positive impact of reactive
forward-backward force on propulsive work is determined by the forward
speed of the feet at the instant the poles tips leave the ground.
calculate entire-body complexity
Different kinds of moves:
-
add func= 2, artic= 5 for poling direct push
-
add func= 1, artic= 1 for legs forward-backward reactive force
-
add func= 3, artic= 6 for build gravitational potential energy
Total propulsive moves available from entire body:
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