what's here
details of each phase
for double-push
technique, the "in-push"
phases ip0, ip1, ip3, and ipA are described on a separate page.
They replace Phase 0 of the normal-push stroking sequence given here.
see also
This is a detailed analysis of the sequence of moves for Leg-push motions
of "normal push" method of skating.
The additional "in-push" moves and phases
for the "double-push" skating technique used by expert inline skaters are on a
separate page.
The focus is on the effectiveness of various moves and timing
sequences for propulsion, not fun feelings. But of course the main
reason I choose to skate is because it feels magical and fun -- we say
more about connecting the moves to those goals on other pages.
The immediate concern is for skating with skis on snow, but there are
also notes for inline skating and ice skating, how the motions are
different for those different kinds of equipment and surfaces.
This sequence of phases is not the "right" way to skate. Rather it
offers a reasonable set of options, and analyzes the reasons for
choosing (or not) each one. Few skaters do all these moves, and I doubt
there is any skater who does all of them all the time. The main purpose
of this analysis is to expose skaters and skate instructors to more
choices -- more variety and more freedom.
Sources of these moves and timing sequence:
- analysis of the basic physics and biomechanics.
- videos of elite racers, analyzed with pause and
single-frame-advance.
- suggestions from other skaters and coaches.
- my own personal experimentation with different moves.
for lots more detail, see
separate page.
Here's some key findings:
-
Theme: Prepare to add reactive force to Set-down
phase, and perhaps currently add reactive side-force to the other
leg's push.
-
The parts of the leg are brought inward further toward the other side
(while in the air) than would be necessary to reach the landing
position of the set-down. This adds propulsive work in this phase
(for double-push stroking), or enables added propulsive work in the
next Set-down phase (for normal-push stroking).
-
There may be propulsive work from bringing parts of
the leg further backward (while in the air) than would be necessary
to reach the landing position of the set-down phase -- but only if
there are certain motion patterns in the push phases of the other
leg.
[ normal-push: ] If using simple obvious push with a
constant aim-angle throughout, there's little need to give attention to forward-backward leg motion in the Recovery and Set-down phases.
[ double-push: ] The
"lite"
style is better suited for extracting propulsion from
forward-backward moves in Recovery and Set-down phases. So if using the
"big"
style of double-push, less need to give attention to such forward-backward leg motions.
for lots more detail, see
separate page.
Here's some key findings:
-
Theme: Add reactive side-force and perhaps
forward-force to the finish of the other leg's push, and land the
foot in position and with momentum to extract the most power out of
this leg's upcoming push.
-
Set down the next foot before the previous
leg-push finishes pushing: (a) to stop the mass of skater's body
from falling too low; (b) to support the last part of the push by
the other leg; and (c) to minimize any "dead spot" or "low
power" gap in the stroke-cycle, by starting this leg's push as early
as possible.
-
Go for maximum effective range of motion in the
start of the main-push: [ ski: ] Land the ski with
the minimum inward tilt needed to transmit force through the inside
edge. Set down as close toward underneath the pushing hip and with
as little ankle-pronation as possible. [ skate
normal-push: ] Land the skate on outside edge further inside
than its hip, and with the ankle supinated to reach across the
centerline a little further.
-
Pelvis + hips do not face with aim of next
ski or skate at set-down (which is different from shoulders).
Optimal is to start with pelvis and hips facing somewhat toward the
opposite side, so during the leg-push the non-pushing hip moves
forward ("forward pelvis rotation" move). Then the pelvis + hips
have turned to face with aim of the skate or ski at the end
of the leg-push. (Also, the most propulsively effective positions
and rotations of the torso + shoulders are often opposite to
those of the pelvis + hips).
-
The set-down move can do actual propulsive
work in itself -- not just preparation for work in other phases.
for lots more detail, see
separate page.
Here's some key findings:
-
Theme: Transmit side-weight-shift energy
from previous phases into current push-force through the foot.
Vertically raise the mass of the hips and upper body, to build
"potential" energy which will add to push-force in future phases.
Just after Set-down with the foot underneath the hip is the most
effective configuration for this lifting.
-
The time just after the foot lands underneath the
hip does not have to
be "passive glide". The leg can already be doing actual propulsive
work using moves describe here (also by starting some Phase 2 moves
early, especially transverse-hip-abduction).
-
Maximum transmission of side-weight-shift energy
into the foot: No absorption or collapse. One absorption "trap" is
to allow the hip to go outward relative to the knee, instead of
stabilizing the hip-knee configuration with the
lateral-hip-abduction muscles.
-
Key move for raising the upper body is
knee-extension. These strong muscles are at a more effective angle
in this phase than in Phase 3.
-
Ankle-flexion move is also effective for raising
the upper body in this phase, and helps to bring the hips forward.
for lots more detail, see
separate page.
Here's some key findings:
-
Here are moves which are effective from close to
underneath the hip (and less effective further away):
transverse-hip-abduction, inward-hip-leg-rotation (with bent knee),
and ankle-pronation. Also forward-pelvis-rotation is effective
either close or far.
-
?? inward-knee-roll ?? There's another propulsive move available:
ankle-flexion -- ?? provided it has been prepared for by an
inward-knee-roll move which includes some hip-adduction. The
drawback is that the inward-knee-roll is counter-productive for
other propulsive work in the phase (especially the hip-abduction
move), so it's used mainly by ski-skaters, not much by inline or ice
speedskaters.
for lots more detail, see
separate page.
Here's some key findings:
-
Theme: Push with the leg-extension moves,
after the foot has moved far enough away from underneath so that
these moves can be effective. Also use the forward-pelvis-rotation
move.
-
Engaging the hip-extension muscles requires moving
the knee and foot backward, not just out toward the side.
Tilting the shoulders to the other side and moving the chest and
shoulders upward and toward the other side, simultaneous with the
hip-extension move is a possible way to enable the foot to move less
backward.
-
Extending the knee joint is critical for effective extension,
but often gets overlooked -- perhaps because it requires pushing the foot forward
relative to the hip.
-
Actually it is not effective to go to true maximum
extension, because some of the muscle moves needed to achieve it are
either not propulsive or have bad side-effects.
-
Hold back the final toe-push / ankle-extension
move: The heel should stay down through the finish of the
hip-extension and knee-extension moves, for best
transmission of their big push-forces.
-
Ankle-extension can also add a little force to
inline skates and non-klap ice skates, if combined with
outward-ankle-rotation.
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