This page summarizes the most important video
analysis checkpoints for the most common skating styles +
situations. Although some of these are tricky to observe accurately,
some others of these are fairly straightforward to observe in a front view
or side view (provided you analyze only the segment of a side view
video where the camera viewpoint was roughly 90 degrees from the
side).
I've marked the trickier observations as:
[ not easy to observe ]
what's here
see also
[ under construction ]
This is the simplest motion technique for handling
high-force situations -- critical technique for the majority of
cross-country skiers to be able to enjoy skating on hilly trails. Nice
thing than even if you run out of strength and can't get any glide on
some of the strokes, Single-poling still works for getting to the top of
the hill . . . very slowly.
Usually not the fastest for skaters with
lots of skill and strength in poling, for that see
V1 skate. But even fast cross-country ski skaters should still
remember Single-Poling for getting over a very steep hill early in the
day while saving strength to have fun for lots more easier hills
afterward. Or for workouts where the objective is to avoid high stress
on the muscles.
Analysis? Likely not much point in getting too deep
into analysis of Single-Poling skate, since the main point of using it
is to "keep it simple". Simple either because the skater has different
priorities for what to focus on for technique improvement, or simple
because the only time they use Single-Poling skate is when climbing up
the hill seems so hard that there's little energy left over for working
on technique anyway.
Skaters who are concerned about optimizing their technique for
high-Force situations with poles might do better by switching to V1 skate.
overall
Usually the pole is planted distinctly after the
foot is set-down on the same side, roughly after phase 1, so the
pole-push assists the Extension phase 3 of the leg-push.
leg-push
video observation points and priorities for leg-push are pretty much
the same as for high-force
Normal-push with No poles.
except that perhaps the hips would not drop as
much in phase 3, because the reactive force from the pole-push is
supporting them.
video observation points and priorities for most torso and shoulder
motions are the same as for
high-force Normal-push with No poles.
pole-push
little or no abdominal crunch, little or no
dropping of upper body weight onto pole-push -- so don't expect to see
much of those things in a video.
The distance of the pole-push is usually
pretty short in Single-Poling skate, so it better already be aimed in a
way that allows it to immediately transmit force in a directly
propulsive direction -- usually diagonally forward and toward the other
side - (not just straight down into the ground in the hope that it will
get into a more propulsive direction sometime later).
Not much need to worry about the pole-plant
absorbing sideways momentum, since the pole-plant isn't usually
performed until distinctly after the foot has been set-down, so usually
most of the sideways component of kinetic energy has already been
transmitted thru the first phase(s) of the leg-push.
Often by the time of pole-plant the sideways
motion of the upper body is getting started back toward the other side,
so aiming the pole somewhat outward is helping that work, and little or
none of the outward component of the arm's pushing force is going to
opposing the glide of the foot, since little or none of it will be
transmitted to the foot -- and the glide is close to stopping anyway
regardless of the aiming of the pole-push.
The idea of the pole-push in Single-Poling
skate is not mainly to "extend the glide" of the current foot
further sideways -- rather it's to assist the Extension push (so there
might be longer glide on the next foot). Just accept whatever
glide you got from the previous push from the other side, and time this
pole-push and leg-extension push to fit with that.
The leg + hip moves doing "V1" technique with Poles
have some similarities to the leg moves for
high-force Normal-push without poles -- but also two key differences:
The leg-pushes on the two sides are
not symmetrical.
Although the pole-push is not an immediate
direct application of the Extension work, it's a very reliable and
effective use of leg Extension work for propulsion (at non-high speeds).
The typical higher hip position and shorter range-of-motion for climbing
up a steep hill tends to give a smaller leg-lean angle, which transmits
a smaller percentage of Extension work thru the skate-push directly
into propulsion (and the indirect transmission is more complicated and
less effective than for applying it first toward the Pole-push).
Specific differences include:
-
the knee-extension muscles typically push twice on the
recovery-side (mainly vertical lifting in phase 1, skate-push more
sideways in phase 3), with a slight pause in between) -- while they
push only once on the poling-side (extension in phases 2 and 3).
-
the hips rise overall through phases 1 and 2 of the
Recovery-side
leg-push. The hips do not rise thru phases 1 and 2 of the
poling-side leg-push (perhaps drop slightly in phase 1, but mostly
remain steady).
There may be a momentary hesitation in the
raising of the hip
in the middle of the R-side push -- but overall the hip rises during the
Recovery-side leg-push.
The important purpose of this is to build gravitational potential energy
to be released into the pole-push.
Overlap of the feet on the ground is important
for the lifting of the weight of the upper body on the Recovery-side -- so at first the two legs work together to start raising the
mass of the hips and upper body upward (at the end of phase 3 of the
Poling-side and the start of phase 1 of the Recovery-side). Also the shoulders may start
rising before set-down of the Recovery-side leg, so there is usually already some upward kinetic energy
of the upper body, before the recovery-side leg starts its hard solo
work of lifting the weight of the upper body.
-
the hips drop at the end phase 3 on the
Recovery-side. The hips start rising at the end of phase 3 on the
Poling-side.
-
the P-side leg-push has more horizontal
sideways distance than the R-side leg-push.
-
in phase 1 after set-down of the Recovery-side leg,
the leg-push has a definite upward component, especially from a
knee-extension move.
There is also a substantial Out-sweep move
starting immediately on set-down, especially by the
medial-hip-knee-rotation move.
Then the knee-extension move starts again in
phase 3 Extension, but its sideways distance is shorter than on the
poling-side, because the pushing hip is higher than it will be on the
poling-side.
It also tends to reduces gliding friction, at
a moment when the Recovery-side glide is in danger of stalling out.
There is little or no loss in propulsive work
from this abdominal crunch move, because it converts potential energy to
downward kinetic energy (and adds downward kinetic energy of its own).
At the pole-plant the kinetic energy is transmitted thru the arms into
the poles, which then convert it into forward-propulsion work at the
ground.
No poles? An early dropping of the shoulders
might also help in some similar way when climbing up a steep hill with
No poles (though there can be no net reduction in average gliding
friction without using poles).
There's also a key difference in the sideways motion of
the upper body:
specifics
In the points about leg moves here below, the focus is on how they
are different
from the leg moves of the High-force
situation for Normal-push without poles -- but many of the points from
"High-force without poles" still apply, so check
that section too. The points here below
also are about how poling and upper body
moves should coordinate with the leg moves.
overall
(a) the feet can work together to
accelerate the mass of the upper body upward, which reduces peak-force
intensity stress on the Recovery-side Extension muscles, so they can
sustainable handle a larger vertical range-of-motion. By quickly getting
this vertical lifting up to speed, it tends to reduce the amount of
precious stroke-cycle time, which can enable either a higher turnover
frequency or a larger vertical range-of-motion to be sustained.
(b) gliding friction: Vertical force to the
ground is higher in the initial upward acceleration of upper-body weight
(higher than just normal support of body weight) -- so spreading this
higher force across both feet tends to reduce the downward force thru
each foot, and thus avoid this increased gliding friction.
(a) at this point in the stroke-cycle the pole-push
converts a much higher percentage of vertical force and energy directly into
forward propulsion work than the skate-push.
(b) gliding friction: applying extra downward force to
the skate-push would greatly increase gliding friction (over the friction from
just normal support of body weight).
Typically the pole-tips touch the ground only an
instant (.03-.04 second) before the Poling-side foot sets down.
Hips start dropping before the pole-plant (but do not
continue dropping much afterward). The gravitational kinetic energy of the
elevated weight of the upper body is converted into (a) kinetic energy adding
work to the Recovery-side skate-push; and (b) downward kinetic energy which is
transmitted thru the abdominal crunch + shoulder + arm muscles into the
pole-push.
Head + shoulders are already moving downward
before pole-plant and set-down.
The upper abdominal muscles are already "crunching
down" before the pole-plant. Then statically transmit the downward kinetic
energy immediately following pole-plant. Then continue active positive motion "crunching" down on
the poles.
Starting the abdominal crunch move before the
pole-plant has benefits, see
above.
Shoulders are positioned down + forward at set-down, and
moving
further down + forward.
Start the arm-push move (and abdominal crunch move)
before the pole-plant, for quicker and more "rigid" transmission of vertical
kinetic energy into the poles.
The main role of the arms is to statically transmit
the energy from the upper body, not to add positive work of their own. Any
active positive pushing by the arms later in the stroke-cycle is at most just an
after-thought.
-
both pole tips are planted roughly at the same time.
-
the more elite the competitive level, the more aggressive
and explosive is the pole-plant move.
Training the arm + shoulder muscles to quickly and
"rigidly" transmit the high impact force is the "price of admission" to higher
levels of competitive cross-country ski racing. (Trying out the aggression or
explosiveness in the pole-plant move before a careful progression of appropriate
training is asking for injury.)
Training the abdominal crunch muscles to deliver
explosive "crunch" force and transmit force from the dropping hips -- and
training the Back-extension muscles to quickly recover the weight of the
shoulders + upper torso + head up high again -- is the "price of
admission" to higher levels of competitive cross-country ski racing. (Too much
or too aggressive vertical shoulder motion before a careful progression of
training of the Back-extension muscles is asking for injury.)
There's a place for "smoothness" and "relaxed muscles"
in elite racing technique, but it's not in the pole-plant move.
Poling-side pole-push is initially aimed down
toward the Recovery-side or down straight backwards, not
initially aimed down at all toward the Poling-side.
Because if the pole-push is initially aimed
partly toward the Poling-side, then a portion of the sideways kinetic
energy from the torso and shoulders will be transmitted into the pole
instead of into the foot. But the skating foot can convert sideways
kinetic energy into forward-propulsion work fairly effectively, and as a
simple side-effect of its normal skate-push role, with no distraction. The pole cannot make this
conversion very effectively, and anyway it's already got a different
important role to focus on: converting downward force and energy into
forward-propulsion work. So any sideways energy that goes into the pole is
wasted and/or distracting.
Key: It is not OK if the Poling-side hand moves
outside the P-side pole-tip only later in the P-side push, after
the hand started on the inside at Set-down. The
starting configuration is critical. Therefore . . .
Make sure to move the Poling-side hand outside
farther before planting pole or setting down foot, and make sure to plant the Poling-side pole tip
close beside the Poling-side foot.
Key: It is not OK if the pole-tip is
definitely aiming backward only after the pole-plant.
The downward kinetic energy from the falling weight of
the upper body must be immediately converted into forward-propulsion work at the
moment of the pole-plant. If the pole-tip is aimed mainly vertically instead of
backward at the pole-plant, this energy just goes into pounding the pole-tip
deeper into the ground and bending the pole shaft -- it's forever lost for
propulsive work.
The "optimal" pole angle range for converting vertical
force to forward force is for use thru the brief time of transmission of
downward kinetic energy at and immediately after the moment of set-down. It is
not "saved" for active pushing by the arm or shoulder or abdominal crunch
muscles later afterward.
The primary source of power for poling is from the
Leg-extension and Back-extension muscles elevating the weight of the upper body
before the pole-plant and/or pole-push moves. There's simply more
aerobically-trained muscle mass available in those muscles than the other
muscles "closer" to the poles. So their resulting downward kinetic energy gets
the optimal pole angles for converting into forward propulsion work.
Other muscle moves active during the pole-push
afterward get to use the angles and whatever ground-contact distance and time
that are "left over" for delivering and converting their work into forward
propulsion. Though actually some of that poling muscular work performed later
goes partly into starting to elevate and accelerate the mass of the upper body
upward just before the start of the next Recovery-side push.
set-down of Poling-side foot
There's two ways to get this wrong: (1)
shoulders already over on the Poling-side and already slowed down and
(nearly) stopped; and (2) sideways torso-shoulder moves too symmetrical,
not enough commitment to the Poling-side.
A possible mental image to help this: Think about trying to set down the Poling-side foot
further inside
underneath, with the hips and upper body "falling over" it sideways
toward the outside.
Some elite cross-country ski racers have the
recovery-side hip slightly higher than the poling-side hip.
Exception: Strong skaters sprinting up a short
hill can have the pushing hip forward.
relative motions thru midway of Poling-side leg-push
As the hip drops in phase 1 to add work to the
pole-push, it can be tempting to allow the knee to collapse inward.
Fight to prevent this -- if anything try to move the knee outward in
phase 1 (using the hip-abduction muscles). Often it's difficult to
achieve any visible outward motion of the knee from the hip, but it's
still important to prevent the knee from moving inward as the hip drops. The medial
hip-knee rotation move adds propulsive work not by moving the knee
inward under the hip, but by driving the ankle outward from under
the knee.
Partly because the initial phase of the
pole-push is aimed partly toward the poling-side -- not straight in the
direction of the skater's overall forward motion. (Then later in
the stoke-cycle the pole-push is aimed more toward the direction of
overall forward motion.)
A frequent timing mistake is to stop the sideways
motion of torso + shoulders toward the Poling-side soon after set-down (perhaps
with the idea of helping to drive the Recovery-side pole). But the better
strategy is to continue "crunching" down over the Poling-side pole, and hold
back on turning away. The torso + shoulders start moving away toward the
Recovery-side only in the final phase of the leg-push and pole-push -- and then
they move quickly.
Related timing point: The shoulders do not
start rising up until after the Poling-side hand pushes down by
the Poling-side hip.
midway configuration in Poling-side leg-push
but not much lower either, and perhaps the hips are
not at all lower than at set-down. When skating with No poles, you might expect
the hip to rise a little after set-down, then start to fall. On the other hand,
With Poles, the weight of the upper body is supported thru the Poling-side
leg-push by the reactive upward force from pushing on the poles (as well as some
reactive upward force component from the skate-push) -- so it's difficult for
the hips to fall much during the P-side push. But it is unhelpful for the hips
to rise before the later part of phase 3, because that would absorb propulsive
work from the continuing pole-push, and also (after phase 1) from the leg's
skate-push.
This is a sign of medial hip-knee rotation muscles
contributing propulsive work thru the skate-push.
set-down of Recovery-side foot
-
[A] front view: Other poling-side foot is still on the
ground, so the two legs can work together in raising the hips.
-
[A] front or side view: Hips are already moving
upward some before set-down(and
perhaps the shoulders a little, also).
-
[A] front view: Shoulders positioned vertically over hips
or slightly over toward Recovery side
-- but not already clearly over on the Recovery side. (but Moving quickly
toward the Recovery side).
If the shoulders are already clearly over on the
Recovery-side, that's a sign of the frequent error of turning away from the
Poling-side too early.
Perhaps the point is to initially make it easier for
the Poling-side leg acting solo to start accelerating the hips upward --
hold adding the burden of additional rise of shoulders until the two legs can
work together.
-
front view: Pelvis + hips tilted slightly toward
Recovery-side, with the Recovery-side hip lower. (to sort of "lead" the
tipping and swinging of the torso + shoulders over to the Poling-side).
-
side view: Recovery-side hip not forward ahead of
Poling-side hip -- usually better if Recovery-side hip is somewhat behind.
(Exception: strong skaters on sprinting up a short hill can have pushing hip
forward.) [ not easy to observe ]
relative motions thru midway of Recovery-side leg-push
-
[A] hips definitely rising above their vertical position
at set-down, and knee joint is more extended than at set-down.
-
[A] shoulders definitely rising above their vertical
position at set-down.
-
[B] not much sideways motion of shoulders.
-
[A] no "wiggly" in the motion between Set-down and
Midway: see details under
high-speed Normal-push.
midway configuration in Recovery-side leg-push
-
[A] side + front views: Shoulders getting high above
hips, with spine straightening up.
-
[A] front view: Shoulders definitely over on the
Recovery-side (with their side motion finally stopped) -- not already
moving back toward the Poling-side.
-
Key timing point: Torso + shoulders "tip" over
toward the Recovery-side, and then hold there until the final phase of
the Recovery-side leg-push. Then they make a quick move across and down
onto the Poling side.
But what matters is not how extreme the sideways
position is -- but rather the quickness of the side-to-side motion of
torso + shoulders, and preparing for that quickness by first holding it back.
Better to have a less extreme sideways tipping
position, and higher overall stroke-cycle turnover frequency.
finish of Recovery-side leg-push
- [A] side view: Recovery-side leg goes pretty near to full
extension (at some time before the finish)
Key: If the leg does not go to full extension,
that's a sign that the hips were allowed to drop too low on the Poling-side
("butt down in the bucket")
Or it could be a sign that hip-raising "tricks" were
not used to avoid making a "solo single-leg press". The key tricks are: (a)
starting the raising before the end of the Poling-side push; (b) overlapping
feet on the ground to work together; (c) early abdominal crunch move to drop the
shoulders and apply reactive upward force to the mass around hips and butt.
-
[A] side or front view: Abdominal crunch move starts
during Recovery-side phase 3, before the pole-plant --
see more detail.
-
[A] side or front view: Hips are dropping down before the
pole-plant and before the set-down of Poling-side foot.
This is the typical falling of the hips seen in phase
3 of Normal-push skating with No poles. The key difference is that the energy of
the falling upper body while skating with No poles falls onto the other
leg, while in this technique for skating With Poles, it falls onto the poles.
Note that this motion of the hips in later phase 3 on
the Recovery-side is opposite to their motion in later phase 3 on the
Poling-side.
recovery of leg
see under "recovery" for
high-force Normal-push without poles.
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