Optimal racing technique is not the "right" way to
skate. There are many possible goals for skating:
short-term speed, long-term efficiency, the feeling of glide, the
feeling of relaxation, the feeling of explosiveness, . . .
Climbing up a hill, efficiency really counts,
otherwise you're "burned up" when you reach the top, or you
"stall out" before. There aren't many choices for best
efficiency.
[ more to be added ]
Actually this doesn't work from a standing
start. The "magic" only happens at speed:
because then most of the power of the push gets sucked into the
direction of the speed. So even though the ski is angled so the
force is pointed mostly sideways, the power gets directed forward.
That just
happens to be how the physics of power for motion works. And it delivers wonderful results
in skating -- if I give in to its superior magic, and resist
falling back into the instinctive static concepts of classic striding.
(Actually in our normal skating we want the
benefits of both sideways-push and backwards-push. But
pushing backwards with our leg to make our body go forward is
obvious and natural -- while the effectiveness of the sideways push
is strange and unexpected. So it's a key learning stage to isolate
the pure sideways leg-push and let our unconscious muscle control
centers recognize it and master it.)
Some people avoid using
Single-Poling Skate (or "coaches
skate") because they never see elite racers doing it. And double-poling
when skating on the flats can be fun.
But when we really need the help of the poling
to climb up a steep hill, the coordination with the leg-pushes and other
body motions gets tricky to manage effectively. So most skaters who do
not have the sophisticated multi-part coordination and upper-body
strength of an elite racer are better off keeping it simple with
Single-Poling Skate.
I "shift gears" between low-speed and
high-speed by choosing the angle of my ski on the snow as I push it
partly sideways.
The more I aim my skate-push purely backward instead of
significantly sideways, the more I fall back into the fixed-gear limitations of
classic striding.
(On flat terrain, aiming the pole-push at an angle to the side
doesn't help with gear-shift, because the two-dimensional plane of the
poling motion is basically vertical. To shift gears in poling,
need to play games with angles in that vertical plane -- see further
below)
Some bodily motions may feel like I'm getting
something for free -- by "falling" or "pendulum" to the other side, or
by "extending the glide".
Physics says that it's true that some of these
motions can increase the amount of force in a particular phase of the
stroke-cycle. But they can do that only by robbing power from
some other phase -- or by wasting time and slowing down some other
phase.
Don't get fooled by the easy promises:
feeling the "glide" or the "fall" can be fun -- but it
really helps only comes
together with the muscular work of a "push" or a "lift"
-- though that muscular work might come at different time
than the "free lunch" feeling.
Better to learn which of your muscles can really help you go -- in
clever unexpected ways.
The obvious major muscles to use for skating are:
(a) big leg muscles for skate-push:
quadriceps and rear butt (gluteus maximus)
(b) arm muscles for pole-push
But there are some less obvious muscles which can
contribute power to skating, if I learn how to use them. Using
these muscles is real work, so not a free lunch. But there's
not much else for these muscles to be doing, so they can help take
some load off the obvious muscles which are getting tired, or
contribute that extra power needed to make it over the top of a
hill.
(c) hip abductor (gluteus medius) muscles -- to
push the whole leg out to the side -- to give some power to the
"phase 1" of the skate-push.
(d) swing-the-shoulder-sideways muscles in the
abdomen: starting a quick "swing" or rotation of the weight of
the shoulders (and chest and head) sideways -- away from the
ski edged into the snow -- automatically generates a "reactive"
force (by Newton's Third Law) toward the direction of the
skate-push (phase 2). Then after stepping onto the other ski,
the stopping of this swing motion generates another
"reactive" force to help the next skate-push (phase 1).
(e) abdominal forward-bend muscles -- to add
down-force to the pole-push (phase 1)
(f) front-chest muscles -- to add a "crunch"
motion to the pole-push (phase 1) -- so it's a forward "curling" of
the upper body, not just a "hinging" at the waist.
(g) back muscles -- to lift the weight of the
torso + shoulders + head upward (in the pole-recovery phase) -- so
it can then be dropped down onto the pole-push.
(h) quadriceps leg muscles -- to lift the hips up
-- along with the weight of the entire upper body -- and push the
hips on forward, to "launch" the upper body forward (in the
pole-recovery phase) -- so the weight of the entire upper body can
drop down onto the arms and poles -- to add major force to
the pole-push (phase 1).
(i) calf muscles -- to make a "toe-push" that adds
some force and range-of-motion to the end of the skate-push (phase
2b).
More? There could be a couple more muscles
that can help sometimes.
Revisit the "obvious" muscles -- how do they
coordinate with all these other muscles?
(a) big leg muscles (quadriceps and rear butt) --
are engaged primarily in "phase 2" of the skate-push, while the (c)
hip abductors and (d) stop-the-shoulder-swing muscles give the power
to "phase 1".
(b) arm muscles -- most of their push can be
delayed until "phase 2" of the pole-push, so that "phase 1" of the
pole-push can focus on the abdominal and chest crunch (e) + (f),
with extra power from dropping the upper body weight, previously
lifted by (g) + (h) muscles during the pole-recovery phase.
Though there are many muscles that can contribute to
forward motion in skating in many ways, trying to learn them all at
once is too complicated. For most people it works best to
start with the "foundation" -- focus on the hips and below.
First learn how to balance and push effectively with the legs and
keep the upper body simple.
Then add the fancier stuff. But even later,
keep going back practicing to that simple foundation of the hips and
the legs.
I can start my skate-push earlier by consciously
initiating with my hip abductor muscles. Its effective range of
push is roughly the same regardless of the height of the hip.
The main leg-extension push with the quadriceps gets
a longer effective-push range when initiated from a low hip
position. So if the motion-technique includes up-and-down motion
of the butt and upper body (like for more pole-push power on gentle
terrain), time the main leg-extension so it starts at the down-point
(which would come after at least half the pole-push). If
down-motion of the butt has been mostly eliminated (like climbing a
steep hill), then the main leg-extension with the quadriceps can start
pretty early.
Coordinating with the pole-push: I'm
making a pole-push that is overlapping with my skate-push, I need to
be even more careful to delay extending my knee and ankle joints until
after much of the pole-push (especially until after any upper-body
crunch and butt-drop actions in the pole-push) -- because the
extension of the leg naturally tends to raise my butt and upper-body
-- and that's in opposition to effective pole-push power (see
below under pole-push for up-and-down work).
But pushing out to the side with the hip abductor
muscles actually drops the butt a little, so it actually helps the
pole-push. So the "secret" of coordinating the
skate-push with the pole-push is to start pushing early with the hip
abductor muscles, and delay the extension of the knee and ankle.
Because:
(1) gravity increases the minimum force required
to keep the skating motion going, and not "stall out".
(2) force in the vertical direction dominates
the problem, but the "magic" of the skate-push isn't as effective
against this force, because the vertical direction is mostly outside
the plane of the skate-push on the surface of the snow..
(3) using body-weight as a trick to maximize
pole-push force gets inefficient. Once I've used my leg muscles
to accomplish the critical work of lifting my butt and upper body
vertically, the point is to "lock in" my gain. It's
wasteful to drop it down again to add power to my pole-push.
The key strategies for success skating up a steep hill
are:
(a) Eliminate phases with no or low force.
Instead place each "pusher" into position to start pushing immediately,
in a biomechanical configuration that uses the strongest muscles in
their strongest sub-ranges. And as soon as any pusher gets into
that position, actually start pushing on it. (This results in
fewer shorter phases -- so what do I do when my stroke-cycle finishes
in a shorter time?)
(b) Find ways to more directly lift the weight of my
body in the vertical direction -- and then hold onto each vertical
gain. It's still good to use my back muscles to lift my chest
and head and then drop their weight onto the pole-push -- but it's
inefficient to use my critical leg-power that way in a vertical-focus
environment.
This is the main hidden cost of making sure to
include some passive glide after each skate-push -- or phases with low
work. They waste
stroke-cycle time. Physics says that if my goal is to go faster,
wasting time on phases with low force or no force reduces my power and
speed. Because:
(1) the time used for those phases results in fewer
stroke-cycles per minute, so my average work per minute is lower --
so my power and speed are lower.
(2) I can try to make up for one low-force phase by
applying stronger forces with muscles in other phases, to keep the
average work output from dropping. But this puts higher
peak-force stresses on those other muscles, so they will fatigue
faster and risk injury. (If those other muscles could handle
those peak force levels without fatigue and injury-risk, why wouldn't
I already be using them at those higher levels?)
Some say that taking a longer rest gap between
harder pushes is a way to improve endurance performance of
muscles. But if that were true, pro bicycle road racers would be
using longer crank-arms and pedaling at a slower cadence frequency --
or figuring out how to insert gaps into their stroke cycle. And
elite mountain runners would be doing "moose-hoofs" and
hill-bounds.
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So dropping my body weight is only worthwhile if
it's to directly push the pole-handles down and back.
On gentle terrain, raising my upper body
weight can add to my forward-motion only if done before the start of
the pole-push, and in preparation for soon dropping it into the next
pole-push. Raising my upper body is counter-productive during the
pole-push, and wasteful if it is then dropped without getting applied
to a pole-push.
Up-and-down work is not very effective in helping
the skate-push, because physics says that the butt and upper body must
drop down vertically in order to apply power -- but the big power of
the skate-push is from applying the big leg muscles to extend
the leg in the knee and ankle joints -- which tends to raise
the butt and upper body.
Instructors recently have told me to practice
eliminating up-and-down motion when skating without poles -- even
though I rarely skate without poling otherwise. I think the
reason is because if my pole-push is overlapping with my skate-push, I
need to learn to eliminate the natural tendency of the skate-push
leg-extension to raise my butt and upper-body -- because that's in
opposition to effective pole-push power.
The high gear is the more vertical angle (further
back), the low gear is the more horizontal angle (further back).
It's the geometry of the triangle that enables a slower muscle speed
pushing through pole handle to best match a high forward speed at the
pole tip in the snow when the pole is closer to vertical.
Then at high speed, there's a little
"magic" like with the skate-push: Most of the power of the push gets sucked into the
direction of the speed. So even though pole is angled so the
force is mostly downward, the power gets directed forward.
So at low speeds up hills, I plant my pole tips
back, and extend the push longer back -- to focus on the low-gear
angle range. At high speeds on the flats, I plant my poles
closer to vertical, and cut off my follow-thru near my hips -- to
focus on the high-gear angle range.
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