what is it
Just do it all with your poles. Move both poles together in
parallel. Bring your hands up in front of you to about shoulder
height. Plant the tips in the snow with the shafts of the poles
angled back a little -- and then push. Then bring your arms back
up and forward for the next push. And there are some tricks for
getting more power out of this -- see below.
what for
Often used for gentle downhills or flat terrain.
An excellent motion technique -- but using it long or strong
requires special training of triceps, abdominal, and back muscles.
advantages
Makes an excellent "alternate" to classic
stride, because the weaknesses of classic stride are exactly
covered by double pole's strengths:
(a) good for higher speeds than striding:
The problem at higher speeds with matching the velocity of the
push with the snow surface is easier for the pole tip and arms than it
is for the leg and ski with grip wax -- so it's a better
"high-gear" motion.
The snow-contact distance is longer for the pole-tip
then for the leg and ski, because of the geometry of the human body --
so the snow-contact time is longer. And the shortening of the
snow-contact time due to higher speed can be compensated for by
applying higher force intensity through the pole and its tip, without
it slipping.
(b) makes excellent use of the abdominal and back muscles.
(c) less gliding friction than classic stride, because the skier's
weight is spread between the two skis.
disadvantages
(a) Not so good for slow speeds.
The poling motion delivers less power at lower speeds -- not a
good "low-gear" motion. Each motion has a
Speed-Power curve. In Classic skiing, poling is thought of as
a "high-gear" motion, best for higher speeds.
The force must go through the shoulder joint, which is a long way
from the surface of the snow -- so its leverage is good for
converting shorter muscle movements into much longer snow-surface
movements. But this same leverage ratio makes it difficult to
deliver high forces at slow speeds -- so lower power output.
(b) Slow-speed "gearing" problem is worse going up steep
hills
Recovering up to the high start position takes significant time --
with nothing else pushing in between -- so when going up a steep hill you lose
significant velocity in between
pushes. So the speed at the start of the pole-push is at its
lowest -- but the start position of the pole-push is the worst
configuration for delivering high forward-push force at low speed.
(c) Inefficiency of using leg muscles to drive poling up hills
In pure double-poling in Classic skiing, using the leg muscles is a
major source of the power of poling. This is done by dropping the hips
and upper body down and back to drive the poles, then using the big
leg muscles to lift the body-mass above the hips up high in recovery
to build "potential" energy to be released in the next
pole-push.
One the flats, using the capacity of these "hip-lifting"
muscles like this makes sense -- applying vertical work to drive
forward motion.
But when climbing up a substantial hill, over 80% of the skier's power
is applied to fighting vertically against gravity -- not just
moving forward. The skier lifts the
hips and large body mass above them, only to drop it down again
to drive the poles, then lift it all that again to really finally
move that mass up the hill. Lifting it once is required, lifting
twice it through the same vertical range has the smell of inefficiency and wasted
energy. Moving one part of the body down to move another part
forward and up sounds strange and like wasted energy.
(a) It's OK to plant the pole tips in front of the feet
unlike with Classic stride -- because with
double-poling there is no grip down-force which
this extra pole down-force could disrupt.
The faster you're going the further forward you can
plant the tips of your poles.
But not in front of the hands.
(b) You put less stress on your elbow joints if you
"wing" each elbow out to the side a bit, instead of keeping it in a straight
vertical plane with your wrist and shoulder joint. It doesn't seem to
hurt power any. It's what the pro racers do
nowadays.
(c) see more on the Learning
program page.
There's lots of tricks for more effective double-poling
technique.
check the
Kris Freeman double-poling video
strategy
The racer's strategy is to use clever physics and
biomechanics to engage more muscles to push through the poles
than just the arms and shoulders:
-
"potential energy" lift to engage quadriceps,
gluteus, back extensor muscles -- even calf muscles.
-
"reactive force" to engage quadriceps and hip
flexors. (see below on "thrust lower legs forward")
-
forward-shoulder leverage position for maximum
engagement of both upper and lower abdominal muscles.
-
actively pull legs up off ground during the
pole-push, to force full body-weight onto the pole-push.
-
winged-elbow leverage position to engage
inward-shoulder-rotator muscles.
Therefore the role of arms and shoulders is not just to
push the poles back -- but to transmit into the poles all that
additional force from all those other muscles.
So the maximum forward-propulsion power is not
necessarily achieved thru maximum range-of-motion or forward-extension
or backward-extension of the arms. Might be better to compromise the
utilization of the arm muscles, to coordinate with the other propulsive
muscles.
specific moves for racers
Racers can get
more power out of each double-pole push by:
(a) "crunching" down with the chest and abdominal
muscles -- to get the most from this, start it early and strongly.
Not just hinge at the waist, but "curl" the
whole upper body forward. The upper-abdominal "chest curl" muscles are
actually better positioned to push back than the lower-abmominal
"waist-bend" muscles.
(Note that when poling is done together with
skating, the pro racers start the "chest-crunch" of the upper abdominals
clearly before the pole tips hit the snow, while in pure classic
double-poling the "crunch" is not as early).
(b) Get the shoulders as far forward as possible at the
start of the pole-push: so far forward that you're out of balance, and
you have to fall forward onto the poles with the weight of your
upper body.
The further forward the shoulders start, the
larger percentage of abdominal muscles can be engaged to push the poles
backward, and through a longer range-of-motion. Compare the feeling of
the percentage and length of abdominal + chest muscles being used in
crunching onto the poles when you stand straight versus when you get
your shoulders way forward.
In addition to bending shoulders forward
relative to the feet and hips, can also do a sort of "forward shrug" and
bring them ahead of your lower neck before the pole-push begins. Then
during the pole-push, you can pull them back behind your lower neck /
upper spine. This forward-to-backward shoulder-relative-to-neck move is
already effective early in the push.
(c) pull the legs up off the ground during the
pole-push -- to force full body-weight onto the pole-push.
If the weight of the legs is resting partly
directly on the ground, then the legs are not doing everything
they can to use gravity to help drive the poles. This move could be
delayed a little later in the push, since the upper body tends to get
lifted anyway at the initial contact of the pole tips with the ground,
because the poles are closer to vertical.
(d) hands pass by legs low -- at knee level.
(e) get shoulders and hips as high up as possible
before starting the pole-push: extend the back, hip, knee joints to
straighten both the upper and lower body.
These actions build "gravitational potential
energy" by lifting the mass of different body parts vertically --
fighting against the force of gravity. Then during the pole-push this
stored "potential" energy is released and converted into the "kinetic"
energy of motion.
Notice that the pro racers also extend their
ankle joints -- use their calf muscles to push their toes and
raise their ankles -- to build a little more potential energy.
Of course getting the extra power from these down-moves does not come
for
free: It means that in order to "recover" to
get into position to start the next double-pole push, you have to do
some work with straightening up your back and pushing up with your
legs. (So if one of the reasons you were double-poling was
to give your legs a rest, then you can skip part of that last idea.) Also, sometimes the back does not respond well to large
increases in work-load, so start these extra-power things small and
gentle, then build up the duration and intensity over several weeks or
months. (f) when you "wing" your elbow out to the
side, try using the "inward shoulder rotator" muscles to help push the
pole back -- not just the obvious tricep muscles.
Experiment with bending the elbow at a 90-degree "right" angle. Play
with finding the strongest combination of elbow bend and elbow wing-out.
Your best position might change as your muscles develop in their new
roles.
But careful not to overdo it at first: start
gentle and for a short practice-session duration, then build up the
duration and intensity over several weeks or months.
Can also play with spreading your hands out wider just before the start
of the push. Maybe even try feeling what pushing the poles a little bit
inward feels like. (g) thrust your lower legs
forward as the pole-push is ending. This
"secret" move works by "reactive force" -- Newton's Third Law, "every
action has an equal opposite reaction". Therefore the action of starting
the mass of your legs forward makes a reaction of a push backward thru
your poles. But have to get the timing just right: the starting of the
legs must occur while the pole tips are still pushing against the snow,
and the stopping of the legs must occur after the pole tips have come up
off the snow. So you have to delay the start, other wise the stopping
would come while the pole tips were still in the snow.
The sharper and quicker the thrust, the more
forward-motion power is added to the overall stroke cycle. If the ankles
are back a little just before the start of the thrust, there's more room
to accelerate them to a higher maximum velocity during the thrust move.
usage zone
- When your arms and abdominals and back are getting tired because
they're not as well-trained as the legs -- switch to kick
double pole
or classic stride.
- When the hill is too steep and speed gets too slow for poling to
be effective, switch to classic
stride.
more Motion techniques
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