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  • Like Classic

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Where this question came from

Cross country skiing techniques are some of the most complicated human-powered propulsive motions.  So it's reasonable to try to find some common themes and ideas to try to simplify understanding them all.

Many people learned Classic striding first, and then want to try skating.  So it's reasonable to try to re-use some of their skills and concepts.  And it's reasonable for instructors to help them build on their Classic skiing capabilities.

There have also been some coaches who have tried to make "skating is really like classic" into a general theory of technique design.

December 2005 ideas

Skating is Like Classic

(a) Poling helps a lot for both (at least at low and moderate speeds).

Some positions and moves are the same because, "It's what you do for maximum poling power".

(b) There's a backward-push component to leg-push propulsion power in both.

Some of the same muscle moves help both: hip-extension (gluteus muscle), ankle-extension (calf muscle), and . . .

(c) "Forward hip rotation" helps propulsion for both.

By this I mean that as I finish pushing with my right foot, I advance my left hip ahead of my right hip as I step onto my right foot.

(d) Shifting shoulders sideways over toward the next pushing ski as step onto it helps both.

Though for completely different reasons: For classic striding it helps grip. For skating it adds to propulsion (but only if the timing is right and if it doesn't distract from other more important things).

Putting (c) and (d) together yields something odd: Shoulders and Hips turn in opposite directions as step from one ski to the other.

Not like Classic

Some coaches and writers have said that Skating is really like Classic. But in some crucial ways, I think Skating is opposite to Classic diagonal striding:

(a) the sideways component of the leg-push adds major power to Skating propulsion, but not to Classic striding.

Because push-force can be transmitted to the ground while the skate or ski is rolling or gliding, Skating can use the "inclined plane simple machine" principle of mechanics to convert sideways push into propulsive forward-backward force.

This sideways push engages a different big leg muscle group for Skating: the quadriceps or knee-extension muscles -- and some additional little-known muscles . . .

(b) muscles along the outside of the leg can add to propulsion in Skating, by pushing directly out to the side early in the stroke . . .

with these three muscle moves: tranverse hip abduction, medial hip rotation (if knee joint is in strongly bent position), and ankle pronation. (I think these muscles are why the upper legs of some elite speedskaters look so "wide".)

(c) setting down the foot with ankle out in front of knee (and pressure on toe+ball of foot) is usually good for Classic striding -- but always bad for Skating.

Because getting the ankle joint way behind the knee is the prerequisite to engaging the big quadriceps knee-extension muscles to push out to the side to add propulsive power to Skating. This ankle-behind-knee position also adds range-of-motion to the final ankle-extension "toe-push" for Skating.

(d) overlapping both feet on the ground is bad for Classic grip, but usually good for Skating power.

Eliminating the mistake of setting the next foot down before the current leg-push is finished is the crucial prerequisite for all the advanced moves for Classic striding power.

But smoothly setting down the next foot while the current leg is still extending is the sign of expert-racer V1 Skate technique for full continuity of push-force climbing up a hill. (? Is overlap of timing of both skis skating on the ground actually possible ?)

October 2004 ideas

Like Classic

Both are done on skis

  • Balance is important.
  • Balance on a single ski is important.

Both use poles for propulsion

Since the most effective physical/biomechanical configuration for starting a pole-push is with shoulders high and forward, motion techniques which emphasize the pole-push will have these positions -- at least at the start of the pole-push:

  • strong forward ankle flex -- because this gets the upper body forward without also making it low.
  • forward curl or "slouch" of the chest + back -- with more curve higher, because bending sharply from the waist is a trade-off between more forward versus lower shoulders.
  • not much flex of the knee (at start of pole-push) -- because this moves upper body down and back, just the opposite of what is desired.

Skating with No Poling:  Note that when "Skating with No Poling", there is no physical/biomechanical benefit in using a body position which is high or forward.  So it is strange to have ski coaches advocate practicing skating with no poles in a high hips forward position -- since it's hard for the skier to feel any positive benefit from it.

So perhaps the training benefit is that in the high hips forward position it is difficult to effectively use the big leg muscles (gluteus maximus and quadriceps) for skating, so it forces the skier to learn to use the hip abductors and torso rotators for propulsion. 

And if in the name of the "quiet upper body" doctrine, the coach further forbids torso rotation, then the focus is on the hip abductor muscles.

Not Like Classic

Leg-push is completely different

  • Thrust of the classic leg-push is all straight front-to-back,

. . . but the magic of skating is to push out to the side.

Key point for learning to skate is to start feeling that special magic.  Practice pushing directly out toward the side, with no backward motion at all.  Even try to slice the ski forward while pushing out to the side.

  • Classic leg-push is inherently explosive,

. . . but the skating leg-push is inherently smooth.

The classic striding leg-push "kick" is explosive, because the ski must be stopped on the surface of the snow (in static friction) while the push-force is applied.  The pole-push in skating is also somewhat explosive, because the tip of the pole must be stopped on the surface of the snow during its push. 

But the leg-push can be smooth, because it is done while edge of the ski is gliding on the snow.  I don't know any reason to try to make the skating leg-push explosive (any more than a bicycle racer should try to push on the pedals sharply or explosively).  Trying to be explosive may feel strong, but in the objective physics it just puts more stress on muscles and joints without increasing total forward-motion power.

Side-to-side commitment + motion is different

  • Committing all body weight to one ski is difficult to achieve in classic striding,

. . . but in skating it's nearly impossible to avoid.

  • Committing body weight to one side in Classic striding is a "necessary evil" in order to achieve good grip -- to be done only as much as necessary

. . . but in skating the side-to-side motion of the upper body adds propulsive force to each leg push -- to be done as much as possible, without unduly interfering with the pole-push.

Classic skiing lacks a way to convert side-to-side action into forward-motion power.  So the side-to-side commitment is an inefficient waste of power in Classic striding.  But the magical physics of skating makes it possible to get useful work out of side-to-side "wiggling".

Key point is to feel the side-to-side action driving forward propulsion and learn to enhance that magical propulsion, not just do "the same as classic".

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