what's here

more comparisons

see also


Introduction

see Introduction on Leg muscle comparison page

 

?? [ more to be added ]

   

summary of results

see also

Complexity as Number of muscle moves

The number of muscle moves available for commonly-used ski-skating motion techniques is about 15-20% more than for Classic diagonal striding technique -- and 50% more than for Classic double-poling.

Considering that the complexity of the interaction effects between different factors is typically proportional to the square of the count of factors, the technique for V1 ski-skating might be 35% more complicated than classic striding, and 2 times more complicated than double-poling.

motion technique:
major
moves
simple
min
articu-
lations
range
articu
de-sync
points
skating no poles 5-6 1-2 15  12-18 1.5 (or 2)
skating V1 9 2-4 20  18-22 2.5 (or 3)
skating V2 8 2-4 20  19-21
clas striding no poles 4-5 3-4 10.5 9-12
clas striding with Poles 7 4-5 17  16-18
pure double-poling 6 1-2 12  12 1.5

Number of muscle moves, using poling:

  • V1 skate:  func= 9,  artic= 20  (range 18-22), desync 2.5 (or 3)

  • V2 skate:  func= 8,  artic= 20  (range 19-21), desync= 2

  • Classic striding with poling:  func= 7,  artic= 17  (range 16-18), desync= 2

  • pure Double-Poling:  func= 6,  artic= 12, desync= 1.5

See details below under  Poling included in Comparison.

no poling

  • skating on (non-short) skis with no poling:  func= 5-6,  artic= 15  (range 12-18), desync 1.5 (or 2)

  • classic striding on skis with no poling:  func= 4-5,  artic= 10.5  (range 9-12), desync= 2 (or 2.5)

See details below under No-poling motion techniques.

Other kinds of Complexity

timing differences

Another measure of complexity is how many different groupings of moves -- with each grouping needing its distinct timing relative to one or more other groupings.

for Classic striding with poling, the main tricky or counter-intuitive timing coordination is:

for V1 skate, there are:

  • holding back the start of torso side-swing move relative to start of leg-push;

  • coordinating nearly-symmetrical leg-push moves with highly-asymmetrical pole-push moves in V1 skate;

  • starting torso-side-swing away from poling-side before the pole-push on that side is finished (even though the torso-side-swing toward the poling-side is roughly synchronized with the start of the pole-posh).

motion paths

In skating there are some complicated and highly non-intuitive motion paths, including:

  • across-behind-the-other-leg path and strange joint configurations for the Leg-recovery move;

  • outside-inside path for recovery-side arm-recovery move in V1 skate.

see also

No-poling motion techniques

Ski-Skating with No Poling

see calculation and discussion of normal-push stroking on the Compare Complexity of Muscle Moves page.

Results from Leg + Hip moves:

  • skating on (non-short) skis with no poling -- Leg+Hip: func= 3,  artic= 9  (range 8-10)

Total propulsive moves available from entire body:

  • skating on (non-short) skis with no poling:  func= 5-6,  artic= 15  (range 12-18), desync 1.5 (or 2)

Classic Striding with No poling

These are only the Upper Body muscle moves.

see also

The upper body moves are pretty similar to those for running.

Possibly there could be a positive contribution from up-down reactive force, but the obvious upper body up-down moves have negative impacts on forward-backward reactive force.

major move "functions"

a portion of another move function has slight benefit:

sub-moves + "articulations"

upper body forward-backward

(with timing for reactive backward-force)

  • arm swing forward from shoulder

  • forearm swing forward from elbow

  • scapula-abduction -- shoulder reach forward relative to spine

  • (small contribution) upper-abdomen-chest-flexion

  • (small contribution) neck-flexion

de-synchronization of timing among moves

My analysis of the stroke-cycle shows these points where the amount of propulsive work is impacted by the accuracy of de-synchronization:

  • 1 for Start of leg-recovery forward (and arm-swing-forward) should be delayed until after the other foot starts to actually push backward against the ground.

In striding on skis, this is significantly after the next foot sets down onto the ground. For maximum work, hold the leg extended out behind after it lifts off the ground, while the next foot lands and glides. Don't let it start drifting down and forward too early, while the other foot is still gliding.

  • perhaps 0.5 for start of arm-swing-forward could be delayed until after the start of leg-recovery move, then bring the arm forward quicker than the leg.

The easier timing to learn is to synchronize the start of the arm-swing-forward move with the start of the leg-recovery move to bring the opposite leg forward -- (following the old advice to synchronize the arm moves with the opposite-side leg) -- which is sufficent to gain some work from the arm-swing-forward move. But perhaps not the maximum work.

  • 1 for Start of arm-swing-backward should come before Start of the opposite leg-kick-backward push (and after the foot on the same side comes off the ground -- so during the glide phase of the leg on opposite side as the arm) -- and the stopping of arm-swing-backward could come (mostly) while the opposite leg is still pushing on the ground with weight on it -- before the opposite foot comes up off the ground.

This timing results in maximum (non-self-cancelling) propulsive work from reactive forward-backward force from the arm-swing-backward move.

The easier timing to learn is to synchronize the stopping of the arm-swing-backward move with the stopping of the opposite leg's "follow-through" after its leg-kick-backward move  (following the old advice to synchronize the arm moves with the opposite-side leg). But that easy timing does not generate any propulsive work from the arm-swing-backward move.

Note that this starting of the arm-swing-backward for no-poles striding on skis is similar to the "offset pole timing" used for the arm-pole-push-back move for classic striding with poles.  Interesting that for "striding with poles" the main reason for this timing is not propulsive work, but grip: So that the pushing of the pole tip downward against the ground does not reduce the grip-force.

Actually for "no poles" there is also a benefit for grip force, because: (a) the first half of the backward swing of the arm is also a downward move, and starting a downward move produces a reactive upward-force which is negative for grip, so starting it during the glide phase is not a problem; (b) the second half of backward swing of the arm is an upward move, and stopping the downward half produces a reactive upward-force which is positive for grip; (c) and starting any upward motion of the second half is also positive for grip, but stopping the upward motion is negative for grip, so it helps to stop it early before the negative gets too large and the ski slips before the leg-push motion was intended to complete.

calculate entire-body complexity

Results from Leg+Hip complexity:

  • classic striding on skis with no poling -- Leg+Hip only:  func= 3,  artic= 6.5  (range 6-7)

Upper body moves:

  • add  func= 1-2,  artic= 4  (range 3-5)  for upper body forward-backward (counting the "small contribution" moves as adding 0.5 each to complexity).

Total propulsive moves available from entire body:

  • classic striding on skis with no poling:  func= 4-5,  artic= 10.5  (range 9-12), desync= 2 (or 2.5)

Upper Body muscle moves for Poling

Double-poling while ski-skating adds more upper body muscle functions:

major move "functions"

sub-moves + "articulations"

poling direct push

abdominal crunch down:

  • lower-abdomen-flexion

  • upper-abdomen-chest-flexion

arm-push:

  • scapula-adduction -- drive down and back thru shoulder

  • elbow-extension

  • internal-shoulder-rotation

  • (perhaps)  muscles to drive down through thru wrist

build gravitational potential energy

by vertically raising the mass of the torso+shoulders+head, which will help drive the next poling push.

  • lower back-extension

  • upper back-extension

calculate upper-body complexity

which yields this total for available propulsive muscles moves:

  • add  func= 3,  artic= 7  Upper Body moves for Poling

Comparison of different skiing motion techniques

summary of results

Number of muscle moves, using poling:

  • V1 skate:  func= 9,  artic= 20  (range 18-22), desync 2.5 (or 3)

  • V2 skate:  func= 8,  artic= 20  (range 19-21), desync= 2

  • Classic striding with poling:  func= 7,  artic= 17  (range 16-18), desync= 2

  • pure Double-Poling:  func= 6,  artic= 12, desync= 1.5

V1 skate

(a.k.a. "offset", "paddle-dance")

major move "functions"

special offset poling for V1 skate

??

  • additional sideways chest-shoulder move to drive down the poling-side pole.

special recovery-side arm recovery path for V1 skate

(small contribution)  arm-behind-outward

(small contribution)  arm-side-swing (inward)

sub-moves + "articulations"

special offset poling for V1 skate

poling direct push
  • additional sideways spine-torso-shoulder move to drive down the poling-side pole.

poling arm recovery

sideways inward-outward path, timed to generate positive reactive side-force in both directions.

  • (small contribution)  accelerate recovery-side arm more outward while weight is still on the poling-side ski. (lateral shoulder rotation)

  • (small contribution)  decelerate and stop recovery-side arm's outward motion after weight has been transferred to the recovery-side ski. (medial shoulder rotation)

remove some no-poling-skating Upper Body side-swing moves

because some are in conflict with Poling moves

  • arm side-swing inward from shoulder

  • arm side-swing outward from shoulder

  • (small contribution)  forearm side-swing inward from elbow

  • (small contribution)  forearm side-swing outward from elbow

remove some no-poling-skating Upper Body up-down moves

because some are in conflict or redundant with Poling moves

  • (small contribution)  lower-back-extension

  • (small contribution)  upper-back-extension

de-synchronization of timing among moves

My analysis of the stroke-cycle shows these points where the amount of propulsive work is impacted by the accuracy of de-synchronization:

  • 0.5 for Starting the phase 1 leg-sweep-outward move early, perhaps overlapping with phase 3 of the previous push by the other leg.  Then starting the leg-radial-press move later, but with some overlap between the two different kinds of pushing motions by the same leg.

  • 1 for Delaying start of the spine-torso-side-swing moves until later during the leg's main push

. . . so that their highest sideways speed will be attained as weight is transferred from one foot to the other, and their deceleration and stopping will occur during the main push of the next leg on the other side. The temptation is synchronize the start of the side-swing moves with the start of the main leg-push move -- but then the deceleration occurs mostly while the weight is on the same foot whose push is still aimed toward the same side -- so the resulting reactive side-force yields negative work which roughly cancels the earlier positive propulsive work.

  • perhaps 0.5 for the direction of the rotation of the torso and shoulders (spine-torso-side-swing move) moving opposite from the rotation of the pelvis and hips (pelvis-twist move).

Actually this is not de-synchronization of timing, but the feeling of moving linked body parts in opposite directions is surely is strange for most skaters -- and the concept is counter-intuitive for many coaches (as of 2006). There is no de-synchronization of timing, because for maximum propulsive work, the timing of the starting and stopping of the pelvis-twist move can be simultaneous with the starting and stopping of the main leg-push.

  • 0.5 for transition from spine-bend-forward and spine-torso-shoulder-twist moves early in the pole-push to later focus on arm-pole-push-backward move.

Actually in videos of elite-racer technique the spine-torso moves start before the pole-tips reach the ground, and before the poling-side leg-push begins. And sometimes perhaps the pole-push starts just a little bit before the leg-push.

  • 0.5 for extra sideways outward-then-inward move of the recover-arm-forward move of the recovery-side arm.

Note that there would be additional reactive side-force work if the inward move were delayed so that Stopping occured mostly after the poling-side leg is set down on the ground. But most eliter racer videos do not show this timing, which suggests that it's more important to get the next pole-push started early.

calculate entire-body complexity

Results from ski-skating with no Poling:

  • skating on (non-short) skis with no poling:  func= 5-6,  artic= 15  (range 12-18), desync 1.5 (or 2)

Impact of upper body and poling moves:

  • add  func= 3,  artic= 7  Upper Body moves for Poling

  • add  func= 1,  artic= 1 for special V1 "offset" poling

  • add  func= 1,  artic= 1  (range 0 to 2)  for propulsive pole-recovery path special for "offset" poling.

  • subtract  func= 1, artic= 3  (range 2 to 4)  for skating Upper Body side-swing moves in conflict.

  • subtract  func= 0-1, artic= 1  (range 0 to 2)  for skating Upper Body side-swing moves in conflict.

Total propulsive moves available from entire body:

  • V1 skate:  func= 9,  artic= 20  (range 18-22), desync 2.5 (or 3)

V2 skate

(a.k.a. "1-skate", "double-dance")

major move "functions"

in addition to the upper-body pole-push moves:

to build gravitational potential energy

  • leg-radial-retract : tries to move the ball of the foot closer to the hip. Can use these moves: hip-flexion, knee-flexion, ankle-flexion.

sub-moves + "articulations"

build gravitational potential energy

Leg+Hip moves during the pole-push. By vertically raising the mass of the legs, more weight is kept on the poles as the hips drop, and less weight on the feet, which means more force transmitted propulsively to the ground through the pole-tips.

  • hip-flexion -- to pull mass of legs upward

  • knee-flexion -- to pull mass of lower legs upward

remove some no-poling-skating Upper Body side-swing moves

because some are in conflict with Poling moves

  • arm side-swing inward from shoulder

  • arm side-swing outward from shoulder

  • (small contribution)  forearm side-swing inward from elbow

  • (small contribution)  forearm side-swing outward from elbow

remove some no-poling-skating Upper Body up-down moves

because some are in conflict or redundant with Poling moves

  • (small contribution)  lower-back-extension

  • (small contribution)  upper-back-extension

de-synchronization of timing among moves

My analysis of the stroke-cycle shows these points where the amount of propulsive work is impacted by the accuracy of de-synchronization:

  • 0.5 for Starting the phase 1 leg-sweep-outward move early, somewhere in the main part of the pole-push.  Then starting the leg-radial-press move later, but with some overlap between the two different kinds of pushing motions by the same leg.

I'm not sure if V2 skate by elite racers shows the overlap between the later part of phase 3 of the previous leg and initial part of the phase 1 leg-sweep-outward move which is typically seen in other skating modes -- because of the intervention in V2 of the preparation for and start of the pole-push.

Typically in elite racer videos from actual races there is an overlap of the two feet on the ground at the same time, with the previous leg in phase 3. Instead it looks more like an overlap of using the next leg to raise the hips vertically to build gravitational potential energy for the pole-push.

  • 1 for Delaying start of the spine-torso-side-swing move until later during the leg's main push -- and for the transition from pelvis mostly stable facing forward during most of the pole-push to later making a pelvis-twist move as weight is transferred to the other leg.

. . . so that their highest sideways speed will be attained as weight is transferred from one foot to the other, and their deceleration and stopping will occur after weight has been transferred to the next leg on the other side.

Perhaps this delay is easier in V2 skate, because the upper body is "anchored" by its pushing on the poles, which helps keep it "centered" until the pole-push is mostly over. Which could lead to a different temptation: to forget to make the spine-torso-side-swing move at all.

  • 0.5 for transition from spine-bend-forward move early in the pole-push to later focus on arm-pole-push-backward move.

Actually in videos of elite-racer technique the spine-bend-forward move starts before the pole-tips reach the ground.

calculate entire-body complexity

Results from ski-skating with no Poling:

  • skating on (non-short) skis with no poling:  func= 5-6,  artic= 15  (range 12-18), desync 1.5 (or 2)

Impact of upper body and poling moves:

  • add  func= 3,  artic= 7  Upper Body moves for Poling

  • add  func= 1,  artic= 2  for special V2 poling

  • subtract  func= 1,  artic= 3  (range 2 to 4)  for skating Upper Body side-swing moves in conflict.

  • subtract  func= 0-1,  artic= 1  (range 0 to 2)  for skating Upper Body side-swing moves in conflict.

Total propulsive moves available from entire body:

  • V2 skate:  func= 8,  artic= 20  (range 19-21), desync= 2

Classic striding with poling

(a.k.a. "kick-and-glide", "diagonal stride")

Using ski poles to help push adds more muscle functions to the no-poles list further above:

major move "functions"

sub-moves + "articulations"

poling direct push

abdominal crunch:

  • upper-abdomen-chest-flexion

  • lower-abdomen-flexion

arm-push:

  • scapula-adduction -- drive down and back thru shoulder

  • elbow-extension

  • internal-shoulder-rotation

  • (perhaps) muscles to drive down through thru wrist

build gravitational potential energy

by vertically raising the mass of the torso+shoulders+head, which will help drive the next poling push.

  • lower back-extension

  • upper back-extension

remove some no-poling-skating Upper Body forward-backward moves

because some are in conflict or redundant with Poling moves

But perhaps should not remove the moves for the forward arm-swing, which generates reactive forward-force.

  • (small contribution)  upper-abdomen-chest-flexion

de-synchronization of timing among moves

My analysis of the stroke-cycle shows these points where the amount of propulsive work is impacted by the accuracy of de-synchronization:

  • 1 for Start of leg-recovery forward and arm-swing-forward should be delayed until after the start of the next arm-pole-push-back move which transmitting force through the pole-tip into the ground.

In striding on skis, this is somewhat after the next foot sets down onto the ground. For maximum work, hold the leg extended out behind after it lifts off the ground, while the next foot sets down and starts gliding. Don't let it start drifting down and forward too early, before the pole-push starts.

  • 1 for Start of arm-pole-push-back move should come during the glide phase of the leg on opposite side as the arm (before the start of the leg-kick-backward push).  And the Stop of arm-pole-push-back move (or at least most of the deceleration) should come during the leg-kick-backward push phase of the leg on opposite side as the arm (before the pushing foot comes up off the ground).

This timing would result in maximum (non-self-cancelling) propulsive work from reactive forward-backward force from the arm-swing-backward move -- reactive force transmitted through the foot and the ski into the ground.

The problem with this timing for the Stop is that it interferes with getting maximum (non-reactive-force) propulsive work from the pole-push move directly through the pole-tip into the ground. So for many skiers in many situations it is better to continue the backward motion a little after the pushing foot comes up off the ground -- one of the compromise trade-offs of Classic striding. But as long as much of the deceleration takes place while the foot is still pushing against the ground, then much of the positive propulsive benefit from reactive force is also gained.

Typically if the pole-push is started early before the leg-push, and the pole is pushed with strong force, then as a matter of course much of the stopping will have occurred before the pushing foot comes off the ground -- so the attention to coordinating the timing of the pole-push should go on the Start of the move.

Even without the early timing of the Stop, the de-synchronization of Start timing is still useful for avoiding a negative impact of reactive forward-backward force on propulsive work. This early timing of the Start is also important for getting maximum grip-friction for the striding leg-push: so that the pushing of the pole tip downward against the ground does not reduce the grip-force. [ see more on this offset pole timing "secret" ]

The easier timing to learn is to synchronize the starting and stopping of the arm-pole-push-back move with the starting and stopping of the opposite leg (following the old advice to synchronize the arm moves with the opposite-side leg). But that easy timing does not generate any propulsive work from the arm-swing-backward move (and is also bad for grip-friction)

calculate entire-body complexity

Results from classic striding with no Poling:

  • classic striding on skis with no poling:  func= 4-5,  artic= 10.5  (range 9-12), desync= 2 (or 2.5)

Impact of upper body and poling moves:

  • add  func= 2,  artic=  5  for poling direct push

  • add  func= 1,  artic=  2 for build gravitational energy

  • subtract  func=0-1,  artic= 0.5  (range 0-1)  for Upper Body forward-backward moves redundant.

Total propulsive moves available from entire body:

  • Classic striding with poling:  func= 7,  artic= 17  (range 16-18), desync= 2

pure Double-Poling

major move "functions"

during pole-push:

  • leg-radial-retract : tries to move the ball of the foot closer to the hip. Can use these moves: hip-flexion, knee-flexion, ankle-flexion.

  • leg-kick-forward : tries to move the ball of the foot forward relative to the hip. Can use these moves: hip-flexion, knee-extension, ankle-flexion.

during recovery:

  • leg-radial-press : moves the ball of the foot away from the hip. Can use these moves:  hip-extension, knee-extension, ankle-extension.

sub-moves + "articulations"

poling direct push

arm + shoulder push on poles:

  • drive-down-and-back thru shoulder

  • elbow-extension

  • internal-shoulder-rotation

  • (perhaps) muscles to drive down through thru wrist

crunch abdomen and legs down + back:

  • upper-abdomen-chest-flexion

  • lower-abdomen-flexion

legs forward-backward

(with timing for reactive backward-force)

  • knee-extension (timed just as pole-push is ending)

build gravitational potential energy

during the pole-push:

By vertically raising the mass of the legs, more weight is kept on the poles as the hips drop, and less weight on the feet, which means more force transmitted propulsively to the ground through the pole-tips.

  • hip-flexion -- to pull mass of legs upward

  • knee-flexion -- to pull mass of lower legs upward

during the recovery for the next pole-push

  • back-extension

  • hip-extension

  • knee-extension (to lift upper body)

  • ankle-extension (raise heel of foot up off ground)

de-synchronization of timing among moves

My analysis of the stroke-cycle shows these points where the amount of propulsive work is impacted by the accuracy of de-synchronization:

  • 0.5 for transition from spine-bend-forward move early in the pole-push to later focus on arm-pole-push-backward move.

  • 1 for Hold back the Start of knee-extension move (to thrush the feet forward) until later in the pole-push, then move very quickly, so the maximum speed of the move is attained at the instant the pole tips come up off the ground, and all the deceleration occurs while the pole tips are up in the air.

The amount of the positive impact of reactive forward-backward force on propulsive work is determined by the forward speed of the feet at the instant the poles tips leave the ground.

calculate entire-body complexity

Different kinds of moves:

  • add  func= 2,  artic= 5 for poling direct push

  • add  func= 1,  artic= 1 for legs forward-backward reactive force

  • add  func= 3,  artic= 6 for build gravitational potential energy

Total propulsive moves available from entire body:

  • pure Double-Poling:  func= 6,  artic= 12, desync= 1.5