what's here

Matching motion selection to goal selection

Slow techniques -- and slower

• V1 skate / offset
• Single-poling skate
• classic Herringbone walk
• uphill side-step

Fast techniques -- and faster

• V2 skate
• Open Field Skate
• Skate No Poles
• downhill tuck

see also

• Motion techniques for ski skating
• Factors driving technique performance

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Motion selection and Goal selection

The discussion on this page assumes that the ski skater's goal is highest sustainable speed and power.

Many skiers have other goals, like maximum passive glide per stroke, or biggest range of motion per stroke, or maximum work per stroke, or minimum work per distance.

So much of this analysis does not apply to many skiers during much of their skiing.  Though I suspect the "Slower Techniques" stuff applies to most skiers who are confronted by the need to climb  up a steep hill.

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slower techniques

motion techniques for higher resistance / steep hills --

from faster to slower and slower

V1 skate

(also known as "offset" or "paddle-dance")

V1 is the normal technique used by elite racers for climbing up steeper hills.

The key physics / biomechanics factors driving the transition from V2 to V1 are:

• quicker start of next leg-push, because maintaining safe control on set-down is easier at slower speeds -- so less gap overhead
   
• up a steep hill, using the leg muscles to lift the upper body to drive the pole-push (as in V2) is less efficient than more directly pushing forward and lifting up.
   
• up a steep hill, gain is possible by "direct lifting" of the weight of the leg and setting it down higher up the hill

Less gap overhead implies that the optimal leg-push stroke length to match it is shorter -- so it can be more focused on the sub-range of motion that best matches the force / speed situation -- which is higher force / lower speed (therefore straighter leg).

Since the start of next leg-push can be very quick with almost no gap, the pole-recovery phase for the pole-push must be during the other leg's push -- so there is not enough time for two double-pole-pushes and two pole-recoveries during the stroke-cycle.  Therefore there is only one double-pole-push (and one pole-recovery) per full stroke-cycle.

Physics says that the exact timing of this double-pole-push is not critical, since the kinetic energy it produces can be transferred to other parts of the stroke cycle as needed.  The critical point is that the double-pole-push must not be allowed to make a longer gap or delay between leg-pushes.  Other that that, I choose a time to start my double-pole-push which is simple for control and balance, and advantageous for biomechanical leverage.

questions

• Is there a temptation to "hold on" to V2 too long up steeper slopes?

I have strong arms and abdominal muscles, so doing lots of pole-pushes feels strong and powerful to me.  But the message of the arguments above is that it's better to move to V1 sooner, because of the better focus of "gearing" in the leg motion sub-range, and the inefficiency of diverting leg-push motion though a "big V2" pole-push when climbing up a steep hill.

• Is there a role for Open Field Skate "in between" V2 and V1?  (for hills too steep for V2)

My current guess is:  No. 

If I'm going fast enough so there's such a big "set-down control" time gap that there's delay enough for isometric strain and time to raise my hips on one side for a stronger (but delayed) double-pole-push on that side -- then the speed and "set-down-control" time gap on the other side must also be large enough to justify a double-push on the other side too -- which is V2.

If the "set-down-control" time gap is too small to justify raising my hips to fight isometric strain and get a stronger pole-push, then I might as well start pushing as early as possible with both my leg and my poles on the hang-side.  If I'm not raising my hips, then there's no justification in physics for delaying either the leg-push or the pole-push.

• Is there a place for a "three-beat" V1, with a distinct pole-push-only phase between the two leg pushes?

see discussion on the More on V1 Skate page.

single-poling skate

As the hill gets steeper, it reaches a point where in the V1 motion, the extra kinetic energy boost from the hang-side double-pole-push "runs out" before the leg-push on the recovery-side has done enough, and the force required of the unassisted recovery-side leg exceeds its few-repetitions-strength capability.

The way to prevent "stalling out" on the recovery-side is to provide direct muscular assistance during the leg-push:  with a simultaneous pole-push.  But there is not enough time for two double-pole-pushes and two pole-recoveries.  So it must be a pole-push with a single pole, since the single-pole recovery move can be executed during the single-pole-push on the other side.

For more on this motion technique, including performance hints and detailed analysis, see

Single-Poling Skate

puzzle

But in fact many skilled skiers who have learned a solid V1 technique find that they have very little use for herringbone skate. 

question

• Why not use single-pole-pushes for skating up less steep hills?

One guess is because this blocks the big contribution of the "crunch" of the abdominal and chest muscles, and the vertical lift of the back muscles in pole-recovery move.  But against this, V1 as performed by elite racers does not use much "crunch" either.

Another guess is that herringbone skate does not make effective use of torso rotation, because the direction of motion of the rotation is opposite to the pole-push, and therefore tends to cancel it out.  But with a two-phase leg-push, the main pole-push could be made during the first phase, then the torso rotation during the second phase.

classic Herringbone walk

As the hill gets even steeper, the glide runs out.  But the friction of the base and edge of the ski helps "lock in" the gain of directly lifting each leg and stepping it higher up the hill.  (see classic Herringbone)

question

• Why not take advantage of this friction, and cut out the glide to help survive on some hills less steep?

My current guess is because once the glide goes away, there is no way for the hip abductor muscles to assist in pushing.  Also the glide-waxed skate skis must be angled out very wide to get enough friction from edging, and the uphill walking muscles are biomechanically less effective in such a wide-angle position.

uphill side-step

At some point of steepness, the only way to sustain enough friction is to set the edge of the ski down straight across the fall-line of the slope.

But the big less muscles do not have good biomechanical leverage in this configuration.

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faster techniques

motion techniques for low resistance / flat + gentle downhills --

from slower to faster and faster:

V2 skate

(also known as "1-skate" or "double-dance")

V2 is the normal technique used by elite racers for speed on flat terrain and gentler hills.

The key physics / biomechanics factors driving the transition from V2 to V1 are:

• higher speed requires more time for safe "set-down-control" of the next ski -- a time delay before the skate-push can begin -- so more overhead per stroke cycle.
   
• no danger of running into few-repetitions strength limits of either leg-push or arm-push muscles.
   
• there is isometric strain while gliding on a bent knee during the "set-down-control" delay. 

Since the overhead "cost" of each stroke cycle is larger at higher speeds, I need to try to "get more" out of each stroke in order to balance that cost.  To accomplish this, each stroke must embrace some less powerful motion sub-ranges (e.g. longer leg-push) and add some less powerful or less efficient motion phases (e.g. add a second pole-push).

The isometric strain on the bent knee can be relieved by straightening the leg, which raises the hip and upper body.  But raising the hip and upper body makes the pole-push stronger, so it makes sense to delay the pole-push to take advantage of that -- especially if there is no danger of running into a few-repetitions strength limit in some other phase of the stroke cycle.  That eliminates the normal pole-push timing of V1 skate:  "plant the poles simultaneous with landing the new ski".

And since the skier's speed will be highest just after pushing with both leg and arms on one side, so this speed must be at least as large as the speed that skier started with on this side.  Therefore if the speed that started this side was high enough to justify a strong pole-push with delay, then the speed that starts the next side must also be high enough to justify another strong pole-push on that other side.  So V2 skate is to be preferred over Open field skate.

question

• Is there a role for Open Field Skate "in between" V1 and V2?  (for hills too gentle for V1)

see the same question above under V1 skate.

Open Field Skate

(also known as "V2 Alternate" or "2-skate" or "single-dance")

Actually I'm not sure if there is justification in the physics / biomechanics of optimal power and speed for much of a role for Open Field Skate technique.

Here are my best attempts at justifying a role for Open field skate:

• as speed gets higher, it gets beyond the "high gear limit" of normal poling in V2 skate, and the only way for the pole-push to be speedy enough to make an effective contribution to power is with extra set-up time to prepare to most effectively engage the best pole-push muscles.  This extra set-up time cannot be justified on both sides separately, so it must begin during the previous stroke.
   
• as speed gets higher, the "set-down control" and balance gets more tricky, especially when combined with the impact on balance of that extra-speedy pole-push.  So there is advance preparation needed already during the previous stroke, and the only way to get this time is by eliminating one of the double-pole-pushes.
   
• V2 requires strong single-ski balance.  Skiers with only "normal" single-ski balance are more effective and having more fun with Open Field Skate.  I think this is the main reason so much Open Field Skate is seen at many ski centers.
   
• some snow and terrain conditions may have more problems with balance even at lower speeds.  Narrow trails, tilted trails, ruts, and variable fast + slow patches all point toward Open Field Skate.  This is the main reason that Open Field Skate is used by elite racers (who generally have excellent balance).
   
• as speed gets higher, the power cost of air resistance gets higher.  Air resistance is highest when raising the hips and upper body for the pole-push.  Therefore it is more difficult to justify two pole-pushes per stroke-cycle.
   

Skate No Poles

As the speed gets high enough, the pole-push goes beyond its "high gear limit" of effectiveness -- even with the help of advance preparation during the previous leg-push.  And the relative cost of air resistance gets higher.

One of the key advantages of Ski Skating over Classic Striding and Poling is that skating allows a wider adjustment of "gearing" to effectively deliver power at a wider range of speeds -- because the skate ski can push while gliding on the snow, while the pole tip or striding ski must stop against the snow in order to push.

So when the speed gets high enough, poling must be eliminated, and then it's all legs -- with the help of reactive side-force from sideways torso swing.

Downhill Tuck

At some point the speed (especially down a hill) can get so high that the safe "set-down-control" is too risky, or takes too much time to be worth it.

And the air resistance  cost of even a low skating position is too high, compared with a downhill tuck position.

Then it's no longer worth it to push with the legs, and the skating is replaced by a simple tuck position.

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