see also


[ under construction ] 




generate muscular Work


sweep of leg to push on ground


Why V2 fails for climbing up steep hills:

To exploit the double-pole-push requires substantial up-down motion of the weight of the upper body. But that takes time for recovery during which the main propulsive force can only be one of either the Sweep muscles or the Extension muscles -- because both cannot at the same time be in a good configuration angle for a substantial percentage of direct contribution to forward propulsion. But if the foot is set down close to underneath, the Sweep muscles working alone without aid from Extension or from poling is not enough to reliably sustain forward speed until the next double-pole-push.

But if the foot is set down further outside in order to start using Extension push immediately after set-down, then (a) the pole on that side must be planted further outside from the hip, so it tends to be aimed more inward and tends to absorb sideways kinetic energy of the upper body which otherwise could be converted into propulsive work by being transmitted into the next skating leg-push; (b) the pole on the other side must be aimed more sideways (so one pole is pushing more sideways in the direction which the other pole is tending to block); and (c) there is more downward impact force on the snow at set-down and at larger edging angle, so there is higher friction; (d) since more of the Extension leg-push is going into the skating push and less into the vertical potential energy for the pole-push, the double-pole-push is less effective; (e) if the foot is set down further outside, then each skating push is shorter in distance, also shorter in time, so there isn't enough time for much up-down motion of the upper body.

So once the foot is set down significantly outside from underneath its hip, there just isn't time to make an effective enough double-pole push to be worth it. Making only one double-pole push per stroke-cycle as in V1 skate solves the problems of V2 by:

(a) allowing enough time to generate enough up-down motion of upper body weight for an effective pole-push;

(b) on the P-side the foot can be set down close underneath it's hip because the Sweep muscles have immediate assistance from the pole-push, so . . .

(c) the P-side pole can be planted closer to its hip and shoulder, so it does not block or absorb the sideways energy of the upper body and does not oppose the sideways aim of the R-side pole-push.

Which leaves the problem of how to get through the R-side leg-push which has no assistance from the pole-push. Two possible ways:

(d) by dropping the shoulders later during the R-side push, a reactive upward force is applied to the R-side leg and foot, which makes it easier for the ski to keep gliding up the hill without stopping, and easier for the R-side Extension muscles to keep pushing to full extension.

(This dropping implies that there must have been in a rising of the shoulders earlier in the R-side push, which applied an added downward force on the R-side leg and foot -- but that extra load comes before the leg-push reaches its Extension phase, to the Extension muscles are in static mode ("isometric"), so they are better able to sustain the extra force load).

(e) If the R-side push goes on too long a time to avoid stalling and stopping, can shorten out by setting the foot down further outside and having a shorter leg-push which focuses mainly on the Extension push. This creates no problem with planting the pole tip further outside because no pole plant is needed until after the R-side leg-push has finished. This shorter R-side stroke does result in less up-down motion of upper-body weight, and so a somewhat less effective double-pole push (but not so ineffective as the V2 version of this situation).

At some point with planing the R-side foot even further outside, there isn't enough time remaining in the R-side stroke for enough up-down motion of the upper body weight for this one double-pole push in the stroke-cycle to be more effective than two single-pole pushes -- since the only advantage of one double-pole push over two single-pole pushes is the contribution of upper body muscles and vertical motion other than the direct pushing by the shoulders and arms. That's when we give up on V1 skate and switch to "Single-poling Skate" (a.k.a. "herringbone skate" or "coaches skate".

extension of leg to push on ground


up-down motion of body mass


side-to-side motion of body mass


arms + shoulders push on poles


hip-abdomen-chest push on poles


? which kinds of move take priority ?

With six different kinds of move, they cannot all be performed with each one at its optimal configuration and length and timing. So which ones get priority for optimal exploitation and which ones are more compromised to fit in?

"side-to-side motion of upper body mass" usually gets compromised in V1 skate nowadays. It would tend to deliver higher Power at lower turnover frequency, and with the Extension push at a higher leg-tilt angle (aimed more sideways and less upward). Ten years ago there was more concern to optimize side-to-side motion, but now the pro racers focus more on high turnover and on the contribution of poling. Nowadays the pro racers are glad to accept the power contribution of whatever side-to-side motion of upper body fits easily with their other moves, but they're not much concerned to do anything special to increase it beyond that.

"arms + shoulders push on poles" usually gets compromised in V1 skate nowadays. Mainly in that P-side shoulder turns away from the P-side and starts rising up before the pole-push is finished, instead of continuing to help drive the P-side pole to its finish. This is to fit with higher turnover frequency. Also when climbing up a very steep hill where there isn't enough distance and time in one stroke cycle to allow for a full-length pole-push, it's the "arm and shoulders" active push phase at the finish which gets shortened (not the transmission of up-down motion and upper body weight in the early part of the push).

"extension of leg to push on ground" is an important source of Power, but in recent pro racer technique it gets shortened and taken at a less effective angle -- because the same muscles can also make an effective contribution to propulsive Power by raising the mass of the upper body to build gravitational potential energy.

but the overall use of the leg extension move (for "push on ground" and for "up-down motion of body mass" combined) is not compromised, in the sense that in V1 skate by pro racers, each leg is always pushed to nearly full extension. The only compromise is in the starting configuration -- where the bend of the knee and hip joints is less than it used to be (higher hips nowadays than back around 2000

"sweep of leg to push on ground" is normally not compromised because: (a) this move in its good configuration transmits a very high percentage of its work immediately directly into forward propulsion; (b) the distance of its push is limited anyway, so it doesn't gain much from low frequency or lose much at higher frequency; (c) tends not to interfere much with other drivers of Power and speed; (d) tends to have lower friction than the Extension push; (e) there's no other way for these muscles to contribute positive propulsive work.
So normally it only gets shortened (by landing the foot further outside) on very steep hills, in favor of allowing more focus on the Extension push (because that's better able to sustain the higher forces required for surviving to the top of a very steep hill).

The other key moves above are compromised normally only in order to achieve higher turnover frequency -- not to improve the effectiveness of some other move. 

transmit muscular Work


typically a muscle move must simultaneously transmit work from other muscles and actively generate work of its own.


if one muscle move does not do a good job of transmitting, either the stroke-cycle must be delayed or else other muscles must have their effectiveness reduced by transmitting that work.

Two cases of special interest:

transmit up-down motion of body to poles


transmit side-to-side body motion to foot-ground contact



Power = rate of Work


turnover frequency


Speed + Power + resistance


reducing expenditure of Work and Power

Two strategies to go faster: Work harder or Make the skiing easier.

The second way to go faster is to modify the skier's moves or positions to reduce the amount of resistance against motion at the current speed. Then the skier can go at a higher speed (which results in higher resistance, but not as high as it would have been without modifying the moves).

The nice thing about the strategy of reducing resistance is that it tends to have fewer "side effects" than the strategy of recruiting more muscle mass to add more work. The two problems of recruiting more muscle mass are: (a) the added muscles consume critical shared resources -- especially oxygen transported in the blood; and (b) the work from the added muscles usually must be transmitted thru already-used muscles whose independent contribution is then reduced.

Despite the side effects, usually it's still worth it to learn to recruit more muscles because: (a) the body adapts to increase the amount and effectiveness of available shared resources (e.g. enlarges the heart and major blood vessels); and (b) transmitting force from other muscles moves the already-used muscles to a better point on their force-speed-power curve, so there's a net gain in power.


friction of gliding on the snow


determiners of the amount of friction in the snow not affected by the skier's motions techniques:

  • softness of snow

  • history of the snow (e.g. melt + refreeze)

  • temperature

  • moisture

  • design and shape of the ski

  • design and materials of base of the ski (relative the weight and skiing style of the skier)

  • structure in the base of the ski

  • wax or other substances on and in the base of the ski

determiners of the amount of friction which are affected by the skier's motion techniques:

  • downward force on the ski

  • edging angle of the ski

  • length of the path of the ski through the snow

downward force:  reducing downward force has a significant influence on choosing technique moves for V1 skate. One of the changes to top pro racing technique around 2000-2007 was to use a little less downward force on the ski.

A certain minimum amount of downward force is required in order to enable the edge of the ski to "cut" down into snow to be able to "hold" its grip to transmit propulsive force components aimed out backwards and sideways into the snow.

(gravity climbing uphill)

V1 skate is most often used when climbing up a hill, so handling gravitational resistance is important for V1 technique. Really there's no way to reduce the total gravitational resistance in climbing up a specific hill. If your rate of overcoming gravity is lower, your rate of getting up the hill is slower. It's the law.

You can try some tricks with gravitational resistance to help manage it better in its distribution over the stoke-cycle -- which might offer some subtle indirect way to increase sustainable speed. Here's a couple of ideas . . .

The resistance of gravity is not equal to full body weight, because the skier is not trying to move directly upward vertically. Instead the resistance force is proportional to the mathematical "sine" function of the upward slope of the motion. The steeper the hill, the higher the resistance. But . . .

It also matters what path you take up the hill. The more the skier's body zig-zags from side to side, the more the average path is aiming away from directly up the hill, and lower the average slope of the skier's motion. Therefore lower gravitational resistance through most of the stroke-cycle.

Note that simply aiming the ski out more to the side does not accomplish this: The skier's total body mass must move more side-to-side. So the pushing force must be aimed more sideways. But that tends to work better when the ski is aimed more forward.

Another problem is that reversing the sideways motion and then getting up to speed and traveling a large distance in the other direction takes more time -- so the strategy of taking a more "zig-zag" path tends to result in lower turnover frequency and thus larger range-of-motion in the muscle moves -- not a good thing when they're sustain the high forces needed to keep on overcoming a steep hill.

Also increasing the proportion of sideways motion increases the total amount of work applied to overcome friction to get to the top of hill -- not a good idea when snow is soft so friction is high.

So the strategy of increasing sideways motion doesn't get used much. Instead skier's try to use a turnover frequency and ski-aiming angle that enables the leg muscles to sustain the high forces required, and accept whatever sideways motion results from that.

The strategy of reducing gravitational resistance can be applied to a key move of V1 skate: using leg-extension on the Recovery-side to raise the weight of the upper body. If the upper body is moved more forward instead of vertically upward, then the "upward slope" of its motion is less, so the leg-extension muscles encounter less gravitational resistance.

The way to do this is to drop the shoulders down and forward during the Extension phase of the Recovery-side push. Just holding the shoulders lower and more forward does not accomplish this -- they actually have to drop forward (sometimes called "forward fall", actually partly a sideways-forward fall). But it's easier for the shoulders to drop if they're already leaning way forward, because there's less support underneath to prevent them from falling.

(It could also be possible start from a higher shoulder position and move the shoulders down and forward by using muscular force instead of gravity, but this has undesirable side effects which contradict the goal of reducing load on the leg-extension muscles)

The drawback of this shoulder drop move is that the Recovery-side leg extension moves are generating a smaller amount of propulsive work. By reducing both the resistance and the pushing force, we have not increased the overall forward (and upward) speed. So what's the point?

Obvious answer is that the Recovery-side leg push is the "weak link" of V1 skate, so taking load off its leg-extension muscles is necessary to make the overall stroke-cycle sustainable at a higher power rate.

But couldn't we accomplish the same result just by not pushing as hard? and not through such a large range-of-motion?

? Possible answer?: That would help the "weak link", but still the leg-extension muscles are operating a better point on their force-speed-power curve by pushing against lower force ? [but I don't know why this should be true]

Further answer: There are other important reasons to get the shoulders low and forward: so that pole-push muscle moves are aimed more backward and less downward, so a higher proportion of their work goes into forward propulsion instead of just pounding down into the snow.

But then why not just hold the shoulders more low, and not raise them up in recovery any higher than necessary?

Possible answer: Because (a) it already takes strain and oxygen even just to hold the shoulders in that position; (b) the shoulders don't have anything else useful to do in the first half of recovery, so there's no harm in lifting them higher; (c) the extra raising builds additional "potential energy", and when the shoulders later drop that gets converted into "kinetic energy", which gets converted into propulsive work then they "land" onto the pole-push; (d) raising the shoulders in the first half of recovery put more down-force on the ski when it is flatter so there is less effect on friction, then dropping the shoulders later takes down-force off the ski when it is more edged so it helps reduce friction just when it's most critical.

So having written all that, it seems like mostly the shoulder-drop move is done for good reasons of its own, and its interplay with gravitational resistance is just a side effect.

(air resistance)

Air resistance is real, but it doesn't determine any aspect of V1 skate motions. Some moves and positions of V1 skate increase air resistance, but they're performed anyway. Some moves and positions of V1 skate decrease air resistance, but they're still performed even when speed is so low that air resistance is not significant.

Some moves and positions of V1 make a difference for air resistance, but that doesn't influence the choice of the move or the manner in which it is performed.

The force of air resistance is significantly smaller than gravitational resistance in situations (climbing up a hills) where the V1 motion is used by strong competent skiers.


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