Upper Body moves for skating without using poles

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How to coordinate the timing of multiple dimensions of upper body moves:

  • for each different group of upper body parts

  • for different kinds of leg-push stroking.

 

The three dimensions are:

  • side-swing

  • up-down

  • forward-backward

 

[ more to be added ]

 

Timing of Up-Down versus Side-swing moves

For the arms and for the torso, controlling up-down motion is somewhat independent from side-swing motion. Though it's simpler to make a single straight path of the hands from the start to the finish of an arm-swing move. And it's easier to move up-left to down-right than it is to move up-left to up-right. Also easier to move middle-left to middle-right than move down-left to down-right.

But producing effective propulsive work is never "easy", so we can use extra muscle moves to change the direction of our hands in the midst of the arm-swing: e.g. from down-left move the hands upward to mid-level across the center, then turn the hands downward to finish down-right. In skating the optimal timing is often not "simple", but it's an interesting challenge to learn to coordinate a more complex rhythm.

So for arm moves and torso+shoulder moves, there is lots of flexibility to coordinate timing to obtain simultaneously a substantial percentage of the propulsive work available from both the up-down and side-swing dimensions.

simple Normal-push stroking

Since forward-backward upper-body moves are self-cancelling for simple "straight-stroke-path" normal-push, we get this phase-sequence of upper body moves:

  • phase 1:  Slow and stop the torso + shoulders and the arms + hands -- in a position high and out toward the side of the current leg-push.

  • later in phase 1 or early in phase 2:  Start lowering the shoulders, and the arms even more so -- but keep them out toward the same side -- try to avoid letting the hands drift back into the center.

  • early in phase 3:  Stop the shoulders and the arms in a position low and out toward the side of the pushing leg.

  • later in phase 3:  Start the torso + shoulders and the arms + hands moving upward and inward across the center toward the other side of the next leg-push.

Forward-backward components of arm+hand motion are irrelevant for this kind of stroking -- allow whatever seems to make the other moves easier -- when in doubt use less forward-backward.

(The "angle-switch" or "hop" variations of normal-push could also get more complicated.)

Double-push stroking with nearly horizontal torso

When the hip-shoulder line is somewhere near horizontal (for aerodynamics), forward-backward shoulder moves are mostly determined by the timing of the side-swing moves (because the side-swing moves are simpler to control and have a bigger impact on propulsion).

(Double-push in a somewhat erect position gets more complicated for torso + shoulder moves -- see under Timing Forward-Backward versus Side-Swing moves)

So we get this optimal phase-sequence for the torso + shoulder moves:

  • phase 3 of previous leg-push:  Start the torso + shoulders moving upward -- while keeping them out toward the side of this previous leg-push. Try to avoid starting the next side-swing move too early, and try to limit the "drift" in toward the center.

  • phase ip1 + ip2:  Stop the upward move of shoulders, and start the shoulders moving across toward the side of the new pushing leg.

  • phase 1: Slow and stop the side-swing of the shoulders, way out toward the side of the pushing leg. Start moving the shoulders downward.

  • phase 2: Continue lowering shoulders, while keeping them out toward the side of the current leg.

  • early in phase 3:  Stop the shoulders in a position low and out toward the side of the pushing leg.

So the shoulders make both their upward and downward moves mostly while facing toward the side of the currently pushing leg -- not while facing ahead forward.

Timing Forward-Backward versus Up-Down moves

Arm swing moves

For the arms and hands we have lots of freedom to move in various combinations and sequences of all or some of the three dimensions. Though it's simpler to make a single straight path of the hands from the start to the finish of an arm-swing move. And it's easier to move back-down-left to forward-up-right than it is to move forward-up-left to forward-up-right.

But producing effective propulsive work is never "easy", so we can use extra muscle moves to change the direction of our hands in the midst of the arm-swing: e.g. from down-left move the hands upward to mid-level across the center, then turn the hands downward to finish down-right. In skating the optimal timing is often not "simple", but it's an interesting challenge to learn to coordinate a more complex rhythm.

So for arm and hand moves, there is lots of flexibility to coordinate timing to obtain simultaneously a substantial percentage of the propulsive work available from both the forward-backward and up-down dimensions.

For most skating phases:

  • Positive for propulsive work:  Stopping downward or backward, and Starting upward or forward tends be positive.

  • Negative for propulsive work:  Stopping upward or forward, and Starting downward or backward tends be negative.

Therefore, if forward-backward upper body moves can add non-self-cancelling propulsive work, it tends to optimal to:

  • move the arms diagonally forward and upward.

  • recover the arms diagonally backward and downward.

Double-push arm-swing

The truly optimal coordination of timing of all three dimensions of arm-swing for double-push not that hard to describe theoretically, but overwhelmingly complicated to learn and to control -- since each of the three dimensions has a completely different timing sequence.

Here's three levels of simplification for double-push arm-swing:

  1. Figure out the best timing for moving the arms forward (and backward), and use the same timing for moving the arms upward (and downward). This gets only half the benefit from up-down, but that's something.

  2. Minimize up-down motion of arms, just focus on side-swing and forward-backward moves of arms.

  3. Ignore both forward-backward and up-down motion components of arms: Just focus on good timing of side-swing, and whatever other motion components seem to go with that.

Torso + Shoulder moves

There's less freedom in coordinating forward-backward and upward-downward for torso + shoulder moves: because in a typical body-configuration for skating,

  • If the torso is held aimed facing forward, then moving the shoulders forward tends to require some downward (and backward tends to require some upward).

  • If the shoulders are held at a constant level and are currently aimed toward one side, then the only way to bring them forward is to also move them sideways in toward the center.

  • If the shoulders are held at a constant level and are currently aimed forward, then the only way to send them backward is to also move them sideways out toward one side.

Unfortunately the propulsive impact of a downward upper-body move tends to be opposite to a forward move, and upward has opposite propulsive impact to backward.

So what's good for the timing of up-down moves tends to bad for the timing of forward-backward moves.

In simple "straight-stroke-path" normal-push, forward-backward upper-body moves are a wash, and there is slight benefit to blending some well-timed up-down torso-shoulder movement with the side-swing.

For double-push it's more complicated because forward-backward can have an impact on propulsive work. And in the three-dimensional geometry of skating, the forward-backward impact tends be larger than upward-downward -- so could be better to prefer to give forward-backward considerations influence on the timing-coordination of moves.

But usually the impact from side-swing tends to be even larger (and simpler to manage), so it should dominate both the up-down and forward-backward dimensions.

For most of us non-elite speedskaters, likely it's better to just not worry about forward-backward and upward-downward moves in our double-push, and instead focus on getting good timing with our side-swing moves.

Forward-Backward versus Side-swing moves

The optimal timing of Forward-Backward moves has an interesting relationship to the Side-swing moves.

Double-push stroking

Optimal coordination of timing is:

  • Backward -- The starting and stopping of the Backward move should be roughly simultaneous with the starting and stopping of the Side-swing move.

  • Forward -- The starting and stopping of the Forward move should optimally be performed in between the Side-swing move in one direction and the next Side-swing in the other direction, while the Side-swing is being "held back".

Arm + Hand moves

This implies a rather non-intuitive arm-swing sequence:

  • In the later part of the leg's in-push, the arms start to swing sideways toward the current pushing leg -- and also backward. (phase ip2 into phase A)

  • Stop the arms way out there on the side (and back), in the earlier part of the leg's main-push. (phase 1)

  • Keep the arms out there to the side and back during phase 2 -- try to prevent them from drifting in toward the center, and hold back against the temptation to start the next arm-swing move too early.

  • Arms start moving forward during the later part of the leg's main-push, but remain over on the same side as much as possible. (phase 3, perhaps simultaneous with phase ip0 of the next leg)

  • Arms finish moving forward as much as possible during the early part of the next leg's in-push. (phase ip1 of the next leg).

Torso + Shoulder moves

Side-swing moves of the torso + shoulder inevitably produce some forward-backward component.

If the shoulders are very low in an aerodynamic position, so that the line from hips through the shoulders is nearly horizontal, then forward-backward is mostly determined by the side-swing motion and position. Which implies that the shoulders move forward during the first half of the side-swing, then backward during the second-half.

If the shoulders are somewhat erect, at a significant angle above horizontal, then the skater can affect the forward-backward component by using up-down moves of the shoulders.

  • Increase forward-backward: If the shoulders move down during the first half of the side-swing and/or up during the second half, that increases the forward-backward component.

  • Decrease forward-backward: If the shoulders move up during the first half of the side-swing and/or down during the second half, that increases the forward-backward component.

Unfortunately the propulsive impact of a downward upper-body move tends to be opposite to a forward move, and upward has opposite propulsive impact to backward. But a higher percentage forward-backward impact tends to get transmitted -- see discussion under Timing Forward-Backward versus Up-Down moves.

torso-shoulder moves for nearly horizontal torso

If the hip-shoulder line is something close to horizontal (for aerodynamics), then up-down moves will have virtually no impact on forward-backward component of torso + shoulder motion. So the main way to change forward-backward component is with side-swing moves. But the propulsive benefit from reactive side-force is bigger and simpler to control, so it makes sense to let the side-swing considerations drive the timing.

So in the case of skating with a nearly horizontal torso, there's no point in worrying about forward-backward motion of shoulders. Just let that be whatever is required by the side-swing moves -- instead try to coordinate up-down torso moves, as in Timing up-down versus side-swing moves

torso-shoulder moves for somewhat erect torso

If the shoulders are somewhat erect (rather than nearly horizontal with the hips for aerodynamics), this sequence below seems to be the best way to exploit forward-backward motion.

  • phase ip2 into phase A:  In the later part of leg's in-push, the shoulders start to swing sideways and backward (and perhaps upward).

  • phase 1:  Shoulders stop out there toward the side (and back) during the earlier part of the leg's main-push.

  • phase 2: Shoulders are kept there out toward the side of the current pushing leg, held back from drifting in toward the center, or starting the next side-swing move too early.

  • phase 3: (if the hip-shoulder line is not close to horizontal) Shoulders start to duck forward during the leg's main-push.

If the hip-shoulder line has some significant angle above horizontal, ducking the shoulders also moves the forward. The forward-backward reactive force from that move propulsive force. During this phase there is high transmission of forward force into effective propulsion (because the foot is aimed more out toward the side than during the in-push or aim-switch).

Unfortunately the downward motion has a negative impact on propulsive force, but up-down forces are not usually transmitted as well as forward-backward forces, so there is often a net gain from this move. But if the hip-shoulder line is near horizontal, then the downward component will be much larger than the forward component, so even with less transmission of downward, the net impact will be negative.

If the start of the next side-swing is held back until the in-push of the next leg, then the only way to move the shoulders forward is to duck them down. If the

It's hard to avoid also starting some sideways-move toward the other side. If

  • Shoulders finish their forward (downward) move during the early part of the next leg's in-push (phase ip1 of next leg) -- and at the same time start moving strongly sideways toward the other side.

Elite racer videos

Some elite racers in their videos of double-push stroking show this timing:

  • move the shoulders down during the first half of their torso-shoulder side-swing move, which increases the forward speed of the shoulders.

Since they start their side-swing (earlier than optimal for exploiting side-force) during phase 3 of the leg's main-push, this might (if the hip-shoulder line is not close horizontal for aerodynamics) more propulsive force during a high transmission of forward-force phase.

  • move the shoulders up during the second half of their torso-shoulder side-swing move, which increases the backward speed.

Since this comes during the in-push and aim-switch phases, it subtracts more propulsive force during a low transmission of forward-force phase.

Since the positive comes during a higher-transmission phase than the negative, there is a net positive contribution of propulsive work -- provided that the hip-shoulder line is not close horizontal for aerodynamics.

On the other hand, since the associated vertical component of torso-shoulder motion has an opposite impact on propulsion, the overall gain from this is reduced.

But I think the bigger drawback is the less-effective timing for the side-swing.

Normal-push with angle-switch or hop

Optimal coordination of timing is:

  • Forward move starts together with Side-swing move.

  • Forward move stops while Side-swing move is near maximum velocity.

  • Backward move starts before Side-swing move finishes.

This timing is possible to execute, but not the coordination is surely not easy to learn or control.

 

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