what's here: topics of video analysis | who this is for | role of video


main topics of video analysis

    phases in skating stroke-cycle:

    more

detail in topics

what + who this is for

role of video in learning skating technique

how it works

definitions

key analysis + observations for major styles

with Poles

Overall -- observations over the whole stroke-cycle

Set down

   front or foot-aim view at Set-down

   side view at Set-down

   more on Set-down

Midway thru leg-push

   front or foot-aim view at Midway

   side view at Midway

Finish of leg-push

   front or foot-aim view at Finish

   side view at Finish

   more at Finish

Recovery of leg thru air

   goals for Leg Recovery

   physics of adding Work from Recovery moves

   simple Normal-push

   Double-push

Double-push specific phases

   Set-down for inward leg-push

   Max-In-Push (Front view)

   Finish of In-push (Side view)

   Crossing from inside to outside (Front view)

more . . .

 


what's here below on this page

what + who this is for

role of video in learning skating technique

  

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what + who this is for

These pages about video techique analysis are not intended for most skaters. They are intended for (a) researchers in the physics and biomechanics of skating; (b) a few skating coaches who want another set of ideas about what to look for in video analysis, or to try to get more background in the physics and biomechanics of skating.

Spending lots of time reading and understanding this will likely not make you a faster skater -- for several reasons given under video in learning.

If you want to get faster technique, spend lots of time skating behind and alongside skaters who are faster than you -- or find a good coach, which might mean going away to a special weekend workshop. Many good coaches nowadays use video as a tool -- and I think that's the right place for it: as one tool in an overall coaching program.

So I think the only helpful use of these pages for an athlete would be to: (a) see if this approach to using video is roughly what you'd want; and (b) find a technique-coach who can show they are experienced at shooting and analyzing video in this way -- or better than this way.

I've done lots of analysis of the physics of skating, and written lots about it, but it's not easy to connect with it when it's lots of words and static diagrams. I'm hoping that tying it to video will make it easier to get into it.

I'm not any sort of coach or instructor, and I'm only a little bit of a racer. I do enjoy trying new moves in skating, and I've had some good training in the physics of the kinematics and dynamics of human-like linkages. So that's what I focus on in these pages: the physics of Power + speed in skating, and what it looks like in video.

I leave most of the mental images and creative exercise drills and progressive learning stages to coaches + instructors.

I do say something about prioritization, but that's based more on my estimates / guesses about which aspects of technique are bigger or smaller gains in propulsive power output in physical Watts (not prioritization in terms of learning progression).

ways that video can help coaching

  • sharpening the coach's perceptions for observing a skater's technique in (the very many) non-video situations.

After you use the ease of video analysis to learn to see that different skaters are handling a check-point of technique in a different way, you can more accurately observe that same check-point in live skating without video.

Even if you don't agree with what's presented in these pages as the best way to handle some technique observation points, just getting better at observing them can be helpful for coaching.

  • for coaching elite or aspiring-elite racers to refine their techniques to gain a small competitive edge.

In most sports nowadays, video analysis is used at the elite competitors to enhance their technique. Athletes at non-elite levels start to expect it too.

also to watch videos of the world's fastest to see small new moves and timing-changes that they are experimenting with to gain advantage. The techniques of skating are very complicated, so there are still opportunities for successful innovations. The next development of technique might be a new move combined with a modification of equipment -- and there are so many possible combinations that you'd want a good knowledge of the physics to at least make a good guess about which ones to start trying.

In the end, speed is determined by physics, so at the highest levels of competition it is important to know what the components of propulsive power (in Watts) look like in video.

  • skating athletes are going to shoot video and look at it -- with or without the coach.

Many aspects of technique for skating fast are non-intuitive, and look very different in video than the mental concepts the coach has been teaching. This could be confusing or even discouraging. It can help if the coach gets "out in front" of the process by helping skaters have their early encounters of themselves on video in a guided context -- help skaters perceive their positive fundamentals instead of only the obvious discouraging shortfalls -- help skaters work on core skills that build power instead of only eliminating moves that "look funny".

ways these pages can help researchers

  • by suggesting new questions to study, related to specific points of analysis.

  • measuring Forces associated with different points in video analysis.

  • making theory about why certain moves shown in video are more effective for higher speed for skaters in some situations.

some ideas here sound different from famous coaches

I think most of the advice that most coaches are giving is very helpful to most learning skaters.

I also know that some things in these pages here about video analysis sound different from what some coaches are teaching -- and that will be confusing for some people. If I were good at resolving other people's confusions, I'd be rich or famous. Instead I'll try offering some context for the confusions.

Here's the main reasons for the differences:

  • Coaches giving advice about how to skate are mainly dealing with the conscious human mind, but most skating moves are mostly controlled by the brain's unconscious muscle control module. Video shows both the conscious and the unconscious moves.

The conscious mind is mainly good at things like talking, planning, worrying. Its view of what's happening with body moves is simplified and distorted. So getting the conscious mind involved with skating is about as likely to mess things up as it is to help -- unless it is carefully managed.

Many skilled experienced skating coaches have found that the safest way to manage giving advice to the conscious mind is to over-simplify, exaggerate, and sometimes distort. Video analysis (at its current level of sophistication) does not play along with that strategy. (Video does distort things, but in an a whole different paradigm.)

Giving advice to a group of learning skaters requires even more careful management of the multiple conscious minds. Which usually requires even more simplification. Exposing video of a skater in the context of a group of her/his peers does not strike me as likely to be the most effective approach.

  • Skating is the most complicated human propulsive movement (at least on land) -- way more complicated than the rational conscious mind can handle. Video captures and displays that full complexity. A critical success factor for effective speed coaching is to hide that complexity.

A key source of this complexity is that the motion of skating is fully 3-dimensional. Unlike running or most bicycling, in skating all 3 dimensions interact to create propulsive power -- for example, pushing sideways thru the foot gets converted into foreward motion power. Which means there's a whole lot more possibilities for engaging moves and muscles to increase speed.

Scientific researchers (as of 2007) do not have complete models of the complexity of how all the moves contribute to skating power and speed. No one yet can really demonstrate scientifically what the truly optimal skating motion is for any situation. Likely there are new speed tricks yet to be created by the next generation of racers.

Exposing the minds of learning skaters to this complexity is more likely to be confusing than helpful for improving their skating. (A key reason why these pages here are not intended for most skaters).

Expecting most coaches to understand the complexity is not realistic. It's more the province of scientific researchers and a handful of coaches working with elite racers.

Here's some other reasons for some of the differences:

  • Lots of points about skating technique have not been carefully scientifically studied. But coaches have to say something. Understandably they take their best guess -- or rely on some famous coach or racer's best guess.

But sometimes that famous racer is just repeating the (over-simplified, exaggerated) good advice she absorbed from her first coach. Or saying what her conscious mind intends, or feels (or thinks it remembers feeling) -- often a distorted or at least simplified version of what's really happening objectively in the muscles and joints. Or it's what the racer consciously works on in practice sessions -- even if that's not exactly what's really effective objectively for going fast to win a race.

What you learned from the famous coach really is good advice for your conscious mind. Just don't be surprised if it's different from what you see in objective video of that same coach skating in a real race.

  • The physics of fully 3-dimensional motion of a linkage of multiple joints has some tricky and non-intuitive aspects.

So when coaches try to apply their normal intuition to guessing the answer, they sometimes get it wrong. Even people who know physics tend to assume that how skating motions produce and transmit power could not be that complicated -- so they cut off their analysis early. Which sometimes works and sometimes does not -- because the actual speed of person skating is determined by the full 3-dimensional full complexity of many human bones + joints + muscles interacting.

  • Some of the old coaching ideas were correct as objective physics -- for pre-klap ice speedskating. They are no longer objectively accurate for inline speedskating -- but some of them are still valuable as (simplified, exaggerated) advice to feed the skater's conscious mind.

role of video in learning technique

Video analysis is only a small part of an effective strategy for learning techniques to skate faster. There are some tricky pitfalls from relying on video.

To try to help show the limited role of video in learning, here's some of the other questions that need to be considered before changing some aspect of a skater's motion based on seeing it in a video.

sequence of questions for changing a move

Suppose a move is identified in video analysis which could be changed to improve skating power and speed. Here's some questions that could be important for implementing that change:

  1. Although the analysis of physics says that making this change "normally" results in an improvement of propulsive power, is this skater's style and approach different from "normal" in ways that might lead to an unhelpful result from this change?

  2. Is this a change of something that mostly just "looks funny" in the video, or is does it deliver a significant increase in propulsive power?
    (It's not wrong to work on changing some skating move for appearance's sake, but it's good to keep clear on which changes are for which reason.)

  3. Does this change fit with the larger learning progression for this skater? or for the team? Does this skater have the "prerequisites" for succeeding with this change? Or would it be better focus on a different change which will have a smaller immediate benefit in skating power, but serve as a foundation for bigger improvements later?

  4. What makes it difficult to learn this change? or difficult to get an increase in power + speed after the change?
    (If this change were easy to learn and immediately resulted in an increase in power, most athletic skaters would already be doing it. The trap of many uncoached athletes using video analysis is they think if they see how their favorite champion racer does it, then it will be no problem to make their muscles do the same.)

  5. Are there other changes that need to be made at the same time in order to get a significant gain in power from it?
    (One obvious problem is that to increase propulsive Force in skating, you have to manage both "ends" of it, action and reaction. Subtler and harder is that the brain's unconscious muscle control module might be secretly "in love with some other moves which block the effectiveness of this change.)

  6. Are there other skaters on the team who are good models of the changed move? Are their clever mental images or special isolation / exaggeration drills that can help learn how the changed move should feel "from the inside"? (or how it should not feel?)

  7. Are there special workouts to more quickly develop some of the skater's muscles in new ways to deliver the increased power enabled by this changed move? or is it better to allow the new muscular capacity to develop in the usual way from the overall training program?
    (Other than downhills and maybe fixing some obvious beginner problems, there is no "free lunch" in skating power. An increase in power output from a change in technique must be delivered by an increase in real muscular work -- either from new muscles getting engaged, or old muscles getting used differently or used more. Often it takes at least a month for the muscles to develop the capacity to deliver this work sustainably.)

Video analysis does not improve skating power and speed because there's nothing in it that forces you to ask those questions -- and nothing in it that tells the answers.

methods for learning

[ more detail to be added ]

  • self-perception

  • concepts from magazine article or web page

  • following a good skater

  • face-to-face coaching

  • video analysis

pitfalls with using video

  • objective video usually looks very different from a skater's own self-perception. It's "not what they expected" -- and often it's discouraging.

  • video does not record Forces.

I might be making a move in my video which looks much like the positions and direction and range-of-motion distance of winning eliter racer -- but the amount of Force I am applying through that move might be completely different. This difference is critical for propulsive Work + Power.

  • angles and lengths as seen in video are often misleading.

It's not that what's in the video image is incorrect data. But it's captured in a different way how we normally get visual data through the lense and retina of our eye and the (unconscious) pre-processing by our brain's super-computer vision modules.

So sometimes if you try to "see" angles + lengths in a video image, your built-in visual processing calculations which are "tuned" for direct eye data will deliver inaccurate judgments. One problem is that a video image is often sort of "foreshortened": Your brain assumes that it was shot from a much closer distance that it really was. Working from that 2-dimensional video image, your brain performs the amazing task of automatically inferring and "calculating" angle and length relationships in 3 dimensions. But in this case its calculations are based on a false assumption about baseline distance.

So when analyzing video for technique, it's important to select for analysis only the short segment (or individual frame) that was shot from a camera viewpoint angle that is appropriate for the specific aspect of motion or position you want to analyze.

Often the camera viewpoint angle relative the skater shifts a lot during a video clip, so only a short segment of it is accurate for analyzing a technique checkpoint - (These pages sometimes say what angle is best to select for a specific observation).

  • objective physical relationships in video are different from effective conscious mental images

the image of what the move is supposed to look like "from the outside" in video does not necessarily help you do it that way -- because lots of time what it feels like "from the inside" to make the move is very different.  Often it turns out that different mental images work better for different people to discover the right feeling. Or sometimes it's not a mental image, it's a special exercise drill that enables discovery of how to feel the move so it looks right in video from the outside. Takes experienced and creative coaching (and a little luck) to find the right combination for each skater's learning style. 

  • tendency to focus on visually obvious points

like notice things about the hands and head and angle of the skate -- instead of the subtle important points, like stable transmission of force near the hips.

  • static positions + angles versus dynamic motions: especially with over-use of the "pause" function to view single frames.

The static positions + angles in a single frame sometimes feel more "objective". But in the physics usually it's the motions and accelerations that determine the amount of propulsive Power + speed. Static position and angles are sort of like props and scenery for a stage theater production: sometimes necessary to enable the acting, but never a substitute for the real acting.

  • 99.9999th-percentile elite racers might not be helpful video models for 99th-percentile athletic skaters.

 

progression of learning stages

  • the motions of effective skating for speed are (objectively) very complicated.

  • often a learning skater needs to first absorb a simpler style of skating to train their perceptions and timing, before they are ready to effectively learn to coordinate complex moves which are optimal for maximum speed.

that's why the approach here includes a "standard-form perceptual check" style.

  • different skaters are different in what mix of emphasis on moves + strategies will be fastest for them.

  • different skaters are different in how they learn (e.g. verbal, video, feeling) and in their progression of skating stages to learn

  • Priorities: often the aspects of moves and positions that look most obvious in a video are of secondary importance for increasing power + speed.

 

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