tracking your CoM and your BoS

Discussion in 'Ski School' started by LiquidFeet, Sep 30, 2019.

  1. LiquidFeet

    LiquidFeet Making fresh tracks Instructor

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    COM = Center of Mass, a point, but not a fixed point since our bodies bend and twist ... it's usually somewhere in the middle of the torso
    BoS = Base of Support, fancy way of saying the feet, or the foot, or somewhere between the two, depending....

    I have some questions about tracking these two points. Any responses are fine. I'd like to get a discussion going in any of these directions.

    1. Tracking two points
    Do you continuously sense where both of these points are as you are skiing? Do you ever pay conscious attention to their relationship? I don't mean do you feel what's happening pressure-wise at the sole of your foot or under your skis; that's different. Tracking that pressure down at the snow involves paying attention to only the pressure point under the foot or ski. What I'm asking about is sensing/feeling two things at once, CoM and BoS, with some conscious awareness of their spatial relationship to each other. Do you feel these two things at once, tracking where your CoM is and where your BoS is and how the space between them might be changing? I'm talking about not only the fore-aft plane along the length of the ski (as in, am I aft or forward or centered), but also the up-down separation (to what extent am I stretching tall then scrunching small), and the lateral separation of these two points as well (how far out from my body are my feet going? ... are they uphill or downhill of me when they are out there? ... and when I bring them back in where are they under me, in front, behind, or centered beneath?) Do you consciously track two points this way as you ski?

    2. Tracking two lines
    Here's a more focused way of asking about your tracking of the lateral separation of the CoM and BoS ... do you track the line your CoM takes and the other line your BoS takes? Do you "see" those lines in your mind as you ski? Do some turns lend themselves to this visualizing more than others? That's two lines, with you paying attention to both of them simultaneously? Those two lines cross each other between turns, and they move apart in the middle of each turn. (Attending to the two lines focuses on the lateral separation of the two points, and the fore-aft relationship, but not the vertical relationship.)

    3. Conscious or unconscious tracking
    I'm asking about consciously maintaining awareness of these two points. Do you attend to them but your attention is unconscious - because you've been skiing 40 years or so and this tracking action got embedded long ago when you were younger? Here I'm asking if unconscious tracking works, or if it's necessary to keep this monitoring somewhat conscious.

    4. Learning to do this tracking
    If in any way you simultaneously track these two points and where they go, when did this kick in? Do you remember how you got started doing this? Was it under instruction, or a breakthrough that came to you on your own? And a related question for you instructors out there, do you teach clients to do this, and if so, how, and at what point in their development? As instructors, we often have to deal with the client's need to consciously focus on one new thing at a time, but this is focusing on two things at a time.

    5. Why do it
    Comments about the worthiness (or lack thereof) of doing this tracking?
     
    Last edited: Oct 3, 2019
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  2. mdf

    mdf entering the Big Couloir Skier

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    Simple answer: no.
    I think the CM is important for understanding what is going on, but of limited real-time use.

    You can feel the relationship between the BOS and CM in the pressure distribution on your BOS. And then you can react to the pressure distribution directly, without reasoning about your CM.

    Or if you get your CM on the wrong side, you feel toppling in the wrong direction start. Again, CM is an abstract construction, not something you feel.

    I guess the closest I come is when I'm struggling to ski on one ski on the "wrong" edge I am acutely aware of where my CM needs to be. But even then, I'm not sure I feel it.

    I'll be interested to see if there are other points of view on this.
     
  3. markojp

    markojp mtn rep for the gear on my feet Industry Insider Instructor

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    My view is much more truncated... I travel DOWN the hill. I align myself to manage forces I feel on my skis. That's about it.
     
  4. Thread Starter
    TS
    LiquidFeet

    LiquidFeet Making fresh tracks Instructor

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    So, some nopes. Anyone else?
     
    Last edited: Oct 3, 2019
  5. surfsnowgirl

    surfsnowgirl Instructor Skier

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    What @markojp said.......... Waaaaay too much thinking for me. I just ski and adjust my body as it needs to be adjusted.
     
    Last edited: Sep 30, 2019
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  6. JESinstr

    JESinstr Lvl 3 1973 Skier

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    Just like golf.....you should only have a single swing thought. In skiing you need a single sensory home base and that is feeling the compression of the arch. And just like Goldilocks, stand on the heel... too hot, lean over the toes, too cold.... between the balls of the foot and front of the heel....just right.
    Pretty much in line with markojp and MDF
     
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  7. elemmac

    elemmac AKA Lauren Skier

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    Another "nope" here. Sounds way too difficult for me to think about when I'm skiing. I change position if I feel unbalanced, not because my CoM should be somewhere else, or my CoM is not aligned correctly with my BoS. So I suppose this would be analogous to unconsciously "tracking" these two points :huh:
     
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  8. KingGrump

    KingGrump Most Interesting Man In The World Team Gathermeister

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    I am supposed to think while skiing? Who knew.
     
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  9. T-Square

    T-Square Terry Moderator Instructor

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    The COM is the integration of all your body parts, clothing, and equipment. It’s actual location is constantly in movement as you flex, extend, reach with your arms, etc. It is not something you can feel or are consciously aware of, quite honestly, I don’t believe you can be aware of it other than as an abstraction. BoS is similar. It varies as you move your skis from parallel to wedge and in width. It is easier to comprehend because you can see it underfoot. I agree with others, use them to visualize and understand what is going on.

    As stated above, you are better off concentrating on feelings and the feedback you get from those feelings.
     
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  10. cantunamunch

    cantunamunch Meh Skier

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    I submit that we feel CoM most (#3,#4) when it *doesn't* travel the path tracked by our eyesight and inner ears.

    Someone beginning to sense CoM, therefore, is essentially first sensing error.
     
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  11. David Chaus

    David Chaus If I am skiing the world is a perfect place. Skier

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    I think of the relationship of COM and BOS as constantly adjusting, so to me the real trick is to notice “normal operating range” of their relationship and when I’m out of that range. I don’t separately track the slightly different paths of the COM and BOS but whether I feel them, well, coiling and uncoiling, like a medium strength spring that compresses or stretches and returns to center (like a binding I suppose).

    I need (and by “need” I mean “really really need”) experienced observers who can observe/inform/advise me on whether I’m actually doing what I think I’m doing, so I can readjust my perceptions of that COM/BOS relationship.

    But no, I don’t think I’m tracking the exact trajectories of BOS and COM. I just have to trust that my BOS is moving a certain direction, and my COM is also going the same way but not as much, and that everything is more or less moving in the direction of my focus.
     
  12. Don in Morrison

    Don in Morrison I Ski Better on Retro Day Skier

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    I just ski, oblivious to the fact that my brain is unconsciously solving a multitude of complex mathematical equations per second, based on a multitude of inputs per second. Some of those calculations produce estimated inputs based on previous actual inputs. Then the brain runs simultaneous calculations on both estimated and actual inputs. The body then moves in response to those outputs.

    When you get the math right, you are blissfully unaware that it is even happening. When you get it slightly wrong, you can make adjustments on the fly and get back in the groove. When you get it really wrong (estimated inputs deviate significantly from actual inputs) you find yourself collecting the debris from a yard sale and reassembling yourself.
     
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  13. Kneale Brownson

    Kneale Brownson Out on the slopes Instructor

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    If I could put up multiple "likes", I would. I'm kinda in your #3 category because that's the only way one can perform a complicated athletic activity. If I unconsciously make some kind of mistake, I consciously make a correction.
     
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  14. Crank

    Crank Out on the slopes Skier

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    Dynamic balance.

    I might think about where I want my weight or CM to be but never about where it is between my head and my feet.

    To me, tracking those points doesn't make a lot of sense.
     
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  15. graham418

    graham418 Making fresh tracks Skier

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    Nobody has inserted Bob Barnes' Infinity Move yet , so I will


     
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  16. Scruffy

    Scruffy Out on the slopes Skier

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    Along these lines ^, if you were, as a slack line beginner, to attempt to walk a slack line or tight rope, I think you'd feel your CoM going out of your BOS range and then take immediate actions (sometimes violently jerky) needed to correct it, or fall off. With skiing the BOS range is fairly large, and the margin for error is large; we've all seen the really bad beginner skier hunched over at the waist, butt way back, and in a death V wedge barely able to turn scream by, and wonder how they've not crashed by now. I think by the time skiers get proficient enough to even want to understand the terms BOS/Com, they've achieved a level of instinctive balance between those two, that thinking about them while skiing is hard to unwrap.
     
    Last edited: Sep 30, 2019
  17. markojp

    markojp mtn rep for the gear on my feet Industry Insider Instructor

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    ... to add just a bit, there are effective ways to get down the hill, and less effective ways. That's another thread.
     
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  18. geepers

    geepers Out on the slopes Skier

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    Think only of balancing over BoS. Where the CoM goes is merely a byproduct of staying in balance.

    @LiquidFeet , when you ride a bicycle do you track both CoM and BoS (the tyres) or just think about maintaining grip and incline as needed to get around a corner?
     
  19. cantunamunch

    cantunamunch Meh Skier

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    Depends on whether she needs to bunny hop that log to get to the corner...or not :duck:... you simply can't do a proper bunny hop without separating the two.
     
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  20. Ski&ride

    Ski&ride Getting on the lift Skier

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    Am I aware where my com and bos is? Some of the time.

    Do I track them? Nooo....

    Should I? Why?
     

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