Posture and Forces

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  • Carl Valle
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    Carl Valle on #17842

    I prefer running on the ground and using force plates for research analysis for many reasons. Running on a treadmill tethered is ok for people trying to deal with the realities of snow, such as Joe Defranco having a Tredsled and trying to get a stimulus going. If you are using it for research you are likely to get some readings that are not going to be very valid. When accelerating the horizontal

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    W.E. Price on #110781

    I wish there was a way that I could get access to Goodwin’s work.

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    star61 on #110784

    I prefer running on the ground and using force plates for research analysis for many reasons.

    I’m not aware of the research you’ve performed using force plates. Could you pass your studies along for us to read?

    When accelerating the horizontal forces are drastically different than when at max speed because of posture and foot strike. Some proponents of the horizontal debate cling to studies showing a higher correlation of horizontal forces with performance, but after looking at the studies, the same problem that we see with regular sleds being used at top speed, or past 40 meters. Jon Goodwin’s presentation was very elegant with his visuals showing what happens at acceleration and at max speed. My added photo of the Tredsled is a polite reminder to examine the research before we start drawing the wrong conclusions.

    The fact that horizontal force diminishes as speed increases, posture becomes more erect, and GCT limitations become paramount, does not directly answer the question, “What is the factor limiting Max V?” The fact that horizontal forces show a higher correlation with performance as well as the fact that sprinters are capable of producing more vertical force at Max V than they demonstate in a sprint, should be clues that the empircal data is trying to tell you something and should not be ignored in favor of theoretical musings, regardless of how pretty the slides are.

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    oshikake@ymail.com on #110795

    The fact that horizontal force diminishes as speed increases, posture becomes more erect, and GCT limitations become paramount, does not directly answer the question, “What is the factor limiting Max V?” The fact that horizontal forces show a higher correlation with performance as well as the fact that sprinters are capable of producing more vertical force at Max V than they demonstate in a sprint, should be clues that the empircal data is trying to tell you something and should not be ignored in favor of theoretical musings, regardless of how pretty the slides are.

    Carl Valle
    Participant
    Carl Valle on #110798

    I wish there was a way that I could get access to Goodwin’s work.

    We could get more people to share, such as Jon, but again, the tone of this board needs to be better with the debates. It’s ok to disagree but the intentions have to positive and snide remarks don’t’ entice people to contribute.

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    star61 on #110830

    [quote author="W.E. Price" date="1316261288"]I wish there was a way that I could get access to Goodwin’s work.

    We could get more people to share, such as Jon, but again, the tone of this board needs to be better with the debates. It’s ok to disagree but the intentions have to positive and snide remarks don’t’ entice people to contribute.[/quote]Everyone agrees with that Carl, but everyone has to be on board with that, including you.

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    rcfan2 on #110840

    Star61,

    The fact that horizontal force diminishes as speed increases, posture becomes more erect, and GCT limitations become paramount, does not directly answer the question, “What is the factor limiting Max V?” The fact that horizontal forces show a higher correlation with performance as well as the fact that sprinters are capable of producing more vertical force at Max V than they demonstate in a sprint, should be clues that the empircal data is trying to tell you something and should not be ignored in favor of theoretical musings, regardless of how pretty the slides are.

    In this post, and previous posts regarding horizontal and vertical forces, you’ve stated that “as the fact that sprinters are capable of producing more vertical force at Max V than they demonstate in a sprint“.

    I guess I’m not real clear on this. Obviously, a sprinter could create a huge vertical force by placing their foot well in front of their COM (as in a HJ takeoff). Repeating this without a loss of velocity seems unlikely. Likewise, while bounding, a larger vertical force is applied – but the overall velocity is lower than sprinting.

    Under what circumstances can a sprinter apply greater vertical forces than those seen at maximum velocity – without a corresponding loss in horizontal velocity?

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    star61 on #110859

    …Under what circumstances can a sprinter apply greater vertical forces than those seen at maximum velocity – without a corresponding loss in horizontal velocity?

    I would argue that he can’t. A sprinter is obviously capable of inputting more vertical force in the early phases of acceleration, but he does not, because doing so will in fact result in a corresponding loss in horizontal velocity. Maximum vertical input is never applied, optimum (hopefully) is, with as much force translating to the horizontal as possible. What happens at the moment acceleration ceases and Max V is reached is still open for debate, IMHO, but it has been suggested in the literature (I will try to track down the references) that even at Max V, the sprinter has the capacity to generate more vertical force than is being applied. That point is debatable, and lies at the crux of the question. Is it the inability to generate sufficient vertical force to allow for the continued application of excess (exceeding all resistive forces) horizontal force allowing for continued acceleration, or is it the inability to apply sufficient horizontal force itself, regardless of the sprinter’s capacity to generate enough vertical force? I believe the question has yet to be adequately answered.

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