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Thread: how many steps

  1. #1

    how many steps

    I notice that most elite level sprinters take about 44-46 strides (male) and 46-47 (females). this is a very vague question with thousands of variables. But lets say you have a HS girls who sprints about 12.4 fat. What would the reduction of one stride possibly yield in regards to time? I will answer what I can but I believe the question can be adequately addressed in general terms without adding too many specifics.

  2. #2
    Moderator glaeser's Avatar
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    Re: how many steps

    Are you assuming that only her stride length would change and that her stride frequency would remain the same? If so, it's relatively easy to calculate.

    Best,
    Christopher

  3. #3

    Re: how many steps

    I'm going to go out on a limb and say that a 12.4 girl is about 50 steps. If we assume the stride lengthens for good reasons (so her frequency doesn't change), that's good for a 2% savings, so about a quarter of a second.

  4. #4

    Re: how many steps

    Good questions. She has a good stride rate already and I wouldnt want to slow that. I have ideas on how to maintain that but any particular concepts and ideas you have on making significant strength gains, monitoring effectiveness of ground contact and the ancilliaries of this function, and hip strength would be appreciated.

    Thanks by the way for both of your responses. It answered my question

  5. #5

    Re: how many steps

    A small word of caution, if the goal is to increase your runner's strength and ability to apply force into the ground, thereby reducing the number of necessary strides for her to naturally cover 100m and try and calculate the improvement of her time, then so be it, that would seem to me to be a reasonable approach. If however, it's simply a question of trying to increase the amplitude of her stride to eliminate one step across 100m, then I'd suggest maybe not doing that and concentrate on increasing her strength levels and her ability to apply force, then see where you stand on the number of strides over X distance.

    As for the math, 12.4 FAT divided by # of strides over 100m gives you the time per stride. Once you have that, just reduce the # of strides by 1 and reverse the calculation. Time per stride multiplied by the desired number of strides = new FAT. That assumes (naively maybe?) that all other things remain equal.

    So to use the numbers listed...

    12.4 FAT / 50 steps = 0.24s which is the average time per stride over 100m.

    reverse the math to get the new time

    .24s * 49 steps = new (very guesstimated FAT) of 11.76

    That's a substantial reduction in time across 100m and is a good indicator of why taking one less step over 100m is such a difficult proposition. The amount of strength and efficiency increases necessary to make even a seemingly small reduction in steps is actually quite a large jump and should be looked at holistically I feel, and not in isolation, as there are a large number of factors in play that will influence the how and why of the results.

  6. #6

    Re: how many steps

    Janic you rounded 0.248/stride to 0.24 before multiplying by 49. Without the rounding, you get 12.15 (or a quarter of a second savings).

  7. #7

    Re: how many steps

    Which is pretty much your 2% hey? You're absolutely correct though.

    Man that is substantial. Ok important safety tip, don't forget decimal places when doing math relating to athletic performance metrics!

  8. #8
    Member sady's Avatar
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    Re: how many steps

    The longer the stride length the faster the footfall will be, gravity says Usain bolt will stay in the air the same time as everyone else regardless of the stride length.

  9. #9
    Member sady's Avatar
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    Re: how many steps

    Do you take into account acceleration, shorter steps at the start?

  10. #10
    Moderator glaeser's Avatar
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    Re: how many steps

    Quote Originally Posted by sady View Post
    Do you take into account acceleration, shorter steps at the start?
    It's an estimate in answer to a thought experiment.

    Best,
    Christopher

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