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How does foot pod work?

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  • How does foot pod work?

    I've been enjoying my footpod and forerunner and have managed a very accurate calibration, mightily impressed by the 'bang per buck' of the FR50. My question was from an interest mainly point: is it an inertia device or a pedometer/stride counter; i.e. if my wife borrows it will she get the same accuracy or will it need to be re-calibrated?

    Thanks in advance.

  • #2
    The footpod uses accelerometers to estimate the path that your foot takes while it's in the air and from there to determine the length of each stride. It also counts the number of strides and works out your pace. All that stuff then gets transmitted to the watch. At that point the watch applies the calibration factor you've entered to the distance and speed metrics.

    So if your wife happens to have similar stride characteristics (i.e. pronation, toe-in or out, as well as how the pod mounts on her shoe) then it will give similarly accurate results. Otherwise she'll get results that are off by some consistent scale factor, unless you recalibrate and store that factor on the watch.

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    • #3
      Great

      Thnx...well answered

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      • #4
        You may also notice a difference between trainers for the same runner. When I run in Nike Lunar Glides the calibration factor is 985, where as the same pace for me in Mizuno Wave 5's is 992.

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        • #5
          Originally posted by T_SMIT View Post
          The footpod uses accelerometers to estimate the path that your foot takes while it's in the air
          More precisely, the accelerometers are used to measure the length of time your foot is in contact with the ground. The original (ancient) research was conducted at Penn State. "A Study to Determine the Biomechanics of Running in Skilled Trackman" by Richard C. Nelson published March 11, 1970. Copy at

          http://www.wired.com/images/multimed...ning_Speed.pdf

          From which the path of your feet can be estimated.
          Last edited by SATHOMASGA; 10-27-2009, 06:15 PM.

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          • #6
            I've just started working with my FR60 footpod and discovered an rather odd characteristic.

            My calibration factor for my Asics training shoes is 97.8%
            And for my light weight Asics racing shoes is 91.0%

            Running speed and average cadence is the same for both.

            These calibrations are done very carefully on a HS track using 1600m. The calibration factors were checked by running the 1600m again. Results were right on in each case.

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            • #7
              I've had even wider variances. My Nike Equalon+3 factor is 0.800 while my Zoot Tempo is 0.974.

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              • #8
                So if my understanding is correct, if your style of running changes throughout a run, whether it be from fatigue or running on a different gradient, the foot pod will not be accurate.

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                • #9
                  Originally posted by JOELMC78 View Post
                  So if my understanding is correct, if your style of running changes throughout a run, whether it be from fatigue or running on a different gradient, the foot pod will not be accurate.
                  Correct, mostly. There are reports that some people don't see
                  such changes, but they are quite probably exceptions ro the rule.
                  DISTANCE: 3000M___ - 5000M___ - 10000M__ - 21098M_ - 42195M_ --- Current VDOT: ?
                  PB______: 10:50,09 - 18:40,20 - 38:39,00 - 1:25:39 - 3:10:26

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                  • #10
                    from fatigue or running on a different gradient
                    Or surface, ie. pavement to dirt trail, etc.
                    I train with SportTracks.

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                    • #11
                      Will a foot pod work for inline skaters. I am trying to measure cadence and from distance travelled can calculate the glide length.
                      Because there is no stationary position but there is change in acceleration, I wondered if it would work.
                      Win

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                      • #12
                        This info I needed..

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