Metric to study height of the leg?


#1

Hi all !

I just ordered my RunScribe Pro, and I can’t wait to get them :slight_smile:
I was wondering if there’s a metric or a combination which allow to measure the height/movement of the legs during a run ?
I think it could be interesting to see how high our legs are according to the pace, workout etc.

Thanks for your help !
Simon


#2

Do you mean the height that the heels rise above the ground after toe-off ?

If so, I second the motion (ouch)


#3

Yes that’s what I meant :slight_smile:


#4

Given the hardware that is in the footpods I am certain that this COULD be done. It is a matter of developing and verifying an algorithm for interpreting the accelerometer output data streams (not particularly easy). The decisions about which metrics are to be included are I’m sure based relevance either to increasing performance or avoiding injury and I’m not sure where this one falls.

Here is some intriguing food for thought that involves measuring the heel lift height during the stride:

https://www.researchgate.net/publication/258922756_Stride_Angle_as_a_Novel_Indicator_of_Running_Economy_in_Well-Trained_Runners

And if you are just curious about measuring your own heel lift right now you might look into the Milestone Pod. I recall that their pod (at least at one point) did pick off the heel lift height at intervals (i.e. not for every step) during a run.


#5

To me, this one falls into the increasing performance/efficiency category. I can see it being correlated with the flight ratio for example.
Thanks for you inputs, I’ll look at the publication later today :slight_smile:


#6

I’m not sure this is as easy as it first appears to calculate.

You could integrate the line on a graph showing rate of change in vertical G against time, but as the sensor is rotating you would need to record G in all three dimensions and then use a reading from the gyroscope to calculate the vertical G vector for every point in time. Then you could do your integration. Maybe the device already records enough data already…

Alternatively, have you read the bit in the paper above where they say how they get the “stride angle”? They don’t actually measure it. They measure where the foot breaks LED beams just above the treadmill surface. Then they assume a perfect parabolic motion between these points and magic the numbers with a formula. As Runscribe already gives stride length they could copy the paper’s bodge method.

Edited to correct: I’m suggesting integrating the wrong graph. The Y-axis would need to be an integral of a graph of G against time. This could then be integrated for a second time. The X axis would be time.