TSS Fudge Factor and Running Power

  • Creator
  • #69350
    Rob Sterling

    I, like many of you have adopted the Uphill Athlete ‘Fudge factor’, for TSS on Training peaks, and I do think its a better reflection of the stress, however, recently Garmin have implemented running power as a native option on many devices (when used with their heart rate),and after aligning my ‘power’ threshold with heart threshold, my TSS scores have all been a little bit higher… to about the point I would fudge them up under our UA doctrine. So my question is, with running power being more common now, will this take into account some other data and make fudging redundant? – I know there is no ‘standard’ for running power, and Coros, Apple, Garmin and stride all have different outputs, but I would be interested to know everyones thoughts?

  • Participant
    Reed on #69353

    There’s an article on Garmin’s website about the high-level makeup of the “running power” calculations: https://www.garmin.com/en-US/garmin-technology/running-science/running-dynamics/running-power/

    It seem like it’s an imputed / calculated / implicit metric, unlike a bike power meter, ergometer, or even running foot pod power meter. So, it’s pretty similar to heart rate in that it’s a proxy metric – i.e., not a direct measurement of the amount of energy expended per unit of time. While there isn’t yet a great way to measure running power, there’s definitely a standard unit of measure: Watts!

    The “potential power, power required to run up or down a hill” is the most compelling part of the Garmin Running Power, I think. Have you found that it’s been a comparable or better measure of your perceived exertion than heart rate stress + “fudge factors”?

    The air resistance element seems hard to evaluate (does the local prevailing wind data really reflect the wind’s impact on your run?). And the “horizontal oscillation power” is an interesting measure of running efficiency. If you’re running inefficiently, you’ll have more oscillation and exert more power… but is that a helpful training impulse? Or just undesired extra stress?

    josswinn on #69610

    I know I’m not answering this question directly, but I’ve posted something on an older thread which is relevant: https://uphillathlete.com/forums/topic/power-zones-and-training/

    I’ve found the power numbers on my Garmin watch to be very responsive to even slight changes in elevation and it definitely recognises when I turn to run into wind.

    My guess is that there’s no need to fudge TSS if Training Peaks is using your Power data and you have your FTP set correctly. By default it uses power data if it’s there, but choosing rTSS switches to using HR data (e.g. Pa:Hr, instead of Pw:HR)

    Rob Sterling on #69630

    Thanks, the more I use it, I think there might be something in it – TBH I havnt done an AET or treadmill steady state to benchmark, just working off Garmins ‘FTP’ for me, which is pretty much at my lactate threshold HR anyway, but some more testing wouldn’t go amiss.

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