Cycling

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  • jkoch6599
    jkoch6599 Posts: 30 Member
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    Have you seen the Firstbeat white paper on their beat-by-beat method of estimating energy expenditure? This algorithm is used in most of the recent Garmin cycling GPS devices.

    https://www.firstbeat.com/app/uploads/2015/10/white_paper_energy_expenditure_estimation.pdf

    I'm still not sure how HRV can account for the difference between Chris Froome pushing 400 watts at 130 bpm and me about half that at the same HR, but they claim 7-10% error.
  • robertw486
    robertw486 Posts: 2,388 Member
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    That is interesting stuff, but I tend to think that without other metrics involved HR can only be a rough gauge even if the HR data itself is fairly in depth. Short of comparing HR to wattage load at various exercise types, I'm not sure how accurate HR could ever be.

    It is interesting how some of the newer devices are using some type of VO2max testing, LT testing, etc. But in my mind, it's giving it a better estimate that remains short without some measure of power. And really a lot of the tests could easily be biased by the data a user already has. As an example, I avoid running due to back issues in the past. But I spend a lot more time on the elliptical and bike, and the elliptical has a lot of data. I'm sure I could test higher on that machine than say a run test, simply because I have pace data, power data, etc and I know my base.

    Using HR as a general gauge isn't a bad idea, but overall I'm not convinced it's the end all either. Really short of lab testing we can only get so close regardless.


    400 watts at 130 BPM. Yeah, I can do that... for a few seconds if I start from a resting HR! But I'd imagine even among us mere mortals HR data compared to output data might be fairly widely varied. Even blood pressures and such can affect HR, and here and there you just have the genetically gifted even if they don't train hard.
  • kcjchang
    kcjchang Posts: 709 Member
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    Yes in a few posts back. Basically adjustment of MET based on VO2, it's been the stable of higher end HRM for decades although this is the first publication I have seen comparing the results. Chris Froome would have a very different VO2Max and intensity at 400w verse 200w is not trivial. (And hence a higher MET used; determined by measuring pace and user sport selection?) Supporting references for MET is also pretty dated and incomplete as far as cycling goes. Maybe they have a more extensive database. (Inferred on Table 1 although I'm confused why compare with FLEXind which sounds like a mix bag of lab and general results.) Same caution on the estimation, see "PRACTICAL USE OF THE BEAT-BY-BEAT ENERGY EXPENDITURE ESTIMATION". Not sure if it's that revolutionary. Had SRM made a different play, HRM would never been that entrenched in cycling. Greg LeMond was using a PM back in 1985ish. I bought my first HRM in1989 after the price dropped and it was still around $500 if memory serves. I probably would have forgo getting the multiple N+1 (actually a road and a track) for a PM. Glad for the 23 year hiatus and can afford a few things again. Using student loans for the sport was not my brightest moment.

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