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20min avg power during training as a measure of ftp?

sven_jtosven_jto Posts: 183
I just finished a 3 week training block and was taking a recovery week, decided to do a chaingang for the fun of it and got a new 20min pb avg power during one of the longish climbs.
It's about 12watts higher than my previous all time 20 min pb and about 18watts more than my 20min test from the month before.

The powermeter was calibrated and zeroed so I'm sure the data is reliable I was barely conscious at the top and almost started going in the opposite lane :D. The training block was really hard and good quality, I was coming back from a bit of a break but I doubt my ftp has increased by 11watts in 25 days.

Do you thing data from hard training should be used for determination of of FTP or only data from testing should be valid?

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  • I just finished a 3 week training block and was taking a recovery week, decided to do a chaingang for the fun of it and got a new 20min pb avg power during one of the longish climbs.
    It's about 12watts higher than my previous all time 20 min pb and about 18watts more than my 20min test from the month before.

    The powermeter was calibrated and zeroed so I'm sure the data is reliable I was barely conscious at the top and almost started going in the opposite lane :D. The training block was really hard and good quality, I was coming back from a bit of a break but I doubt my ftp has increased by 11watts in 25 days.
    Why not, if you are confident of the pre and post data? It's possible that FTP hasn't risen at the exact same rate as 20-min power, but it won't be far off.
    Do you thing data from hard training should be used for determination of of FTP or only data from testing should be valid?
    Use all data. Performance is performance (provided the data is good quality).

    Proof of the pudding is in the eating. If you adjust your training levels and power ranges for any specific efforts, e.g. lift power range target for threshold level work and are routinely able to sustain a higher power than you were before, then you have strong evidence of improved fitness.
  • EBEBEBEB Posts: 98
    What sort of average power? I ask because I know I can get a higher normalised power than I can get an FTP.

    A lot of software and firmware defaults to NP. It is a simple formula and, given the maths, can't possibly be anything more than an estimate. I'm not aware of anything better, but I always view the numbers with a degree of scepticism
  • What sort of average power? I ask because I know I can get a higher normalised power than I can get an FTP.

    A lot of software and firmware defaults to NP. It is a simple formula and, given the maths, can't possibly be anything more than an estimate. I'm not aware of anything better, but I always view the numbers with a degree of scepticism
    Normalized Power isn't an estimate of anything, it is what it is.

    You can however use it to estimate other things, e.g. FTP. But only from hard efforts of ~ 1-hour duration. In that case almost invariably FTP will be closer to NP than to average power (assuming it's been calculated correctly), and for the majority of people NP from such a ride will at most be 5% higher than FTP.
  • sven_jtosven_jto Posts: 183
    The numbers are from avg power. The Np power for those 20 mins was like 15 watts higher as it's a chaotic chaingang...
    I think it's useless to use np for anything under an hour?
  • The numbers are from avg power. The Np power for those 20 mins was like 15 watts higher as it's a chaotic chaingang...
    I think it's useless to use np for anything under an hour?
    20-min is a little short to be looking at NP as an indicator of quasi-steady state capabilities.

    At most I'd consider it an indicator of "repeatability" when looking at sections of a ride for durations of ~20-30-min or so.
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