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Power Training - Explain FTP Measurement

doyler78doyler78 Posts: 1,951
I have read the book, Training and Racing with a Power Meter, but one thing has me confused.

If watts are watts and terrain, etc then become irrelevant then why do FTP and power profile tests have to be conducted on the same road in roughly similiar weather conditions. It seems a contradiction to me though I am sure there must be a very obvious reason.

When I think of it like this it makes finding reasons even harder because if terrain, weather, etc are determinants of calculated FTP then surely how can you ever be sure that you are training with the right FTP however my understanding is that you can only have one FTP and the reason for that is because you are putting in an all out effort and that effort if it is all out means that nothing else is relevant and FTP with fitness levels remaining same should end up with the same number.

Can anyone explain reason for the need for consistency in the testing.


  • That's a good question. A few comments:

    FTP is defined as the highest average power you can sustain in a quasi-steady state for about an hour. So, to do a test for FTP, you need terrain that will enable you to maintain a quasi-steady state power output.

    Relatively constant gradient terrain helps with this. It can be difficult in very hilly terrain to maintain the same average power.

    There are other factors that impact our ability to generate high quasi-steady state power as well. The include, inter alia:
    - Altitude variation
    - Body temperature changes
    - Motivation levels
    - Hydration levels
    - Fatigue levels and so on

    Hence, when testing for FTP, it makes sense to at least minimise some of these variations by testing at similar altitudes and not doing so in extreme heat/cold conditions or if indoors being sure to have plenty of body cooling with fans. Make sure you have similar levels of fatigue/freshness for the test and so on.

    Some riders do notice a different ability in generating sustained long duration power when climbing vs flat land vs indoor trainers. There are various reasons for that.

    In essence, it makes sense to settle on a test method that will provide an FTP value where by it is at least a consistent and reliable indicator of fitness levels.

    Then whether you choose hills, flats or an indoor trainer might depend on where most of your riding is being done.
  • doyler78doyler78 Posts: 1,951
    Thanks Alex that does make sense.
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