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Effect of Pauses on Normalized Power Calcs

esrein
over 4 years ago

Hi!

Am I correct in assuming that the Normalized Power calculations do not take into account pauses/breaks in the ride?  For example: If I take a 30 minute coffee break mid-way in my ride, during which the activity has been paused and my device is temporarily turned off, when I restart my ride the power averaging in the NP calc just pretends that break never happened?  (As opposed to the reality which is that for 30 minutes, I was putting out 0 Watts).

It seem this can cause drastically inaccurate estimations (too high) of NP, IF, and TSS.  I've considered, if taking a break, completely ending my activity and starting a new one, however this would then cause the new activity to be unaware of the power history before its creation and result in NP, IF, and TSS that are too high.

Is there any good solution to this?  It seems that the ideal thing would be for the Garmin device to refer to clock time for the calculation of NP so if a pause does occur, (coffee stops, traffic lights, etc) the device will see the change in clock time and input 0 watts for those times.

Thoughts?

Thanks!

  • 0 over 4 years ago

    The short answer is just don't use auto-pause and leave the timer running when you stop. This is in affected what you are asking for. Treat the elapsed time as the activity time.

  • 0 over 4 years ago

    I would have thought that including all that time at zero watts provides more misleading data than just removing the time and zero watts completely.

  • 0 over 4 years ago in reply to mcalista

    The zero watts issue (including vs not-including) is one relating solely to the Average Power calculation.  Normalized Power was developed with recognition that there are times in which one is putting out less, or no, power and those zero watts are considered.  

    Keeping the timer running (and including zeros) will result in a Average Power result that is not indicative of the efforts made during cycling, however, this does not adversely affect the Normalized Power calc.

  • 0 over 4 years ago in reply to esrein

    Using the elapsed time will inflate your TSS value.

    There are numerous threads on this topic on such forums as the wattage forum. Search for Bear and Burrito 

  • 0 over 4 years ago in reply to aweatherall

    I'm not sure why elapsed time will inflate TSS.  If we never use autopause and keep the timer running, both the NP and the TSS makes use of that running time.  When taking a coffee break, for example, the running time causes a gradual decrease in the activity's Normalized Power (and therefore, also Intensity Factor).  This reduced Normalized Power (and IF) is used with the running clock time to calculate a TSS that takes into account the break through the reduced NP/IF.  

    If the Garmin device made use of the Clock Time of the Activity Stop and Start, the Normalized Power could reflect the passage of Clock Time and gradually reduce even when the Activity is Paused.  The TSS calculation would also make use of the Clock Time between Activity Start and Finish - it would be the same duration of time that happens when we turn off AutoPause.

    Through the eyes of the NP and TSS calculations, there is no difference between 5 minutes of coasting down a hill at 0 Watts and stopping for a bathroom break for 5 minutes.