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Normal Power NP

Posted: Mon Jan 10, 2011 1:34 am
by madmaxx
Im not sure if this has already been discussed and i apologize in advance for my ignorance but i have noticed that the NP and Ave Power for a particular ride is different granting that the ride started and ended the same time why is it that the NP is always higher than the ave power reading?
thanks...

Re: Normal Power NP

Posted: Mon Jan 10, 2011 3:41 am
by KenS
Normalized power takes into account the physiological effects of training. This varies with the fourth power of power output.
So to get normalized power you take the 30 second moving average power, raise it to the fourth power, add them up for the whole ride then take the fourth root. Unless you have constant power output this will invariably result in NP being higher than average power.
Put another way, NP tells you what constant power output for the same training time would have the same physiological effect as your training session with varying power.

Re: Normal Power NP

Posted: Mon Jan 10, 2011 1:20 pm
by racerfern
NP gives more credit to harder efforts. So, doing intervals or blasting up a short hill gets more credit than the easy spin riding between intervals or the coasting down the hill. The greater the difference between AP and NP the greater the variability of your ride.

OTOH, if you ride steady state for one hour your AP and NP should be very close.

Re: Normal Power NP

Posted: Tue Jan 11, 2011 12:58 am
by madmaxx
Got it! thanks.....

Re: Normal Power NP

Posted: Tue Mar 25, 2014 1:25 am
by Pete
I presume NP does not account for accumulated time?
EG Putting out 200% FTP for 1 minute after an hour of 90% FTP is harder than the same effort after say doing the 200% effort first and then the 1hr @ 90%.
In fact the 90% 1hr effort would get progressively harder towards the end, and yet TSS for say 1hr at 90% is the same as 2hr at 45%?
But you could ride at 45% all day.

Re: Normal Power NP

Posted: Tue Mar 25, 2014 11:58 am
by racerfern
http://www.endurancecorner.com/wko_definitions

Two hours at 50% is substantially less effort than one hour at 100%.

IIRC one hour at 50% is only 25TSS or 33TSS (sorry, I'm trying to recall from memory) points where as one hour at 100% is 100TSS. So at 50% it's going to take either three or four hours to accumulate 100TSS which is one only hour at 100%

Re: Normal Power NP

Posted: Tue Mar 25, 2014 10:20 pm
by Pete
Ah - thanks for that link.
I must have read an over-simplified description elsewhere.