NP readings for shorter VO2 max?

hollow_r

I've noticed that with WKO the Normalized Power is not listed for intervals less than 5 minutes (in a created range), hence with the VO2 max as prescribed, for all but you immortals out there who can last for 5" @ VO2 max, it appears an unavailable parameter.

Should I just use the average power instead or is there some super secret keyboard strokes that you only get access to after a certain number of gallons of koolaid?

On everything else it seems we focus on NP and seeing as how NP always seems to be higher than AvP, I hate to give up those few watts.  Call me greedy.

Scott Alexander

I use PAvg for any interval that's not recordable by your device(s). Also helps you stay consistent with the application of power/watts to do so, instead of spiking too much (which lowers your VI).

Scott Alexander

Let me clarify here, if your nose is buried in the PM, then look at realtime watts/power (maybe 3-5 rolling average) - but if you're staring at WKO+ (or other software), then the average power for the interval is the only thing you can look at in most cases.

hollow_r

Thanks for the input.

Kevin Walter

Yes, use Average Power instead of Normalized Power for short intervals. For short intervals AP and NP are the same.

William Jenks

What everyone says here is correct in operation, but not quite in detail. :-)

Average Power is just that...average power.

However, as you probably know, NP involves raising the instantaneous power to the 4th power and then eventually taking the root of that again after the averaging. Because of this 4th power business, the transitory noise in the data get hugely exaggerated. As a result, the NP is not done with the actual transitory power, but with a running average transitory power. I forget exactly how long it is, but I *think* it's 30 seconds. Regardless, this means that the NP calculation is not very meaningful until you get out to intervals that are significantly longer than the averaging period. As a result WKO has an arbitrary cutoff that says it won't even bother to calculate an NP for an interval of less than 5 minutes duration.

So, yeah, what you want to do is use AP for short intervals. In theory, you could write an algorithm to calculate NP for them (and it wouldn't necessarily just give you AP), but in practice there is too much noise in the data for it to work very well.


(The xPower in Race Day and Golden Cheetah have an exponentially weighted power averaging designed to do the same kind of thing...but the way it's done there always makes the xPower a little lower than the NP. But this averaging method is the source of that difference.)

hollow_r

I'll put the slide rule away and just use the AP.
Thanks for taking the time to explain it.

kurshing

William = wow

tuckerm

Yes it's 30 seconds William. Showoff.

TH3 FRB

Posted By Kevin Walter on 26 Dec 2011 11:48 AM

Yes, use Average Power instead of Normalized Power for short intervals. For short intervals AP and NP are the same.

AP = NP for any steady state interval, no matter the duration.  All NP does is take variability into accountby basically giving you a bit more credit for higher power output beyond what simple averaging would.  So basically, as VI approaches 1 (as it sould for our intervals), NP approaches AP.