The value of normalised power

The foundations for successful riding

The value of normalised power

Postby triangle » Fri Sep 02, 2011 3:34 pm

I started training with a power meter about three weeks ago. I had already read Allen and Coggan and a bunch of other training texts before getting my power meter so, at least in theory, understand how to use it etc. Am using WKO+ for data analysis.

One thing I have been wondering is the extent to which normalised power is really seen as a better alternative to average power. At the moment I am never sure if I should consider my average or norm power as the best indicator of my power effort across a long ride (the two are pretty much the same on very short rides or intervals for obvious reasons). On longish rides (upwards of two hours), of which I do two or three a week in addition to shorter rides, I find the two can vary markedly. For example - my tested FTP is 215 watts. On a 76km ride that takes 2hrs 40mins I might average 175 watts (81% of FTP) but have a norm power of 192 watts (89% of FTP).

Any advice would be greatly appreciated - new to cycling and even newer to using power instead of HR.

Ty in advance ...
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by BNA » Fri Sep 02, 2011 4:19 pm

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Re: The value of normalised power

Postby zero » Fri Sep 02, 2011 4:19 pm

If you sprint 100m and walk 100m, and keep doing that, you'll get to 1000m at the same time as a jogger does, which is the same work done, but you'll be more fatigued.

Normalised power reflects that average power reads disproportionately low compared to effort in a ride if the exigencies of the ride require you to vary effort.
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Re: The value of normalised power

Postby triangle » Fri Sep 02, 2011 4:55 pm

zero wrote:If you sprint 100m and walk 100m, and keep doing that, you'll get to 1000m at the same time as a jogger does, which is the same work done, but you'll be more fatigued.


Ha! That is an excellent analogy! That makes amazingly good sense - I see exactly why norm power is a better idea than average power. Thank you ... much appreciated!
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Re: The value of normalised power

Postby toolonglegs » Fri Sep 02, 2011 5:02 pm

But it's not better than average power!...if you train with NP you will have pretty screwed up training.
NP is great for races and comparing to average power in TT's...but it is not a substitute for Av power during efforts etc.
Last edited by toolonglegs on Fri Sep 02, 2011 5:03 pm, edited 1 time in total.
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Re: The value of normalised power

Postby triangle » Fri Sep 02, 2011 5:03 pm

toolonglegs wrote:But it's not better than average power!...if you train with NP you will have pretty screwed up training.


So ... what do I use it for then? And why should I train using average power rather than norm power? I'm confused again :-/
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Re: The value of normalised power

Postby toolonglegs » Fri Sep 02, 2011 5:12 pm

Because average power is what you have actually done...for training anything under 5 minutes NP is pointless...for longer efforts in training you should still be focused on average power.

In a race where you have to do what you have to do...NP can give you good insights into how hard a race was...my personal best was a 350w NP for 2 hours in a killer hard race...first hour was 380w NP....had I only had the average of 280w for 2 hours it would give me a completely different view....but when view together you get more understanding after the event...my meter at the time didn't show NP during an event.
As you are a newbie maybe you don't know that you can show you average watts for intervals while doing them instead of looking at the average watts for the entire ride...the powertap old heads took a bit of getting used to see what you need.
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Re: The value of normalised power

Postby Alex Simmons/RST » Sat Sep 03, 2011 3:08 am

triangle wrote:One thing I have been wondering is the extent to which normalised power is really seen as a better alternative to average power.

They are not alternative measures, they are complementary.

NP provides additional insight into the physiological strain encountered when riding, especially when such effort is highly variable in power output and provides a means to compare rides of different types and provides a better means than simply kJ to track overall workload in an acute and chronic sense.

when doing specific interval work, you are concerned with average power for the effort.
when inspecting over all ride/race data (or sections of a ride/race), then you will look at both to gain some insight into the demands.

as highlighted in the jog v sprint/walk example:

Let's say a rider can sustain 200W for 30-minutes as a maximum sustained effort, reasonably evenly paced.
There is no way that same rider would be able to do 300W for 1 min, then 100W for 1-min, repeated 14 more times in succession even though that's the same average power.

In the first case (even pacing) the normalised power is 200W, but in the latter (300W/100W on/off) it would be 233W. That's because NP weights sustained periods of higher power more heavily (in a manner consistent with the strain it places on us).

For longer durations such as this, then the NP one can attain is typically no more than 5% above what a rider can sustain at steady state effort (i.e. 210W in this example).
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Re: The value of normalised power

Postby triangle » Sat Sep 03, 2011 11:47 am

Thanks Alex and Toolonglegs ... that really helps. Complementary rather than alternative makes lots of sense, in particular ... thanks again, guys.
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