Normalized power is similar to average power in that it's a description of your power over a period of time.

But unlike average power it attempts to account for the physiological differences of increased power.

If you went 200W for one minute and then 400W for a minute, average power would tell you you averaged 300W.

But going 200W/400W has a higher physiological cost than going 300W for two minutes. It's harder.

So normalized power accounts for that and would tell you the normalized power was 330W (or something like that, didn't do the actual math).

It's for of like "feels like" in weather. Going 200/400W "feels" harder than just going 300W for 2 minutes.

The math is here.

That is incorrect.

When I'm wrong, I'm wrong. I guess I never really pay attention to average or NP over a whole ride anyways. Individual intervals sure, but except for a flat course where the delta between the two isn't much, I haven't seen the point.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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Without whipping out my Training with power book.... basically here is the ideology....

If your FTP was 200W, and you did 60 minutes of low FTP% of 50%, so 100W, but then did (3) 15 second sprints in there of 300% FTP, the average power would come out to 106.25W. But Surely this exercise was more difficult then doing an average of 106.25 watts (53% FTP) for 60 minutes. Normalized power takes into account that this high intensity bursts are "worth more" than just their average. Hope I said all of this correctly.

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- Jordan

My Strava

Normalized power is just that, your power normalized. It's telling you what the physiological cost of your ride was if you had done it at a steady state effort. If you ride steady at 225 watts then your normalized and average power will be the same (225w). If you're doing intervals then it will normalize/flatten the power to a number equivalent to what the effort would have been if you did it at steady state.

Edit: Normalized power is:

As I remember the math is a 30 second rolling average of: Each data point raised to the 4th power, added together and then take the 4th root of that amount

The higher numbers are given more weight than the lower numbers and that is supposed to better represent the cost of the effort.

Average power is just that... average.

NP accounts for the dips and peaks, and translates that into "what would've felt like if it were in average power".

^^This is what I think of when I think of NP in a non-scientific, non-mathematical, easy-to-understand way.

So others have done a very good job of explaining normalised power but potentially haven't explained what the problem is with plain old power.

Put simple looking at raw power is nearly useless. Power fluctuates massively on a sub-second basis due to the process involved and specifically the inherent dead phase-power phase nature of each crank rotation. In order to make any sense of the data you really need to look at an average across multiple crank rotations so the sub-second variability goes into hiding. This is why when we talk about power its always averaged or normalised over a time period 3 second, 5 second, 20 min, 1 hr etc. etc. Straight averaging makes the numbers easy to understand BUT it doesn't take into account that the inherent variability in power is a big factor in physiologically stress. In effect by averaging away the variability you are losing key information related to physiologic stress.

Normalised power is a way to express the physiologic stress of power variability in a simple number. Others have stated the formula and theory.

Overall raw power data is not useful on its own but becomes very useful when you mathematically summarise it. Normalised power is one way of doing this summary which expresses average physiological stress over a recorded time period.

I believe I heard this on a podcast, seems to resonate with me...

Average Power is exactly that, average power.

Normalized power is "the cost of doing business", when compared to average power.

NP = attempt to put the physiological cost on the body into a value for the purpose of TSS scores and other stuff.
AP = actual real world average of the power generated........almost totally worthless to look at for a workout on its own

So,

NP = physiological cost
AP = real world measure

NP is a number that represents stress on your body.

It only exists to explain why 10 min @ 300w followed by 10 min @100w is harder than 20 min @ 200w

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Strava

OK. I have got it. Thank you. That is actually pretty simple. Geesh, I should have come here in the first place!