Average Power vs. Normalized Power and the relationship between them

I’ve recently gone back through a bunch of ride data and found that on rides that are fairly similar of 30ish miles with 1400 ft or so of vertical have average powers that can range from call it 190-225 or so, but in most of the rides the normalized power number is in a much tighter range around 235-245. In some cases, average power is 20 or so watts lower on a given ride, but normalized power is actually higher. This is all using Garmin connect data.

How should I be interpreting this?

“All models are wrong, but some are useful”

Normalized power is a model to try and give you a sense of what an equivalently difficult effort would be if ridden at a steady state for a similar duration, but its incredibly course and effort dependent in terms of fitting within the rolling 30s window under which it is calculated.

So I’ll turn the question around to you, as the one who rode the courses

How do you interpret it relative to how you felt on the day?

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The feeling is hard to tell given there has been a month or two in between some of these. I was most interested to find my recent avg. watts being lower than late may/early June. I don’t feel a difference, but probably a 10-20 watt decrease for avg power depending on ride from the peak.

This is pretty common for folks not adhering to a training plan, and is totally fine.

What happens, in my experience:
People tend to ride roughly the same overall “effort” each day unless they are intentionally, consciously choosing to ride at a different effort level on the day. Depending on the stochastic nature of the ride course that they are doing they’ll have higher or lower overall average power, but a relatively tight range for their normalized power from day to day.

Hillier courses or stop-and-go courses will result in lower average power but normalized power will remain elevated, if the rider is riding to the same relative effort.

Conversely, a long steady ride might result in normalized power and average power being quite close, but if the rider rides to the same overall end-of-ride perception of effort, the normalized power is often quite similar to the other hillier rides, where average power is much lower.

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That makes sense. And I’m definitely not on a training plan. Yet at least. I just subscribed and got a trainer. Hard for me to want to come inside in the nice weather though so following a plan may have to wait until winter. I know there is an outdoor option for workouts I just don’t think I’ll be able to follow it well on the roads. I am trying to sprinkle in more moderate and lighter effort days in though. I used to just ride at a pretty high effort all the time which left NP around my FTP with average 10% lower or so.

When normalized power was developed, it was really only meant to be used for assigning an equivalent TSS for tracking training, so be careful with any further extrapolations

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Avg power for an entire ride can be hard to compare because coasting and stops can severely drop that number. So unless you are sure that both are comparable in that aspect then NP might be a slightly better way to compare them.

Huh? It has nothing to do with a training plan. But since you brought it up, doing intervals will usually result in higher normalized power vs average power. So will riding up and down hills where you put out more power going up, and less power going down. If you ride at exactly 200W, then normalized and average power will be identical.

Like stevemz said above, normalized power was created to equate training stress to rides with different power variation.

The normalized power model is based on how much blood lactate accumulates in your blood based on power output relative to threshold/FTP power. Higher power = more lactate = more strain / training stress. Lower power = less lactate = less strain / training stress.

I’ll add that you can’t assume that you could actually hold the NP wattage in a steady state scenario. The high power is weighted more than the lows.

It can however be a reliable indicator for how intense a ride is relative to your FTP.

I just meant that it’s a common experience for someone not following a training plan, to have more variable AP, and more tightly grouped NP numbers.

Folks who follow a training plan tend to have decidedly harder days, and easier days. Thus, wider range of daily AP, and NP values.

Folks who are newer and “just riding” (as I usually do), but who like to feel like they got a good workout each time they go out for a ride (as I also do), tend to autoregulate a bit, and often end up with very similar or tightly bunched NP values for many of their rides.

My experience is very similar to the OP here. My NP is often in the 240-260W range, but my average power may range from 140-240, a much wider quantitative range.

For riders on most good training plans, and on plans like that put out by TR, where there are easy days (say… 130W AP, 170W NP), more steady state aerobic days (say 220W AP, 225W NP), and interval days (say, 220W AP, 290W NP), there tends to be a wider range of both AP & NP, rather than a tight cluster of daily NP values and a wider range of daily AP values.

Apologies if I was unclear before. I was attempting to comment on the human psychology of training plan adherence vs. no training plan, and what tends to happen with AP & NP values and their ranges.

You could most certainly achieve more highly variable NP values while not on a training plan.

I didn’t mean that this tight NP spread and wider AP spread was a guaranteed result of lack of training plan adherence. Just a human psychology quirk that tends to occur for some folks.

It just takes some level of intentionality to have more widely spread NP values from ride to ride, for some people, myself and my wife included. If left to my own devices, while training 3-4d/wk outdoors, I’ll have pretty tightly bunched NP values out of personal preference (and no attention paid to power numbers while riding), This happens just because there is a tight range where I feel like I got a good workout, but not killed myself… which is where my brain tends to self-select on most days. How I might achieve that could be widely variable from sprints-and-soft-pedaling, to steady riding on flats, to climbing up and down a local hill.

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Guilty

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