What is "Normalised Power"?

[Marcellus]

(or should that be Watt?)

Can anyone give a simple laymans explanation of "Normalised Power"?

Looking at my last 3 road rides I can see
- Ride 1 - 101miles, Avg Power 155, Max average Power (over 20 mins) 183, Normalised Power 193
- Ride 2 - 20miles, Avg 164, Max Avg 177, Normalised 192
- Ride 3 - 48miles, Avg 148, Max Avg 163, Normalised 196

Not looking for "you're weak" or "I/I've got a mate who can push 500watts for 100 hours without breathing" type replies, just trying to understand what Normalised Power is and thought it might be useful for an explanation to give some real life data!

[Dannbodge]

Average power with all the 0s removed iirc

Strava says this but calls it weighted power:

[Marcellus]

There's significant differences between the numbers though and the trend isn't consistent, so can't be a pure calculation of ignoring the zeros can it?

- ride 1 - weighted power is 179 verses normalised 193
- ride 2 - weighted 180 versus 192
- ride 3 - weighted 175 Versusi 196

[upsidedownmark]

Basically it's an attempt to come up with the equivalent 'cost' of a steady state ride of the same length. Surging over the average costs more than you recover when you're below the average, so the easiest ride will always be holding the exact same wattage for the whole time. Any variability will raise NP over average, and the more 'bursty' the ride is, the bigger the difference.

https://www.trainingpeaks.com/blog/what-is-normali...

The actual formula:
1) starting at the 30 s mark, calculate a rolling 30 s average (of the preceeding time points, obviously).
2) raise all the values obtained in step #1 to the 4th power.
3) take the average of all of the values obtained in step #2.
4) take the 4th root of the value obtained in step #3.

(Andrew Coggan, not me)

ETA: As I understand, NP is copyright by training peaks/Andrew Coggan, so you either license, or come up with an alternative but similar concept as Strava has done.. don't know the strava calc, but it isn't the same.

Edited by upsidedownmark on Monday 25th September 15:59

[Marcellus]

good job I didn't ask for the complicated explanation!

(i'm sorry but I'm still none the wiser)

[Scabutz]

Marcellus said:

good job I didn't ask for the complicated explanation!

(i'm sorry but I'm still none the wiser)

Its represents the physiological cost of the ride. If you did 60 mins steady on the turbo at 80% FTP that would have a stress score of 80, and an average power of 200W and NP of 200W (using an example FTP of 250W).

If you did 60 minutes of intervals with power spikes up into the 300-400W range and then recoveries at 50-60% FTP your average power for the 60 minutes still might only be 200W. But that intervals session is going to create more training stress and produce more fatigue. But comparing average power both rides would look the same. Normalised power takes into account the spikes. In this example AP is 200W but NP might be as high as 240W for example.

Watts are a measure of work done. So looking at NP in the example above you have done more work. AP doesn't show that.

Normalised power is very useful if you use a PMC (Performance Management Chart) in something like WKO or TrainingPeaks as this is used to calculate the TSS (training stress score) which overtime measures your Acute and Chronic training loads - Fitness and Fatigue.

[upsidedownmark]

Marcellus said:

good job I didn't ask for the complicated explanation!

(i'm sorry but I'm still none the wiser)

If you ride for an hour at exactly 200 watts, NP, AP will be 200 watts.
If you ride for an hour alternating a minute at 100, a minute at 300, AP will be 200, NP will be > 200 (let's say 230).

That's because riding at average+100 watts for a minute does more 'damage' than you recover by riding at average-100 for a minute. The NP attempts to quantify that effect.

Can't make it much simpler than that.

[Marcellus]

OK cheers all I think I'm getting it.

So if I take 2 rides of equal distance say 8 weeks apart and the stats show;

Ride 1 - 99miles, 123ap, 149ap, TSS 345
Ride 2 - 101miles, 155ap, 192 np, tss 661

does that indicate that for Ride 1 I was "taking it easy" and using this data could I then set a realistic target for ride 1 based on ride 2 data?

Or does it indicate that ride 2 was just harder as i was c12% slower but I did try more?

[upsidedownmark]

If you want to quantify your rides:

TSS is 'how much work you did'. It's a function of time and NP.

NP gives you an idea of how much damage you were doing as an 'intelligent' average. Obviously 170watts NP for 2hrs is more effort than 170NP for 1 hr (and consequently TSS of the 2hr ride would be 2x the 1hr ride).

IF (Intensity Factor) is another useful number - it's the ratio of your NP to your threshold, so is a decent measure of how hard you're working relative to your capability.

Between those three, you can get a pretty good idea of most rides.

Yes, ride 2 was a lot harder than ride 1. Only seeing the IF could tell us whether you were taking it easy on ride 1, or utterly smashed yourself on ride to.

Edited by upsidedownmark on Tuesday 26th September 13:05

[anonymous-user]

TSS of 661 in 101 miles is very high indeed (IME)

If you look at the AVG. TSS / WEEK column in this table ( taken from https://www.trainingpeaks.com/blog/how-to-plan-you... ), you will see why I say that

[Marcellus]

I'm new to actually trying to train for anything so new to all of this and thinking "it's all numbers" so your comments are really helping me understand the stats guys so I really do appreciate it;

The IFs for the rides were;

Ride 1 - 0.82
Ride 2 - 1.06

With the table looking back at the last 4 weeks I've averaged; 10hours and 741tss

The high TSS from ride 2 could explain why I felt broken yesterday

[ChrisMCoupe]

How are you calculating your Avg Power and NP? Powermeter?

[anonymous-user]

Marcellus said:

OK cheers all I think I'm getting it.

So if I take 2 rides of equal distance say 8 weeks apart and the stats show;

Ride 1 - 99miles, 123ap, 149ap, TSS 345
Ride 2 - 101miles, 155ap, 192 np, tss 661

does that indicate that for Ride 1 I was "taking it easy" and using this data could I then set a realistic target for ride 1 based on ride 2 data?

Or does it indicate that ride 2 was just harder as i was c12% slower but I did try more?

upsidedownmark has covered this. My 2p:

Ride 2 was harder than ride 1, because over the same distance more or less your average power was quite a bit higher.

NP can be thought of (at least by me) as a measure of efficiency. Ride steady state on a flat surface and ave power = NP. Once you introduces surges in power (eg for climbs or sprints) NP will rise. Forex: on my ride home from work, I am constantly stopping for lights then pulling away hard to make the front of the pack. Not usual for NP to be more than 1.5 times AP, because all of those power surges pushing 4/5/600w for a bit* to get going cost me dearly.

But if I ride at the weekend out of London I will aim to keep NP within 10% of AP, because I'm largely moving all the time and riding at a steady state.

* as others have said, pushing big wattages is disproportionately costly. If you could say ride at 250W for an hour, you'd have no chance of riding at 500W for 30 minutes or 1000W for 15mins - it's not a linear relationship. Holding 250W for an hour might mean you could *hold* 1000w for may anywhere between 3 and ten seconds. The big numbers take disproportionately more out of your physiology. NP is a very specifically weighted average that reflects the impact that surges of high power have on the body.

[upsidedownmark]

Marcellus said:

I'm new to actually trying to train for anything so new to all of this and thinking "it's all numbers" so your comments are really helping me understand the stats guys so I really do appreciate it;

The IFs for the rides were;

Ride 1 - 0.82
Ride 2 - 1.06

With the table looking back at the last 4 weeks I've averaged; 10hours and 741tss

The high TSS from ride 2 could explain why I felt broken yesterday

Your threshold power setting is wrong (low), by quite some margin! (hence your TSS is way high)

an IF of 1.0 is threshold for 1 hr, then fall off and vomit, so by definition any ride of >1hr will have an IF of <1

An IF of .82 for a 100 miles is pretty solid too. 1.06 is 'impossible'.

As painful as it is, if you're trying to use a PM properly, I'd recommend doing a threshold test.

[anonymous-user]

^ yes, this.

How have you determined your NP for the purposes of getting TSS and IF numbers? And how are you measuring your AP and NP?

[Marcellus]

All this data that I'm using is taken from actual rides uploaded in to TrainingPeaks.

(ride 1 was on the 30th July in London and Ride 2 was last sunday in Brum)

Power is measured using Vector 2 pedals, I've done 2 FTP tests (12 weeks apart) and the latest recored;
Part a) 5 minute full gas climb AP 262 and NP of 277
Part b) 20minutes level constant full gas AP 190 and NP 196

So, currently FTP set at 182

[Marcellus]

upsidedownmark said:

Your threshold power setting is wrong (low), by quite some margin! (hence your TSS is way high)

an IF of 1.0 is threshold for 1 hr, then fall off and vomit, so by definition any ride of >1hr will have an IF of <1

An IF of .82 for a 100 miles is pretty solid too. 1.06 is 'impossible'.

As painful as it is, if you're trying to use a PM properly, I'd recommend doing a threshold test.

How sensitive is the IF to the Threshold?

I've never taken my FTP tests to the point of fallen off, vom'd and died so perhaps understated a little but we do know that my power isn't that great as I really struggle on climbs (and i used to pedal with only 1 leg).

If I think about the 0.82 and 1.06 and how I "felt" after the 0.82 I rode the 10 miles back to the hotel, went out for dinner that nigth and had a ride on teh Monday etc whereas after the 1.06 I had to ride 200m back to the car and felt that was too far, got home, had a sleep for a couple of hours, the day afterwards was struggling and couldn;t look at the bike (back on it today for a gentle 3/4s hour mind)

[Marcellus]

Greg66 said:

Ride 2 was harder than ride 1, because over the same distance more or less your average power was quite a bit higher.

yes ride 2 was harder 6,243ft climbing versus 4,065 on ride 1.

[upsidedownmark]

Marcellus said:

How sensitive is the IF to the Threshold?

I've never taken my FTP tests to the point of fallen off, vom'd and died so perhaps understated a little but we do know that my power isn't that great as I really struggle on climbs (and i used to pedal with only 1 leg).

If I think about the 0.82 and 1.06 and how I "felt" after the 0.82 I rode the 10 miles back to the hotel, went out for dinner that nigth and had a ride on teh Monday etc whereas after the 1.06 I had to ride 200m back to the car and felt that was too far, got home, had a sleep for a couple of hours, the day afterwards was struggling and couldn;t look at the bike (back on it today for a gentle 3/4s hour mind)

Very. IF = NP / Threshold. If your threshold is low, your IF will be high. 20 watts will make a significant difference.

Your IF numbers are still proportional, but they're too high.

Threshold is what you can do for an hour - by definition what you can do for 2 is less, and 5 or 6 a lot less.
an IF of 1.06 says you did more than your hour power for the whole 100 mile ride. Realistically, just not possible.

For comparison - without wishing to sound like a cock, I'd expect a 100 mile IF of 0.8 based on my experience. So that'd put your FTP nearer 240.. which sounds reasonable without knowing anything about you

FWIW I think it's pretty much impossible to do a good threshold test on the road, it simply involves going too deep. It really is an 'I think I'm gonna die' effort, and takes a bit of experience to learn to pace properly. I suggest it's done on a turbo.

If you have a garmin that can do apps, there's an FTP estimator app from xert that purports to figure out your Ftp from hard efforts.. so far it seems if I put in a really hard smash for 5mins or more, it generates a number that's reasonably close to my actual ftp..

Edited by upsidedownmark on Tuesday 26th September 17:21

[upsidedownmark]

p.s. personally I also struggle on climbs, doesn't mean you're low power. I have decent power but I'm a fat git, good on the flat, sucky on the climbs as the weight bites