Normalised power

[beldon]

Ok then, I cant get my answer elsewhere so thought I would try here.

NP or average??
1. If my NP shows 326 and my average is 315 for an hours ride, what is my FTP!
2. On my other training rides and there is a significant difference between the two (as like today when my 3 hours ride av was 228 but the NP was 268) which is most important?

Thanks

 

[acoggan]

Ok then, I cant get my answer elsewhere so thought I would try here.

NP or average??
1. If my NP shows 326 and my average is 315 for an hours ride, what is my FTP!

That's tough to say, since we don't know whether you went "flat out" or not.

2. On my other training rides and there is a significant difference between the two (as like today when my 3 hours ride av was 228 but the NP was 268) which is most important?

Thanks

Normalized power should be more indicative of the physiological strain.

 

[beldon]

That's tough to say, since we don't know whether you went "flat out" or not.

I was trying. It was a hilly course

 

[acoggan]

I was trying. It was a hilly course

Meaning that you were at least trying to go "flat out"? If so, then I'd say that 325 W is the better estimate of your functional threshold power.

 

[beldon]

Meaning that you were at least trying to go "flat out"? If so, then I'd say that 325 W is the better estimate of your functional threshold power.

Thank you for replying.

 

[acoggan]

Thank you for replying.

You're welcome.

 

[PSUcycling]

You're welcome.

well its nice to be nice to the nice....

 

[jstock]

Meaning that you were at least trying to go "flat out"? If so, then I'd say that 325 W is the better estimate of your functional threshold power.

I'll probably make a fool out of myself as usual, but I have to ask....

If you don't go "flat out", isn't it probable that you could have sustained a higher AP? So maybe NP will overestimate but FTP would still be higher than AP for the ride?

 

[whoawhoa]

I'll probably make a fool out of myself as usual, but I have to ask....

If you don't go "flat out", isn't it probable that you could have sustained a higher AP? So maybe NP will overestimate but FTP would still be higher than AP for the ride?

If you don't go "flat out" (assuming that by that you mean a maximal effort over the duration) then by definition both the NP and AP will be less than your FTP.

 

[jstock]

If you don't go "flat out" (assuming that by that you mean a maximal effort over the duration) then by definition both the NP and AP will be less than your FTP.

But wouldn't that mean that NP is always a better estimate than AP? Which from acoggan's answer does not seem to be the case.

I assumed that there was a universal definition of "flat out" that everyone else but me knew about

. I would assume that "flat out" would mean going as hard as you can for the entire duration (no variable pacing, no rest periods).

 

[acoggan]

If you don't go "flat out", isn't it probable that you could have sustained a higher AP? So maybe NP will overestimate but FTP would still be higher than AP for the ride?

While what you say is technically possible, it would be tough to generate an "NP buster" sort of ride w/o going close to "flat out". That, plus the fact that beldon's normalized and average powers aren't very far apart, says to me that his functional threshold power is closer to 325 W (i.e., his normalized power) than it is to 315 W (i.e., his average power). Indeed, it is possible that his functional threshold power is greater than 325 W, although it certainly sounds like he was giving it "full stick".

 

[jbvcoaching]

But wouldn't that mean that NP is always a better estimate than AP? Which from acoggan's answer does not seem to be the case.

I assumed that there was a universal definition of "flat out" that everyone else but me knew about

. I would assume that "flat out" would mean going as hard as you can for the entire duration (no variable pacing, no rest periods).

In this case, the low VI (1.035) indicates that it was a very steady ride, just not perfectly steady.

In the bigger picture, there was a less than 4% difference between AP and NP, and even NP's creator will tell you that +/-5% isthe rough margin of error.

I'd have split the difference and gone 320 to cover my bases.

 

[jstock]

While what you say is technically possible, it would be tough to generate an "NP buster" sort of ride w/o going close to "flat out". That, plus the fact that beldon's normalized and average powers aren't very far apart, says to me that his functional threshold power is closer to 325 W (i.e., his normalized power) than it is to 315 W (i.e., his average power). Indeed, it is possible that his functional threshold power is greater than 325 W, although it certainly sounds like he was giving it "full stick".

Maybe I should rephrase my question:
When is AP the better estimate?
If you don't go hard at all then then FTP>NP>=AP. You state (and I believe you) that if you go hard NP is a god estimate of FTP. But when is AP the better estimate of FTP?

Thanks,
J

 

[acoggan]

But wouldn't that mean that NP is always a better estimate than AP? Which from acoggan's answer does not seem to be the case.

For normalized power to not be the better estimate of functional threshold power would require that it overestimate to a greater extent than average power underestimates. That can happen, but usually the opposite is true. For example, even restricting the analysis to "NP buster" workouts (during which normalized power is, by definition, more than 5% higher than functional threshold power for a ~1 h effort), normalized power is closer to functional threshold power the vast majority of the time (i.e., for 23 out of 27 cases that I just examined).

EDIT: Some other stats for these 27 "NP buster" files...

Average duration (h): 0.99+/-0.13
Average average power (W): 227+/-53
Average normalized power (W): 308+/-39
Average VI (as already mentioned): 1.38+/-0.28
Average IF: 1.08+/-0.04

Average error if you used average power to estimate functional threshold power: -19+/-12%

Average error if you used normalized power to estimate functional threshold power: +8+/-4%

Correlation between average power and functional threshold power: R^2=0.69

Correlation between normalized power and functional threshold power: R^2=0.90

Remember, this is for a selected group of files for which, by definition, the normalized power algorithm failed to live up to it's billing...

 

[acoggan]

Maybe I should rephrase my question:
When is AP the better estimate?
If you don't go hard at all then then FTP>NP>=AP. You state (and I believe you) that if you go hard NP is a god estimate of FTP. But when is AP the better estimate of FTP?

I think the best answer to that question is "rarely" (but not "never").

Note: the average VI for the four files in which AP was the better estimate of functional threshold power was 1.21, which is actually less than the average for all of the "NP buster" files I've collected (which is 1.38). IOW, the degree of variability doesn't seem to be a distinguishing factor. Similarly, I have been unable to identify any common characteristic of these files - or for the 27 "NP busters" that I have collected - that would explain what makes them different.

 

[jstock]

I think the best answer to that question is "rarely" (but not "never").

Note: the average VI for the four files in which AP was the better estimate of functional threshold power was 1.21, which is actually less than the average for all of the "NP buster" files I've collected (which is 1.38). IOW, the degree of variability doesn't seem to be a distinguishing factor. Similarly, I have been unable to identify any common characteristic of these files - or for the 27 "NP busters" that I have collected - that would explain what makes them different.

Ok, thanks.
OP asked " NP or average??" and "If my NP shows 326 and my average is 315 for an hours ride, what is my FTP!"

And you answered " That's tough to say, since we don't know whether you went "flat out" or not."

Somehow I thought that your answer was related to the first question, hence my question. Also I seem to remember on other occasions when you have answered similar questions about whether to set FTP to 60 min NP with something like "that is not necessarily correct" without elaborating (or maybe I have been dreaming this).
But if I read your answers in this thread correctly FTP would, in the normal case, be close to 60 min NP (or higher if you have been lazy).

As always, thanks for educating me!
/J

 

[acoggan]

Somehow I thought that your answer was related to the first question, hence my question.

Sorry, I didn't mean to mislead you.

Also I seem to remember on other occasions when you have answered similar questions about whether to set FTP to 60 min NP with something like "that is not necessarily correct" without elaborating (or maybe I have been dreaming this).

No, that sounds like something I'd write.

More seriously, I think the issue here is that beldon asked "which is the better estimate of my functional threshold power?", not "what is the best way to estimate my functional threshold power?". As I hope is clear from my posts in this thread, normalized power is almost always closer than average power, but not always closer. Moreover, while it is almost always closer, the margin of error (for a ~1 h all-out effort) appears to be about 5%. So, while normalized power is almost always a better estimate of functional threshold power than average power, I don't consider it sufficiently precise to be relied upon as one's sole method of establishing your functional threshold power (and hence training levels, etc.).

 

[peterpen]

Tagging onto the end of this, what would people say about the following #'s?
Race:
Duration: 2:02:50
Work: 1805 kJ
TSS: 200.1 (intensity factor 0.989)
Norm Power: 287
VI: 1.17
Distance: 80.31 km
Min Max Avg
Power: 0 955 245

Peak 60min (268 watts):
Duration: 1:00:01
Work: 964 kJ
TSS: 113.5 (intensity factor 1.065)
Norm Power: 309
VI: 1.15
Distance: 40.227 km
Min Max Avg
Power: 34 955 268 watts

This was a flat RR in which I was very active (attacking, working for our sprinter) so there were some 2-4m sections w/ avg watts 100 over FTP, which might pump up the VI a bit. TSB was -7TSS, it was the end of a solid week of build, and I did two crits the day before.

When combined with recent intervals, these data make me feel I should adjust FTP up from 290w - any guesses as to where it will land?

 

[Alex Simmons]

http://www.cyclingforums.com/showpost.php?p=3176879&postcount=30

My original FTP estimate at the time was 295W but that was revised up to 310W following best ever 16km TT testing at 328W (AP & NP) and MAP test (399W) as well. But no ~ 1 hour TT to validate I'm afraid.

1 week later did a hard ~1hr TTT with NP of 295W.

 

[Alex Simmons]

When combined with recent intervals, these data make me feel I should adjust FTP up from 290w - any guesses as to where it will land?

303 - a powerful weapon that