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JaRok2300




Joined: 01 May 2014
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Location: Worcester, UK

PostPosted: Mon Oct 30, 2017 8:31 pm    Post subject: AP v NP Reply with quote

I did a fairly undulating ride on Sunday where I was the heaviest and least fit rider so had to work particularly hard up hill to stay with the group (or at least keep them in sight)
The result of this was an average power of 168W and normalised power of 212W over the ride 2hrs 15mins.
Is NP a representation of what power you could have averaged had a more even effort been held and if so would that be a better indicator of FTP than a 20min test (for example) particularly for "real world" rides?
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jibberjim




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PostPosted: Mon Oct 30, 2017 10:01 pm    Post subject: Re: AP v NP Reply with quote

JaRok2300 wrote:
Is NP a representation of what power you could have averaged had a more even effort been held and if so would that be a better indicator of FTP than a 20min test (for example) particularly for "real world" rides?


That's the idea, if it's more representative of an FTP value, really depends on what you want an FTP value for, FTP is pretty meaningless really.

If you want it for some sort of training stress measurement then it's likely to be a lot more accurate (since NP is used in the TSS metric) if you want it for judging how hard to go for a 20 or 60 minute Time trial effort, then it's worse.

If you want it to just wave around in the café after the ride, well then you'll just pick the bigger one of course.
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iwaters




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PostPosted: Tue Oct 31, 2017 9:01 am    Post subject: Re: AP v NP Reply with quote

JaRok2300 wrote:

Is NP a representation of what power you could have averaged had a more even effort been held and if so would that be a better indicator of FTP than a 20min test (for example) particularly for "real world" rides?


Pretty much, NP is represents the physiological cost of the ride. If your power output had been constant then for the same "cost" you could have hit the NP number as your AP. For FTP testing though your output should be pretty constant whether you do a 20 or 60min test. The purpose of NP is to factor in short bursts or hard climbs that are evened out by coasting when looking at AP.

The danger of doing an FTP test and using NP is you dump a load of anaerobic output in the closing stages which spikes the NP but isn't really sustainable.

I am a big heavy rider and my NP is always a higher than AP by 30W or so because climbing a big hill really requires high power output.
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JaRok2300




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PostPosted: Tue Oct 31, 2017 9:03 am    Post subject: Reply with quote

Thanks Jim, the context is around using that figure for future workout levels.

I'm not sure a 20min test works very well for me as I don't think it scales up to an hour. I.E. I am weaker over an hour than the 20min test would suggest.

So I'm thinking that NP for any ride of an hour or more might be a better way of assessing FTP and therefore training levels from it. So if I did a ride of exactly an hour and my NP was 200W that is saying I could have held 200W steady for that hour even if the actual average was say 180W. I found something in training peaks similar to that after my initial post.

•Functional Threshold Power (FTP): •Your Functional Threshold Power is by definition the Normalized Power for an all out effort of 60 minutes. However, you can get a fairly accurate estimate of your FTP by doing an all out effort of 20 minutes, then subtracting 5% from the average power value for that interval.

PS. Café willy waving is not an option. 2W/Kg ain't impressing anyone!
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JaRok2300




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PostPosted: Tue Oct 31, 2017 9:10 am    Post subject: Reply with quote

Thanks iwaters

On a slight tangent, but related issue, what power output is considered to be "burning matches"

At my weight I struggle to get up anything resembling a hill below about 300W. If my FTP was say 200W would that be considered too high and ultimately impact me over longer distances. What % FTP should you be aiming to stay below as an upper limit?
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Jorgan




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PostPosted: Tue Oct 31, 2017 9:29 am    Post subject: Reply with quote

The two figures should be almost identical on a trainer though, for obvious reasons; or any segment where the effort is consistent like a steady climb.
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iwaters




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PostPosted: Tue Oct 31, 2017 11:54 am    Post subject: Reply with quote

JaRok2300 wrote:
Thanks iwaters

On a slight tangent, but related issue, what power output is considered to be "burning matches"

At my weight I struggle to get up anything resembling a hill below about 300W. If my FTP was say 200W would that be considered too high and ultimately impact me over longer distances. What % FTP should you be aiming to stay below as an upper limit?


I think a lot of this is trial and error and also depends on the overall distance. Lots of info here:

https://www.trainingpeaks.com/blog/what-is-a-match/

I am the same that on a reasonable hill I will be going over 300W to get up it. Really steep and I will need to push 400-500W.

In an Oly distance I can burn a few hills at 350W and not impact my run. I recently did a tough middle distance and although there were no big hills repeated efforts at 100-110% FTP killed my run.
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ttowel




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PostPosted: Tue Oct 31, 2017 11:58 am    Post subject: Reply with quote

Check that your garmin recording is set to "Do not include zeros" if you want a more useful AP.

Soft pedalling is one thing, but freewheeling does drop AP numbers very quickly
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jibberjim




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PostPosted: Tue Oct 31, 2017 1:37 pm    Post subject: Reply with quote

JaRok2300 wrote:
Thanks Jim, the context is around using that figure for future workout levels.


Forget about FTP for this, it's useless for it.

Either use PE with feedback from similar durations for previous efforts of very similar durations. Or just use efforts at similar durations. A single number (FTP) is an utterly pointless way of doing it that can only introduce error.

If your FTP is wrongly identified your targets will be wrong. If your curve does not fit the decided "norm" then deriving it from FTP will be wrong. And your curve certainly won't fit the norm, especially if relatively unfit, or have a disproportionately large anaerobic component (which unless you're very overweight you probably do if you only have 2w/kg as it varies much less with training compared to the aerobic)
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Jorgan




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PostPosted: Wed Nov 01, 2017 10:24 am    Post subject: Reply with quote

ttowel wrote:
Check that your garmin recording is set to "Do not include zeros" if you want a more useful AP.

Soft pedalling is one thing, but freewheeling does drop AP numbers very quickly


Which school do you belong to, include zeros or no zeros?
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stenard




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PostPosted: Wed Nov 01, 2017 12:30 pm    Post subject: Reply with quote

Jorgan wrote:
ttowel wrote:
Check that your garmin recording is set to "Do not include zeros" if you want a more useful AP.

Soft pedalling is one thing, but freewheeling does drop AP numbers very quickly


Which school do you belong to, include zeros or no zeros?

I thought it was pretty much a given that you should be including power zeros?

As said on the below ST thread, if you want to know your AP for a given interval/climb/etc, then just use the lap average field and hit lap.

http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Do_I_want_zero_averaging_for_power_P4528943/

The thing I hadnt thought about which is also referenced in that ST thread is the impact of smart recording on other metrics like NP/IF/etc. I can certainly see that if the file doesnt contain the data points, then those metrics can't possibly be accurate. Would that explain the difference between the power values you were getting between your 920 and Edge Jorgan?
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explorerJC




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PostPosted: Wed Nov 01, 2017 1:17 pm    Post subject: Reply with quote

Jorgan wrote:
ttowel wrote:
Check that your garmin recording is set to "Do not include zeros" if you want a more useful AP.

Soft pedalling is one thing, but freewheeling does drop AP numbers very quickly


Which school do you belong to, include zeros or no zeros?


if you don't include zeros you don't at least capture the full performance....this is especially so for those who coast a lot, obviously..
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Jorgan




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PostPosted: Wed Nov 01, 2017 3:35 pm    Post subject: Reply with quote

For the record, I include zeros. Hywel sounded like he was suggesting not including them to the OP, although that might not be what he does himself.
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explorerJC




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PostPosted: Wed Nov 01, 2017 3:52 pm    Post subject: Reply with quote

Jorgan wrote:
For the record, I include zeros. Hywel sounded like he was suggesting not including them to the OP, although that might not be what he does himself.


that's how i interpreted it....but i've seen him race and i doubt there's much freewheeling going on :0
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stenard




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PostPosted: Wed Nov 01, 2017 5:07 pm    Post subject: Reply with quote

Jorgan wrote:
For the record, I include zeros.

Have you double checked that that's the case on both your edge and 920? It was just something that sprang to mind as a reason for your mismatch in power data between the two. Smart recording is the other potential reason ... are you using that on one of the devices?

Slightly off topic, as it relates to a post of yours in a different thread from a while back, but obviously related
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