FTP - Average or Normalised Power?

FTP - Average or Normalised Power?

Postby nsidirop » Wed May 29, 2013 9:15 am

Today I did a 30 min all out ride as described by Joel Friel in his book Power Meter in order to check my FTP.
I did it in Fit Train mode and did not use the setup menu and FTP test in my iBike Newton.
According to Isaac my average power during the 30 min test was 253 W and norm power 259 W (I had some surges due to traffic and road conditions).
Which number would you use as FTP?
If I ran the test in the Newton setup menu would it use average or norm power? Logically it should be normalised power number as FTP, since IF and TSS are based on norm power, but it would be valuable to get feedback on this since I am not sure.

If i had used the FTP test in Newton would it also subtract the 5% in order to account for that the test is 30 min but is used for presenting max power during 60 min?
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Re: FTP - Average or Normalised Power?

Postby Davis6022 » Wed May 29, 2013 10:51 am

You should use normalized Power for a 60 minute test. Otherwise, take 95% of your average power for a 20 minute test. That's what the Newton does. There are some who disagree with 95% of the 20 minute average power since the 95% could be lower for some people. Look to see what your best 20-minute average power is from your ride today and take 95% of that.
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Wed May 29, 2013 12:19 pm

Interesting, do you know the reason for using average power in the shorter test and normalised power in the 60 min test?
I thought the choice was not dependant on test duration but rather on varability, if there is a significant difference between ave and norm power meaning variability could not be neglected, then norm power should be used since it reflects actual effort in a better way than average power during variable conditions.
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Re: FTP - Average or Normalised Power?

Postby Davis6022 » Wed May 29, 2013 1:46 pm

Take a look at the article in the link. Note the comments below the article. http://alex-cycle.blogspot.com/2008/05/the-seven-deadly-sins.html
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Re: FTP - Average or Normalised Power?

Postby racerfern » Thu May 30, 2013 1:09 am

FTP is your average power for 60 minutes. If using 30 minutes, I would treat it like a 20 minute test and use 95%. In your case 95% of 253w equals 240W.

FWIW, normalized power should not be used to calculate FTP regardless of the test duration. You can easily kill an FTP test by blasting for 2 minutes then doing temp for a few minutes then blasting again.

Note that in the seven deadly sins, the NP version is number 4 while the AP for one hour is the best indicator of all at number 7. Remember these are sins, with #1 being the worst.

Lastly, NP / AP = VI which is your variability index. Activities with very low VI are excellent indicators of your true abilities, activities with high VI such as activities with hard intervals are not good indicators, they're simply hard activities.
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Thu May 30, 2013 2:28 am

That really clarifies things, thanks.
Looks like I have to do a new test, going full out during 20 min. I am pretty sure I would be able to raise the watts if I am looking at a 20 min test compared to a 30 min.

How about the fact that doing this test alone as a workout and not in a race or competition with training partners would probably result in lower watts, should that not be taken into account somehow?
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Re: FTP - Average or Normalised Power?

Postby racerfern » Thu May 30, 2013 11:53 am

I think you're missing the forest for the trees. By concentrating on a 20 minute test instead of a 30 minute test you're look at a change of two watts, everything else being equal.

FTP is not a constant, it's a general number to work from in the hopes of gradually raising it over time. Your FTP might have been 253 the other day and tomorrow it might be 260 and three days after that it might be 240 because you didn't eat properly the day before. It's a moving target to say the least.

I suggest you take the 240w number and build a plan around that number. Then in six weeks do the same test at the same place and see how much you improve. You'll suddenly jump then flatten out, then jump again but you'll see a general upward trend if you're training properly It's the nature of the beast. Your initial results should be quite impressive then you'll settle in. Have fun and keep us posted on your progress.
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Re: FTP - Average or Normalised Power?

Postby heith » Thu May 30, 2013 11:22 pm

Take the last 8 minute avg.(22-30min) of that 30min test. That's your FTP if you went "all out" from the beginning. Meaning you started above your FTP and gradually decreased especially between 12 and 18minutes. I actually find that method to be the most accurate for me and spot on for a 1 hour TT.
should feel like this.
1m-8m: lets do this! I'm so strong right now I'm going to shatter my last session.
9m-12m: wait, this is really starting to hurt, did I warm up enough.
12m-15m: ok, I definitely can't hold this. I want to quit
16m-18m: guess who's trying to recover and hold watts at the same time.
19m-22m: Ok, I'm recovered and starting to settle in.
22m-30m: focused and settled in.
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Sat Jun 01, 2013 5:03 pm

Heith, you are spot on, I went through the same emotions every time :lol:

Fernando, thanks for your valuable input. Even if being new to training based on power I am aware of that the FTP is a moving target. I've actually done three FTP tests also on my indoor Tacx Bushido trainer earlier this year. On the indoor trainer my NP and AP have been essentially equal because I've been able to hold steady efforts during the entire test. That was not possible on the outdoor test due to road and traffic conditions. That's why the question came up in my head on which parameter to use.

As info, here is my test series:

Week 30 min AP LTHR (last 20 min HR average) Type
13w04 234 166 Indoor trainer
13w10 248 169 Indoor trainer
13w16 252 172 Indoor trainer
13w22 259 166 Road

The first 3 tests that I did on the indoor trainer were no doubt significantly harder. I was really hurting the last 20 min. That can be seen in the HR figures as well. I don't really now what happened on the w16 test with my HR, maybe I had an espresso too much or the fan was set on too low level, I am pretty sure my LTHR is not as high as 172.

The last one is the test I did outdoor as I've descibed in this topic. After checking my ride file again in Isaac I actually had 259 W average and not 253 as I wrote earlier. Now of course it could be difficult to compare the iBike figures for the outdoor test with the trainer figures since the power is measured in different ways, test conditions were different etc etc. But none the less it looks like I am making progress, wouldn't you say?

Lets assume that the last test is representable for my abilities.
If I use the 95% rule I get my FTP = 246 W
If I use the AP for the last 8 min I would according to the ride file have an FTP = 264 W, that's 7% higher

Now on Thursday I have a 100 km / 1000 ascending meter race which is probably going to take me about 3h30min. In theory FTP is the power level I can manage for 1 hour. If I use the 5% subtraction rule for each additonal hour I should be able to manage 1-2*0.05-0.025=87.5% of my FTP for the entire race.

Using the two rules above gives me 215W and 230W respectively

I believe the lower figure is close to my ability. Should I use it as an average power (or NP?) target during the race?

/Nikitas
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Re: FTP - Average or Normalised Power?

Postby racerfern » Sat Jun 01, 2013 5:27 pm

Average power. Good luck and most of all, HAVE FUN!
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Fri Jun 21, 2013 4:32 pm

Here is the ride file from the race in case anybody cares to take a look. I wasn't able to keep 215-230 W average but wisely decied to cover from wind by staying behind a rotating team in the front of a 50 man peleton most of the race.
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Re: FTP - Average or Normalised Power?

Postby racerfern » Fri Jun 21, 2013 7:35 pm

Great effort whether you're the one in the wind or tucked in. Your best 60 minute average is from 19m to 1h 19m with an average of 195watts. Note that your NP was 236 for this one hour so there was a fair amount of variability.

However your best 20 minutes were at the very end of the event with a 243 avg. So you saved enough to bring it home with guns blazing. Nice.
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Sat Jun 22, 2013 7:28 am

Thanks Fernando! I think my race strategy went very well, at about 10 km from the end I had enough power left to make a break and keep it to the finish out of the 50-man group, this way I was able to finish 6th in my starting group. The 20 min with 243 W average include this part, at about 3 hours into the race is the spot where I hit the throttle. In the wind plot it can clearly be seen were the blue hanging ice pickles suddenly dissapear. Once clear from the peleton I had a great feeling emptying myself along side with feeling of acid filling up my muscles and the sensation of my lungs not being far from exploding. These last 15 min my power average is above my estimated FTP level.

Also very interesting to see that you actually detected the spot (at 1h19min into the race) where I get caught by the peleton. Is there an automatic way in Isaac to detect best 1 hour, 30 min, 20 min etc etc average ? Would be a nice feature to have in Isaac.

The ride file clearly shows the different conditions I experienced during the race. From the start to about 1h19min into the race I am part of a small group (maybe 5 riders or so) going quite hard and in some sections I am in the front or by myself. This part includes the steepest hills in the race. At 1h19min I get caught by the larger group which I join until I make the break as I describe above at about 3 hours into the race. Some statistics I notice:

Road speed/Effort speed//AP/NP:
Start - 1h19m: 30.74 / 25.76 / 180 / 225 (5 man group)
1h19m-3h00m: 32.64 / 26.31 / 167 / 193 (tucked in the peleton)
Last 15 min: 35.85 / 36.05 / 260 / 302 (in solo break)

Interesting to see how much faster the middle part went compared to the first, even with a relative low effort.
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Re: FTP - Average or Normalised Power?

Postby racerfern » Sat Jun 22, 2013 5:27 pm

Is there an automatic way in Isaac to detect best 1 hour, 30 min, 20 min etc etc average ?


In Isaac you would have to highlight the section you think has the best effort which obviously is not easy. I use SportTracks along with a plugin called Training Analysis. You can also use WKO+
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Re: FTP - Average or Normalised Power?

Postby ronpei » Sun Jun 23, 2013 8:30 am

Another very good option is Golden Cheetah. I have the Sport tracks and Training load add on but I prefer Golden Cheetah. The GC documentation isn't that great but it has all kinds of great features, one of which is the CP curve, also known as the peak power curve or mean maximal power curve. It has all of the features one could want and can read the CSV file format from the iBike. If you merge a GPS track and expert the file it will import that as well. It is freeware and a really great product. Well worth a look.
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Re: FTP - Average or Normalised Power?

Postby racerfern » Sun Jun 23, 2013 5:59 pm

Golden Cheetah is awesome. However the only two programs I've seen that highlight the actual area is WKO+ and the Training Analysis plugin with SportTracks. The others have some sort of CP curve that show your max power for whatever amount of time but not where it occurred during a ride.

I thought it was interesting that nsidirop's best hour was from 0h19m to 1h19m but his best 0h20m was right at the end of the event. The best 20m generally lands within the confines of the best hour but he saved a bit of energy for the end.
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Re: FTP - Average or Normalised Power?

Postby nsidirop » Thu Jul 11, 2013 4:16 am

Did another FTP yesterday. This time I warmed up properly for about 30 minutes and then started a 20 min max test. During a part of the test there was quite a bit of a headwind, I don't know if that affected the power estimation of the Newton so that readings are too high (or too low).
Anyway, according to Isaac AP=289 W during the 20 min test meaning FTP = 0.95*289=274 W
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Re: FTP - Average or Normalised Power?

Postby racerfern » Fri Jul 12, 2013 12:22 am

Nice! Now let's see 285 in 6 wks!
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Re: FTP - Average or Normalised Power?

Postby JoseJ » Fri Sep 20, 2013 10:40 am

I prefer Hunter Allen‘s messurements and explanations.....do a 20 minutes all out ride..take average power and multipli by .95..thiz iz the easiest and accurate way and you will get your FTP
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