Monday, August 18, 2008

FTP Confirmation Test

I’m a scientist-athlete at heart (see Athlete Types below). I like to tinker with things in training to see what happens. My client-athletes are often the subjects for this tinkering. For example, for the past year or so I’ve been playing around with a less-stressful way of finding Functional threshold Power (FTP) than the very stressful 30-minute time trial test (CP30 test) I’ve used for several years and written about in my books. While I’ve found the CP30 test to be pretty accurate it is quite challenging and has a significant post-workout recovery component. There are times when I don’t want to stress the athlete that much but would like to check to see that we have FTP correct for the coming weeks. So I’ve been using another, much less stressful test to confirm that what we found earlier with a CP30 test is correct or to slightly modify what we have been previously using for FTP. This test requires having a very well-established lactate threshold heart rate (LTHR) which may have also been determined with CP30 tests, races and workout data. Having an accurate LTHR is critical to the test I’m about to describe.

LTHR occurs at about FTP. And since LTHR doesn’t change much from month to month or even year to year in well-conditioned athletes in a given sport (it varies between sports) it serves as a nice standard. FTP may, and should, change significantly over the course of a season, however. Yet it should always occur at about LTHR.

Here’s how I’ve been doing the FTP confirmation test.

On a bicycle indoor trainer the athlete warms up for 10 to 20 minutes. Then he/she starts a graded exercise test which consists of several four-minute work stages separated by one-minute recovery stages. The first work stage begins at a power that is about 80 watts below what FTP is currently considered to be based on previous testing. Each subsequent work stage is increased by 10 watts. This continues until LTHR is observed. The average power for this last stage is considered to be FTP.

As mentioned, I’ve used this confirmation test for about a year with some of the athletes I coach and the results have appeared to be fairly accurate. But I recently decided to check its accuracy. So last Saturday I had an athlete do the above-described indoor trainer confirmation test. The first chart here illustrates that test. The next day I had him do a CP30 test on the road. The second chart is his CP30 test.

The confirmation test predicted his FTP would be 235 watts since he achieved his LTHR of 152 bpm during the eighth stage when the mean average wattage was 235. The next day when he did his CP30 test his mean average power for the 30 minutes was 240 watts (241w normalized power) and mean average heart rate was 151. The mean average heart rate for the last 20 minutes of the CP30 test was 153. So the effort seems to have been quite high for this test.

The results of the cp30 test would indicate that the Saturday indoor trainer confirmation test was off by about 2% (235w vs. 240w). That’s pretty good so I’m fairly well satisfied that the confirmation test is an accurate predictor of FTP – and is much less stressful than the CP30 test. But I’ll keep gathering data for different athletes to see if it holds up under such scrutiny. It could be that there was a margin of error built into the procedure in that some fatigue was realized from the Saturday test and so the Sunday test may have yielded a lower FTP than might otherwise have been realized. (The athlete reported feeling rested and strong in the Sunday CP30 test.) It’s also possible the athlete held back too much in the first half of the CP30 test since average power increased 6% in the second half. That’s somewhat outside of the 51-49 negative split principle I’ve written about here.

If you try the confirmation test please let me know how it compares with your most recent CP30 test. Thanks!


At August 19, 2008 5:13 PM , Anonymous Anonymous said...


I am confused you said LTHR stay's the same, I thought it went up as your FTP increases, I thought it became a higer percentage of you max heart rate? could you eplain this to me? Thank you

At August 20, 2008 9:23 AM , Blogger Joe Friel said...

anon--For athletes who have well-established fitness LTHR changes little if any. For those who are new to the sport or coming back after a long layoff LTHR will probably rise significantly.

At August 20, 2008 4:35 PM , Blogger rick said...

i'm think FTP and LTHR vary if i'm climbing a gradual grade vs trying to steady push on flats ....

thoughts ??

At August 20, 2008 4:50 PM , Blogger Joe Friel said...

rick--Possibly. Your cadence changes and that often affects LTHR and FTP. I suppose it would depend on how much difference there is between your flat and climbing cadence. If you climb like Lance did, with a very high cadence, I suspect there would be little if any difference.

At August 21, 2008 5:07 AM , Anonymous willy said...


Why did you choose to use 10 watts intervals, with 4' efforts separated by 1' rest ?

Wouldn't it be simpler to use 2' intervals with no rest between and 20 watts increments.

It would also be less stressfull than a FTP test, and as accurate once "calibrated", (I mean once one has found the stage equivalent(HR + watts) to FTP. )

At August 21, 2008 4:35 PM , Blogger Joe Friel said...

willy--Your way may work well also. I chose 4 minutes because I wanted HR to stabilize in each stage and I wanted to create some fatigue by going for about 32 minutes total. But not nearly as much fatigue as with a straight 30-minute TT.

At August 22, 2008 9:22 AM , Blogger D3 Multisport said...

Great post - and I enjoy reading your blog. I always find good info here. Thanks!

At August 22, 2008 9:24 AM , Anonymous Mike Ricci said...

Great post. I enjoy reading your blog, its always full of great info! Thanks for sharing.


At August 23, 2008 4:48 PM , Blogger D3 Multisport said...

Joe -
Upon further thought - do you do any kind of similar testing for the run test for the LT? 4' efforts bumping up the speed .2 mph or so with 1 recovery (until the athlete reaches LT)?
Thanks again,

At August 24, 2008 5:17 AM , Blogger Joe Friel said...

Hi Mike--I haven't but it seems like it should work as well. Perhaps 800s on a track but only doing 5-6 of them. Maybe start at a minute or so per 800 slower than FTP. Decrease times on each subsequent 800 by about 10 sec until LTHR achieved. If you try something let me know how it worked. Thanks!

At August 24, 2008 12:09 PM , Blogger D3 Multisport said...

will do Joe and I'll let you know.

At August 25, 2008 3:05 PM , Blogger Baublehead said...

I tried it and it seems pretty close to what I thought is right.

One question, how does FTP compare to LT? I've been getting LT tested for some time and its always lower than the 20 mins minus 5% field test that most guys I know use.


At August 25, 2008 5:37 PM , Blogger Joe Friel said...

baublehead--Thanks for the feedback. FTP is the rough equivalent of LT/AT.

At August 26, 2008 3:52 AM , Blogger Bahzob said...

Hi, did the test on turbo. FTP is 305 so started at 225, with LTHR target of 172. Hit 172 in last 5s of 8th interval (298W) so went on and did another which averaged 310W with HR average of 169, max 175.

So test seems to be in right area. I think I will incorporate as regular session in next years schedule. Partly because as you say its a relatively non stressful way of testing (entire workout including warm up/cool down was 82TSS.

However main benefit I see is from the intervals just before threshold. This are the key ones for my events and I think having a simple, repeatable test that lets me monitor power, HR and RPE will be useful in judging training effect and event pacing.

(just a thought: could RPE be used as alternative ceiling for this test? After reading your Total Heart Rate Training book I became aware that my style of breathing changes around threshold and I have started to become attuned to this as a pacing indicator. I noticed similar in the test above.)

At August 26, 2008 5:15 AM , Blogger Joe Friel said...

Hi bahzob--Thanks for the feedback. RPE (Rating of Perceived Exertion) can certainly be used, esp if you are well-versed in using it due to lots of practice. Using it only once every few weeks is not generally a good idea, though.

At August 27, 2008 8:17 AM , Anonymous Iano said...

Hi Joe

I attended your talk at Cyclelab during your recent visit to South Africa and found it really informative. In the talk, you mentioned that you do not train an athlete if he does not use a power meter to measure effort.

On that Saturday morning, you joined the Cyclelab group for a training ride on a fairly hilly course. Most of the rides I do is on a similar type of route. How would you suggest using power on such a course where it is (presumably) difficult to maintain a steady power out-put?

At August 27, 2008 4:05 PM , Blogger Joe Friel said...

iano--Thanks for your note. That really was a rolling course. Realize that a workout does not have to be steady state. A lot can be accomplished by riding the uphills at a high power (in excess of FTP) while seated, soft pedal the downhills and ride aerobic threshold (2 zone) on the flats. This is great for building force. If you work at it you really can make such a course steady state also. It's a matter of controlling power up and down hill to a predetermined level. The real challenge on such a course is riding it for recovery.

At September 20, 2008 2:38 AM , Blogger Alessandro Martinelli said...

Hi Joe,
i'm from Italy...i made the confermation test on trainer yesterday...i reach 174bpm my LHTH on 9th interval averaging 265W....on a CP30 min test made 1 wk prior i made 270W....really perfect....thanks

At October 23, 2008 8:19 AM , Anonymous Anonymous said...

Dear Joe,

Thank you so much for this brilliant test. I will try to use this test in conjection with the Conconi that I do also in the indor ergotrainer.

I will e-mail you the files and complete analysis.

Thanks for reading,
Louis Leventer.

At October 23, 2008 8:29 AM , Blogger Joe Friel said...

HI Louis--Thanks but no need to send me the files. My schedule won't allow me the luxury of looking at the details of everyone's data. Just report what you found. Thanks for your interest, though.

At January 12, 2009 6:59 AM , Blogger Darrelld2 said...


I am curious on where you stand with the FTP confirmation testing. Did you get much feed back and are you satisfied that the results are close enough to forgo a regulaar 30 minute FTP test?
Thank you for your support to the sport.

At January 12, 2009 7:55 AM , Blogger Joe Friel said...

darrelld2--I've had good success with this so continue to use it.

At January 29, 2009 8:34 AM , Anonymous Marshall Hance said...


Jan 7th, this test confirmed my FTP of 312w. Three months of consistant base training prior, a 30min test revealed my FTP to be 292w. Reasonable, but not impressive gains. Yesterday, after three weeks of including muscular endurance workouts, four minute repetitions repeatedly showed 350w at LTHR. RPE suggested slightly higher than LT, but not VO2max. Are these gains feasible, or is LTHR affected by environmental (rainy) conditions? Should I plan to retest soon?

Thank you,

-Marshall Hance
Asheville, NC

At January 29, 2009 8:54 AM , Blogger Joe Friel said...

Marshall--Yes, it's feasible. I've seen greater gains when training is very consistent and done correctly as far as intensity and volume. Well done.

At July 16, 2009 5:43 PM , Anonymous TWMD said...


I wanted to provide my results based on your 4-min FTP protocol.

June 13, 2009 - 256W full 40K TT
July 16, 2009 - 306W for the 13th 4' interval

My FTP up to June 13th was my first 40K TT. I have been doing some specific training (2 x 20', etc. based on Power now) to increase my FTP in the last month. I really didn't anticipate my power increase, so I kept going until I reached my LTHR, 183.

I have a few questions.
1. Will doing 13 intervals versus the 7-8 to discover my new level skew the results?
2. Based on my results below, is that my FTP, VO2max Power, CP30 or CP20?

If it is my CP30 or CP20, does that mean I multiply it times .95 or .94 respectively to get my CP60? Note, I have only been cycling for a year, so I am seeing large increases in all my cycling skills when I actually train for the area.

Time Avg Power
0:10:06 176
0:15:08 191
0:20:10 200
0:25:12 217
0:30:14 223
0:35:17 230
0:40:21 241
0:45:23 251
0:50:24 269
0:55:26 276
1:00:30 285
1:05:32 297
1:10:33 306

Thanks for the informative site and books (I do own the Training Bible),

At July 16, 2009 8:43 PM , Blogger Joe Friel said...

twmd--Thanks for your comment. At some point fatigue will set in on this test and may screw up the results. Is 13 stages going to reach that point? It depends on your fitness. The increase looks to be rather linear so nothing seems unusual. The power at which you first achieved your LTHR I've found to be close to your FTP.


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