AI FTP Detection Update

[yokuha]

What‘s the actual x axis on the plot?

[yokuha]

@OreoCookie

FTP supposedly means (e. g. 60-minute max power)

I am honestly confused to get the 60 min up here again and again in an otherwise (partly) highly educated discussion.
AFAICT even Coggan „and friends“ realized and stated long ago that FTP (ans MLSS) corresponds to durations of approx. 40–70 min depending on the individual.

[OreoCookie]

@yokuha

I am honestly confused to get the 60 min up here again and again in an otherwise (partly) highly educated discussion.
AFAICT even Coggan „and friends“ realized and stated long ago that FTP (ans MLSS) corresponds to durations of approx. 40–70 min depending on the individual.

Yes, exactly, i. e. power at lactate threshold ≠ 60 minutes best power, which was my point. Lactate threshold (and FTP as its proxy) is a physiologically determined point in your power profile that is not defined in terms of duration. The typical duration (40–70 minutes) is just an experimental fact that follows from the definition of LTH. (Although I would suspect untrained and less trained individuals won’t be able to hold their FTP for 40 minutes.)

Some people erroneously equate the two, i. e. if you cannot hold power x for 60 minutes, then it is not your FTP. Presumably, this is a misunderstanding that stems from Coggan’s early works where he tested (indirectly) lactate threshold by looking at power data from 40k TTs of trained cyclists. That’s what I meant. Does that clear up any confusion? Or add to it?

[yokuha]

@OreoCookie

Does that clear up any confusion?

It clarifies that you got it (mostly/generally/essentially/fully?) right;-)
However, it (FTP corresponds to 60 min power) has been used many times in this thread, by different people, and not always in ways that seemed to be in line with your explanation (nor general consensus in the field).

[rswagler1]

So sounds like fitness score will be ready for release in a month, or later… really looking forward to seeing this.

[DocSavage]

New name for FTP suggestion.

Functional Aerobic Stress Threshold. (FAST)

Or for Chad Baseline Estimated Energy Reserve

If either are used I want a free entry in to Gears with Chad

[jlsazart]

Thanks Nate – the thing I don’t get is that there ARE rides those weeks, and they are on my calendar. I looked back and I installed the power meter March 19. I count 42 rides that were between 25 minutes to 2 hours long (mostly outdoor commutes) from then until the initial ramp test. They have TSS scores. Any insight as to why the AI doesn’t like them?

[brenth]

I dont really see a benefit to another metric. Fitness score? How does it have meaning? Isnt the main function of the fitness score going to be impacted by where I am in following TR plans?

[BenB]

@Nate_Pearson

this could be a pretty cool way to show small fitness increases and motivate people to stay consistent.

100% I would love to see this, I’d probably not even religiously press the FTP detection button every 336hrs if this were implemented.

[Lupusoff]

Great update! Many thanks! Will it arrive in June or July?

[OreoCookie]

@yokuha

However, it (FTP corresponds to 60 min power) has been used many times in this thread, by different people, and not always in ways that seemed to be in line with your explanation (nor general consensus in the field).

Yes, a lot of digital ink has been spilled over this, here on this forum and elsewhere. Very often in the context of various FTP test methodologies and protocols (e. g. ramp test vs. 20-minute test vs. TTE tests). However, if you go to the primary sources, the story is cut and dry, FTP is a measurement of your lactate threshold power in a field test.

It gets more complicated when you look at the scientific literature. AFAIK they always report the actual numbers, e. g. FTP20 is the power someone did in a 20-minute FTP test, which (when done correctly) lies above lactate threshold. Newer literature often uses a ramp test and they report MAP (maximum aerobic power). That is different from how most athletes use the term FTP.

This is also the reason why @Nate_Pearson feels tempted to replace FTP with something else. I personally think estimate lactate threshold power would be the most straightforward and accurate, but I understand when he says that this train has left the station a few years ago and it is too late to change.

Overall, most of the discussions on FTP testing methodologies is usually in the context that the ramp test overestimates people’s FTP. I don’t want to regurgitate all the arguments, but I think people make several obvious mistakes:

• Any FTP testing methodology has significant systematic and statistical errors. E. g. inferring lactate threshold power from a 20-minute FTP test means you subtract 5-15 % from that figure. (Initially it was 5 %, but I have seen up to 15 % in he later literature.)
• Any FTP testing protocol only infers lactate threshold power, and likely the standard formula that is used to compute lactate threshold power from the power they tested at is not accurate for you — most people are not at the mean of the Bell curve.
• Back-of-the-envelope computations suggest that the error is of similar size for all testing methodologies.
• The longer and more elaborate a test is, the less often you can do it. So properly executed TTE test involve a ramp test to give you a power figure to shoot for (a first estimate for your FTP) and then you go out and do it.
• Some people really hate tests to exhaustion.
• Some people prefer tests that produce lower numbers, because they can more consistently finish workouts. Holding your lactate threshold power or thereabouts for longer stretches of time is mentally very exhausting, and you need to train your mind in addition to your body to cope with that.
• Some people want a test that is 100 % accurate for them every time and not think about it. In my experience it is much better to “trust, but verify” and build from experience. If you “test too high”, then the percentage by which you do does not change very quickly. So apply your correction to the number and presto. Plus, verify with a few workouts and/or outdoor rides when in doubt.

[toyman]

@OreoCookie

However, if you go to the primary sources, the story is cut and dry, FTP is a measurement of your lactate threshold power in a field test.

Agreed 100%

This is one of the best FTP related posts on the forum

[ChrisDe]

I would like to have a graph with my historical set ftp and as a second line the Continuous AiFTP modified after each (significant) ride.

[yokuha]

@OreoCookie

However, if you go to the primary sources, the story is cut and dry, FTP is a measurement of your lactate threshold power in a field test.

Thank you for the nice and comprehensive clarification!
However, I guess with some semantic nit-picking, FTP is a functional approximation of power at MLSS.

[OreoCookie]

@yokuha

However, I guess with some semantic nit-picking, FTP is a functional approximation of power at MLSS.

As far as I understand the point is that you are not measuring lactate levels, but inferring power at lactate threshold indirectly in a field test (as opposed to a lab test). But you are right, it is an approximation since you are indirectly inferring power at lactate threshold. This is also the reason why any FTP test has a statistical element to it — the relation between power at lactate threshold and the power you measure is not fixed, but has a statistical variation, be it 20-minute test or a ramp test.

Here is an excerpt from Chapter 4 of Friel’s The Cyclist’s Training Bible:

@Joe Friel

Dr. Coggan had a simple solution. Instead of requiring a 1-hour effort, he proposed doing a 20-minute test and then subtracting 5 percent from the test results. The result would be an estimate of one’s AnT. Since it’s not an actual measure of one’s lactate or anaerobic threshold, and since it is done in a field test, he called the resulting measure a “functional threshold.” The other important products of his 20-minute test are functional threshold heart rate (FTHR) and functional threshold power (FTP).

Here is an excerpt from pp. 4–5 of an early publication by Coggan, which might be the origin of the conflation of FTP = hour power comes from, and where he proposes a 20-minute FTP test rather than a TT to measure FTP.

@Coggan

Given the limitations of laboratory testing as discussed above, probably the easiest and most direct way of estimating a rider’s functional threshold power is therefore to simply measure their average power during a ~40 km (50-70 min) TT. This highly pragmatic approach is justified by laboratory research showing that the power a cyclist can generate for 60 min correlates very highly with, but is slightly greater than, their power at LT (defined as a 1 mmol/L increase in blood lactate over exercise baseline) (2). […] If for some reason (e.g., phase of training) it is considered undesirable to have the athlete perform a full 40 km TT, data from a shorter TT can be used instead, although this may require slight adjustment of the exact percentages of threshold power for each level and/or application of an appropriate correction factor (e.g., threshold power = average power during a 20 km TT multiplied by 0.93). Again, however, given the breadth of the specified power levels, day-to-day variability in performance, and individual differences in the precise shape of the power-duration curve, the real effect of employing such a correction factor may simply be to convey a false sense of precision.

An even easier way of estimating an athlete’s threshold power is to just measure the power that they can routinely produce in training during long intervals or repeats aimed at raising LT (e.g., 2 x 20 min at level 4). Typically, this will be very close (within perhaps 5 percent) to what can be sustained during a 40k TT, with the shorter duration and recovery period(s) between efforts compensating for the generally lower motivational level in training vs. competition. […] The primary advantage to this approach is the ease of measurement, which in some cases may make it preferable to more formal testing.

So Coggan gives a precise scientific definition for lactate threshold in terms of lactate concentration in your blood, and then links it to power levels in various tests. This paragraph is a bit technical, but includes a lot of practical considerations (e. g. that your level of motivation in training is different from a competition, and is something that likely has an effect on the power numbers you measure).

[Jesse_Vernon1]

@Nate_Pearson I think this is a great idea! There’s a legit rationale for having a training benchmark, call or tFTP, but also for having a clear idea of what your PD curve looks like and how it’s changing (even if that’s a smaller subset of nerds like me).

[Gaggy15]

@Nate_Pearson

Then put a 60-minute power approximation after every workout that would be based on your threshold level.

or even better, predicted power curve?

[PhilSJones]

I don’t think you are that much of an outlier, unless I am also Frankly, that is close to my typical 100m TT race performance.
100m TT this year

• Time 4h:26m
• TSS 282
• IF 0.8

12hrs TT (2021)

• Time 12hrs
• TSS 564
• IF 0.68
  

I don’t try and find workouts to match these. I am waiting for outside rides AND RACES, to catch them.

[Pbase]

The more I read this thread the more I am convinced that TR should just leave it as FTP and go the “educate the users” route.

As Nate pointed out, the change would be a HUGE one…imo not worth the effort, and won’t solve the problem. No matter what you do, people are going to nitpick. Change it to TFTP (or similar) and you will have invested considerable time and money but a very small minority of users will just continue to say things like, “yeah, that’s great and all, but what’s my actual FTP and why doesn’t it exactly match my lab tested results?”.

[ChefAcB]

I agree, it makes things more confusing especially for new riders using power meters.
I also want to point out my TR estimated FTP is in line with intervals.icu and garmins estimated FTP. Fwiw