Critical Power test protocol?

Triathlon Forum
1

If one were to attempt a critical power test, what would a resonable protocol look like? I’ve read a number of posts here, as well as Eddie Monnier’s paper on Velo-Fit and the section on CP testing in “Training and Racing with a Power meter”. I think I have a reasonable handle on what the power-duration curve means and how to derive it (thanks largely to Eddie’s Excel spreadsheet ;-). What I don’t know is, what is a valid test protocol? I’ve read Dr Coggan’s recommendations that the three durations should be between 3 and 20-30 minutes, so I was thinking of trying 3, 8, and 15 minute tests. Are these reasonable points? How much rest/recovery should be allowed between tests? Is it reasonable to do them all in one session with enough rest between efforts? What sort of warmup is recommended? Is doing this on a trainer with a powermeter (Ergomo) OK (it would certainly help me eliminate many variables like weather, wind, road conditions, etc and make the test more repeatable). Thoughts?

Edit- the next chapter in the book outlines a “Power Profile Test” (pp. 65-66). This protocol sounds like a reasonable approach to me (substituting the CP test durations)… warmup as outlined followed by the three tests in descending order (15 min, 8 min, 3 min) with 5-10 min rest between sets and cooldown. Thoughts?

2

I think it really depends on what you’re trying to accomplish with the tests. Are you a triathlete trying to monitor progress? For most triathletes who are not road racing, there is no need to complete out the values of the power profile chart aside from FTP. That value alone is really what is going to define your success as a triathlete more than peak power at the shorter durations. That is not to say that it isn’t fun to fill out the whole chart but those other values are not that indicative of success in a triathlon.

If you’re trying to devise a test that is good measure of your performance, you can either use the rubric of FTP, which works quite well, or devise some other testing durations that better fit your needs.

If you’re going to do your tests indoors, and there are good reasons to do so as you mentioned, remember to keep the temperature as constant as possible from test to test and to keep the amount of airflow quite high.

3

What I’m actually trying to accomplish is to determine FTP. From Dr Coggan’s “seven deadly sins” post, and from comments here, I’m under the impression that he favors CP testing over something like 2x20. Since I’m new to training with power, I’ll likely do a 2x20’ also (at a different time) to see how closely the results of the two tests correlate for me, and to see which test I can perform more easily and repeatably on an indoor trainer. 2x20 on an indoor trainer sounds like a bit of a chore, while the shorter durations might be easier to get accurate “all out” results from. I’m still experimenting, but I wanted to make sure the structure of the test doesn’t totally invalidate the results (like not providing sufficient rest between intervals).

4

Also, while we’re at it, has anyone who’s done this test experimented with holding power constant and riding until failure vs targeting a given time interval i.e., hold 450w, 350w, 300w until failure and note the time in seconds and use that to create the plot? I’ve read that both are valid approaches, and the latter would seem to me to yield a more accurate “all out” measure vs trying to pace yourself to go all out over 3 minutes.

5

I’m not AC so I’m not going to speak for him but that would not be the impression I have of his views, i.e. using CP testing for measuring FTP.

You’re right that it is far easier mentally to complete all out tests of shorter duration, particularly on the trainer. The issue is that the shorter the test, the more it includes your anaerobic capacity, something that plays little role in FTP. As a result, there is a lot of variation in accuracy when applying shorter duration tests to the FTP measure between different people. Once you do some longer tests, you’ll likely be able to apply a CP model and know how to interpret the results, but in my opinion you don’t know enough right now to do that with a high degree of accuracy.

6

The issue is that the shorter the test, the more it includes your anaerobic capacity, something that plays little role in FTP.

I believe this is why he recommends that the shortest duration in the test be at least 3 minutes vs 1 min that some others recommend.

As a result, there is a lot of variation in accuracy when applying shorter duration tests to the FTP measure between different people. Once you do some longer tests, you’ll likely be able to apply a CP model and know how to interpret the results, but in my opinion you don’t know enough right now to do that with a high degree of accuracy.

To quote from his book (p 49): “Finally, it’s important to realize that, with any regression analysis, the slope (i.e., CP) is estimated with greater certainty than the intercept (i.e., AWC). In other words, whereas the value derived for CP using this method is rather robust- that is, quite reproducible from one occasion to the next and relatively insensitive to the particular combination of data points used- the value obtained for AWC will tend to be more variable.”

I interpret this to mean that as long as I use three points in the range of 3-20 minutes I can quite reliably determine CP (and therefore FTP) with a good degree of accuracy. AWC doesn’t concern me so much.

Also (p 48): “Nonetheless, despite it’s simplicity,this equation describes the power vs duration curve quite well over a fairly wide range of exercise intensities and durations, from efforts lasting for just a couple of minutes to efforts of a couple of hours…”

I interpret this to mean that determining CP60 from data points of 3, 8, and 15 (for example) is not invalid.

Of course, my understanding of this is based largely on the book and discussions here so I may have totally misinterpreted the concept.

7

My experience is this… No testing indoors. That’s insanity. Test on a steady climb, preferably with a tailwind. Testing on the flats is fine if that’s what you are comfortable with. Testing into a headwind is not valid. Durations should be about 3, 8, and 21 minutes, but don’t test by time. Find markers on the hill to start and stop at that will take you about that duration. One test per day. The shorter the test, the more important it is to be exceptionally fresh. Try to negative-split the 21 minute effort. For instance, 295w the first half, 310w the second half. You should blow up about 30 seconds before the finish. Warm-up is a personal issue. For me, I should have already ridden an hour or so with 10-20minutes total time at about 80-90% of CP.

8

why is testing indoors insanity?
thanks,
pat

11

If you want the most accurate measure of your ftp, do this.

Ride a 40km time trial (or appropriately adjusted distance if you’re really fast or really slow)
If you blow up early on and have obviously gone out too fast, stop, wait a couple days and try again
When you do a hard, full out 40k tt, download your power file. See if you went out too fast (power curve dropping) or had too much juice left towards the end.
Make an educated guess what you could ride if you did it again and paced perfectly
Ride another 40k tt and try to hold your goal pace all the way

You’ll know your true ftp within a couple watts. It’s a tough testing protocol, but gives the best results. The other benefit is that it makes you tougher (8 minute efforts? anyone can do that). If you do 2x20’s year round, that’s an excellent estimate as to how your ftp is improving or degrading.

12

If you do 2x20’s year round, that’s an excellent estimate as to how your ftp is improving or degrading.

Training is testing and testing is training.

13

How do you feel about people putting NP into the ciritcal power formula?

14

For a few years, I would do 5 and 20 min tests regularly. Then I tried holding power constant on an ergometer and riding to failure.

In the end, I abandoned CP altogether and just go by what I can do for 3x20s. I do those on the erg as well and increment the power by 1W each workout or 2W per week.

15

How do you feel about people putting NP into the ciritcal power formula?
In general, I think it is a bad idea.

16

If one were to attempt a critical power test, what would a resonable protocol look like? I’ve read a number of posts here, as well as Eddie Monnier’s paper on Velo-Fit and the section on CP testing in “Training and Racing with a Power meter”. I think I have a reasonable handle on what the power-duration curve means and how to derive it (thanks largely to Eddie’s Excel spreadsheet ;-). What I don’t know is, what is a valid test protocol? I’ve read Dr Coggan’s recommendations that the three durations should be between 3 and 20-30 minutes, so I was thinking of trying 3, 8, and 15 minute tests. Are these reasonable points? How much rest/recovery should be allowed between tests? Is it reasonable to do them all in one session with enough rest between efforts? What sort of warmup is recommended? Is doing this on a trainer with a powermeter (Ergomo) OK (it would certainly help me eliminate many variables like weather, wind, road conditions, etc and make the test more repeatable). Thoughts?

Edit- the next chapter in the book outlines a “Power Profile Test” (pp. 65-66). This protocol sounds like a reasonable approach to me (substituting the CP test durations)… warmup as outlined followed by the three tests in descending order (15 min, 8 min, 3 min) with 5-10 min rest between sets and cooldown. Thoughts?

I’ve discovered a challenge/problem in the sport of triathlon, more specific to IM, when determining one’s FTP. That problem being: There’s too much of a dependence on all-out TTs and not enough on training data (eg mean-maximal). Here’s a paragraph from a current doc I’m writing:

Establishing your FTP is the pragmatic or functional approach to determining power at lactate threshold (LT). It is widely accepted that power at LT is one the most accurate predictors of endurance performance ability. By definition, FTP is the highest power an athlete can maintain in a steady-state (or quasi-steady-state) for a prolonged period of time (i.e., ~1 hour) without fatiguing. There are several well-documented ways of estimating your FTP. However, I believe there are additional factors one must consider when establishing their FTP for IM. Those factors are:

  1. An emphasis on specificity

  2. A de-emphasis on the use of intervals and a greater emphasis using your Mean-Maximal Power (MMP) at >4 hours

Being able to sustain high (relative) power in a reasonably aggressive aero position for 1 hour is one thing. Being able to sustain high (relative) power in a reasonably aggressive aero position for 5+ hours is a completely different challenge. If you haven’t spent an appropriate amount of time doing race-specific preparation training then depending solely on short interval power testing (e.g., 2 x 20 minute) to establish your FTP might lead to some disappointment on race day. Now, when you do test, all of it should be done in your race position. Some people have a tendency to choose the position in which they can produce or sustain the most power for an interval and that’s not necessarily their race position. That’s probably fine for establishing power training levels but your goal for racing is to make sure your FTP is truly reflective of power you can sustain in your race position. What I’ve discovered through my own experience is that the longer you’ve been training and racing with power, the less dependent you need to be on FTP testing.

So, this isn’t so much of an issue when targeting interval power when training but much more of an issue when using a PM to help you appropriately pace the IM bike. However, they’re clearly not mutually exclusive results either, imho. Note that **without fatiguing **is a critical part of the definition of FTP. It is equally critical to see a lack of fatigue as the primary indicator in a declining power profile on the IM bike. My research is pointing to a lack of specificity preparation as the primary cause of that fatigue.

For the computer/networking geeks… I like to refer to it as “TFTP” or Triathlon Functional Threshold Power… :wink:

Thanks, Chris

18

Note that **without fatiguing **is a critical part of the definition of FTP.

I’m confused. The definition of FTP that I’m aware of is the maximal power that can be sustained for one hour. If I’m not fatigued at the end of the hour, likely I could have gone a lot harder and this is not my FTP. If I’ve truly ridden at FTP for an hour and I could not have gone 1 watt harder, there better be a bucket nearby :wink: Clearly this is not the pace I would race an IM at.

19

you ain’t fatigued after 1-hr @ FTP? Then please define “fatigue” …

Don’t blame Chris, he was just paraphrasing what I’ve written.

Anyway, the most common definition of fatigue in the field of exercise physiology is “failure to maintain the expected or required force or power output”. IOW, it entirely an operational definition that views fatigue as an all-or-none phenomenon, not a process or anything that is sensed. In that regard, you can indeed complete ~1 h at functional threshold power without fatiguing, but obviously you can’t continue at that pace forever.

20

My experience is this… No testing indoors. That’s insanity. Why? Like everything else here, it’s just my experience. I can’t stand riding indoors, and living in SoCal I really don’t ever have to. Test on a steady climb, preferably with a tailwind. Why a tailwind??? Can’t explain it scientifically, but I’ve found that riding with a tailwind vs. a headwind is similar to riding uphill vs. downhill in terms of putting out power; it’s just easier for some reason, maybe it smooths out the stroke? Testing on the flats is fine if that’s what you are comfortable with. Testing into a headwind is not valid. Why the h_ll not??? Maybe I just have a sloppy pedal stroke? I have trouble keeping a good rhythm into a headwind, especially as headwinds tend to be gusty and demand that I shift more often than I’d like. FWIW, I also recall reading something to the effect that Lemond didn’t advise doing threshold work on the flats, unless there was a tailwind. Durations should be about 3, 8, and 21 minutes, but don’t test by time. Find markers on the hill to start and stop at that will take you about that duration.Why? That assume you have some long hills available and why bother with two tests on the short end? Again, it’s my experience, and I do have very long hills and mountains at my disposal. I put more stock in the 8 minute effort than the 3 minute effort, but it’s nice to know what I’m capable of. One test per day. Why? I’ve had success splitting 'em morning/evening or noon/evening. Doing three tests chews up time that could be much better utilized. I prefer to do one test per workout, and at the end of the workout, as that seems to simulate my race experiences better. The shorter the test, the more important it is to be exceptionally fresh. Why? Exceptionally implies a significant taper … I’d say just ‘fresh’ or TSB slightly positive. I’ve found that when my legs are super fresh they can handle the supra-threshold efforts far better. I think TSB slightly positive may be a good guide for most, but when I’m in the TSB range of 20-60 I feel like I can absolutey rip the cranks off. Try to negative-split the 21 minute effort. For instance, 295w the first half, 310w the second half. You should blow up about 30 seconds before the finish. Hmmm … maybe not that much spread but yes it should be a maximal effort. Warm-up is a personal issue. For me, I should have already ridden an hour or so with 10-20minutes total time at about 80-90% of CP. Okay it’s a personal issue at you said :slight_smile:
in any case, I prefer to estimate FTP (and CP-Monod is still an estimate) simply from current power levels in my regular threshold workouts (2x20 or other).

21

you ain’t fatigued after 1-hr @ FTP? Then please define “fatigue” …

AC provided you with a more techincal definition. I should do a better job of highlighting key phrases (ie declining power profile). Think about the definition of “sustain”… So if you experience a declining power profile in your test, your results will not be reflective of your FTP because you clearly couldn’t sustain that power. Note: I would probably define “declining” as a 2+% drop off in power. AC put together an excellent preso that shows results and good and bad FTP tests. This explains what fatigue looks like:

http://www.counterpartcoaching.com/coggan_power.pdf

Clearly, this has nothing to do with how fatigued you are after the test.

jkat, Obviously we don’t do IM at FTP. It’s done at a % of FTP which is best determined using IF/TSS. Removing the obvious race tactics often exhibited by Pros at specific IMs (eg IMH), I believe a declining power profile on the IM bike is often indicative of fatigue due to a lack of specificity training. Someone else might say, “No, it’s because they went out too hard in the first 2hrs.” In which I would respond, “Yes and that likely might have been because they over-estimated their FTP due to that lack of specificity training.”

Hope that helps,

Chris

23

Chris,

I understand what you’re saying now- thanks for clarifying. I was initially thrown by a couple of things. First, the definition of “fatigue” which has since been clarified. Second was this:

"However, I believe there are additional factors one must consider when establishing their FTP for IM. Those factors are:

  1. An emphasis on specificity

  2. A de-emphasis on the use of intervals and a greater emphasis using your Mean-Maximal Power (MMP) at >4 hours"
    **
    I believe that establishing FTP is independent of the target race duration. IOW, my FTP might be 280w (for example) and whether my race of choice is a 40k TT or an IM is largely irrelevant. Training and pacing strategy for my target race, however, has to be specific. If I have an FTP of 280w but I’ve never done a ride longer than 2 hours, I’d be a fool to go off and try to ride an IM bike leg at 75% FTP. Again, it’s not an overestimation of FTP, it’s an overestimation of what % of FTP can be sustained for the target duration. Does that make sense? (I’m partly testing my own knowledge here).

Thanks,
John

24

Chris,

I understand what you’re saying now- thanks for clarifying. I was initially thrown by a couple of things. First, the definition of “fatigue” which has since been clarified. Second was this:

"However, I believe there are additional factors one must consider when establishing their FTP for IM. Those factors are:

  1. An emphasis on specificity

  2. A de-emphasis on the use of intervals and a greater emphasis using your Mean-Maximal Power (MMP) at >4 hours"
    **
    I believe that establishing FTP is independent of the target race duration. IOW, my FTP might be 280w (for example) and whether my race of choice is a 40k TT or an IM is largely irrelevant. Training and pacing strategy for my target race, however, has to be specific. If I have an FTP of 280w but I’ve never done a ride longer than 2 hours, I’d be a fool to go off and try to ride an IM bike leg at 75% FTP. Again, it’s not an overestimation of FTP, it’s an overestimation of what % of FTP can be sustained for the target duration. Does that make sense? (I’m partly testing my own knowledge here).

Thanks,
John

I agree with what you’re saying to a certain degree but duration alone doesn’t define “specificity.” What defines specificity is:

http://www.masterstriathlete.com/specificity1.html

Even if you ride 5+hrs it doesn’t mean you’re addressing all principles of specificity. Race position is critical; race cadence is critical; riding alone is critical; etc. And I’m not talking about doing this a couple of times during your race-prep period.

Yes, it’s common sense to not try to ride at 75% of FTP if you’ve never done a ride longer than 2hrs but that’s not the problem I’m seeing.

I’m basing my observations on the endless conversations I’ve had with people who say, “Damn… I don’t understand why I was struggling so hard (ie my neck was hurting, etc, etc) after mile 80 when I was well below my power target…” Not to mention the number of people we see sitting up after mile 80 vs the number of people we see in a nice aero position in the first 2hrs of the IM bike. And their corresponding power files are indicative of some type of fatigue.

Thanks, Chris