Establishing Critical Power

Can you establish your Critical Power (CP) by continuing effort past failure point of a Ramp Test for x number of minutes? This is on the basis that whatever effort I can sustain after emptying my ‘tank’ should be a good estimation of CP.

I’m trying to establish my Aerobic Work Capacity (W’), but need a CP value to do so accurately. My challenge is that I have no power meter on my outside workouts or during races as a MTB’r. Therefore, I have no reliable all-out efforts to establish CP - whilst I could use FTP as a basis for CP, I don’t want to assume that this is the same.

My ultimate goal is to be able to plot my potential power curve to see where my weaknesses are.

If this is not the best method, does anyone have any other recommendations? Oh, and I want to avoid deviating from my TR plan, so would rather not use a method that wipes me out!

Thanks :slight_smile:

probably best using or Golden Cheetah for these things. they will calculate it for you with enough data.

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This is the challenge @noahphence. I don’t have enough instances of all-out efforts in my power curve, since my only measured workouts are TR structured efforts. The only all-out effort that I have ever completed is the Ramp Test, so sites which plot based on historical workout data always tend to use my most recent Ramp Test for all data points to extrapolate. I don’t think that this is accurate.

To give further context, I’ve got all-time PBs across my entire power curve from 1s to 120m since I starting structured training at the start of April, but other than my Ramp Test, I’ve never gone all-out for any of the points in the power curve. Therefore, I think that until I have good base line workout(s) to measure from, my W’ and/or CP will be miscalculated.

There are number of brutal TR workouts that would generate the type of data. Check Intense & Insane and scroll through

Thanks @ExpertOrBust
I fear that is a bit of a rabbit hole…although I do fancy hitting some of those insane workouts once I’ve finished my structured training!

I’m looking for for a test protocol to get an accurate CP. I ran through the list, but don’t know what I’m looking for…eek!

This help?

Looks promising - but a £39 price tag is too much to satisfy my curiosity at this stage :wink:

Any ideas where this may be referenced without having to buy the paper that I can follow?

Thanks for the input :+1:

I’m sure you’ll find some interesting and free links if you search the Internet with the term “critical power test cycling” which I just did using DuckDuckGo (I’m not a Google fan).

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Honestly just do a 30+ min LTHR test. It will be more useful as a basis for cp

Yup tried that - I’ve feel like I’ve fallen into a swamp of information and and I have no clue what is the best test to do. I’ve come onto the forum to seek advise after spending the past week getting lost :slight_smile:

I’m new to measuring my own performance and structured training, and whilst I understand the concept, I have no experience of testing protocol beyond Ramp.

Have you done one that you can recommend?

Thanks for the advise - My challenge is that I don’t know where to set my effort level for 30 minutes and don’t want to deviate from my training too much to have multiple attempts at finding my max effort.

This is where my original question stemmed from - if I am already doing Ramp Testing anyway, is a prolonging of the Ramp Test beyond the failure point for FTP a good way to measure CP? Thus, having no need for separate tests?

Haven’t done a CP test, but had mentally bookmarked the 3-minute all out test (because I did a 4-minute all out test for INSCYD).

Re 3 minute test is that this one? Do you think it’s worth a shot as a starting point? I appreciate your input :+1:

By “continuing the effort past failure point of a ramp test” do you mean instead of stopping, you switch to standard mode (or whatever non-erg) and try to continue to hold the highest sustainable work rate? In theory that could tell you CP, but it’s not really an established protocol. How long would you hold the additional effort for? What constitutes task failure? How would you determine CP?

CP & W’ are protocol-specific definitions. Just like FTP and all the other terms. They all try to approximate generally the same physiological breakpoint.

If you literally want to measure Critical Power and W’, there are specific protocol that you can follow. But they are designed to wipe you out. That’s a necessary part of the test :grin: You could try the 3min all-out CP test, which is at least a single session. It’s about the worst you’ll ever feel for 3min… Highly recommended :laughing:

If you are more generally interested in estimating your FTP, that’s what the TR ramp test is designed to do in the first place. Then in theory you could estimate your work capacity above FTP from the additional work performed above your ramp-test determined FTP to the point of failure?

It’s a bit of a circular method because FTP is just assumed to be a flat percentage of your peak 1min power, but it will give you a number to look at at least? :man_shrugging: But also you won’t be able to assess for a change in work capacity by that method, because any increase in peak power will be expressed as a change in FTP.


just thinking about what you’re trying to achieve. I’m not sure you’ll get this from a CP/W’ indoor test, if you’re trying to determine strengths/limiters for MTB. If you already have power data in TP, you should be able to look at your power-duration curve and see where the ‘gaps’ are from that? That will give you a much broader picture than what a single CP test can offer.

Or probably something like a power profile test like INSCYD, AIS, Sufferfest (I think?) Might be more relevant for a single test session to determine relative strenghts/limiters. Look up AIS power profile test to start. Should give you the basics. Basically it’s a single session that tests a few different durations, to see relative strengths/weaknesses in your power curve.

Yes, I’ve been using Ramp Tests for FTP and the beauty of this test is that you don’t have to know where to set the bar, so to speak (like with a 20min FTP test for example), so can just rock up and go until you can’t.

EDIT: My question re continuing the Ramp after failure point - I was wondering whether a continuous effort for a number of minutes would reflect CP. I may have just been over complicating/simplifying (not sure which) things - sorry:)

This was also recommended by @bbarrera just now too, so it looks like a contender to have a go at. I don’t mind doing a single killer workout to get the data - as long as I’m not having to repeat multiple tests over many days to establish data points. I’m not shy of pain, but don’t want to deviate from the TR structure too much :wink:

Thanks for you help!

You use the ftp estimate from the ramp test to set the effort level for a LTHR/FTP test

@SpareCycles Good point - I can see the weaknesses in my power curve only from the training sessions I’ve completed that are structured, so I don’t know what is real vs just not completed yet. I’m trying to estimate my curve and then perhaps test the water on some of the predicted efforts and go from there.

I think I’m going to try the 3 minute test as a starting point, then explore the power profile tests you’ve suggested after my A race in September (fingers crossed it will go ahead :crossed_fingers:) when I’ll have nothing to lose!

Thanks for your help!

The 3 minute test sucks.

You can download it for free from here.