Training Q: CP vs FTP
 

Google and search function exhausted. Perhaps I'm not using the right terms.

I was looking for something that shows critical power to FTP equivalency. There is a lot out there that mentions CP60 is FTP. However, I was interested in other CP points. For example, CP30 is clearly not 200% of FTP (more like 105%?). How about CP1, CP5 or CP180? Is there a formula that one could apply?

Thanks!

Mr. Burns

It's going to be different for everyone depending on several factors. That is why you can test at several durations and the various power profile such as sprinter, pursuit, and time trial. Also note that CP for shorter durations is going to be higher than longer durations. One "standard" is that FTP (60) is roughly 95% of 20 minutes, BUT someone with a higher anaerobic capacity will be able to produce more power over 20 minutes for the same FTP, and therefore FTP would be a lower percentage.

http://velo-fit.com/articles/critical-power.pdf

http://alex-cycle.blogspot.com/2008/...adly-sins.html

There is definitely a formula. Usually it is obtained by a test at 2-3 minutes and another test at 15-20 minutes. A curve is fit though those two points which can tell you an estimate for critical power at other time intervals. Unfortunately, I can't tell you the equation off the top of my head, but it should be in any number of training books. I believe it is listed in Friel's book, though I am not sure.

Google "monod critical power"

click on the link on this page for velofit's Monod spreadsheet (which you can download) - basically slope of work vs time is "long term" CP, and then you can back out CPs for specific time points. You'll need a powermeter or very good estimate of power for any given interval. As much as I like my KK Road Machine trainer, it turns out the published power curve is not that accurate when I benchmark against my PT.

http://velo-fit.com/new/tools.php

I think Golden Cheetah uses the same calculator.

I use this.
CP180 65-75%
CP120 76-83%
CP90 84-93%
CP60 97-100%
CP30 103-105%
CP12 108-112%
CP6 120-130%
CP1 170-190%

So this implies that anaerobic work capacity tracks changes in aerobic fitness. Is this something you work to maintain, or do you believe it just happens naturally.

See SpongeDad.

Two data points to do a CP curve is pretty light if you're looking for real accuracy. Best measure of various CP's is obtained by shoving all your data files into a custom WKO periodic and setting the dates you want to get data from. Even that presumes you have hit max at the different CP numbers. If you've got a lot of race/TT/test data you can usually get a pretty good handle on this.

Wow, great question, I had never really considered that until you asked. I think the value of trying to do something like this is for setting up training zones and developing pacing strategies. Even taking an MMP curve is really just a best guess as I am certain I have never gone all out for 90 minutes. So under the context of this being a guide, I find that it tracks to a point. After 3 years of using this, I have learned that when I reach about 95% of my peak fitness for the season, I struggle to hit the CP12 and CP6 numbers (I have no idea why, but I can still hit CP1). Prior to that cross-over point the numbers are achievable (I do a 3 X 5's @ CP6 during the season which is my reference). That being said, over the last 3 years as my ftp has increased, there has been a close tracking of the 30,12, and 6 numbers. I am primarily a TT racer so that should give you an idea of where most of my time is spent. I should also add that as I move from late base to build, the lower CP#'s are more challenging, but after a couple of weeks they get easier so it certainly does take some work. So short answer, some natural tracking, but some work is required as well. I am certain it would not work the other way for me.

Exactly. CP90 isn't relevant for 99% of what we do, training or racing.

If you're a 'rounder who does TT's MMP will give you good numbers out to 60, beyond that, see above. And I say this as a guy who's spent more than 2 hours OTF by hisself.

Great thanks.

UMD made an excellent point above, that it's different for everyone based on their natural strengths. This was what I was originally looking for though.

It seems you are a TT guy.

Here's another cautionary bit re relying on calculated projections -

Yesterday I did my hardest/best 5 min interval in terms of watt output. When that number get's crunched into a calculation using my older outputs for longer intervals, the net result is that the calculated FTP goes down - you might think of it as more work in the longer interval is attributed to my increased anaerobic output.

Did my FTP really decrease over the last month? Maybe, but I don't think so. More likely, I've gained across the board and this is an artifact of not having done a long interval that shows this. (My weekend cross races are not done with a powermeter, so I'm not getting data from these 40-45 minute efforts.)

What warmups do you guys use for CP12 and CP6 testing? Also, how do you guys suggest go about doing them? I know for CP1, you sprint hard for 15-20seconds and try to maintain as much power as possible for the remainder of the test. What about CP6 & 12? Do you try to keep it above a certain estimated average power?

Thanks in advance

My 5' power is my crowned jewel. It really has little to do with my mediocre FTP. The further away from 60 minutes you get, the less accurate a guess for FTP is. The power curve is just that, a curve.

You aren't really supposed to mix "bests" from different time periods to calculate the curve.

My 5' power is my best asset. I dont care what it says about my FTP.

From my own testing:

CP20: 105%
CP60: 100%
CP90: 94%
CP120: 91%
CP180: 86%

I'd say Ex and I have similar tactics. Grind people down then attack when everyone is dead. The longer the breakaway the better. Oh yea, I hate crits.

5' power is genetic to a LARGE degree.

I bet your 90 and 120 are closer to your 60 than most.

I would imagine, as is FTP, but as of right now I see little correlation between my 5' and my ftp. One is great, one is fine.

Probably so. I'm a percentage point or so above your number.

I think SpongeDad was talking about the published power curve for the KK trainer, but I see your point. In any case, I am content with feeling my way along for now using approximate correlations. My feeling is that it's easy to get way too caught up in the numbers. It's nice to know my FTP, but I don't feel I need to know it to the watt. I need to know it well enough to set my training zones. I tend to race on feel anyway.

FWIW, I use golden cheetah, which calculates a CP based on historical data, but I don't use that number. I have a pretty good feel for what I can do for an hour and that is probably more accurate than some blind, 2-point correlation model.

Figured so. And that's a mighty dark pain cave.