Power Meter Testing (FTP vs. CP)

Triathlon Forum
1

Can someone explain the difference between FTP (Functional Threshold Power) and CP (Critical Power)? Testing for the two seem to be very similiar. Also, can you explain the best way to use the two numbers in training.

Thanks

2

CP60 is the maximal power you can evenly generate over 60min. CP30 is power over 30min. 95% of CP30 is a good proxy for CP60 and can be a good proxy for FTP. So, FTP and CP60 are essentially the same. Once established, these can serve as valuable baselines and benchmarks in your training. You are probably familiar with training efforts based on HR or PE. Power or wattage give us a way to measure actual work done. HR measures stress to the body. PE is a subjective evaluation of efforts performed by your supercomputer (brain). They are all valuable and all of them have some limitations. For the trained athlete, together, they can provide superior evaluation of training and race planning/execution.

3

Thanks KP. I thought it was that simple but was not sure if I had missed something.

4

Here are couple of links you may find useful.

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

and

http://velo-fit.com/vftools.htm

Download the Monod Critical Power spreadsheet if you would like to calculate your CP.

5

So I would assume that the test to perform would be a CP30 as opposed to the 20 minute TT Test for FTP. What is the best test to find your FTP?

6

KP had me do one a couple of weeks ago. I warmed up for 90 minutes starting off easy and then building up a little bit. Then I rode for thirty minutes as hard as I possibly could for thirty minutes and then I finished ride easy.

7

I believe the Critical Power (CP) terminology was developed by Friel a number of years ago while the Functional Threshold Power (FTP) is what is described in Allen and Coggan’s Training and Racing with a Power Meter. As noted above, CP60 and FTP are essentially the same thing.

8

Do you mean critical power as (mis)used by Friel, or the critical power as defined by Monod:

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

(Keep in mind that Eddie Monnier is a Friel coach, so is quite kind on Friel appropriating the term from an established scientific concept.)

FTP is defined as the power you can sustain for an hour, by definition.
Coggan has given his “Seven Deadly Sins” post to describe ways to estimate your FTP:

http://lists.topica.com/lists/wattage/read/message.html?sort=&mid=910289158&start=0

In the Hunter Allen/Andy Coggan power training book, Hunter Allen uses a method (95% of your 20 minute power after a prescribed warmup) that he uses, but Coggan doesn’t really recommend.

Edit: Sorry to give repetitive info; thought I had hit reply before I put the kids to bed.

As to training with power, you should buy Allen and Coggan’s book. While you’re waiting, go here
http://www.midweekclub.com/articles/
And read the first six articles, as they suggest/

This is also a good starting point:
http://www.cyclingpeakssoftware.com/power411/

And of course, subscribe to the Wattage list:
http://lists.topica.com/lists/wattage/read

The previous articles are the de facto FAQ for the list.

9

X-man – there are a number of different ways to come to terms with FTP. Using 95% of the 30min TT data, if done well (evenly generated maximal efforts), has been a good one. As AC noted recently, using cyclepeaks,you can get a good idea of FTP by simply observing power distributions over time. Rich Strauss likes to use another TT method – and then there is the actual 60min TT. However, the longer the test the greater the recovery costs and the more opportunity for execution error. Keep in mind that motivation and recovery status might influence results, so give a strong effort and come to the test relatively fresh. Get very warm prior to the TT. I suggest you choose your route carefull to avoid lights and traffic over mostly flat terrain.

Cheers

10

I would also add that establishing your FT from ~1hr hard race is the best approach for a lot of people. I know how hard it is to get motivated for a 30min TT, let alone a 60min TT, but it’s not too hard to get motivated for something like an Oly bike. Personally, for IM athlete’s, I like using an Oly bike to establish your FT because it’s probably just a tad on the conservative side (most people tend to overestimate their FT due the “ego issue”). I should note: Any FT test should yield a flat to very slightly increasing profile. Any decline in the profile indicates fatigue and makes the test useless.

Thanks, Chris