FTP & Critical Power from Golden Cheetah

[twizzle]

O.K. - confused here.

My best one hour power in a race, on a number of occasions, has been around the 320w mark, with a best of 329 which just happened to fit in with my 2x20 on the trainer. And I use 350W as my est. FTP for training purposes following on from my 421w-for-14-minutes in a recent time trial. But GoldenCheetah's "Critical Power" calculation based on 3 and 20 minute "best power" efforts estimates my critical power (FTP) at 403W. Against that is one of the best rides : a 45 minute crit where I was on the front for 27 minutes averaging 358W before the power output dropped - which could have been hydration impacting the performance OR the fact I'd just put in a quick lap when passing D grade and the power output had spiked for a lap. Also, there was the hill climb the other week where I averaged 411W in 11:41, but had to keep moving at the top because the lactate spiked when I stopped and my whole body was on fire.

Anyone got some words of wisdom? Should I use 403w as my FTP for training purposes? According to the quicky research I've done the critical power model is supposed to work on power-to-weight and requires a weight input, but the GoldenCheetah process doesn't have an input for weight.

I just don't think I could actually maintain 403W for an hour. Or is it a case of HTFU?

[Alex Simmons/RST]

Refer SOS #8:
http://alex-cycle.blogspot.com/2009/07/ ... ftp-2.html

Body mass is not required to calculate CP, however it is common for CP to be expressed as W/kg, and when using model to predict maximal sustainable power for a given duration, it uses this value.

[twizzle]

In the context of Golden Cheetah, it's providing a CP number that's supposed to be the hour value, but there's no weight.

Looking at the CP calculator from the tools menu instead of the CP value on the chart, it looks like the number on the chart is what it thinks I should be able to do, not what I've done, as using the highest observed numbers over time gives me a CP of 348. I would need to pick up my 20 minute power from 370w to 410w to get to the CP value indicated on the chart (403.3w).

I think what this is telling me is "could do better". But at the moment, my actual CP (based on data in the last month) is ~ 350w.

[toolonglegs]

Yup...I think you actually need to do the testing...not take in from non specific events.
Cheetah gives me a critical power of 353 I think (466 for 3 minutes & 370 for 20 minutes) so pretty close for me.But if my 3 minute power was around my normal results of 420-430 it would kick my CP up to the 370 mark .Bearing in mind my best 3 minute was part of a 5 minute effort and also the 3rd 5 minute effort over 440w for the day.If I had specifically tested a 3 minute on that day I could have gone close to 500 I am sure .
Go and do the HOP or two well rested full on 20 minutes or the 16km TT...and then follow it up with a few minutes of fun doing a MAP test.

[toolonglegs]

Not that I could get anywhere near any of those numbers at the moment! .

[twizzle]

On one of the other threads... you will have seen us all scratching our head re. where we can do a 20 minute test without running out of road or getting hit by a car.

Here's something to think about - criterium on the 10'th November. Three minute of 445w and 20 minute of 361w from the one event... giving a CP of 345w

I think this means I need to HTFU - my FTP is above the 350w I've been using for training goals.

[toolonglegs]

Maybe...send me the .csv file an I will chuck it in WKO+ ...seing that our dimensions are pretty close it will give me a pretty good NP.
...but if you are 350 or 360 it doesn't actually change your training numbers by more than 1 or 2 watts.
shotred@yahoo.com
Also not sure how long the crit was...but when doing the Coogan 20 minute test you have to do a blow out effort first...if your 3 minute effort was part of your twenty minute numbers then not sure how that would skew the numbers.

[twizzle]

Maybe...send me the .csv file an I will chuck it in WKO+ ...seing that our dimensions are pretty close it will give me a pretty good NP.
...but if you are 350 or 360 it doesn't actually change your training numbers by more than 1 or 2 watts.
shotred@yahoo.com
Also not sure how long the crit was...but when doing the Coogan 20 minute test you have to do a blow out effort first...if your 3 minute effort was part of your twenty minute numbers then not sure how that would skew the numbers.

I have wko+, I just don't use it. I'll load some data up at work next week to have a look.

Re. the same event, what it should mean is that my 3 minute number is way low and therefore the CP estimated off the one event is low as well.

[toolonglegs]

Well...if you do the test you will know...you have been wondering for quite a while now.

[Alex Simmons/RST]

Re. the same event, what it should mean is that my 3 minute number is way low and therefore the CP estimated off the one event is low as well.

On the contrary, underestimating your 3-min best power will overestimate critical power (which is the slope of the line) and underestimate your anaerobic work capacity (the intercept).

that's why cherry picking such data from non specific tests is part of the sins of sins articles I referenced.

CP requires dedicated best effort tests, typically one of 3-6 minutes duration and another ~ 20-25 minutes. You can throw in a number in between if you like, provided it really is a best effort. It also requires such tests be done within a reasonable time period of each other, like in the same week.

But putting non best effort numbers in there from non quasi steady state efforts is just GIGO.

[twizzle]

Blah. I'm all confused again as to how the models work.

And how the heck do people find the time to do the proper testing??!

And where does Golden Cheetah come up with a 403W figure from?

[twizzle]

O.K. - the CP number on the CP display is from an estimator that looks at all prior history and tries to apply a curve to the historical data to estimate what it *thinks* you are capable of. No additional info on the web etc., so I might have a look at the source code.

[Ant.]

(Nothing personal, but) I don't believe you can do 400W for an hour.
Don't bother getting fancy by looking at source codes and everything. 2x20s are your ticket.

I vaguely understand the CP model but wouldn't use it personally. Seems like it's too easy to get wrong, needing to do well rested best efforts, and need to do them within a week of each other, and so on.

I have 3 interval locations. One is a 10km circuit (it's around the block.. 5km streets) with rolling terrain, another is a 6km stretch of road with rolling terrain, and the other is a 6km road pancake flat.
Forget the first spot I mention... I just need to stop and do a U turn every 7-8mins. 2 U turns doesn't impact a 20min effort. Plus it gets you really good at doing U turns
Do 2x20s: same power each time = FTP. Maybe round down to the nearest 10W if you're really suffering and burning.


I'm google mapping your location, and I refuse to believe you can't manage to do 2x20s outside. Gundaroo road? I wouldn't complain about having to turn around every 5mins to be honest. It's only a few seconds of coasting.

[twizzle]

Neither do I.

re. 2x20, easier said than done around here. Gundaroo is a popular tourist destination, the road is narrow and rough as guts...

[toolonglegs]

Jump on the federal highway?...I don't have any roads 20 minutes long,taking maybe 2 or 3 corners doesn't effect Av much at all...maybe 2 or 3 watts compared to NP for the same time.

[Ant.]

5km stretch of road, s'all you need Both of mine are very close to the CBD.
Jump on a popular group ride, and I'm sure they'll go through more than a couple of suitable locations.
Look harder Everyone in Perth told me I couldn't do my 20min intervals except if I go waayy out that way. They were wrong.

2x20s are the bees knees.

3 U-turns don't affect AP at all for me, because I'm pretty quick around corners and because the few seconds of coasting is made up for by the few seconds of accelerating (out of saddle for me) over the AP.

[Alex Simmons/RST]

Blah. I'm all confused again as to how the models work.

http://74.125.155.132/search?q=cache:9Q ... =firefox-a
http://www.velo-fit.com/articles/critical-power.pdf
http://teamhealthfx.com/files/7/general/entry1758.aspx

And how the heck do people find the time to do the proper testing??!

Pithy Power Proverb: Training is testing, testing is training. - A. R. Coggan, PhD

And where does Golden Cheetah come up with a 403W figure from?

Don't know, you'd have to ask the providers of GC.

But if it's commiting one of the Sins of Sins, then it will give you garbage.

[DanielS]

On the contrary, underestimating your 3-min best power will overestimate critical power (which is the slope of the line) and underestimate your anaerobic work capacity (the intercept).

Ahhhhh..... okay something just clicked.

Golden Cheetah provides an estimate for CP from the mean-maximal power plot. It has always estimated mine too high (it says 300W but I'm closer to 280W). I've never done a proper 3-min test so that makes sense now.

The best way I think is to do two dedicated tests, one of which is 20-30 min long, and the other 3-5 minutes, and calculate it directly. Or use one of the spreadsheets out there to do it. There is also a calculator built into GC that you can use if you do a 20 min and 3 min test (under the Tools menu).

[toolonglegs]

OK...no real idea .But is it suggesting that if your 3 min power is high compared to your 20min then it is just taking a % of the 20 minute in relation to the 3m/20m ratio.Yes Alex is right...the higher your 3 minute power compared to 20 minute...the lower your estimated "critical power".I expect there is more maths to it than that .

[twizzle]

Jump on the federal highway?...I don't have any roads 20 minutes long,taking maybe 2 or 3 corners doesn't effect Av much at all...maybe 2 or 3 watts compared to NP for the same time.

Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Screw it - where can I do VO2Max and LT testing in Canberra?

Or, seeing as all of the estimates using the calculator on reasonable efforts in December come up with a 350 - 360W range, does it really matter if it's five percent (>15w) out when the 20min testing just uses an estimate for hour period anyway?

[Alex Simmons/RST]

Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.

Screw it - where can I do VO2Max and LT testing in Canberra?

What for?

[twizzle]

Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.

Narrow, 100km/h road frequented by bogans... Which is why I've never used it as a training road.

Screw it - where can I do VO2Max and LT testing in Canberra?

What for?

Beats the heck out of dealing with SOS 2,3,4,6 & 9 on a regular basis.

What's going to be more accurate - an excellent 2 x 20, or an actual blood lactate/VO2Max test session I can repeat every 3 - 6 months?

[Alex Simmons/RST]

Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.

Narrow, 100km/h road frequented by bogans... Which is why I've never used it as a training road.

Screw it - where can I do VO2Max and LT testing in Canberra?

What for?

Beats the heck out of dealing with SOS 2,3,4,6 & 9 on a regular basis.

What's going to be more accurate - an excellent 2 x 20, or an actual blood lactate/VO2Max test session I can repeat every 3 - 6 months?

You're making a mountain out of a molehill.