Extended CP and 2-Parameter CP

[Dave Krenik]

I'm puzzled by the different CP/FTP values I get when using these 2 models.

I've used the 2-parameter model for years and it typically yields a number that is very close to my FTP (just a little high - not much).  I use a 4-5 minute effort along with an 17-20 minute effort for the parameters.

When I look at the Extended CP model, it indicates a CP/FTP (they are only 1-2 watts apart) that is ~20 watts lower than than the 2-parameter model.

Why such a great difference?

Dave

[Andy Coggan]

I don't think it is surprising that a different model yields a different result. The question to me would be, how was the extended model validated? 

[Mark Liversedge]

The extended model attempts to extract the contribution from each energy source; there are some words to explain some of that in the science section of the gc website.

Where the 2p model does not take into account why we fatigue the extended model attempts to. It looks at performance sustained over much longer durations to account for that. If your data does not contain sufficiently maximal efforts in the extended aerobic range then 1hr power will be reduced -- you can change the parameter intervals to suit the way you test and train to account for this.

The approach you take (~2 and ~20 TTE and 2p model) is what we always recommend for establishing CP

Mark 

[Mark Liversedge]

On Friday, 12 September 2014 02:36:26 UTC+1, Andy Coggan wrote:

I don't think it is surprising that a different model yields a different result. The question to me would be, how was the extended model validated? 

Until we can afford to run a study which collects reliable and accurate data used as inputs validation is going to be impossible. 

We /could/ collect a bunch of data and make unverified claims about its veracity, follow that with assumptions about the data based upon how it fits our models and then publish claims about the model fit in a marketing webinar. But folks see through that kind of nonsense pretty quickly.

Mark 

[Andy Coggan]

On Friday, September 12, 2014 3:19:33 AM UTC-5, Mark Liversedge wrote:

On Friday, 12 September 2014 02:36:26 UTC+1, Andy Coggan wrote:

I don't think it is surprising that a different model yields a different result. The question to me would be, how was the extended model validated? 

Until we can afford to run a study which collects reliable and accurate data used as inputs validation is going to be impossible. 

So what you're saying is that you've simply skipped that last step entirely, and expect everyone to trust the extended model results based simply on faith?

[Mark Liversedge]

We suggest people TEST to establish their CP.

I may get a t-shirt made and send it to you.

Mark 

[Andy Coggan]

That doesn't really address my question.

[Andy Coggan]

BTW, has the extended model ever been documented/described anywhere? If so, I'd be happy to use my (ever-growing) database of P-D numbers to test it for you. 

[Mark Van Akkeren]

says the guy that publishes on Facebook.

[Ben Blizard]

I'd buy that t-shirt.

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[Andy Coggan]

On Friday, September 12, 2014 12:11:55 PM UTC-5, Ben Blizard wrote:

I'd buy that t-shirt.

Would you buy one that reads "training is testing and testing is training"?

[Dave Krenik]

I'm not surprised that different values are generated from my efforts.  I am surprised by the magnitude of the difference.

I'll play around with it (Extended CP) some more and try Mark's suggestion.

[Dave Krenik]

Just for the record, I stated that I use 4-5 minute and 17-20 minute efforts.

[Andy Coggan]

On Friday, September 12, 2014 2:32:49 PM UTC-5, Dave Krenik wrote:

I'm not surprised that different values are generated from my efforts.  I am surprised by the magnitude of the difference.

Bigger or smaller than the 14% difference reported in this study? 

http://www.ncbi.nlm.nih.gov/pubmed/24566607 

[Dave Krenik]

Smaller.  2-parameter yields ~260 watts CP and Extended yields ~240 CP.  About 8% either way you look at it.

Dave

[Mark Liversedge]

Vague meaningless crap like that might go down well over on wattage, but here we tend to deal in substance.

If your training does not contain maximal efforts for any given duration then it is not a useful input for /any/ of our PD models.

Mark