Critical Power and AWC questions



whoawhoa

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Oct 28, 2004
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Since getting my PM I've had my FT set at 300 watts since I had come off a good break and was fitness was down. I didn't have any real indication that I should raise it until last weekend, where I had some good short term numbers from a crit/circuit race. Unfortunately, it wasn't hard enough for the entirety of the race to get a good 60min NP that might approximate FT. But, after the critical power talk around here lately, I cherry picked some values from that race to make up a critical power curve. I used these values:
2-min AP: 380
5-min AP: 335
10-min NP: 322

Obviously using NP for the 10 minute entry isn't the most precise, but it's all I had. This ended up coming out with:
r^2: 1
FT: 310
AWC: 134

So, given the r^2, should I have a lot of confidence in these results? Or should I wait until I can do more formal testing? (I've been lazy for the past few weeks). Also, how pitiful an AWC is this?
 

RChung

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Sep 12, 2006
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whoawhoa said:
I cherry picked some values from that race to make up a critical power curve. [...] So, given the r^2, should I have a lot of confidence in these results? Or should I wait until I can do more formal testing?
Cherry-picking values from a single race isn't a particularly robust way to estimate FTP. Your AWC estimate is low in part because in the middle of a race you probably weren't using up all of your AWC. In addition, even if you had collected the data from separate and specific tests, there's some evidence that a CP estimated using a very short duration test (like 2 minutes) may lead to a CP that is above FTP.
 

RapDaddyo

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May 17, 2005
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Cherry picking either AP or NP numbers from a ride for use in the Critical Power model is problematic for several reasons, but let's just focus on the 2 and 5 min numbers for a moment. How valid those numbers are depends on where they came in the race and what preceded them. The 2min effort in particular is mostly AC and the sum total of prior AC efforts (matches burned) would have reduced your AC for the remaining duration of the ride. So, to get a valid 2min number, you most definitely want to be fresh. This is true to a somewhat less extent for the 5min number. So, these numbers are probably understated but to an unknown extent. The 10min number may be the most valid, but I prefer to use a longer duration (>= 20mins) for the CP model due to the influence of AC on a 10min number (especially NP). Bottom line: the curve parameters you got are probably wrong (in spite of the R^2).
 

whoawhoa

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Oct 28, 2004
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RapDaddyo said:
Bottom line: the curve parameters you got are probably wrong (in spite of the R^2).
Agreed. After posting, I searched for anything regarding AWC and it appears 130 is off-the-charts low.
 

frenchyge

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Apr 3, 2005
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whoawhoa said:
LOL :D

whoawhoa said:
So, given the r^2, should I have a lot of confidence in these results?
I don't think so. I've wiggled numbers up and down in that model and it's almost difficult to get r^2 to drop below .99. AWC does move around a lot, as Robert's mentioned.
 

AndROOb

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Nov 20, 2004
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Correct me if I'm wrong, but I have come to understand that FTP is the first thing to deteriorate without regular maintenance. I mention this based on your statement: "I've been lazy for the past few weeks".