Monod/CP - AWC



DancenMacabre

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For several months I've been using the Monod/CP spreadsheet as one of my inputs in determining FTP and quantifying changes in my profile. I'd always used the same format for the process: 2 tests (5 & 20 minute), same time frame (within the same week), same weight, same location (all tests done on trainer, etc).

More recently though after some thinking about my power at various levels and how I seem to respond to certain training & rides, I decided to redo the tests and add a 3rd one. Specifically a 3 minute one. My rationale was that the 5 minute test is not the best indicator of anaerobic/AWC ability.

After performing the 3 tests, but keeping all other details the same (test protocol, etc), it seems monod is giving me some new information.

My AWC from these tests appears to be > 200. That seems a bit high especially in light of comments by Dr. Coggan that women in general have lower anaerobic capacity than men, even when lean mass differences are accounted for (this was in the book).

The obvious question you might have (or at least the ones I can think of) are whether the tests were performed/paced well and truly 100%. All I can say is 'yes', I believe they were and even if I tinker with monod and give myself an extra few watts on the 20 minute test (which I'm not sure I could have actually done!), AWC is still > 200.
The corollary to this is that this latest test then shows a decrease in CP to correspond with the increase in AWC - as compared to past tests. If I remove the 3 minute test, then AWC seems to be a fairly average 90ish.

I've pondered whether this is due to altitude and how it affects aerobic abilities more so than anaerobic ones, allowing for the possibility that relatively (not absolutely) speaking, AWC is now contributing more energy to the total required for an effort, than it did when I lived at sea level.

I know that AWC as defined by Dr. Coggan is simply resistance to supra-threshold exercise, not KJ's, etc.

For those of you who use Monod/CP frequently:
what's your AWC?
CP?
Does 200+ seem unusually high for a woman?
If you do have a relatively high AWC, have you altered or changed your training approach for developing FTP/sustainable power for longer events (e.g., RR's, crits, etc)?

EDIT: wanted to add that R^2 for the 3 tests was 0.997 which I think is quite high, suggesting the numbers fit the line well...
 

Fightin Boba

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DancenMacabre said:
I've pondered whether this is due to altitude and how it affects aerobic abilities more so than anaerobic ones, allowing for the possibility that relatively (not absolutely) speaking, AWC is now contributing more energy to the total required for an effort, than it did when I lived at sea level.

I can't help you with your queries, since I don't use the Monod test myself. However, I am trying to understand your Monod results in the context of your current test, which was apparently done at altitude, and comparing it to prior tests. Were you prior tests performed at altitude as well?

I would expect that AWC would be relatively unaffected by altitude, while the aerobic contributions to MMP would diminish. I would further expect that in a 3min test, the anaerobic:aerobic ratio would be be much less affected at altitude than with a 5min test, which would, in turn, be less affected than a 20min test.

Is the Monod test reliable across different altitudes (in the same subject, under otherwise similar conditions)?
 

RChung

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Sep 12, 2006
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DancenMacabre said:
For several months I've been using the Monod/CP spreadsheet as one of my inputs in determining FTP and quantifying changes in my profile. I'd always used the same format for the process: [...] More recently though after some thinking about my power at various levels and how I seem to respond to certain training & rides, I decided to redo the tests and add a 3rd one. After performing the 3 tests, but keeping all other details the same (test protocol, etc), it seems monod is giving me some new information.

EDIT: wanted to add that R^2 for the 3 tests was 0.997 which I think is quite high, suggesting the numbers fit the line well...
What you've discovered is this: the Monod estimation method is not at all robust to changes in the test protocol. Both the CP and AWC estimates (but especially AWC) are sensitive to changes in the protocol. This is partly due to statistical reasons alone, i.e., in regression problems like this, intercepts (like AWC) are less precisely estimated than slopes (like CP).

1. If you want to compare changes over time in either parameter you're going to have to stick with the same protocol.

2. If you do change protocols, don't fall into the trap of thinking that your underlying physiological characteristics have changed.
 

DancenMacabre

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Fightin Boba said:
I can't help you with your queries, since I don't use the Monod test myself. However, I am trying to understand your Monod results in the context of your current test, which was apparently done at altitude, and comparing it to prior tests. Were you prior tests performed at altitude as well?

I would expect that AWC would be relatively unaffected by altitude, while the aerobic contributions to MMP would diminish. I would further expect that in a 3min test, the anaerobic:aerobic ratio would be be much less affected at altitude than with a 5min test, which would, in turn, be less affected than a 20min test.

Is the Monod test reliable across different altitudes (in the same subject, under otherwise similar conditions)?

Hello Steve. I've done several monod tests, both at altitude and at sea level. The only thing I did different this time is perform a 3 minute test, in addition to the 5 & 20 minute tests I had used previously. Before this most recent test, I'd always noted AWC was in the 80-100 range both at sea level & altitude. With the inclusion of the 3 minute test though it more than doubles to 200+. The protocol was otherwise the same - indoor tests, separate days (test 1 - monday, test 2 - wed.), same body weight/mass, even the same warmup.

Like you suggested, I would expect 3 minute power to be less affected by altitude than longer durations. Unfortunately I never performed a 3 MMP test at sea level so I've no data point for comparison from which to say that that power metric has changed or not.

RChung said:
What you've discovered is this: the Monod estimation method is not at all robust to changes in the test protocol. Both the CP and AWC estimates (but especially AWC) are sensitive to changes in the protocol. This is partly due to statistical reasons alone, i.e., in regression problems like this, intercepts (like AWC) are less precisely estimated than slopes (like CP).

1. If you want to compare changes over time in either parameter you're going to have to stick with the same protocol.

2. If you do change protocols, don't fall into the trap of thinking that your underlying physiological characteristics have changed.

Robert, what you are mentioning here rings true. I don't think I've magically doubled the size of my anaerobic engine/system over the past few weeks. Moreover, I don't even do any dedicated L6 work. All of this correlates well with your comments that physiological ability isn't changing necessarily, simply because one adds an extra test and the outputs, being sensitive to the inputs, change.

That said, my profile does shift downward slightly from left to right. I suppose I ought to do a 1 MMP and see how that's changed as it has been 4+ months since my last such test.

I should research and learn more about the statistical limitations of such a model. If you know of any links or sites that help explain some of this then I'd enjoy reading them to educate myself.

Thanks for the comments gents :)
 

RChung

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DancenMacabre said:
That said, my profile does shift downward slightly from left to right. I suppose I ought to do a 1 MMP and see how that's changed as it has been 4+ months since my last such test.

I should research and learn more about the statistical limitations of such a model. If you know of any links or sites that help explain some of this then I'd enjoy reading them to educate myself.
Are you talking 1 hr MMP?

We discussed some of the problems with Monod testing here:
http://www.cyclingforums.com/power-...al-power-10-minute-20-minute-discrepancy.html
 

DancenMacabre

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RChung said:
Are you talking 1 hr MMP?

We discussed some of the problems with Monod testing here:
http://www.cyclingforums.com/power-...al-power-10-minute-20-minute-discrepancy.html

Actually I was referring to 1 minute power. It would be more to get my power profile up to date as I've not done such a 1MMP test in months. The different protocols I've used for monod (2 tests vs. 3 tests most recently) netted a very different value of AWC. As you clearly stated though, the test is highly dependent on protocol and may not be indicative of any underlying physiological changes or innate ability. Moreover, AWC seems imo - the y-intercept as I understand the model - to be the least robust/reliable metric to come out of the monod model, with CP being more solid/useful.

I plan to do the 1 MMP test more as a convenient gauge on anaerobic ability (despite the 50% aerobic contribution). I believe it would confirm that my anaerobic ability has not suddenly doubled or increased miraculously. Although I'd expect improvement to generally track that which has occurred on the right side of the profile given I'm a newer trainee.

Correct me if I'm wrong please, but it would seem to make more sense to compare your 20 minute monod data point to...........well, your previous 20 minute monod data points. Ditto for the shorter test. All this with the caveat of performing the protocol in the same fashion.

What's interesting is how in effect, I did use the same protocol......5 MMP test monday.......20MMP test wed...........same as every other monod test I'd done....but then simply added a 3 MMP test on friday. That was enough to lower CP by 0.2 downward but double AWC. So perhaps the CP value isn't quite as robust as I imagined it to be.

2 vs. 3 points just doesn't seem to be enough of an absolute change to alter the confidence one has in the results. I'd think you'd need many, many more (far more than could be done in a short time) tests to significantly up the accuracy.

The discussion link you provided (and some others I dug up) helped enlighten some of the concepts. :)
 

RChung

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DancenMacabre said:
Correct me if I'm wrong please, but it would seem to make more sense to compare your 20 minute monod data point to...........well, your previous 20 minute monod data points. Ditto for the shorter test. All this with the caveat of performing the protocol in the same fashion.
Well, you're not wrong if what you're interested in is comparing 20 minute power to 20 minute power, and 5 minute power to 5 minute power. You may not even be wrong if you're interested in more than that. However, the goal of Monod (and other similar types of testing) isn't simply that but to figure out a way to "fill-in" all the intervening power durations and to extend beyond 20 minutes, too. The trick is in figuring out how much to trust that kind of extrapolation. Being consistent in testing protocol is at least part of that.
 

DancenMacabre

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RChung said:
Well, you're not wrong if what you're interested in is comparing 20 minute power to 20 minute power, and 5 minute power to 5 minute power. You may not even be wrong if you're interested in more than that. However, the goal of Monod (and other similar types of testing) isn't simply that but to figure out a way to "fill-in" all the intervening power durations and to extend beyond 20 minutes, too. The trick is in figuring out how much to trust that kind of extrapolation. Being consistent in testing protocol is at least part of that.

Right. I am seeing your point & realize some people use monod as a basis for predicting what power level they can sustain for many different time periods. Personally I've never used it much for those purposes as I tend to think that for durations beyond one hour, the accuracy is sketchy at best. For durations less than an hour, I tend to think I have a good idea of what I can do...

I think this thread has brought to light some observations for me. From my discussions off-line with people who use monod, it seems that there are two common themes regarding the 3rd test and those are: a) individuals are dubious of test 1 and/or 2, hence the third data point gets tossed in (violating what you've said about 2 good data points being better than 3 so-so ones...), b) then said data point usually ends up being at a time duration between that of test 1 & 2, e.g., adding a 5 or 6 minute test to an already existing 3 & 20 minute set of tests.

My situation is a bit different in that the test I added (3 minutes) was not between, but slightly outside my existing tests (5 & 20). For the inclusion of all 3 data points, I get R^2 = 1 & for 2 data points it is roughly R^2 = 0.99. I'm very fuzzy on statistics, but I vaguely recall that R^2 is more an indication of goodness of fit rather than an association being statistically significant. Regardless, I gotta think the accuracy of 2 vs 3 data points is probably trivial.

Yet there's some consistency:


  • if I omit the 5 minute data point & look only at the 3 & 20 minute tests, then AWC hardly changes and CP remains the same.


  • if I omit the 3 minute test, then the test results are consistent with past tests, AWC in the 75-100 range and CP remains the same.


  • It is only when I add the 3 minute test to the 5 & 20 minute ones and put them all into monod that I get the differing values...

Finicky little model it is....All of which agrees with your suggestion to keep the test protocol very consistent :)
 

frenchyge

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DancenMacabre said:
For the inclusion of all 3 data points, I get R^2 = 1 & for 2 data points it is roughly R^2 = 0.99.

Do you have that backwards? For 2 data points I would think R^2 would always be 1 since it'd be impossible for them to not fall in a perfect line. For the same reason, any goodness of fit would be meaningless for only 2 points, unless I'm mistaken.