Monod Test Protocol

[bbrauer]

I understand the general principles of CP as defined by Monod and Scherer, but how is the Monod test applied to determine a corresponding power slope to estimate power at different time durations? A cursory google has not yielded much fruit.

 

[daveryanwyoming]

I understand the general principles of CP as defined by Monod and Scherer, but how is the Monod test applied to determine a corresponding power slope to estimate power at different time durations? A cursory google has not yielded much fruit.

Have you checked out this site: http://www.velo-fit.com/articles/critical-power.pdf

It pretty much lays it all out and even gives you a free spreadsheet you can plug numbers into. Basically the model doesn't directly fit a power slope, it fits a line to energy (work) vs. time, not power. But it's easy enough to predict power from that work vs time data. The Y intercept is AWC or your energy reserves for pure anaerobic efforts and the slope is CP and is in units of watts per kg.

A couple of things to keep in mind:

• It's best to use dedicated test efforts that represent the best power you can hold for the duration rather than cherry picking off your MMP or trying to take several points from one longer effort. Both of those methods will almost certainly underestimate power for the shorter efforts since it's hard to do a best possible effort of say 3 minutes duration as part of a best effort for say 20 minutes. Cherry picking MMP points may work, but it's a random approach and hard to know if the point you chose represents an actual best effort for the duration or just a high point among many submaximal efforts.
• The point above is important in part because low estimates for short efforts will actually predict a higher FTP than you're actually capable of. That's counterintuitive, but a lowball short effort basically undervalues your contributions from anaerobic metabolism and the model will then predict your contribution from aerobic metabolism is higher than it actually is.
• You can minimize those impacts by making your shortest effort a bit longer, say in the 4 to 6 minute range. You should also limit your long effort since it's hard to stay totally focused for really long efforts and lowball long efforts will underpredict your FTP.
• Rchung made a very good argument that a couple of data points carefully collected beat a larger number of points loosely collected. Make the effort to really give your best effort for two or three time durations and make sure you really gave it your best.
• Even with well collected data points the model isn't very accurate for very short efforts or efforts much longer than an hour.
• In terms of estimating FTP, use the model's CP prediction (in units of watts/kg) rather than the 60 minute power prediction. The latter tends to be a few watts higher and overestimates your anaerobic contribution out that far.
• Try to use data points collected in a short time period and with similar weight. The predicted power curve allows you to enter a different weight and the results seem counterintuitive. The spreadsheet on the site linked holds CP constant so your predicted power will drop as you enter lower weights. It probably would make more sense to hold power constant and show how W/Kg changes with weight gain or loss, but that's not how the spreadsheet is coded.

Good luck,
-Dave

 

[bbrauer]

Have you checked out this site: http://www.velo-fit.com/articles/critical-power.pdf

It pretty much lays it all out and even gives you a free spreadsheet you can plug numbers into. Basically the model doesn't directly fit a power slope, it fits a line to energy (work) vs. time, not power. But it's easy enough to predict power from that work vs time data. The Y intercept is AWC or your energy reserves for pure anaerobic efforts and the slope is CP and is in units of watts per kg.

A couple of things to keep in mind:

• It's best to use dedicated test efforts that represent the best power you can hold for the duration rather than cherry picking off your MMP or trying to take several points from one longer effort. Both of those methods will almost certainly underestimate power for the shorter efforts since it's hard to do a best possible effort of say 3 minutes duration as part of a best effort for say 20 minutes. Cherry picking MMP points may work, but it's a random approach and hard to know if the point you chose represents an actual best effort for the duration or just a high point among many submaximal efforts.
• The point above is important in part because low estimates for short efforts will actually predict a higher FTP than you're actually capable of. That's counterintuitive, but a lowball short effort basically undervalues your contributions from anaerobic metabolism and the model will then predict your contribution from aerobic metabolism is higher than it actually is.
• You can minimize those impacts by making your shortest effort a bit longer, say in the 4 to 6 minute range. You should also limit your long effort since it's hard to stay totally focused for really long efforts and lowball long efforts will underpredict your FTP.
• Rchung made a very good argument that a couple of data points carefully collected beat a larger number of points loosely collected. Make the effort to really give your best effort for two or three time durations and make sure you really gave it your best.
• Even with well collected data points the model isn't very accurate for very short efforts or efforts much longer than an hour.
• In terms of estimating FTP, use the model's CP prediction (in units of watts/kg) rather than the 60 minute power prediction. The latter tends to be a few watts higher and overestimates your anaerobic contribution out that far.
• Try to use data points collected in a short time period and with similar weight. The predicted power curve allows you to enter a different weight and the results seem counterintuitive. The spreadsheet on the site linked holds CP constant so your predicted power will drop as you enter lower weights. It probably would make more sense to hold power constant and show how W/Kg changes with weight gain or loss, but that's not how the spreadsheet is coded.

Good luck,
-Dave

Thanks Dave. As always a great help.

What's your opinion of doing the shorter AWC efforts out of the saddle? I wonder if staying seated for all tests for the sake of consistency is preferable. I can usually get better readings when I'm out of the saddle. Even my best 5 minute efforts are done on a climb in and out of the saddle.

 

[daveryanwyoming]

Thanks Dave. As always a great help.

What's your opinion of doing the shorter AWC efforts out of the saddle? I wonder if staying seated for all tests for the sake of consistency is preferable. I can usually get better readings when I'm out of the saddle. Even my best 5 minute efforts are done on a climb in and out of the saddle.

I do all my Monod efforts in the saddle, it seems to me to be a better apples to apples comparison. I haven't given much thought to doing them as you suggest but it doesn't feel right to me. Seems you'll bring your upper body into play and different range of motion putting different stress on the working muscles. It doesn't seem right to me to estimate metabolic work capacity in a way that utilizes additional muscles for the short durations but not the long efforts.

But to be honest I don't really know the answer to your question and others may give you a different response.

-Dave