I’m doing a 9.7 mile TT tomorrow morning that is put on by Beat the Clock and benefits the Livestrong Foundation. They put several of these on every year, approximately every month or two, so it’s a good opportunity for me to gauge fitness as the season progresses. In addition to gauging progress from TT to TT, I’m wondering what the best way is to use the result from this TT to determine FTP? This effort should be in the 24ish minute range, so I’m thinking of following it up a few days later with a maximal 5 minute test, and then using the two time/avg power values to calculate CP in the Monod spreadsheet. Is the latter test needed, or does it increase accuracy, or can I just take a % of the TT effort as my FTP?
I would go with the critical power (Monod) approach just as you suggest. You could just apply a fixed correction factor to the TT power (e.g., knock off 5%), but that would not be quite as precise. Furthermore, by establishing your anaerobic work capacity (or alternatively, your personal ratio of functional threshold power:10 mi TT power) you will be able to use future TT results to track changes in your functional threshold power with more confidence even w/o doing another 5 min test (assuming, of course, that the focus of your training remains essentially the same such that your anaerobic work capacity also stays the same).
I think cp60 = 0.95 (cp30) so seems like you’d be in the ballpark taking 6-7% off…its not like you have to be that accurate. There has to be at least a few% day to day variation in FTP anyway.
Dave
I think cp60 = 0.95 (cp30) so seems like you’d be in the ballpark taking 6-7% off…its not like you have to be that accurate. There has to be at least a few% day to day variation in FTP anyway.
Dave
The problem with ass u m ing a constant shape to the power-duration relationship is that it isn’t constant. For example, the ratio of my functional threshold power to my 20 min power is 0.97, whereas when my wife was pursuiting her ratio was 0.92. That’s not a huge difference, but I figure that if you are going to the trouble of performing a formal test*, why settle for only an estimate that is no more precise than what can be obtained without any formal testing?
*Of course, jkatsoudas is going to use data from a race, so there is no additional effort required to determine his ~24 min power output. With just one additional shorter (albeit more painful test), though, he will not only have a more precise estimate of his functional threshold power now, but also a feel for his personal power-duration decay.
Thank you very much!
I think cp60 = 0.95 (cp30) so seems like you’d be in the ballpark taking 6-7% off…its not like you have to be that accurate. There has to be at least a few% day to day variation in FTP anyway.
Dave
The problem with ass u m ing a constant shape to the power-duration relationship is that it isn’t constant. For example, the ratio of my functional threshold power to my 20 min power is 0.97, whereas when my wife was pursuiting her ratio was 0.92. That’s not a huge difference, but I figure that if you are going to the trouble of performing a formal test*, why settle for only an estimate that is no more precise than what can be obtained without any formal testing?
*Of course, jkatsoudas is going to use data from a race, so there is no additional effort required to determine his ~24 min power output. With just one additional shorter (albeit more painful test), though, he will not only have a more precise estimate of his functional threshold power now, but also a feel for his personal power-duration decay.
Just to embelleish what Andy has said, here are a few more details on the topic (much/most of which is drawn from Andy’s prior writings on the topic):
http://alex-cycle.blogspot.com/2008/05/seven-deadly-sins.html
I’ve been using CP instead of just 20-30 min efforts this winter indoors and I would have been 6-7 watts off of FTP using just the intermediate trial. It is also telling me something about my relative strengths that may prove useful in designing further training. Whether 6-7 watts of accuracy is worth 4 minutes of painful riding (the first minute isn’t too bad…) is up to you. But since I’m a scientist, another opportunity to play with numbers is a big bennie.