What used to be here were two paragraphs of ranting about how lab tests can't inform our training and how what we use as cyclists doesn't relate. Then, instead of assuming my logic was infallible here in my ivory tower (which I would have done ten years ago), I looked to confirm it. Every single study I found that tested time to exhaustion at MLSS was 50-70 minutes. Here is a fascinating study that shows that 90% of your MLSS velocity (not power because air resistance isn't linear blah blah), give or take about 5%. Let's talk about it before we go on.
Four subjects actually do 38-40kph for a true 1 hour time trial (or as close as I'm willing to forgive based on no criteria). The AVS column tells the whole story, showing velocity at MLSS and velocity in the 40k TT. What I'm fascinated in is the variation of the 5km TT time. I calculated 40kmh at around 8 minutes, so what we know as the long side of a VO2max interval and this we know to be variable among cyclists. We can conclude from the table above is that while the average of 5km TT speed is about 92% of your MLSS speed, the variability is between 86-95%. This is a very wide range, and let's make up some numbers. Let's pretend briefly that power and speed are close enough to linear at these speeds, so 5% of 300w is 15w. Over a long TT, if this overestimates your FTP, trying to hold the extra 15w is going to blow you up in short order. Going under won't blow you up, but 15w can make a big difference over 30-60 minutes.
Real life example of short efforts being variable: last year with a 300w FTP I was doing 5' VO2max intervals at 380-400w, let's average it at 390. My friend was doing 400w on the same 5' hill with an FTP of 370w. That's 108% of his FTP and 133% of mine. He now trounces me on any duration longer than 2 minutes, but this illustrates that I've got a larger amount of readily available anaerobic reserve. This is going to greatly influence any efforts I do in terms of estimating my true MLSS/FTP. Including 20' tests? Yes.
I just equated MLSS and FTP, so, quickly: FTP is a reference defined as the power maintainable for one hour. In many studies where MLSS has been held to exhaustion in various sports including running and cycling, the times I've seen were 50-70 minutes. So for my purposes, equating the two will be close enough. It's not precise, it's not scientific, but it's my way of relating commonly used training parameters to the existing body of literature.
Anyway, since I don't know any cyclist who sets their training zones based on speed, well go back to last post's study that some great variability in 20' TT performance when it comes to predicting MLSS. My educated guess is that this comes from a high level of FRC involvement which will vary by individual. I'm sad that the individual power data wasn't published because then we'd be able to perform some of our own statistical analysis.
It'd be nice to see is 20' power vs measured MLSS by rider type. The hypothesis is that the variation in 20' test results is influenced by FRC, and in conjunction with the advanced metrics in WKO4, we'll be able to get a more accurate picture of where an athlete's FTP is in terms of %20' mean maximal power. You're saying this is a very small point to harp on, and it is. It's also reasonable, based on the analytic tools to want to be able to tell a rider his or her FTP is only 93% of a 20' test, or 97%, or wherever their phenotype puts the estimate. 95% is a pretty good estimate for people inside the bell curve, but for the people outside of it (speaking for myself and some athletes), it can be frustrating.
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