As far as I understood their algorithm, they still use the extrapolation method. Ideally you have a negative split session as intensity increases and fatigue sets in. In lab-conditions they do a this deliberately in a (quite physically challenging) step-test to reach MaxHR to actually observe Max Power and observe the O2 uptake via a mask at the moment just before you collapse (I've done this test decades ago, and yes, to actual collapse it goes). An issue is that you'll never know if Max HR is really Max HR or just the point where a person is fed up with all the running/cycling and the mask. And this test takes a couple of days to recover from, so it is useless to track progress for serious athletes as it hugely interferes with their training schedule.HornetMaX wrote: ↑October 2nd, 2023, 10:18 amI tried to look at FirstBeat white papers but they seem very secretive on what they actually use. They do explain that they throw away part of the data if it looks suspicious (e.g. halting at a red light) but other than that they do not say what they do with the resulting data.
The key underlying study here that seems to enable FirstBeats approach is an 'Suboptimal" approach to this test: there is a method where a step-test is incomplete (i.e. MaxHR isn't reached) and the data is extrapolated to MaxHR. So, basically they map what HR you need to produce a certain power. Based on that, they can project the maximum power you'd produce if you would hit MaxHR (hence the extreme dependence on that very unreliable number!).
This extrapolation only works well if your HR and power both show a decent variation. So a steady state session, where power (and potentially HR) are supposed to be very flat for a far majority of the time would result in weird readings as the base for extrapolation is too narrow. So a steady state Zone 2 session for an hour should actually not give a VO2Max this way as basically you only have a single datapoint (i.e. one tupple of HR and power). So to estimate it decently, you actually want a negative split of some kind.
A second twist is that Firstbeat can not measure O2 uptake, as there is no mask. But given the projected maximum power you can produce, they calculate the corresponding amount of O2 you would need to produce that power. In essence, the numbers you see are formula for each specific sport to transform power/speed/etc. to the needed oxygen uptake to produce it. Again, the huge generalisations (both in technique and effectiveness) that are found here make this number not very accurate.
But it is a reliable number: its generalisations are not random across sessions, so for a single athlete, it produces the same number for the same effort (although that number might not campare to another athlete).
They also do this for cycling. But it is indeed very limited.
I think the approach has some value, but it has a lot of challenges. People do not want to do a 2K Max effort on a weekly basis, but they want to track progress.HornetMaX wrote: ↑October 2nd, 2023, 10:18 amFor indoor rowers I'm not convinced you need all that stuff: only thing that may be of interest is to provide an estimate without doing a max effort 2K.
Once you're OK to do a max effort 2K, a simple formula (backed by statistical data) is probably more than enough.
Despite all its flaws, it provides a reliable (but not accurate) way to compare workouts in some way. When systematically applied to one person, where all errors with reality thus become systematic, it can be used to track development for that person. Ideally in training you see your pace improve and/or your heart rate to do it go down. Doing that on a training-to-training basis is hard, and sometimes a training isn't that easy due to a lack of sleep/food etc.. So being able to plot a lot an indicator of fitness in training sessions through time is interesting. Capturing that trend in some way, allowing you to see progress in fitness, without constantly doing max out efforts, helps people stay motivated.
