Did Strava estimate my FTP?

neeb

I recently upgraded (probably temporarily) to Strava Premium due to the free offer thing and noticed that it is giving me power zones based on an FTP figure. I use a power meter and upload all my rides to Strava with real power data. I can't remember ever entering an FTP value in Strava (or maybe I did?). The weird thing is that the value is way higher than my maximum average power for one hour over the last 6 weeks as shown on my Strava power curve, but it's not so far off what I might expect to get if I actually did a flat-out FTP test (well, it's still possibly a bit too high for what it's likely to be at the moment but it's a figure I've been at at or near in the past).

So I'm wondering if Strava estimated that figure using some complex algorithm (obviously not just the maximum for 1 hour on the power curve over the last 6 weeks), or if it's a figure I entered myself sometime in the past (maybe last time I had Premium a year or two ago). Is there any way to tell? Just interested really, especially in how Strava calculated the figure if it wasn't supplied by me.

onionmk

Yes strava can and will estimate your FTP if you use a power meter, as you've said, via complex algorithms and rider data. I'm not quite sure how they do it although I'd like to know! And hey.. Maybe Strava knows that you're not reaching your true potential

neeb

Great, thanks! Do you know if there is an option to recalculate according to the algorithm they use? All I can find is an option to manually change it.

onionmk

I haven't tried it myself but my guess is that it will automatically calculate if you were to delete the manual FTP figure.

supermurph09

Being honest, I don't think it's very useful so wouldn't pay too much attention to it. You'd be better off with Training Peaks or Golden Cheetah.

daechambers88

I tend to find the strava value is greater than a lactate threshold test value so tend not to use the value but find it can give a good trend in terms of slope of progress etc

buckmulligan

If Strava is basing it on ALL your historical data, then it's next to useless. Man up and do an FTP test, then you'll know what your FTP is; the best predictor of performance is performance itself.

neeb

BuckMulligan wrote:

If Strava is basing it on ALL your historical data, then it's next to useless. Man up and do an FTP test, then you'll know what your FTP is; the best predictor of performance is performance itself.

Yup, you're right of course. I hate FTP tests because I'm very strict with myself and know that if it's going to be accurate I need to almost kill myself.. ;-)

Alex_Simmons/RST

daechambers88 wrote:

I tend to find the strava value is greater than a lactate threshold test value so tend not to use the value but find it can give a good trend in terms of slope of progress etc

Putting aside the accuracy of Strava, lactate threshold occurs at an intensity quite a bit below FTP. Typically 10-15% lower power.

neeb

Alex_Simmons/RST wrote:

daechambers88 wrote:

I tend to find the strava value is greater than a lactate threshold test value so tend not to use the value but find it can give a good trend in terms of slope of progress etc

Putting aside the accuracy of Strava, lactate threshold occurs at an intensity quite a bit below FTP. Typically 10-15% lower power.

I was going to say that too but I wasn't sure if he was talking about lactate threshold sensu stricto or the "second lactate threshold" thing (the power output at which lactate concentration keeps going up with power remaining constant).

Alex_Simmons/RST

The intensity that most closely aligns with FTP and is a measure of blood lactate response is maximal lactate steady state. It typically requires 3-4 lengthy (e.g. 30-minutes) iso-power test efforts to establish.

daechambers88

neeb wrote:

Alex_Simmons/RST wrote:

daechambers88 wrote:

I tend to find the strava value is greater than a lactate threshold test value so tend not to use the value but find it can give a good trend in terms of slope of progress etc

Putting aside the accuracy of Strava, lactate threshold occurs at an intensity quite a bit below FTP. Typically 10-15% lower power.

I was going to say that too but I wasn't sure if he was talking about lactate threshold sensu stricto or the "second lactate threshold" thing (the power output at which lactate concentration keeps going up with power remaining constant).

Apols for slow reply! That's fair, I have only ever used the figures for Maximal Lactate Steady State as my guide - to be fair I haven't done an FTP test so that might be a turbo based treat over the winter!!

I guess the steady state lactic threshold is lower as that is equal to the quantity of lactate you can process and remain at a certain output as appose to what you can hold for an hour?

Alex_Simmons/RST

daechambers88 wrote:

I guess the steady state lactic threshold is lower as that is equal to the quantity of lactate you can process and remain at a certain output as appose to what you can hold for an hour?

Pretty much. LT is typically the intensity associated with a 1mmol/L increase in blood lactate concentration over baseline levels (~2.x mmol/L), whereas MLSS occurs at higher BL concentrations (which will vary by individual).

BTW and just for clarity, FTP is (well) estimated by the power you can sustain in a quasi steady state without fatiguing for about an hour. It's not exactly 1 hour power.