8 minute threshold test: Opinions?

[AdamW]

I recently had my first true power test. I do not own a power meter and this was a free offer to get introduced to power training and power meters. It was an 8 minute all-out effort to determine my threshold power. My average power over the 8 minutes was multiplied by 0.92 to determine threshold power. I hadn't heard of this test before. What are your opinions on this determination? Reasonable give or take so many watts? Biased in any way? Thanks!

Adam

 

[jsirabella]

8 minutes???

When I was a fresh newbie after reading the book training with the power meter I went by the 20 minute effort which was part of a longer effort but now after doing enough training for different lengths of time and different intensities I would have to say unless you can hold a wattage for one hour I do not consider that my ftp.

-Js

I recently had my first true power test. I do not own a power meter and this was a free offer to get introduced to power training and power meters. It was an 8 minute all-out effort to determine my threshold power. My average power over the 8 minutes was multiplied by 0.92 to determine threshold power. I hadn't heard of this test before. What are your opinions on this determination? Reasonable give or take so many watts? Biased in any way? Thanks!

Adam

 

[rmur17]

I recently had my first true power test. I do not own a power meter and this was a free offer to get introduced to power training and power meters. It was an 8 minute all-out effort to determine my threshold power. My average power over the 8 minutes was multiplied by 0.92 to determine threshold power. I hadn't heard of this test before. What are your opinions on this determination? Reasonable give or take so many watts? Biased in any way? Thanks!

Adam

Carmichael thingy I believe? Not a good thingy. Too much AWC: maybe 10-15%. Bias up/high. Bad test. Revise and resubmit.

Seriously though if you search CP or Monod here, you'll find that as the maximal effort exercise duration shortens, the contribution of anaerobic energy sources rises. That's lumped into a parameter known as AWC.

AWC is a notoriously variable wee beasty. Prone to all sorts of idiosyncratic behavior and typically highly responsive to acute training. IOW, it can vary a lot depending on personal characteristics AND how you've been training recently.

For an hour TT effort, the percentage of average power attributable to AWC is likely 1-2%. Drop that down to the 8-min mark and the percentage increases a lot (8-12% from my own data).

Let's say it's 10% of the total on one test. 2-3 months later after some hard group ride or races or L6/7 training and it's up to 15% relative to aerobic capacity x duration. You repeat your 8-min and geez get a nice 5% increase - problem is that could come entirely from AWC whereas your threshold power hasn't moved an iota.

In summary: short test. Bad test. Retest.

 

[daveryanwyoming]

... It was an 8 minute all-out effort to determine my threshold power. My average power over the 8 minutes was multiplied by 0.92 to determine threshold power. I hadn't heard of this test before. What are your opinions on this determination? ...

Adam,
I know of a local coach that uses an 8 minute FTP estimating protocol. Personally I'm not a big fan of that approach. 8 minutes is pretty short on a rider's Mean Maximal Power (MMP) curve and that's a relatively steep region of the curve. The 20 minute test is already too short IMHO and folks' vary a lot in terms of their 20 minute to 1 hour power relationship. Andy gave a great example on another forum a while back IIRC when he was focused on TTs and his wife focused on elite track racing his 20 minute to hour power ratio was ~98% and hers was ~92%. That may not sound like a huge difference but say you tested at 300 watts for 20 minutes thats the difference between an FTP of 276 watts and 294 watts which is a pretty big difference. It's going to be a much bigger difference for an 8 minute test.

As best I can guess the 8 minute protocol is easy to administer, not too tough on clients that don't train seriously and provides a starting point swag to begin structuring training. Those reasons may make sense for folks coaching the general public and as a way to establish a starting point without too much stress on the client. But I wouldn't take that estimate too seriously and I'd get a PM or ride some well calibrated gym ergs and track your regular, consistent long intervals to get a better estimate of your FTP.

-Dave

 

[AdamW]

Thanks! I get the picture.

 

[Alex Simmons]

Thanks! I get the picture.

But add to that another all out effort of say 10 miles or about 25 min and with both numbers you can get a pretty good estimate of FTP with the Critical Power paradigm. That would separate out the AWC and aerobic components for you. May not be perfect but it'll be close enough for setting training levels.

 

[Urkiola2]

It all comes down more to how long do you want to sustain a certain amount of power....That is. do you want to be a prologuists?. then you need to do 5 min tests. Do you want to be a climber?. Then you need to do 15-20min. Do you want to be a 40km TT guy, then you need 1h...etc, etc.

Power it is a very tricky question since it can only be sustained for a certain amount of time and it is always dependant on the time at which you can sustain that power. I know that there are so many power fanatics out there but FTP it is a very "relative and vague term" as there could be exist many many FTP's depending on the time and distance you can sustain a certain Power Output. Your FTP from an 8min test would not be the same for a 30km TT nor for a climb nor for a prologue nor for a 3h race on the flat and the wind where you never stop pedaling at a high power output.

Cheers

 

[Alex Simmons]

It all comes down more to how long do you want to sustain a certain amount of power....That is. do you want to be a prologuists?. then you need to do 5 min tests. Do you want to be a climber?. Then you need to do 15-20min. Do you want to be a 40km TT guy, then you need 1h...etc, etc.

Power it is a very tricky question since it can only be sustained for a certain amount of time and it is always dependant on the time at which you can sustain that power. I know that there are so many power fanatics out there but FTP it is a very "relative and vague term" as there could be exist many many FTP's depending on the time and distance you can sustain a certain Power Output. Your FTP from an 8min test would not be the same for a 30km TT nor for a climb nor for a prologue nor for a 3h race on the flat and the wind where you never stop pedaling at a high power output.

Cheers

I think what we are getting at are a few issues:

i. there are many ways to estimate a rider's FTP (FTP defined as the highest power a rider can sustain in a quasi steady state without fatiguing for approximately one hour). I am aware of 10 methods. Each has varying degrees of reliability and repeatability.

Clearly the best way to really know your FTP is to ride as hard as you can sustain for an hour at a quasi steady state power level and see what your average power is.

ii. even then, our ability to generate that FTP will vary day to day due to fatigue/freshness levels, motivation, altitude, location, heat etc etc.

iii. but in the end, does that matter? Our estimate of FTP does not need to be perfect every day for all the useful metrics such as Training Levels, TSS and Chronic and Acute Training Loads to provide us with good guides to our training and progress (but it still needs to be a pretty good estimate - get too far off the mark e.g. 20W and the data can go off course).

iv. training and appropriate measures of performance still need to reflect the specific nature of your event. Since a vast majority of cycling and cycling performance is aerobic endurance, then it makes sense to use measures that define such performance. But think about the specific requirements of your own target events.

v. the overall mean maximal power-duration curve provides an excellent marker