20 minute testing question



specialized31

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Aug 3, 2006
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I just picked up a powertap and I'm getting ready to do a 20 minute test. Should I use my LTHR as a ceiling thoughout the interval to get an accurate number or is it ok to go anaerobic say the last several minutes? In other words, should this be a flat out effort or stay within certain parameters to be as accurate as possible?
 
specialized31 said:
I just picked up a powertap and I'm getting ready to do a 20 minute test. Should I use my LTHR as a ceiling thoughout the interval to get an accurate number or is it ok to go anaerobic say the last several minutes? In other words, should this be a flat out effort or stay within certain parameters to be as accurate as possible?
Maxe effort for the time frame. If following the Hunter test protocal, most AWC will be drained away and taking 95% of your 20 minute AP takes care of the rest.

Doing 2X20 and taking the AP off the second one will be similar. Go as hard as you can with out blowing up. Listen to your legs.

Remember to pick a protocal that you will continue to use, for repeatability.
 
The method described in Andy's book on page 50 works well and gives you a measure of VO2 max watts as well.
 
wiredued said:
The method described in Andy's book on page 50 works well and gives you a measure of VO2 max watts as well.
If you are further along in your training age, you may want to do the full test on page 217 of Andy and Hunters bool "Training and racing with a Power Meter"

The rational is explained earlier in the book, bleeding off AWC and then taking 95% of the 20 minute effort to estimate FTP(what you should be able to hold for an hour. You get some other CPs in this test as well, 1 min and Sprints.
 
Isn't bleeding off AWC and then taking 5% off 20 min power redundant?

On the other hand, IIRC, the protocol is 5 min at 100% which wouldn't use up AWC if 100% = FTP.
 
Squint said:
Isn't bleeding off AWC and then taking 5% off 20 min power redundant?


On the other hand, IIRC, the protocol is 5 min at 100% which wouldn't use up AWC if 100% = FTP.
Well the idea is to the estimate the power you can sustain for one hour.

This his how Hunter and Andy handle this in the book.
Normally you have one hour to use up your AWC. I believe Hunter came up with that protocal working with his atheletes. The only way to know your true FTP is to do an Hour TT, which by definition is your FTP.

Going from my personel experience Hunters full test seems pretty accurate.

Maybe for riders with limited AWC, bleeding it of may be more than redundant and even under estimate their FTP.

Even Hunters full test could over estimate FTP for some one with a very high AWC.

Estimate with testing and confirm in a TT. Adjust your testing protocal as nessasary.
 
While the 20 min power x 0.95 works for some, I think it is rather lacking. I mean here you are using a generic estimate x another estimate. Example, my FTP is only 89% of my 20-min power - if I used 20 min power x 0.95 as an estimate for Level 4 work, I'd blow myself to bits somewhere around the first minute or two of my 2nd set of intervals.

I would opt to:

a) use the cp/monod model.....just do two tests, a 3 minute & 20 minute all-out. Then plug in your results into this spreadsheet and you can predict your power at any duration: http://velo-fit.com/articles/critical-power.pdf

b) 60-min TT, grueling I know having done them, but there won't be any ambiguity or doubt about your true FTP. Warning: Bring the motivation and your A-game!

Once you start doing your Level 4 work it won't take long at all to figure out if your estimate is accurate or wildly optimistic. You can easily then use whatever power you do the intervals at as FTP.
 
I think using 20min power as a proxy for FTP is a short cut and that’s a dangerous precedent to allow yourself in training matters :eek:
 
Lucy_Aspenwind]While the 20 min power x 0.95 works for some, I think it is rather lacking. I mean here you are using a generic estimate x another estimate. Example, my FTP is only 89% of my 20-min power
What is the percentage of your 20 minute power after an all out 3 minute effort, a few 1 minute efforts and some sprints. Likely the 20 minute effort that follows would be much closer than 89%.

if I used 20 min power x 0.95 as an estimate for Level 4 work, I'd blow myself to bits somewhere around the first minute or two of my 2nd set of intervals.
I agree it is unwise to use 95% of a test that only includes a 20 minute effort.

I would opt to:

a) use the cp/monod model.....just do two tests, a 3 minute & 20 minute all-out. Then plug in your results into this spreadsheet and you can predict your power at any duration: http://velo-fit.com/articles/critical-power.pdf
Two questions on this.

One, Would you do both tests on the same day? If so how musch rest in between?

Two, The chart is designed to use at least 3 CPs. One can correct for the use of just 2. My 130 pund rider did 3 min at 254W and 20 min at 232, seperated by a 10 min rest. the Spread sheet only drops the Est 60 min to 229 Watts, that is still over 98% of the 20 min time. 95% would be 220W. This atheletes best 60 was 215W. Which was during a 1:12 TT with an NP of 217 for his best hour, at .986 IF. Hunters short test may have over estimated his FTP but less so than the Spread sheet. Hunters long test would have under estimated it at 208W.

Maybe I am doing somethng wrong with the spread sheet.

b) 60-min TT, grueling I know having done them, but there won't be any ambiguity or doubt about your true FTP. Warning: Bring the motivation and your A-game!

Once you start doing your Level 4 work it won't take long at all to figure out if your estimate is accurate or wildly optimistic. You can easily then use whatever power you do the intervals at as FTP.
Using the long test and Andys levels seems to match this athelete quite well, looking at the Watts this athelete can sustain for the different intervals. Abve L4 he is usually at the bottom of the range. But his relatively low AWC would explain this as well as the test results.

What I can bring home from this is to cut back the AWC draiing intervals a bit for this athelete, say to a 3 min and two 1 minutes before the 20 min test.

Suit the test to the rider to get the ost accurate estimate.
 
Oh I forgot the Velo fit was right on when use this atheletes 1 minute power as another entry in the spread sheet. Came up with 60 min ~ 214. His 1 min W was 338 at the time.

When taking in to account his true AWC, instead of the higher estimate made for a more accurate 60 min estimate.
 
Great thread. I have inputed my data in the Velo Fit article to figure out "Where I am at" and its definately a motivator!! I had to use some guesstimating as I have only done all out 5 sec efforts and a ~7 minute effort (3mi TT) and my input data I chose were portions of all out efforts or Tempo rides. I am looking forward to doing some true tests over the next few weeks to make better use of these resources.

Thanks to all posters (on this and other threads) who take the time to read and post links!!

Ray