Power at Lactate Threshhold vs. Functional Threshhold - Page 2

xcmntgeek · #16 11-08.-2006

Quote:

Originally Posted by acoggan

By definition, maximal lactate steady state (MLSS) represents the exercise intensity at which the rate of lactate release into the circulation is exactly equal to its rate of removal, such that blood lactate concentration remains constant (or quasi-constant) over time. As it so happens, this corresponds very closely to the maximum exercise intensity that can be sustained for a significant duration, and so if you're relying on blood lactate measurements to prescribe training intensities, MLSS (and not LT) is what you really would like to know. The problem, though, is that accurately determining MLSS really requires multiple laboratory visits to progressively narrow down the precise intensity. The lactate minimum test was therefore conceived as a way of getting around this problem, and consists of performing the standard incremental exercise test with sampling of blood to measure lactate shortly after first elevating blood lactate via a preceeding bout of high intensity exercise. As a result, instead of rising exponentially with increasing exercise intensity, blood lactate falls progressively during the early states of the test, until it achieves some minimum (hence the name "lactate minumum test") and then increases again. That minimal point is the point at which lactate removal just equals lactate release, i.e., the same point (at least in theory) as identified when testing to determine MLSS.

Excelent, thanks! I wonder if TOSH will do it....

Justin

JustCurious · #17 11-08.-2006

Quote:

Originally Posted by acoggan

That minimal point is the point at which lactate removal just equals lactate release, i.e., the same point (at least in theory) as identified when testing to determine MLSS.

Andy,

Isn't the rate of lactate removal somewhat dependent upon exercise intensity? In other words, at sustained power levels below power at MLSS, blood lactate levels will spike but eventually level off at some elevated concentration (and not fall as would be expected with a fixed maximum rate of lactate removal)?

acoggan · #18 11-08.-2006

Quote:

Originally Posted by JustCurious

Andy,

Isn't the rate of lactate removal somewhat dependent upon exercise intensity? In other words, at sustained power levels below power at MLSS, blood lactate levels will spike but eventually level off at some elevated concentration (and not fall as would be expected with a fixed maximum rate of lactate removal)?

Yeah, I meant to describe MLSS as the maximum exercise intensity yadda yadda yadda. As you say, it is possible to achieve a quasi-steady-state in lactate concentrations at a lower intensity, although usually it will start drifting downward after some initial elevation.

Another detail that might be worth mentioning is that lactate release isn't constant over time, so even the quasi-constant blood lactate concentration at MLSS isn't the whole story.

acoggan · #19 11-08.-2006

Quote:

Originally Posted by xcmntgeek

Excelent, thanks! I wonder if TOSH will do it....

If they won't, just make sure you get the raw lactate-vs.-power data, from which you can calculate LT using the "Dmax" method (which also gives a good approximation of MLSS/critical power/functional threshold power from a single test).

BTW, these details/nuances are part of the reason that I described lactate testing as "better or worse, depending on how it is done" in that Seven Deadly Sins post on the wattage list.

Quadsweep · #20 11-08.-2006

Dr. Coggan, I have your book on order but in the mean time can you tell me how to determine FTP? I have heard about doing a 20 minute TT on this forum and then taking 92-95% of that power output as your FTP. You mentioned 2 X 20 on this thread. How long do you rest between the TT's? I am guessing your take the average power between the two?

What do think of Carmichaels methods of two 8 minute TT's and then taking 90% of the average as your FTP? Seems that a couple longer TT's might be more accurate.

SolarEnergy · #21 11-08.-2006

Quote:

Originally Posted by acoggan

Should I change that to "no self-respecting scientist"?

Seriously, I would assume that most people publishing in the field of exercise science/physiology would be aware of the difference between LT and OBLA. If you can point to a reference indicating otherwise, I might be able to ascertain the reason for the authors' unusual use of terminology.

While preparing myself to defend my statement, I found one cause of confusion.

Most references I saw to LT defined as being 4.0 mmol/L also use the little word "The" (or "This") in front of LT. They probably mean "The 4.0 mmol lactate threshold" implying that there's indeed an other lactate threshold.

Here's an example :

Quote:

and to compare the physiological responses corresponding to the workload at D-max with those at the traditional 4.0 mml l lactate threshold

http://www.iop.org/EJ/abstract/0967-3334/18/2/005

or

Quote:

corresponding with this 4-mmol l–1 lactate threshold

http://www.springerlink.com/content/6apqp991tmvrmayr/

Though I found a lot of occurences where authors use the term anaerobic threshold refering to OBLA
Such as in

Quote:

Anaerobic threshold, also termed 4.0 mmol.l-1 threshold (AT4), and individual anaerobic threshold (IAT), presumably indicate the workload corresponding to maximal lactate steady state (MLSS) during an incremental workload test

http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_DocSum

or

Quote:

These findings suggest that hyperoxia may raise the lactate accumulation threshold, also known as the anaerobic threshold (AT).

http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_DocSum

Believe me the list is very long.

I find the use of anaerobic threshold to define OBLA unfortunate as it creates a confusion between anaerobic threshold and individual anaerobic threshold, which better describes maxlass really.

padawan · #22 11-08.-2006

Quote:

Originally Posted by acoggan

By definition, maximal lactate steady state (MLSS) represents the exercise intensity at which the rate of lactate release into the circulation is exactly equal to its rate of removal, such that blood lactate concentration remains constant (or quasi-constant) over time. As it so happens, this corresponds very closely to the maximum exercise intensity that can be sustained for a significant duration, and so if you're relying on blood lactate measurements to prescribe training intensities, MLSS (and not LT) is what you really would like to know. The problem, though, is that accurately determining MLSS really requires multiple laboratory visits to progressively narrow down the precise intensity. The lactate minimum test was therefore conceived as a way of getting around this problem, and consists of performing the standard incremental exercise test with sampling of blood to measure lactate shortly after first elevating blood lactate via a preceeding bout of high intensity exercise. As a result, instead of rising exponentially with increasing exercise intensity, blood lactate falls progressively during the early states of the test, until it achieves some minimum (hence the name "lactate minumum test") and then increases again. That minimal point is the point at which lactate removal just equals lactate release, i.e., the same point (at least in theory) as identified when testing to determine MLSS.

Thanks, this is perfect! I know understand (at the layman's level) what the test actually tests for and how that relates to FT.

This will be my first estimation of FT since February of this year. I've put a lot of time on the bike this season so I look forward to seeing the results. I know my FT has gone up but I'm not sure by how much.

Thanks to all who posted. I realize (now) this is a bit of a repeat thread but this stuff is REALLY interesting!

Pad

acoggan · #23 11-08.-2006

Quote:

Originally Posted by Quadsweep

Dr. Coggan, I have your book on order but in the mean time can you tell me how to determine FTP? I have heard about doing a 20 minute TT on this forum and then taking 92-95% of that power output as your FTP. You mentioned 2 X 20 on this thread. How long do you rest between the TT's? I am guessing your take the average power between the two?

Here's my opinion:

http://lists.topica.com/lists/wattag...?mid=910289158

Note that this list does not include Hunter's approach - described in the book - of doing a single all-out 20 min effort and then multiplying the power by 0.95. The reason that I don't like that test is that the precise relationship between functional threshold power and 20 min power varies between individuals, and I figure that if you're going to the trouble of doing a formal (and painful!) test, you should obtain something other than an approximation.

Quote:

Originally Posted by Quadsweep

What do think of Carmichaels methods of two 8 minute TT's and then taking 90% of the average as your FTP?

I think this will likely overestimate functional threshold power in athletes who have a high anaerobic capacity and likely underestimate it in those who do not.

SolarEnergy · #24 11-08.-2006

Quote:

Originally Posted by acoggan

Here's my opinion:

http://lists.topica.com/lists/wattag...?mid=910289158

What does increased certainty mean? Does it mean that you favor the 60min TT as the best predictor of FTP?

acoggan · #25 11-08.-2006

Quote:

Originally Posted by SolarEnergy

What does increased certainty mean? Does it mean that you favor the 60min TT as the best predictor of FTP?

"The best predictor of performance is performance itself." - A. Coggan, ca. 1980.

SolarEnergy · #26 11-08.-2006

I agree and I'm glad to see that it's your recommendation.

I always tell people I coach that we're fortunate enough to be able to test over a (short) duration such as 60min.

Andy, I don't want to hijack this thread, therefore I'm going to start an other one immediately about a concern one of my riders has expressed. Your take (as anyone else's take) would be appreciated.

Quadsweep · #27 11-08.-2006

Quote:

Originally Posted by acoggan

"The best predictor of performance is performance itself." - A. Coggan, ca. 1980.

Sorry that I seem to be " pulling at threads" but what then do you think about Friels method of doing a 30 minute TT and taking the average power as ones FTP, compared to the 20 mminute TT X 95% method? Which on is likely more accurate?
Seems that Friels method might over shoot your FTP a bit and may not be even as accurate as the 20 min TT X95%.

acoggan · #28 11-08.-2006

Quote:

Originally Posted by Quadsweep

Sorry that I seem to be " pulling at threads" but what then do you think about Friels method of doing a 30 minute TT and taking the average power as ones FTP, compared to the 20 mminute TT X 95% method? Which on is likely more accurate?
Seems that Friels method might over shoot your FTP a bit and may not be even as accurate as the 20 min TT X95%.

Well by definition, the average power for a 30 min TT will be greater than what I've termed functional threshold power. As for whether it's more accurate than using 95% of 20 min power, that's hard to say, as it depends on your anaerobic capacity.

Let's see, using some numbers from memory for myself and my wife (who are at the opposite end of things with respect to anaerobic capacity)...

Me:

Functional threshold power = 300 W
Personal best for 30 min power = 308 W
% error (bias, really) using Friel's approach = +8 W or +2.7%
95% of personal best for 20 min power = 295 W
% error using Hunter's approach = -5 W or -1.7%

My wife:

Functional threshold power = 260 W
Personal best for 30 min power = 275 W
% error using Friel's approach = 15 W or 5.8%
95% of personal best for 20 min power = 268 W
% error using Hunter's approach = +8 W or +3.1%

Based on this, I'd therefore say that using a fixed correction factor is better than using the numbers "straight up", but even then you still might be off by several percentage points...

Quadsweep · #29 11-08.-2006

Quote:

Originally Posted by acoggan

Well by definition, the average power for a 30 min TT will be greater than what I've termed functional threshold power. As for whether it's more accurate than using 95% of 20 min power, that's hard to say, as it depends on your anaerobic capacity.

Let's see, using some numbers from memory for myself and my wife (who are at the opposite end of things with respect to anaerobic capacity)...

Me:

Functional threshold power = 300 W
Personal best for 30 min power = 308 W
% error (bias, really) using Friel's approach = +8 W or +2.7%
95% of personal best for 20 min power = 295 W
% error using Hunter's approach = -5 W or -1.7%

My wife:

Functional threshold power = 260 W
Personal best for 30 min power = 275 W
% error using Friel's approach = 15 W or 5.8%
95% of personal best for 20 min power = 268 W
% error using Hunter's approach = +8 W or +3.1%

Based on this, I'd therefore say that using a fixed correction factor is better than using the numbers "straight up", but even then you still might be off by several percentage points...

Great reply and thank you Dr. Coggan.
Do the above result indicate that you wife has a higher "relative" anaerobic capacity than you?

acoggan · #30 11-08.-2006

Quote:

Originally Posted by Quadsweep

Do the above result indicate that you wife has a higher "relative" anaerobic capacity than you?

Far higher - that's why she was elite national pursuit champion, and I can't make the podium at master nationals in the same event.

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