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Old 01-15-07, 11:35 PM   #1
recursive
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Functional vs Lactate?

I've seen various people on this forum talking about FT and LT as if they're different things, and I've also seen websites like this one which seem to imply that they are the same thing.

So what's up?
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Old 01-15-07, 11:43 PM   #2
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FTP is the maximum amount of power you can sustain for 60 minutes and is the middle of L4. It's almost an entirely aerobic effort b/c it's long enough that any differences in anaerobic work capacity are diluted. A shorter effort, like 20 mins, can lead to bad estimations because of differences in AWC. Around FTP, lactic acid should be around 4 mmol.

Lactate threshold is a lower intensity, around 2.5 mmol and occurs somewhere in L2.
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Old 01-15-07, 11:50 PM   #3
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Thanks for the info. I like numbers.

So if FTP > LTP and that website says LT occurs at a 20 minute pace, then the website is wrong I take it?
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Old 01-15-07, 11:56 PM   #4
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Originally Posted by recursive
Thanks for the info. I like numbers.

So if FTP > LTP and that website says LT occurs at a 20 minute pace, then the website is wrong I take it?
The problem is that there are lots of definitions and terms floating around out there. MLSS, LT, FTP, etc. It helps that people started attaching numbers like lactic acid concentration to them. Some people use MLSS, LT, CP60 and FTP interchangeably. FTP and MLSS probably arose due to the constant confusion surrounding the definition of LT. An all-out 20 min effort is going to be 3-10% more power than at FTP or MLSS and lactic acid concentration will probably above 4 mmol as well.

I wouldn't say that website's definition is wrong, just quite a bit different from other definitions of LT so you'll have to keep that in mind.
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Old 01-16-07, 08:12 AM   #5
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Quote:
Originally Posted by Squint

Lactate threshold is a lower intensity, around 2.5 mmol and occurs somewhere in L2.

I have to say this is inconsistent with the things I've read, been told by coach, and my own physiological testing.

First, its my understanding that LT, as measured by blood lactate, is not a set value for the amout of lactate, but rather the point at which the increase in lactate starts to spike.

Second, for practical purposes, power at LT is very equivalent to power at FT, if you define FT, as your 60 minute power. Most trained athletes can ride right around LT for one hour. Hence, LTP is equivalent to FTP.

I've had my LTHR and LTP measured in a lab, and then 2 days later done a CTS field test. My HR and Power at LT as measured in the lab was almost identical to my functional threshold power and HR as predicted by the field test.

My take away from all this, is with a power meter, you really don't need to know your actual LT, or have it measured in the lab.

At some point this becomes a matter of semantics and definitions. Rather than debating how many angels can dance on the head of a pin, the important figures are what you can do on the road . Hence working off your FT, as measured by a one hour TT effort, or the Coggan method (20 minutes reduced by 3-5%,) or the CTS method (92% of 8 minutes) is perfectly adequate for training, and arguably more revelant than a lab number.
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Old 01-16-07, 10:05 AM   #6
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Originally Posted by merlinextraligh
First, its my understanding that LT, as measured by blood lactate, is not a set value for the amout of lactate, but rather the point at which the increase in lactate starts to spike.
As Squint says there is no single definition of lactate threshold so the biggest mistake anyone can make is to think lactate threshold refers to some unique point. Among the many definitions of LT are those that refer to blood lactate concentration (e.g., 2.5 mmol/l, 1 mmol/l above baseline) and those that refer to a change in slope of the lactate concentration/power curve as mentioned above. Even for those that refer to a "spike" in lactate concentration there are many definitions of where the rise occurs. None of these is right or wrong; each just adheres to its own definition. The important thing is not to compare results or training levels across different definitions of LT.
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Old 01-16-07, 10:12 AM   #7
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Originally Posted by merlinextraligh

[snip]
My take away from all this, is with a power meter, you really don't need to know your actual LT, or have it measured in the lab.

At some point this becomes a matter of semantics and definitions. Rather than debating how many angels can dance on the head of a pin, the important figures are what you can do on the road . Hence working off your FT, as measured by a one hour TT effort, or the Coggan method (20 minutes reduced by 3-5%,) or the CTS method (92% of 8 minutes) is perfectly adequate for training, and arguably more revelant than a lab number.
+1

Regarding the lab numbers, another problem is the interpretation of the data. I've done blood lactate tests several times and once saw a particular result interpreted 3 different ways by 3 different people. All of those people had extensive experience in that area, but came up with numbers that were as much as 25W apart. That's huge when you are talking about defining someone's training zones. What I like about the power meter based method is that a watt is a watt is a watt in this case. You look at the data, take the NP or AVGP over a particular interval and that is the result. It is hard to argue with that, assuming that the meter is calibrated properly.

Everyone defines LT differently as a lot of other posts have commented on. Some definite it as the point where you see a 1 mmol increase above baseline lactic acid levels (ie LA at rest). Others say its the exponential increase in lactic acid levels. I have a problem with the notion of a threshold occuring at a particular lactic acid level. Some people are better at processing it than others, and why a value of 4 mmol? I mean its beginning to sound like HRmax = 220-age and we know that doesn't always work. Iknow that value came about for different reasons...but to affix 4mmol to everyone doesn't make much sense either.

Another comment on blood lactate tests vs. powermeter field tests...
I've always done better on the road than I have in the lab. The blood lactate tests never seem to do justice to what kind of power I can produce, regardless of whether you're talking about 5", 1', 5' or 20' power. For some people, I know it's the opposite. I know one guy who does great in the lab tests, but has a hard time doing 5' or 20' field tests on the road when he rides alone.

another nice thing about the powermeter is it's like you're own portable lab and you can test yourself whenever you want. I figure the thing pays for itself in 2 years or so.
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Old 01-16-07, 10:26 AM   #8
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Quote:
Originally Posted by Squint
FTP is the maximum amount of power you can sustain for 60 minutes and is the middle of L4. It's almost an entirely aerobic effort b/c it's long enough that any differences in anaerobic work capacity are diluted. A shorter effort, like 20 mins, can lead to bad estimations because of differences in AWC. Around FTP, lactic acid should be around 4 mmol.

Lactate threshold is a lower intensity, around 2.5 mmol and occurs somewhere in L2.
That clarifies many things I've found confusing in posts by you and asgelle. To my understanding (like merlin's) power at LT and FTP are near equivalents; so I've been told by coaches and I've used this definition in testing -- I've also found that my 60 minute power and "power at LT" as tested are similar.

I understand many of these usages are not "scientific" per se, but it does seem like the standard usage hereabouts is the one merlin mentions. I've never talked to anyone (aside from a couple of spin class instructors, when they tell their classes things like "now we're gonna take it WAY above threshold!") who uses a definition of 2.5 mmol/L2 for LT. Where does this definition come from? I have heard a few people using separate definitions of ventilatory threshold and LT, in which case VT, casually described, is more-or-less equivalent to your definition of LT.

[edit] ...come to think of it, your definitions must be the ones our beloved R600DA is working with. Thanks, Squint...this is really quite the epiphany!

Last edited by popdelusions; 01-16-07 at 10:39 AM.
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Old 01-16-07, 10:48 AM   #9
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Whatever you do, have any physiological testing done by the same person in the same manner. By and large, tests are only good to compare different points in time, and when used this way, discrepancies in definitions and measurments matter little.
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Old 01-16-07, 11:21 AM   #10
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Quote:
Originally Posted by Squint
Lactate threshold is a lower intensity, around 2.5 mmol and occurs somewhere in L2.
I think you're referring to aerobic threshold, which is defined as HR or power where the blood lactate = 2 mmol/L.
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Old 01-16-07, 11:45 AM   #11
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However defined, the numbers are a bit of a moving target, even from day to day. It's why a consistent testing protocol done on a regular basis is important if you're really going to apply those numbers to your training.

And to expand on Snicklefritz's comments, do your testing where you do your training. If you spend most of your time on the stationary trainer (shudder), that's where you ought to do your testing, if you train on the road, test on the road.
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Old 01-16-07, 11:46 AM   #12
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Originally Posted by DrPete
I think you're referring to aerobic threshold, which is defined as HR or power where the blood lactate = 2 mmol/L.
Thanks for the clarification, good doctor. That was what I was trying to get at, in my own physiologically ignorant way.
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Old 01-16-07, 12:21 PM   #13
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Thanks for the clarification, good doctor. That was what I was trying to get at, in my own physiologically ignorant way.
I'll share in the physiologic ignorance and say I still have no idea why the aerobic threshold is important, I just know what it is.
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Old 01-16-07, 12:25 PM   #14
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Quote:
Originally Posted by popdelusions
I understand many of these usages are not "scientific" per se, but it does seem like the standard usage hereabouts is the one merlin mentions. I've never talked to anyone (aside from a couple of spin class instructors, when they tell their classes things like "now we're gonna take it WAY above threshold!") who uses a definition of 2.5 mmol/L2 for LT. Where does this definition come from? I have heard a few people using separate definitions of ventilatory threshold and LT, in which case VT, casually described, is more-or-less equivalent to your definition of LT.

[edit] ...come to think of it, your definitions must be the ones our beloved R600DA is working with. Thanks, Squint...this is really quite the epiphany!
I think we're using the exercise physiology definition. Because it's an exercise physiology term, it's most appropriate.

This is a pretty thorough discussion of all the confusion:

http://www.cyclingnews.com/fitness/?...s03-08#Lactate
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Old 01-16-07, 12:58 PM   #15
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Quote:
Originally Posted by Squint
I think we're using the exercise physiology definition. Because it's an exercise physiology term, it's most appropriate.

This is a pretty thorough discussion of all the confusion:

http://www.cyclingnews.com/fitness/?...s03-08#Lactate
Gotchya. If there's a valid reason to toss the traditional definition, that's worth looking into. Of course, you understand that this equation of CP60 with "LT" or "anaerobic threshold" is the one most amateur cyclists are working with, and you also understand that this issue as to whether or not to equate CP60 with "LT" and/or "anaerobic threshold" has been at the root of most of the recent arguments hereabouts as to whether or not a base period is bad, how to do intervals, where the 400W knob is located, etcetera, etcetera...
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Old 01-17-07, 05:01 PM   #16
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This is a pretty good explanation of LT

the whole AT/LT being the same/different gets a bit confusing.....as i keep hearing different answers

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