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Juerg Feldmann

Fortiori Design LLC
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Posts: 1,530
 #1 
As  we see in a  nicely worded  Blog , lactate threshold is  burnt in our  minds  and  as so often we have  a hard time  to change   " history "

 The  idea  to  make a SmO2   or  HHb  or O2Hb  curve  and than find a   Oxygenation threshold  or  oxygenating point  is  about  on the same track as the idea  that we  can find a lactate threshold. The advantage  at least we have with  NIRS is the direct  an ongoing information so we  will see some great trends  as  shown on this forum  since the beginning.
  The idea  to actually sue  an indirect   lactate curve  where w have point  information every  few minutes     and than find a lactate threshold  is great business  to say the least. But here  a much more direct  answer to this  form some tip people   I showed  this once before   in an overall review.
 

    However, current scientific knowledge refutes the anaerobic threshold theory. Presenting the details here would be tedious, but we highlight the following points:

·         There is no power threshold below which a muscle does not produce lactate. A muscle constantly produces lactate, even from the lowest work level, and a muscle produces lactate even when the supply of oxygen is adequate.

·         During a ramp test (such as the ones carried out in the laboratory in which the runner must run at a regularly increasing intensity until exhaustion], the blood lactate concentration never appears as a threshold, as some people argue. The curve obtained shows no deflection (Figure 3). To see one, a very fertile imagination is required. It is true that many sports scientists (whose fame is somewhat inferior to the revenues they obtain from the tests they conduct) unscrupulously possess such an imagination but, in reality, the shape of this curve is most likely the result of a delay in the appearance of the lactate in the blood (PERONNET and MORTON, 1994).

 To  give  them  some additional fertile imagination , here a  graph, where the  imagine a  threshold  with lactate  and NIRS.

Attached Images
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Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #2 
never  ending. I got a few mails after this post  and it seems never ending.
  My simple answer  would be:
 If you believe there is  such a thing like a lactate threshold  and that NIRS  can be used to find this lactate threshold great  for you.
  As well great  for us, as you can get a MOXY  and use it the way  you see you can read  from MOXY information your lactate threshold. I am sure you can come up  with  different calculations and  algorithm  and will be able to " proof" that it works.
 here just  as  hopefully one more  interesting reading a  nice  article.


Lactate threshold and endurance performance

·      Posted by Sports Science Editor on January 25, 2010 at 12:05pm

·      View Sports Science Editor's blog

Lactate threshold is a commonly used term within the world of endurance sports and is often used to predict performance or prescribe training intensities. Lactate threshold is often described as the highest intensity at which an athlete can sustain exercise for a prolonged period but this term is very general and fails to specify exactly how long a “prolonged period” is. It also fails to identify differences between sports and assumes that lactate levels will be the same for all activities and individuals.

What is blood lactate?
Blood lactate is produced as a consequence of lactic acid generation during exercise and the rate at which it leaves the muscles and enters the blood stream is measured as mmol. There appears to be an exercise intensity above which the body produces lactate at a faster rate than it can be removed (lactate threshold) and continuous exercise above this intensity can create a rapid upward spiral in blood lactate causing the athlete to slow or even stop. Sports scientists have proposed several different blood lactate levels as the “lactate threshold” including:

• The point at which lactate departed from the baseline
• 1.0 mmol above resting baseline
• 2.2 mmol blood lactate
• 2.5 mmol blood lactate
• 4.0 mmol blood lactate

In addition to the above figures, lactate threshold has also been calculated by plotting blood lactate on a graph and examining the curve or introducing best fit lines.

An initial concern is that not all of the lactate thresholds can be correct all the time. To set “4 mmol of blood lactate” as actual lactate threshold is simple, but does not take into account individual differences, exercise duration and type of activity.

Papadopoulis et al (2006)* conducted research to examine all of the above theoretical lactate thresholds to discover which one would be best to predict 10k and half marathon running performance.

Results
Papadopoulis’ results showed that the point at which lactate departed from baseline was the blood lactate level most closely associated with half marathon performance. To be more precise, ran the half marathon with blood lactate levels of somewhere between resting and 2 mmol. During 10k running, however, the speed which corresponded to the lactate threshold of 2.2 mmol was most closely associated to race pace.

These findings indicate that a single lactate threshold cannot be applied for both events. They also indicate that the speed associated with the marker of 4 mmol cannot be used for 10k running (showed least statistical significance) and in theory, athletes are not be capable of sustaining the speed associated to 4 mmol of blood lactate for prolonged periods of time.

The researchers also discovered that the most accurate way to predict half marathon and 10k performance was to plot the points on a graph and examine the curve of plot of best fit lines. This proved more reliable than relying upon a specific blood lactate measurement.

Discussion
The results question whether a single lactate threshold can be applied to both 10k and half marathon running. They also indicate that the pace associated with 4 mmol (commonly used as lactate threshold) would not be sustainable by runners during the event. In contrast, studies have shown blood lactate levels in excess of 4.0 mmol during cycling time trials of 60 minutes in length, suggesting that responses differ greatly between sporting activities.

One of the most interesting facts to be drawn from the results is the relationship between testing and performance. Lactate tests are carried out by gradually increasing treadmill speed or cycle power output at regular intervals, taking lactate or heart rate samples at the end of each time interval and then comparing the results. During the maximal test carried out by subjects, the lactate level most closely associated with 10k race speed was 2.2 mmol, yet during the actual self paced 10k time trial, blood lactate rose continuously reaching almost 6 mmol by the end of the test. These results question whether the maximal testing protocol gives an accurate prediction of race conditions.

It is easy to presume that by cycling or running at a constant intensity, lactate levels and heart rate will also stay constant but this may not be the case. Consider the following scenario:

Bob completes a maximal cycle test which involves increasing the power output (watts) by 20 watts every 60 seconds until he reaches exhaustion. Mid way through the test, he complets 60 seconds at 220 watts and records a heart rate of 146 and a blood lactate level of 3.2 mmol.

Do we now presume that Bob can cycle at 220 watts continuously and his heart rate and blood lactate will stay constant at these levels? It is already recognised that heart rate drifts even when cycling at a constant intensity (cardiac drift) and it appears that blood lactate may well do the same, continuously rising even though a constant pace is maintained. What we actually recorded was a “snap shot” of information within a maximal test which may not be the best way to predict heart rate and lactate levels during sustained race conditions.

Conclusions

• Different thresholds may occur for different sports such as cycling and running

• Different thresholds may occur for different race distances such as 10k or half marathon running or 10mile and 25mile cycle time trials

• Different thresholds may occur for each individual dependent upon individual physiology

• Care needs to be taken when using maximal testing to predict or guide race performance, especially when measuring physical parameters such as HR and lactate.


* Taken from: Papadopoulos et al (2006). Relationship between running velocity of two distances and various lactate parameters. International Journal of Sports Physiology and Performance. 1:270-283.


About the author of this training article
Marc Laithwaite, is Sports Science & Coaching Director, at
The Endurance Coach. Mark has a Bsc (Hons) sports science and is working towards his Phd sports science. He is a member of the British Association of Sports and Exercise Scientists (BASES), a British Cycling Federation Blood Analyst, BTF Level 3 Coach & Coach Educator, UKA Level 3 Coach and ABCC Level 3 Coach.


Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #3 
I like to add  some additional thoughts   to this section here, as  I get   many mails arguing, that the MOXY  can  be used  to find  LT.
  I  completely  disagree. The  MOXY  shows an oxygenation trend  and a blood  flow trend  at the tested are  and as  such is an immediate information. Lactate is a  hopefully  estimation or   value, where we    can argue  , that somewhere in the body    caused  by  possibly  an activity  lactate was produced  and moved into the  circulatory system  and  was transported    through the body  and some of the  lactate in the circulation will somewhere  down the road   be  measured  at your earlobe  and or finger.
 This gives  us  some indication , that something happened  somewhere  before  our  measurement  and  a certain amount of this metabolic  event   is  now   tested  in our finger.
 The problem.
  In many test, when you combine  MOXY  and lactate you get  an interesting similar picture . Here  a  small manipulation from such a picture.
lac moxy inversion.jpg

As you can see, that leads  us easy to  our  idea of LT. The  very interesting part is, that in most studies they seem to always get this  kind of  reactions  when looking  at  SmO2  or  O2Hb  or HHb or Hb diff. All really indicate the same trends..
 What we see   in many assessments sent to us, that this above traces  can look very different  and the idea of  finding a similar  trend  like in lactate is   completely out of the discussion  . Here just a few  trends  we  can see, depending on limiter  and or compensator.

smo2  tHb.jpg 
Kris  SM.jpg


Powe mypahd SmO2.jpg

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