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Juerg Feldmann

Fortiori Design LLC
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Posts: 1,530
 #1 
One of the now  more and more  asked  questions is.
 If  NIRS /MOXY  works , how does it relate  to any current  common ideas.

 First , yes  it  relates  to many common  used  ideas , as it is  at the end all about energy supply and demand.
 We  now try since   nearly  hundred  years ( VO2  Hill / Meyerhofer)  to find a  way  to see and understand , when we  deliver  O2  ,how we use  O2  and  when we  may start to get into some  kind of trouble  with more O2  demand  than delivery ability.
 This is where we  learned the  idea  of " aerobic  and anaerobe..
 That's when we  moved into the idea, that lactate may offer us a  feedback on where this    so called threshold really happened. With the  disadvantage of the delay  and the question of  what is  getting   used  before we  measure it  and so on.
 Now  since many years we argue, that the idea of a  actual threshold is  most likely not a great idea.  we  better  accept the  idea of a    " Zone" , where we have a   O2   situation, rather than a point.where we    " fight " between delivery  and utilization.
 Depending on compensation options we  have a  wider  or  smaller Zone ...
 More on this later.
.
So  when we  go back to what we   look  for  "100 % "  load intensity , we  use in some sports   FTP  in other sports  we  use MAX LASS.
 FTP  and Max  Lass  are  most likely  very close  related. The advantage of FTP is ,that we have a real performance feedback over wattage.
 In many sport  we do not have this advantage  and the   MAXLASS performance  may be in speed or   other parameters.
 Now  as mentioned  many time.
 Performance   is not a physiological feedback    it shows  the end result of a  full team  ( body [wink] at a specific  situation.
 If  we like to  understand  why we  have  up and downs in performance  we  need to have some physiological feed backs  and NIRS is  a nice  option for that as it is cheap  and easy to use  in the filed

Again  combining physical performance  with physiological reactions and feedback would make sense  so we can adjust  on the go by looking at the physical performance  and the physiological feedback and see, that today    physical performance has to be higher, as we  have a better working physiological system.

.Example  is an   increase in SV  due to  an increase in plasma  volume.

  What we see is that a  balanced  SmO2  shows  up   when we  often see a   MAX LASS situation.
 So  a balanced  O2 intake and utilization would   fit nicely  with what   is the reason of a MAX LASS.
 Now the advantage with NIRS is that you do not take blood  and you can do it very easy  outside the lab with a non stop feedback  whether you  go " aerobic  or  anaerobic " ( Bad  words)
 For more critical readers   the question would arise, whether there  are not  papers  and studies, who  would back this idea up.
 For  sure there are  and here is one  of them .
 

Determination of maximal lactate steady state in healthy adults: can NIRS help?

Bellotti C, Calabria E, Capelli C, Pogliaghi S.

Source

Department of Neurological, Neuropsychological, Morphological and Exercise Sciences, School of Exercise and Sport Sciences, University of Verona, Italy.

Abstract

PURPOSE:

We tested the hypothesis that the maximal lactate steady state (MLSS) can be accurately determined in healthy subjects based on measures of deoxygenated hemoglobin (deoxyHb), an index of oxygen extraction measured noninvasively by near-infrared spectroscopy (NIRS).

METHODS:

Thirty-two healthy men (mean ± SD age = 48 ± 17 yr, range = 23-74 yr) performed an incremental cycling test to exhaustion and square wave tests for MLSS determination. Cardiorespiratory variables were measured bbb and deoxyHb was monitored noninvasively on the right vastus lateralis with a quantitative NIRS device. The individual values of V˙O2 and HR corresponding to the MLSS were calculated and compared to the NIRS-derived MLSS (NIRSMLSS) that was, in turn, determined by double linear function fitting of deoxyHb during the incremental exercise.

RESULTS:

V˙O2 and HR at MLSS were 2.25 ± 0.54 L·min (76% ± 9% V˙O2max) and 133 ± 14 bpm (81% ± 7% HRmax), respectively. Muscle O2 extraction increased as a function of exercise intensity up to a deflection point, NIRSMLSS, at which V˙O2 and HR were 2.23 ± 0.59 L·min (76% ± 9% V˙O2max) and 136 ± 17 bpm (82% ± 8% HRmax), respectively. For both V˙O2 and HR, the difference of NIRSMLSS from MLSS values was not significant and the measures were highly correlated (r = 0.81 and r = 0.76). The Bland-Altman analysis confirmed a nonsignificant bias for V˙O2 and HR (-0.015 L·min and 3 bpm, respectively) and a small imprecision of 0.26 L·min and 8 bpm.

CONCLUSIONS:

A plateau in muscle O2 extraction was demonstrated in coincidence with MLSS during an incremental cycling exercise, confirming the hypothesis that this functional parameter can be accurately estimated with a quantitative NIRS device. The main advantages of NIRSMLSS over lactate-based techniques are the noninvasiveness and the time/cost efficiency.

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