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