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Development Team Member
Posts: 1,501
I lie to use the great webinar we just  had, as it opens a  very fundamental discussion on NIRS.
 Now  this is important , as   many years of  work  with NIRS in combination  with  cardiac hemodynamic , blood values  like  lactate and others  but as well in combination with respiratory information  ( blood gas information ) created a very different  picture  , than what we have  form this   great study.
 This opens the discussion on where we  went  so wrong  when compared to this university  and accepted institution study.  I like to  open a  set of  questions  and like to follow up hopefully with your help  with some very very basic physiological experiments  I do  daily with patients but for sure with our  high school students  to show  that  we  do not educate people.
 we  try to  think loud  so no matter whether we  go  wrong or right by loud thin king we  can get the help  form  readers  on  where we  go  wrong.

Here the fundamental   point we have to review.

The findings  where: MOXY webinar  2 comnclsuioo0n.jpg 

Or in other words :
 Classical  lab testing  like VO2, performance, HR  and lactate   show  the same reaction as  NIRS/MOXY

My  take.
 I  actually   use NIS/ MOXY  for HIIT  or strength workouts because  it e\ does not at all  show the  peak  at the same time.
- highest lactate is not  with the lowest  SmO2
-The highest  HR   is often not  with the lowest SmO2
- The highest performance is often  not  with the lowest SmO2
- VO2  max ( VO2  peak ) is  often not  with teh lowest SmO2.

 And  what is missing it is  even  different when looking at different muscle groups.

That means, Using classical lab  equipment  to  compare  with the  use of  NIRS  is an interesting discussion.

Let's  look at first  from a practicality point of  view.

Lactate  and  VO2   are very  hard to be used in the field  and  with a lot  of people like an ice hockey team or  as in this case  with a group of  soldiers.

HR  can be used  and it is used  to guide  HIIT   but  as discussed some limitation  to actual plan a  workout.
 Performance  could be used  for certain activity but  if  we  take just the athlete  and work him out  we have some problem  to actually  use performance  and performance is a physical feedback  with limited  view  for physiological  intensity feedback.

 NIRS /MOXY   is not at all an equipment   to replace the information of the above lab ideas. They do NOT  correlated  with lowest  SmO2 value  and  peak values  of the  other information.
 This is  why  I  strongly believe  NIRS/MOXY  is very different .
 It is   one optimal way  to actually have real  live feedback   for  any  high intensity activity like short intervals   own body weight   activity  strength training   and so on.

Exception. It may  correlate  when we look  at longer  loads  from 5 - 8 min and longer  with  the ability  that by a stable load  the  different physiological system may be able to achieve a homeostasis. This is a very different topic.

Now  back  to  our different  takes here.

MOXY  users  and lactate users 
 here an initial  first experiment.

 Load   all out as in this pilot  study  for  15  seconds  take resting lactate,  than  end of load lactate  and than every  1 min additional  lactate.  for 5 min.
 Now  do the same  with a  30 seconds  all out  load  ,
 than 45  second  all out  load
Use results  to compare  SmO2  lowest level  and   lactate highest level.  Based on the above  conclusion we  should see lowest  SmO2  when we see highest  lactate.

Here  one very old  study independent to us
This is just lactate dynamic  after all out  situation  300 and 600 m.
 Now   add  a  MOXY  to this  and  see,whether the SmO2 trend  is the same.  just like a mirror.

lactate post.jpg

Here another  great feedback on lactate post load From Berit Dool and Derek Kiri in cross country skier.

recovery of lactate.jpg 
And here some many times used papers who  would  argue, that lactate as we tests it has a lag time, which unlikely  fits together with SmO2 lowest point

So the point  is.
 The lowest SmO2 rarely   fits  with the highest lactate values.

The conclusion  therefor is challenged  and   it would be nice to see the lactate datas  from this study as a feedback discussion point.
 The  fact that SmO2  and lactate  do not correlate in most HIIT  workouts  is  exactly why we use  NIRS as a  training intensity/   recovery  and  duration feedback, because  lactate can not be used  for this.

Thirdly, an alternate or a complementary explanation to the pattern of plasma ]La-] response to ramp exercise can be suggested. According to this explanation, lactate is produced in the working muscle: (1) as soon as the exercise begins, as suggested by Brooks (1985); or (2) following a delay, according to the theory of the anaerobic threshold (Davis 1985). Under both hypotheses the onset of lactate production within the working muscles occurs at comparatively low work rates. At that time: (1) the amounts of lactate produced and the gradient between muscle [La-] and plasma [La-], and the amount of lactate released from the muscle remains small; (2) cardiac output and muscle blood flow are also low and do not favour lactate release

from the working muscles and its distribution into S; and (3) the small amounts of lactate released are diluted within the comparatively large S, thus resulting in a very small increase (if any) in plasma [La-]. Therefore,

a delay could be expected between the beginning of lactate production within the working muscles and the parabolic rise in plasma [La-] in response to ramp exercise in a similar way that, in response to a short period of severe exercise, the peak value of plasma [La-] is only observed following a several-minute delay into the recovery period (see Hirvonen et al. 1987, 1992). Consequently, plasma [La-] concentration at a given t during a ramp exercise does not reflect lactate production in the muscle at that precise t and at the

exact corresponding work rate, but at a previous t minus ~ of unknown and probably variable length, and at the corresponding work rate. This phenomenon might have been overlooked in the development of the theory

of the anaerobic threshold which implicitly assumes that plasma [La-] at a given t reflects lactate production and thus the metabolic state of the muscles at that precise t, and at the exact corresponding work rate. This is very unlikely to be the case, particularly during the exercise protocols of short duration and with steep increase in work rate used for the detection of the anaerobic threshold (Anderson and Rhodes 1989). In this type of protocol, where VO2 significantly lags behind the value expected for the corresponding

work rate (Whippet al. 1981), it may be expected that plasma [La-] also tracks the metabolic state of the working muscles with a significant delay, particularly at the beginning of exercise for the reasons presented


So here first one of many test when we do TIP 5/1/5 and therefore have a much longer time to see and understand the delay in lactate.

See pic
A three minute step and than  a 5 min step test will  show it  very nicely.


Development Team Member
Posts: 1,501
Previous  open discussion.
 SmO2 lowest level  and  highest lactate values  do not  correspond inmost cases in a   HIIT. does not

Highest HR  is reached   at the same time as lowest SmO2.

 Like  lactate  which is a systematic feedback we as well have  in HR a more systemic feedback. SmO2  or NIRS information is local  and depending on how many NIRS placement  you have, you can get some indirect feedback on possible systematic reactions.

 Fix a MOXY on the right quadriceps. take  resting lactate and resting SmO2  and resting HR.
 Start  doing a one leg  squatting sets  .
 First  set 15 second every second  one squat.
 than  same  for 30 seconds  same  for  45 seconds.
 overlap  HR lactate values  and SmO2   immediately  after the set  1 min 2  min  and 5 min after.

 Question  do we see by the lowest SmO2 values  the highest  HR  and the highest lactate?
Here a  case study  done by Jiri  on where we still discuss  and where I may be very wrong as well.

 Similar HIIT  and  we have SmO2  and HR.

  hr  adn  smo2  left.jpg

The conclusion that  the lowest  SmO2  is  at the same time as the highest HR is challenged  and again  the overlap   of the data   will  open  the discussion  why in this study this was the case.

As in many  HIIT  workloads the cardiac system  has a lag time or is not  properly challenged  the use  of HR  ha sits limitation for  duration and assessment of intensity in HIIT.
 We therefor  prefer to use NIRS.


Development Team Member
Posts: 1,501
Next  up. Summary:
  -SmO2  and lactate   most often  do not  correlate  with SmO2  lowest  when lactate is highest.
- SmO2  and  HR most often in HIIT  do not correlate  when SmO2 is lowest and HR is  highest.

Next  up .
 Is  SmO2   at the lowest  when VO2 is  at the highest point.?
The first  big  ongoing discussion is the  connection between  SmO2  from a local  area and the  feedback we have  form a  systemic  collection of   gases )  O2  and CO2. )  I like to use  one great study  here which as well answers  the   ongoing  emails  I get   why  SmO2  drops  so far   down with MOXY  but not with some other NIRS  equipment.  Calibration is done by looking in a cuff situation, whether the SmO2 values  can drop very  low. So by doing nothing but  closing delivery of  O2  we  cna calculate how  much O2 we use  till we are very low  ( or  calories / time )
 By going super hard  we  will use despite what we learned  even in an "anaerobic  "test " a lot of  O2  and  when we look at  calories/ time a we can calculate how  fast we suppose to see very low  SmO2 levels.

Now  on the below study look at the  shade for the VO2  values. Is the lowest SmO2 value   at the highest VO2   value ?

deoxy N.jpg 

Conclusion: SmO2 lowest  value is where we have the highest  VO2  value  has to be re-assessed.
Here the interesting question. look at the   data we  actually have.   Athlete  No  96

96 smo2  VO2  time.jpg 2.jpg 
 Even in  their own data  the questions comes up , whether VO2  max value is  at the same time as the SmO2  lowest  values. Supper intriguing is  even the fact the left and right leg  have a different lowest SmO2  timing and all three  VO2 peak and left and right  low  SmO2   are on different times.  To  look at  why we  would need to see the raw  csv  tHb  data  as there could be a  possible answer  why. left and right are different  low SmO2   timings.

 Because VO2  information's are   based on a  systemic  feedback  and have due to the  equipment  as well a  lag time  this  lab equipment  can not be used  to design an optimal  training ideas  for   work load intensity,  recovery duration  and  overall  training duration.
 NIRS  and VO2  w equipment    do not  correlate  together.
 They can enhance if used  together   in some cases the feedback on what is limiter and what may be compensator.


Development Team Member
Posts: 1,501
Last but not least.
 The lowest  SmO2   is  equal to the highest work load  at the same time.?

Workload is a direct immediate feedback on  what we do.
 Physiological reactions  do not  start all  immediately when   load or  do not stop immediate when we  do not lift or run anymore.  That's  why we  have functional reactions  and  structural reactions.
That's  why we  where lost in ideas like  O2  deficit , when  physiological system  do not allow  for a O2  deficit. F Deficit  equals  going below  what we have  so no money on the bank and we borrow. In a physiological active system the pO2  minimal needed  pressure is  protect   on all costs.

Richardson et al have concluded that: ‘‘…intracellular pO2 remains constant during graded incremental exercise in humans (50–100% of muscle VO2max)’’ so that: ‘‘With respect to the concept of the ‘‘anaerobic’’ threshold, these data demonstrate that, during incremental exercise, skeletal muscle cells do not become anaerobic as lactate levels suddenly rise, as intracellular pO2 is well preserved at a constant level, even at maximal exercise’’ (p. 63168). They also conclude that: ‘‘Net blood lactate efflux was unrelated to intracellular pO2 across the range of incremental exercise to

exhaustion’’ but was ‘‘linearly related to O2 consumption’’ (p. 62768). Another study confirmed these conclusions: ‘‘…consequently these data again demonstrate that, as assessed by cytosolic oxygenation state (deoxy-Mb) during incremental exercise, skeletal muscle cells do not become ‘‘anaerobic’’ as lactate levels rise, because intracellular PO2 is well preserved

at a low but constant level even at maximal exercise’’

Like we have  a lag time in HR increase or SV increase and in a sudden  start we sue  O2  available  at the place of need so  do we have a lag  time  to " clean up the  after load   situation.

Small experiment.
 If you have wattage  meter  please show the data  Wattage  and SmO2  so we can see,whether the lowest  SmO2  value is reached by the highest wattage.

S Do an all out sprint  and  plot the  SmO2 graph  with the wattage graph.
 What  do we see.  where is the  wattage the highest and where is the  SmO2 the lowest ?  We have the some problem as we can not use  wattage  and use a VO2  max  test   and than use this wattage  and believe we  really stimulate  a  MAX  VO2  level or  are  above.
 See the  data s we have here.
 They loaded by 125  Max VO2  values on wattage.
 But    how high was the VO2    with this load.
 . Non of them where w even close to a  Max VO2  value.

hitt result   % VO2  max.jpg

    Below a HIT  work load  under general hypoxia  and high CO2  levels. You can see how tHb  can be used  to see the duration +-  of the actual load  but you as well can see the different  SmO2  reactions of  involved  and non involved muscles  due to the local  and as well general CO2  level.
 A high CO2 level shifts the O2  disscurve  to the Right and therefor  reduces  the speed of SmO2  recovery   and in fact   SmO2  may drop further as  O2   still can be released   from the blood to the cell but  SpO2  will  be low  as well as  O2  can not easy be loaded in the lungs  to blood   place.

Summary.  An external load    is not the highest when SmO2  suppose to be the lowest. It can be  but not has to be.
 External loads  are not good guidance  to   be used for physiological   stimulation goals.  As their own data  shows  a  125 %  wattage  load based on a VO2  " max " test  never  really achieved  due to  time lag  VO2 max (  Only  plus  -  80 % )

External loads or performance value  are not an optimal way to  understand the  physiological stimulation we  apply.

Do  to all the above discussion   you may see , why I use NIRS  for  any type of HIT as the  direct feedback   is hat we look and in all the above classical  lab equipment we never had this option.
 Result. Classical lab equipment    was great but NIRS  clearly  can eliminate   most of them   due  to the love  feedback  and mini9mla time lag of the feedback.

In this study the question would be better asked, whether the  classical lab equipment  still can   be justified  for  HITT  control.
 Similar  whether we still  need a  X ray  when we  can make an  MRI.
 Why would I use an x ray to see,whether and MRI is doing what it suppose to do,.
  All  used lab equipment simply  do not   show us  what they suppose  to do , where as NIRS is doing that.

Next up  we could as well discuss , whether lactate end values  in a  VO2 " max " test  actually have any meaning about the effort  during the test.  Below a  small weekend  question.
 Which of the few  top runners   may have the highest VO2  peak in a  VO2  all out  max test.
 . The one with the highest or the lowest  lactate values.

lactate korir.jpg 

There are many  and I mean many   incredible high  VO2 max test values   I have done over the  last  30 years  and many of them  do not even come close  to a lactate of  7 or  8.
 . Using lactate as an indication f  an effort is  an intriguing  thought  with minimal  scientific   back up. 
Remember :
 If  we  argue  of a VO2 max  we need to see a plateau meaning a  zero slope  over a certain  time.
 The fact that we have   up to 10  " excuses"  so we  still can justify we reached a plateau  or a  VO2  max   is  interesting to say the least  and I wonder how many mathematicians  would  accept  the fact that a   zero slope  not  has to be zero  as long we  accept  some additional ideas.

Here  from a  great coach  three  VO2  " max test"  with three different endings but non a  plateau.

vo2  all 3.jpg 
Thanks  for taking the time  to help  to  argue this interesting study  on  the MOXY webinar.


Development Team Member
Posts: 264
I have another "fundamental question"...
Wouldn't be better to first clarify the scenario we are talking about here?
It's a very short interval (like 15s, 30s) or longer (3/5/8 min)?
Is a repeated HIIT with some resting time  or a single shot?
Honestly without these informations I am really lost and cannot make any feedbacks.

Regarding the picture posted below:
Can you again please clarify what type of activity is it?
It looks like HR raises very slowly when the SmO2 starts to fall and then rise very fast when SmO2 is recovering (so I assume the athlete finished the interval).
That's really really strange unless we are doing some tricks like reading SmO2 from a muscle which is involved at the beginning of the activity which is not heavy from the systemic point of view and not involved when the "main systemic activity" starts.
For instance moxy on the arm biceps doing some curls then stop and start an heavy squat.


Development Team Member
Posts: 1,501
Daniel  absolutely agree.
 The  graph you see  form Jiris   discussion  which one is the injured leg  left or  right   .
 So it is a very  similar  load as in the webinar  , where they had  to go all out  125 %  VO2  max  and jit ri had them go out  all out  no  actual  wattage  target  so  very similar  all out  load    till  basically  they had  to slow  down. So very  HIIT  shorty duration in the time  frame of  15 - 30 seconds.  W Yes what is HIIT  and I used  in all my examples   loads   close or identical  to the webinar loads  of  30 seconds  all out. so  all the examples  are short  20 +-  seconds loads.. This  exactly out of  your grate poi9nt. we only can compare  the lab  results  with NIRS feedback when we do this  and in   short  HIIT ideas like  in strength workout or in this  case the live feedback  is live where as the lab  classical tools  like lactate  and VO2  have the  disadvantage of a lag time  which may be balanced  out  as mention dn  interval or load length of  8  min or longer.
Hope this makes sense buts please come back.  The group tied  to show  that  MOXY  can be used to replace  VO2  lactate  HR  and performance  for  short term HIIT  30 +- seconds.
 . It is the opposite. VO2  LT  HR  and performance   can not optimally be sued  to  asses and guide  HIIT. So  the question for me  was strange.  MOXY is the tool  to guide  HIIT  short term duration. The rest  was not able to do this  due to the lag time. So performance  combine  with  MOXY  can do a great job  but NIRS  alone  can do it as well if you have  problems  for an objective  load measurement.

Development Team Member
Posts: 264
ok thanks. I need to look at the webinar first.

For the "injured" leg case, as I wrote, in my opinion there is something wrong on the time alignement between HR and SmO2, because in the first 20/30 seconds "all-out" HR will rise sharply then would continue to rise but very likely with a different slope (typical slow component on the "severe" domain).


Development Team Member
Posts: 1,501
That is  a great point to look at closer. This are just the raw datas set  from peripedal so  suppose to be  synchronized. 
 But  There  are some specific   reasons, when the HR  as you point out .

because in the first 20/30 seconds "all-out" HR will rise sharply then would continue to rise but very likely with a different slope (typical slow component on the "severe" domain).

 It  depends  incredible  strong on how the  athlete  reacts  over his respiration attempt.
 Here  some experiments  you can do. Do all out loads but  hold  your  breath  as you start out.. Than hyperventilate  before  you do an all out load.  so  CO2  down  to 20 mmHg . Than  do these  opp site   hypo ventilate  so CO2  by 50 mmHg  and look  on HRV  and HR reactions. If you know somebody  with a physioflow look at live  how this influences  the  HR as it is a  very small part or feedback n CO  as so often mentioned.

BUT  I will check the datas again and check  with Jiir in this case. Thanks  for the great feedback. This  will be one of this cases, where the data  are  wrong than the theory is great  or the data are  right  but what do we do than with the theory?  Short  fun  part  take the HR now  do 15 seconds  15  frig umps look  how the HR reacts. ?  is it the highest  after the  15 jumps or  does it perhaps overshoot. ?

Development Team Member
Posts: 1,501
There's a  great article in training peaks  on HR  and  decoupling  and  very  great to read, 

[webicon_green]How to Train with Power and Heart Rate | TrainingPeaks
Apr 23, 2014 - Cyclists that train with both a power and heart rate zones often ask which ... Heart rate will almost always have a delayed response to an effort ..
Jiri Dostal

Development Team Member
Posts: 51
Hello guys - I was off for the last week, so I did not have time follow up on the leg story. Will do that later tonight.

However to the SmO2 and HR delay. Juerg used the raw data from Peripedal, and they are correct if I take the numbers in the file. HOWEVER!!!! They they DO NOT reflect reality.

We have used a new device called Mio Link, that should in theory replace a regular chest heart rate strap. What you see there is a typical example of significant measuring error caused by the algorithms implemented into the wrist band. It is an optical based device, that has to have a long averaging signal processing in order to eliminate significant amount of noice coming from plethysmography patterns.

We have compared this to other optical based devices like Apple Watch and Scoche, and found it NON OF THEM ARE SUITABLE FOR HIT. They might be fine for typical endurace based exercise, but not at all for HIT.

I did not use the HR in my original article about the injured legs as I was aware of this error.

So once again - device based measuring error.



P.S. going to disclose, which leg was injured. Stay tuned :-)


Development Team Member
Posts: 1,501
Woww w fun  job Jiri  and great feedback on the problem  with MIO  and many other devices  who  try to avoid the  chest strop.  Great  job  Daniele  to  be critical of the  information  .

There is  in  some cases a  delay in HR  and it depends a lot of the way  we breath, but in reviewing the  extreme reaction Daniele is  absolute  right very veyr extreme  and great  discussion  with using many brains.  hah  I love Jiris  approach as  he  " beats" me  with my own  crazy ideas  when looking at different challenges.
 1.:0  for  your ice hockey team. Be ready  to get the challenge  back [smile]
  I  did  with Roger  some  test  with MIO  and   well we where not too impressed  so   there are   many " promises" out there  from  existing or like to be existing companies  try  to catch people by  showing NIRS  equipment who suppose  to do  as well HR  and many more  ideas all in one. Would be great but may be  some challenges  ahead. We  for the moment are happy to just have a decent nicely working affordable NIRS  with SmO2  and tHb.
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