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Development Team Member
Posts: 1,501
Case study  to the discussion on fundamental differences
 This is a   rare inside  view in  what  we can do  when suing physiological ideas rather than  classical ideas.

This  forum  has the intention to make you familiar  with interpretation options  using NIRS  equipment.
 Or in simple words  as Brian puts it nicely.
 What dies it means when SmO2  goes up or  down or stays  flat.
 This is the starter  option
Next advanced is  integrating  tHb
 next up is integration  HR  and RF
  and the   research level is to back all up  with the tools  we so often mentioned  which help us  to go  all the way  down to just NIRS feedback  and  basic   HR  and RF.

Important as well.
 Try if we  argue or  discuss  to bring  actual practical an  examples  like Jiri  did  with his great  left  right leg  and  with his great   section on HR  and   MIO  problem.  Yes it is great  to  show as well existing research and I used a  climbing example's to show   what  we  often will find.  This may help the practical  coach  to drift somewhat away  form  statistical  conclusions   based on small  sample size  and simply look  as we do one   client at a  time  with the specific    questions  we will have to solve.

Below is a consulting job I  do  for a  coach and his athlete in preparation  to a very important  event this summer.

 I will show  you  some intriguing  live feed backs  where we  will cover  a few  hot topics  I started  to   discuss  in the latest webinar  and I got some very aggressive  feed backs  on may email but  they are all very well appreciated. What   surprises  me  is the still fix  for me  at least a narrow  minded idea , what we can do  when using physiology  smarter.
 I am not surprised  that a few  emails  come  from people who use   or used  hopefully quit,  the  chemical   options to address what we try to address  with physiological smarter  options.

So here a very rare  inside  look in  what is going on in physiological ideas of training.

low ang high smo2 and hr.jpg 

This is  the full training session, where in middle and  at the end  we  planned to  try a very different way of using the  physiological system.. As you can see we did a  preparation ( some would call it warm up )  to the intensity  and physiological base line we need  to have  and than did  2 all out loads  of  30 seconds  so loads  we discussed in the HIIT  discussion or  my monologue.
 Below the  three   areas  where  tried  to create a new  idea  for the  important section of this sport.

low ang high smo2 and hr nplus  cricle.jpg 
Now if you like to be a part of the thinking progress wait  before  you read further  and look the circles. Look  one of the discussions  we had  Lo2  SmO2  high HR. The   great feedback we had  form Daniele

Now  let's go a step further and look at it on our interpretation  program

zone  of the  wokrout idea.jpg 
You can see that the "preparation is a  feedback  control we  have for a 5/1/5 just  slightly adjusted. This is what we  always use in every days   " warm up so it took 15 - 20 min to  than for us see, whether we recovered the physiological system we targeted  yesterday or not  and in this case we  where " race ready.
 The yellow  zone is the  target  or goal of this workout and  at the end  easy to see  we  did a confirmation of the second load.

The goal  of thee experiment was  to  be able to go  all out  but recover  much faster as in this  disciple;in  you have no choice,  but start with an end sprint.
 So  first  can we  go more efficient  and only use  local  energy storage, than refuel as Brian  argues the tank , and than  actually benefit from this effort the delivery systems which now  have to take over  for a  while  and  at the  end another   all out  if possible.

So  lest see closer what happen  with the  physiological manipulation we  tried  to play  with.

load with and wihtou  cardiac system.jpg

Above you see SmO2  and HR   in 2  loads  all out. In one load we  tried to  start cardiac " recovered"  and  optimal possible SmO2  level. In the other load  we  tried  to start cardiac efficient  so good delivery  but  as well as high as possible SmO2 level, Result  . Look at HR  trend  during load. ????? One goes up as we all learn in school  and in Danieles   respond. The other   load shows  HR  ?????

 Now there is a  follow up physiological consequence on this  see below the  graph and make up your own ideas.

load with and wihtou  cardiac system with recoveyr and   delayed recovery.jpg 
  Now in case  this makes  sense  and gives you some hints  look the next step   if  not  simply  quit reading as it is very very different  than  looking  at  %  zoning

watt feedback with and wihtou  cardiac system with recoveyr and   delayed recovery.jpg

In the all out  30 seconds  the  performance  was slightly but insignificant  higher.
 What was very different is the post load reaction  and load  for  other physiological systems  like the respiratory  and cardiac system.

This than reflected  the  different  energy  situation after the all out   30 second  phase of this sport.

thb  and smo2 in zone  play.jpg 
red zone is load  time here above you now have SmO2  and tHb. Most of the reads  now  can  make interpretation of these values.

Now  the end question is , what  do we achieve  with the energy  options and  delivery options  as well as the  Brian's  gas tank  at the  start of the second phase  in this sport.

bias  row  options.jpg 

Your thoughts  whether  current  or  suggested options  may have a  positive effect on the  full activity of this athletes. ?

As mentioned these is a rare  glimpse  triggered by a  flood  of  emails  where  I get the simple response it can't be done.
True  for sure not if we  are   fixated in what we do  and  got educated on
It is all about delivery  and utilization and so often mentioned it is not a test out there to find that it is the race or sport in the filed  sport specific  which gives us the answers  on what I  the reason of the current performance  and what is  the limiter. To find this out  we   can look  at classical  lab tools  and  try to convince the coach and athlete  the lab tells  us the  real world  or we can go into the real world  and look live what happens.  What is the point of  calculation based on a lab test, when it does not agree with real  in the sport feed backs,?

This is NOT to talk anybody into  something  it is a  personal  simple challenge ongoing with myself  since 40 years on how  can I answer  some questions  for the athlete and coach  based on actual reality   and not  on  theoretical  explanations.

I  can tell  hundreds of examples  starting    with athletes  1976  Montreal Olympics  to  this summer events.
 Unseen real  and unreal seen is what we have to solve  if we like to have fun keep  the client healthy  and  try to reach a personal best.  Hope you have fun going through that brain mess !!!


Development Team Member
Posts: 279
Juerg. I am especially triggered by this sentence: "This is what we always use in every days " warm up so it took 15 - 20 min to than for us see, whether we recovered the physiological system we targeted yesterday or not and in this case we where " race ready."

My question is: how did you see this and can you share the exact overlays of the "warmups" from which you deducted whether you recovered the specific physiological system.

Development Team Member
Posts: 1,501
4 interesting  emails  and Ruuds  interesting respond.
Not  to be  impolite but clear. This is a  question of  coaching  and  training ideas  and  has nothing  to do with actual interpretation of  NIRS  data  as mentioned. It is a  rare  insight  view triggered as mentioned by some  clear  emails.
 That is  pretty much all  I  do in the coaching direction. So  no  further comments  and easy  for me to accept  the  mail comments , that we  have no clue  what we  do. Sure  easy to accept.
 One  small feedback on this  specific  case.  One  smart  email  asked the question on functional  or structural reaction.
 What you see  in this case is a  functional immediate  reaction to show the  coach  that it can be done.
 Now  the next  step was to actually go and create a save structure  so the idea is sustainable  and can be used even during an event  when ever needed doe  to  some rare  tactical situations  which in this  sport is not that common but  can happen. The critical reader  can see ,that we tried  the  same idea  at the end of the workout and you are thee  judge  whether we where successful or not.

Step one in NIRS  and physiological ideas will be over the next few  years to try to get comfortable  with interpretation and cases  like Jiris  puzzle  is one  I do  often  with my students. Again in most cases it is not about  who is right but how  do we  make the interpretation and where  to we need  some additional short  assessments  if we  have 2 options to get an answer.
. There is  for example  a very simple way  as many  argue  they do not have a physio flow.
 For base coaches in  endurance sporty   where we  look  on   duration's  of loads longer than 8 min we  have some very simple  options to  actually see, whether we reached a  cardiac limitation or not.
 The same idea really  is done since many years   with VO2 testing  if we where looking at this  as well in VO2 testing  if  we where looking at   respiratory  limitations.

 All VO2  centers and user  can for sure contribute  to this on here.

Here a  feedback  to a  great  data collection of a  super interesting person ( please  do not respond  meaning the person who sent me this data's. ) 

Reason. A very long  and very educational mail  I like to summarize  here.  The  forum post I  do  are veyr entertaining but many points  are physiological nonsense.

 If I argue, that  we can work  with  a  VE  ( l/min )  of close or over the maximal VE tested in a VO2  max (  peak )  test. example  150 VE l/min . but we will see a minimal increase in VO2  really  and basically no increase in HR, than that iss simply not possible.
 Any increase in VE is triggered by  a  high demand of  O2   combined with a high production of CO2  and therefore  VE will go up. A high production as mentioned of CO2  is created by a high demand of  O2  which needs a big  amount  of  active muscles  which will create a high VO2   that is  simple  physiology  and there is no  way we  can train or create a situation over  30  plus min where we   breath 150 l /min VE  and not see  a high HR  as  the  reasons above apply  always. This is  forma  highly respected  institution and a  highly respected   exercise  physiology  and he had many titles  attached on his email.
 First  I am  actually  honored  to have  this person reading the   fun entertainment as he names  it  and I like to show   some  really funny  graphs  here.

 this  is a  graph of a  5/1/5  assessment.  SmO2  and HR

vo2 max  info rf  hr  ve  vo2.jpg 

Above a  section of a VO2 peak assessment  and  look at the VE around 140 l/min. This   will in traditional  set ups  and ideas  need a big  muscle group or  a high intensity  to   move  a lot of  O22  and CO2 through the  systems. As you can see 60 +  VO2  /kg is not  super high but decently  high  which  asks  as you as well can see  for  a relative high cardiac  support  with a HR  in this case of  165.

 In short to  stress or stimulate the respiration   to  push 140 l/min  we  need  to push the   muscular system  veyr hard  and as  such as well the  cardiac system. That is  straight forward  and  clear  common believe  as it seems . 

Is it ?

hr  and  smo2  intercostal.jpg 

You can se e close to an hour  workout end load  was 140 + l/min VE
What  was the HR in red ?

 Below  the   load increase in this  assessment  and the trend  I was looking in tHb.
poly thb incl RF  and VE.jpg 
as you can see the start  was by 52 +-  VE  l/min  and ended   by 140 +-  VE l/min  duration close to one  hour  and HR as you can see never above  100 beats  / min  and if  we would have tested  VO2  it would be some interesting numbers as well.
 Again  fun   but NOT possible. ???

 So  true lots of fun and reams  is it possible  may be.  may be not. It is up  to the challenger to  show  that this is not possible  as to may surprise  we do this since over 15 years  now very successful  and I use the idea  daily if I have to  avoid a cardiac   or a  muscular load  as they either need to  recover  or  should not  be loaded  out  of different reasons.


Development Team Member
Posts: 369
Jeurg, thanks for sharing this - it has my head spinning but it is really fascinating

One question I have. When you target specific systems to give other systems a break, how do you know whether the stimulation is the same for that system as another workout with a similar physiological response tat is not physiologically targeting a specific response? E.g. is it correct that simply because the smo2 and thb trends are similar but say heart rate is very different, that the two workouts provide similar stimulus (other than for cardiac which I deliberately different)?

Development Team Member
Posts: 1,501
That is a  super great question.
 Remember the NIRS/MOXY has   as well limitation so  when we have a MOXY on a  single muscle  we know  the reaction fo this single muscle but than we  have to ask  how this feedback  relates  to a whole body  workout.
 So  that's  where the tHb reactions can  help   and   feedback on HR  as a hint  of cardiac reaction and RF  and TV as a k  hint of  respiratory  reactions.  I will  go  closer into this as I just    had some people  from Switzerland over  and we  discussed  and  did  case studis  under the  theme
 HIIT  and MIS
HIIT is  clear  what is  stands  for
 MIS  is  for muscular intensity  secret.
 I will   try to show on here, why  using SmO2 alone in a HIIT  has  limited  feedback as we  can not just look at  SmO2.
 One of the intriguing feedback  n  SmO2 recovery trend is  its connection with Cr.P recovery as we showed   some where back  and  I   have to refresh this here a little bit as well. Will be back as I am  just in between  clients  here   so  please  be a little bit  patient  for   some additional thoughts

Development Team Member
Posts: 369
Thanks Jeurg. Excuse my ignorance, but could you alo.explain what Cr.P and Cr.P.recovery is when you post the info.

Development Team Member
Posts: 1,501
No it is not  you it is m,e  Swenglish  should have  written 
hat Cr.P and Cr.P.recovery is when you post the info. PCr instead

Here some  fun  " validation feedback  on SmO2/PCr  and  more   direct  measurements.

A cross-validation of near-infrared spectroscopy measurements of skeletal muscle oxidative capacity with phosphorus magnetic resonance spectroscopy

Terence E. Ryan, W. Michael Southern, Mary Ann Reynolds, and Kevin K. McCully

Author information ► Article notes ► Copyright and License information ►

This article has been cited by other articles in PMC.

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The purpose of this study was to cross-validate measurements of skeletal muscle oxidative capacity made with near-infrared spectroscopy (NIRS) measurements to those made with phosphorus magnetic resonance spectroscopy (31P-MRS). Sixteen young (age = 22.5 ± 3.0 yr), healthy individuals were tested with both 31P-MRS and NIRS during a single testing session. The recovery rate of phosphocreatine was measured inside the bore of a 3-Tesla MRI scanner, after short-duration (∼10 s) plantar flexion exercise as an index of skeletal muscle oxidative capacity. Using NIRS, the recovery rate of muscle oxygen consumption was also measured using repeated, transient arterial occlusions outside the MRI scanner, after short-duration (∼10 s) plantar flexion exercise as another index of skeletal muscle oxidative capacity. The average recovery time constant was 31.5 ± 8.5 s for phosphocreatine and 31.5 ± 8.9 s for muscle oxygen consumption for all participants (P = 0.709). 31P-MRS time constants correlated well with NIRS time constants for both channel 1 (Pearson's r = 0.88, P < 0.0001) and channel 2 (Pearson's r = 0.95, P < 0.0001). Furthermore, both 31P-MRS and NIRS exhibit good repeatability between trials (coefficient of variation = 8.1, 6.9, and 7.9% for NIRS channel 1, NIRS channel 2, and 31P-MRS, respectively). The good agreement between NIRS and 31P-MRS indexes of skeletal muscle oxidative capacity suggest that NIRS is a valid method for assessing mitochondrial function, and that direct comparisons between NIRS and 31P-MRS measurements may be possible.

Keywords: mitochondrial capacity, 31P-MRS, oxidative metabolism, mitochondrial function

  Or  some  more  fun readings

Published online 2014 Jul 10. doi:  10.1113/jphysiol.2014.274456

PMCID: PMC4146372

Assessment of in vivo skeletal muscle mitochondrial respiratory capacity in humans by near-infrared spectroscopy: a comparison with in situ measurements

Terence E Ryan,1,3 Patricia Brophy,1,3 Chien-Te Lin,1,3 Robert C Hickner,1,2,3,4,5,6 and P Darrell Neufer1,2,3,4

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This article has been cited by other articles in PMC.

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The present study aimed to compare in vivo measurements of skeletal muscle mitochondrial respiratory capacity made using near-infrared spectroscopy (NIRS) with the current gold standard, namely in situ measurements of high-resolution respirometry performed in permeabilized muscle fibres prepared from muscle biopsies. Mitochondrial respiratory capacity was determined in 21 healthy adults in vivo using NIRS to measure the recovery kinetics of muscle oxygen consumption following a ∼15 s isometric contraction of the vastus lateralis muscle. Maximal ADP-stimulated (State 3) respiration was measured in permeabilized muscle fibres using high-resolution respirometry with sequential titrations of saturating concentrations of metabolic substrates. Overall, the in vivo and in situ measurements were strongly correlated (Pearson's r = 0.61–0.74, all P < 0.01). Bland–Altman plots also showed good agreement with no indication of bias. The results indicate that in vivo NIRS corresponds well with the current gold standard, in situ high-resolution respirometry, for assessing mitochondrial respiratory capacity.



Development Team Member
Posts: 1,501
Here some  fun  results.
 First  the trend in PCr for  recovery  for different  possible fitness levels.
recovery  trends  in Crp.jpg 

Now remember  some great studies  suggest  that ATP  will not  be depleted  but has  to   stay on ac certain minimal level. Remember the suggestion by V Connett  et all that rather to  reduce  ATP   the body  will try  to  avoid splitting  ATP. ( What options  do we  have ?

atp crp.jpg 

Now  what we did  with different  clients. We  created  the three  " categories"
healthy  control
 Obesity  as the  same person  was  fully recovered.
 Than we overloaded  the  same  client   to reduced his    " fitness level " and finally  we really overloaded  the  same person.
 So  very recovered. Tired . overload  perhaps
Here the  SmO2 feedback   of the three  stages

3 stes  smo2  like  Crp.jpg

Dark green  = fit/   middle  green  =  fatigued / = light green equals  overloaded
Than the logic  fun picture

overlap  smo2  CrP.jpg 

Than we   moved back to  some research on metabolic  demand. Now here where  it may be different but there  is no such thing like  anaerobic  but rather  now   researchers believe  that all metabolic  pathways  are kicking in  at the start  and contribute  to one common goal  to maintain the minimal needed ATP level as  long   as possible before the CNS  shuts  down   ATP  utilization by  for example reducing motor unit recruitment or   avoiding  ATP  splitting  ( H +  P   as some suggestions )

As    higher  the  muscle contraction  force ( or performance )  as  higher the  demand on O2  as well as  on PCr. Now  to  rebuild  or refuel PCR  we need  O2

Sports Med. 2002;32(12):761-84.

Factors affecting the rate of phosphocreatine resynthesis following intense exercise.

McMahon S1, Jenkins D.

Author information

  • 1School of Human Movement Studies, University of Queensland, Brisbane, Queensland, Australia.


Within the skeletal muscle cell at the onset of muscular contraction, phosphocreatine (PCr) represents the most immediate reserve for the rephosphorylation of adenosine triphosphate (ATP). As a result, its concentration can be reduced to less than 30% of resting levels during intense exercise. As a fall in the level of PCr appears to adversely affect muscle contraction, and therefore power output in a subsequent bout, maximising the rate of PCr resynthesis during a brief recovery period will be of benefit to an athlete involved in activities which demand intermittent exercise. Although this resynthesis process simply involves the rephosphorylation of creatine by aerobically produced ATP (with the release of protons), it has both a fast and slow component, each proceeding at a rate that is controlled by different components of the creatine kinase equilibrium. The initial fast phase appears to proceed at a rate independent of muscle pH. Instead, its rate appears to be controlled by adenosine diphosphate (ADP) levels; either directly through its free cytosolic concentration, or indirectly, through its effect on the free energy of ATP hydrolysis. Once this fast phase of recovery is complete, there is a secondary slower phase that appears almost certainly rate-dependent on the return of the muscle cell to homeostatic intracellular pH.

Respiration is the fastest way of balancing H + over CO2 release

 Given the importance of oxidative phosphorylation in this resynthesis process, those individuals with an elevated aerobic power should be able to resynthesize PCr at a more rapid rate than their sedentary counterparts. However, results from studies that have used phosphorus nuclear magnetic resonance ((31)P-NMR) spectroscopy, have been somewhat inconsistent with respect to the relationship between aerobic power and PCr recovery following intense exercise. Because of the methodological constraints that appear to have limited a number of these studies, further research in this area is warranted.




[PubMed - indexed for MEDLINE]


So   as  many time mentioned   tHb  can be  an indicator  of muscle contraction  quality and we often  combined  this  information initially  with SEMG
Below the tHb  trend of  our  fit  fatigued  and overloaded athlete.

overlap thb  smo2  for crp  idea.jpg 
Dark  brown  fit / middle  fatigued / light  overloaded Interesting  trend in this  client ???

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