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juergfeldmann

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 #1 
I  have more and more  e mails asking  for  the  ideas on  why  we need tHb  when  we actually  look at  energy supply  so SmO 2 so should be good enough.
 Energy is  supplied  over   blood  so tHb  is a direct  additional feedback , whether the trend in SmO2  is  due  to actual  limitation or interruption  of supply  of O2  or  whether it is   sufficient  and perfect supply  but simply not an optimal   or big  enough utilization ability.

I like to show you  a  fun case study  we id a few  years back with some local student's in their  career  prep  I offer them in our  small town.  Here the task.,
 They had  to move a fixed speed  over  5 min  and had to choose  5 min walking  and  5 min running but same speed.
 The idea was to look  by what speed  running is  more efficient  than walking  and vica verca.
 As usual  not  a new idea just different tools. I  did many years back  during my education the same idea  but  at that time we used VO2  to figure this out. Here  an  example  form the at time  form Holmann
Hollman walk jog.jpg 
So clear answer on  performance  but minimal feedback on the physiological reaction. So  we did  the same  or a similar  idea  and  here   one part of the fun semester  the 5 min  change  form walk  to  jog in an intensity we  figured  out  walking is more efficient  than running.

complete  60 min w r.jpg


Red is O2Hb, blue is HHb yellow is tHb  and  purple  is  Hb difference or a similar trend under certain situations  with SmO2 in MOXY  Now interesting is thee  relative  flat HHb  Blue  reaction  all the time but a much higher  fluctuation in O2Hb  . Why??

Now  for fun they had  to figure out  stride or step  frequency.
 Here the answer  on how they found it. below  a 5 min run section and you can see what the students  where aiming  for.
run close look 5 min.jpg 

 This  is one of many examples ,  that when we use  SmO2 alone or HHb  alone  we  have to   add the question, that a  flat SmO2  or HHb  does not mean that  there is a stable O2  situation. It depends  strongly as well on the tHb  trends.  Question one. Which  is the jog  portions in 5 min steps  and  which is therefor the  walk portion.   To give  some ideas on my last point  when using just SmO2  or HHb  for example in   finding stable metabolic   intensities.  see below.  a  set of  feedback s I got  from south Africa on these topic.

Here a possible  stable metabolic  intensity based on SmO2  and tHb
workout  smo2  thb stabel.jpg 
What specific  additional bio marker  feed backs  may  be stable as well ?  Now below  same person   what seems to be a similar   workout .

mark workout thb smo2.jpg 
What reaction could we possibly see  on a bio marker reactions in this case  and  why. ?


ryinc

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 #2 
Hi Jeurg

The overall message of your post seems to be that Sm02% by itself does not give the O2 picture, and that bloodflow is necessary to complete the picture. There are however individual pieces that i am not sure that i am following.

First up, i am not quite sure i understand the pictures, and what they represent.
  • This is a test which was 5 min walking/5 min running at the same intensity?
  • From point 3000 to 3300, it was 30 sec walk/run (or run/walk
The second picture is a close-up of the section 900-1200 seconds. From what are saying is they were aiming to determine stride frequency (i.e. how many steps per minute?) I don't understand how they determined this from this picture or "what they were aiming for"

Then your questions:

On the first picture:
"Blue  reaction  all the time but a much higher  fluctuation in O2Hb  . Why??"

I assume this picture is in absolute and not percentage terms. Therefore, i would imagine that what occurs is that in the periods with higher bloodflow this is oxygen rich blood, therefore O2Hb increases but HHb stays similar/flat. 

Question one. Which  is the jog  portions in 5 min steps  and  which is therefor the  walk portion. 

My guess is that the run portions are the ones where bloodflow and O2Hb are lower. 

Then the pictures, from South Africa, not 100% sure what the key message is?
- In the first picture, both bloodflow and SmO2 are relatively stable (bloodflow increasing slightly). So additional bio-markers we could be seeing:

Option 1. CO stable and muscle compression (and vasodilation/vasoconstriction) stable. CO increase could be as a result of different HR and SV combinations. E.g. stable HR and stable SV, increase in HR but reduced SV or reduced HR but higher SV.

Option 2. CO increase but largely balanced by muscle compression taking place. CO increase could be as a result of different HR and SV combinations. HR and SV increase (or SV stable), HR increase bigger than SV reduction, HR reduction smaller than SV reduction.


In the second picture, Sm02 is stable but bloodflow initially increases and then reduces. (Also while stable which is similar to picture one, what is different is that the Sm02 level is much lower).
Option 1: Moxy placement. Could be a non-involved muscle, and initially bloodflow increases, but when effort gets harder bloodflow redirected?

Option 2. CO output stable or increasing bu some kind of mild occlusion which has a bigger impact than that of any CO changes - causing reduction in bloodflow. Given that Sm02 stable,  muscle compression looks to be "balanced" between arterial and venous

Option 3 - actual workouts for the two pictures are not similar, even though Sm02 trend is similar. 




juergfeldmann

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 #3 
1. The overall message of your post seems to be that Sm02% by itself does not give the O2 picture, and that blood flow is necessary to complete the picture.

Yes  as we  see very often SmO2  is a great feedback but in combination  with tHb  we  get a much more all include  or more include  picture  on why we  for  example desaturation or not.

Questions like  :  Is there  free delivery or  the other extreme no delivery  or no delivery yet. So  tHb  trends  will give us  additional feedback son this answers.
 For em the most fascinating  part in any  activity is, to start " cold " so  surprise the system  with  the  activity so we create  an immediate demand  for energy.
 The  classical system  would argue  we take ATP  and once this is  reduced  or gone or nearly gone we  take CP  and so  on. The  newer  technology  refutes  this   theory  and rather  would argue ,   that we  use  in the first  10 plus minus seconds  already  a lot of  O2. Problem as  already discussed. We have to change some theories'  and some ideas on   energy  production.  So  here a   very  open statement.
 In any activity we start we  will see a drop in SmO22  very rapidly  at the onset of the   activity  and in  most cases  if the activity has a certain intensity  we as well see a drop in tHb. The point we discussed is:
 tHb drops  due to  initial  muscle contraction  and therefore  compression of blood vessel  and reduce  flow  initially. Counter action hopefully   can show  up  with increase in cardiac  out but and additional  fight and flight alarm reaction  for  vasodilatation.

 So like in t epic  below  at the start., The o O2  is  not  delivered  as  delivery is minimal  and even reduced  at the start , so  O 2 comes  form blood  already there  which  may be not  very much  but   most likley  50 +- %  comes  from  Mb  as O2 is stored  there as well it is easier  to take  form Mb   at rest as the O2  disscurve is  more to the right than  from Hb.
Now  after   1  or  2 loads in a  5/1/5  we  have  now  better  delivery  and  O2    can be used  thanks to a  better delivery option.  If that is  true  a  high   mitochondria density  and a high therefor Mb  content  would be of a huge  advantage  for  sports like ice hockey  or other similar  acyclic  sports, as  we would have a much bigger  O2  tank  and therefore  can  somewhat  longer  create  great  performance (  a few more seconds  but that is crucial  for many   activities  like  ice  hockey.  and we  can reload  easier , as   after a  while the  Hb  O2  disscurve  moved  to the   right and now it is  easier  to load  Mb. More on this for  sure as we go along.


 
  • 2. This is a test which was 5 min walking/5 min running at the same intensity?
  • From point 3000 to 3300, it was 30 sec walk/run (or run/walk

 Yes  and it  answers  your  guess as well. The case study  was a walk  with the same  speed on  a treadmill so 5 min walk  and than  5 min  jog  same speed  and yes  at the end  very shorty  time  intervals between  walking and jogging.
  Yes the higher  " peaks  " is  during  walk  and the lower is the jog section.
 Best represented    with the yellow  trace  which is tHb  or blood flow. The eccentric  load in jogging in this too low  speed is very inefficient  and creates a  high  contraction force  despite  slow  pace and therefor  tHb  drops  to  compression.  when we go back to walking we have   a( a higher  HR than in walking so a higher CO  so a better chance  to  create vasodilatation and as we  give up eccentric  landing  with a  softer impact  during walking we have this nice picture  of a  rapid increase in blood volume in the legs and   less demand of  O22  but still O2  use. So the increase in blood volume  with saturated  O2  O2 Hb    shows  up  with the spike in O2 Hb  but we still need  some  O2  so HHb  does not react that massive.
  Now  step frequency  and south Africa.
Lets  think together  again.

yama super close look and quality of  stroke.JPG 
 


So not  that easy  yet to see RPM/ min on this  so what  do we have to  do. ?

super close look geoff at start after 1 min break.JPG 
 Easier ??
 So  what  did the students  had to  do to get  the  stride  frequency ?

South Africa.
 Same  or nearly  same trend in SmO2  just different   %  but more eon less  flat , indicating. ???  Now  both loads  where  done on a bike    with a specific  idea  that performance is  ??? The flat SmO2  and flat  tHb  indicates  a nice ????  at least over the  shown  duration.
 The  flat SmO2  with a different thB  shows  a  trend in less  and less ??  so    we  will earlier  than later  have to  either readjust  performance    or we  may run into   some delivery limitation changing the physiological reaction and looking  for compensator  which  could show  up  as    ????  Have  fun  and  it is great  to have  many feedback s and more and more   readers see, it is not that  difficult  as   long you are ready  to think simple  and  relative  logic    so not a lot  of theories  really but physiological   reactions  which make sense.


ryinc

Development Team Member
Registered:
Posts: 369
 #4 
Thanks for reply Jeurg.


"So  what  did the students  had to  do to get  the  stride  frequency ?",

I assume the students needed to count the "peaks" within the interval and divide by the time in minutes to get the stride frequency. (This is the principle i suppose, but i imagine there is probably some complexity in considering how frequently the device was taking measurements etc and how this might affect it).

South Africa.
 Same  or nearly  same trend in SmO2  just different   %  but more eon less  flat , indicating. ???  Now  both loads  where  done on a bike    with a specific  idea  that performance is  ??? The flat SmO2  and flat  tHb  indicates  a nice ????  at least over the  shown  duration.
 The  flat SmO2  with a different thB  shows  a  trend in less  and less ??  so    we  will earlier  than later  have to  either readjust  performance    or we  may run into   some delivery limitation changing the physiological reaction and looking  for compensator  which  could show  up  as    ????  Have  fun  and  it is great  to have  many feedback s and more and more   readers see, it is not that  difficult  as   long you are ready  to think simple  and  relative  logic    so not a lot  of theories  really but physiological   reactions  which make sense.


South Africa case study.
First i want to clear up my interpretations of the facts you have given to us:
1. It is the same athlete
2. It is a similar workout

Assumptions that i am making that you have not given to us, but which may affect the interpretation. If these are wrong, then may need to rethink my answers.
1. The "similar" workout does not mean that the wattage in the the workouts was the same. If the wattage was the same across the workouts, then other variables e.g. cadence were not necessarily similar.
2. The workout load was constant through the workout (i.e. wattage was constant)
3. The information was collected from the same muscle, and it was an involved muscle in both instances.



Same  or nearly  same trend in SmO2  just different   %  but more eon less  flat , indicating. ???  
The first picture, has a slightly increasing Sm02 and bloodflow trend. The other picture has an initial increase in bloodflow then reducing bloodflow later in the workout. Its Sm02% trend is more flat and is at a lower absolute percentage.

Now, i am not sure if the question you are asking is:
1. What does the increasing Sm02% trend in the first workout indicate?; or
2. What does the different Sm02% and slightly different trend in Sm02 across the two workouts indicate.

I think you are asking question 1. To me this is a sign of "good" delivery.

with a specific  idea  that performance is  ???
I am not sure what this question is asking. My guess is that the performance/load was constant within the workout itself?

The flat SmO2  and flat  tHb  indicates  a nice ????  at least over the  shown  duration.
I think it indicates good delivery in terms of oxygen and bloodflow, CO and vasodilation are balancing any muscle compression, oxygen delivery and utilisation are in balance. The system appears to be in a good balance. 

The  flat SmO2  with a different thB  shows  a  trend in less  and less ?? 

Bloodflow at the muscle is reducing. Given that Smo2% is flat, we can know that O2Hb is reducing (since the same flat percentage applied to a lower amount will be lower). I.e. total amount of oxygen available for the muscle is lower.

so    we  will earlier  than later  have to  either readjust  performance    or we  may run into   some delivery limitation changing the physiological reaction and looking  for compensator  which  could show  up  as    ???? 

For a workout with a constant load (noting my assumptions above), a decreasing bloodflow could be because:
1. Reduced CO - through any combination of changes in HR and SV such that CO= HR x SV reduces. It seems unlikely to me that it would be reduced HR with assuming the load is not reducing (see assumptions), and so if it was this option it would most likely be reduced SV.
2. Vasoconstriction - seems unlikely to me, given overall pattern of bloodflow (first increase then reduction?)
3. Occlusion/Muscle compression - and is "balanced arterial/venous occlusion" since Sm02% does not increase or decrease. I think this option is unlikely because the bloodflow increases at first.

So this is what my guess on the situation based on the information:
An athlete was asked to perform two workouts at a constant load. The first workout was at a wattage that was relatively easy for them to complete. There were some initial drops in Sm02% and bloodflow, but that is simply because utilisation occurs immediately, but there is a delay in delivery response. After this has normalised it appears that the need for utilisation is not that large (relative to delivery). We can see this from (1)
- The Sm02% is still fairly high
-The Sm02% trend and bloodflow trend increasing (i.e. delivery easily meets and actually exceeds supply).

In the second workout, the athlete was asked to perform the same workout but at a higher load. The performance/load appears to be harder because:
(1) The overall Sm02% reaches lower levels - 30-35% vs 50-60% in previous workout. 
(2) The overall trend in tHb/bloodflow not being similar to the first workout.

To me it looks as though the athlete has a SV related limitation. I think the compensator is most likely Heart Rate.  In the second workout,this is a performance level/wattage which puts limiter (SV) in difficulty immediately.After the drop in tHb at the start, the compensator reacts immediately and HR increases which initially increases bloodflow, but then the HR compensator is stretched and cannot keep up any longer. Either the SV problem gets worse and worse, and HR cannot increase any further or HR itself becomes a problem and can't compensate for SV any longer, even if SV situation does not get worse.

Having heart rate in the analysis and knowledge of the workout details (e.g. wattages) would have helped a lot to confirm whether this is correct or totally incorrect.

Interested to hear whether this is correct or way off? If correct, what would be ways to:
 - Work on SV as a limiter, without stressing compensator HR?







juergfeldmann

Development Team Member
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Posts: 1,501
 #5 
Wowww , what  a great  and thought  full  replay. Do not tell me  that you have no physiological back ground.
 Here  first  the answer  you   where looking  for  and very poor  feedback  from my side.
 It was the same athlete  same  muscle same  bike same RPM. ( Not sure  whether it was the same  day time )  and it was  based on a stable  same wattage  workout.  So  for me  more important  is the   discussion on what if   and this is  what I try to  do  with my students. It is  less a question  of a    right or  wrong  but rather the   start of a thinking process on how the different system  could interact,  limit  and compensate  for each other. Once we have this    set up it is fun   even during a  workout  to  listen to the body , take simple  bio markers  like HR  as you pointed  out  and feeling  on RF  and TV  on your own body  combined  with the live feedback on a watch or on a screen  and you  can see , what I mean  to learn to   create as  close as  possible  same stimulus  guided over physiology  and use  performance if  available  to understand  why we have to reduce  wattage on a bike or speed in a  run  and so  on  so we  stay in the  same physiological stimulation I had  target  my program. This way  I know  what I stimulated  , I  ca reassess and hope the idea  was great and iI improved  . If not  than  my idea  was wrong on Limiter but I  still see, what the stimulation  had changed  and    can use this idea later. If  I base  zoning on an out side  objective wattage , than I  know  what wattage I pushed  but  have no clue  whether it was the same physiologic la stimulus  so I  have no  clue   why I improve  besides I did  workouts  and   for sure have trouble if  I am not improving as I do not know  what I stimulated. Thanks  for that incredible ind detail super nice  feedback.
ryinc

Development Team Member
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Posts: 369
 #6 
Jeurg i need some more hints for South Africa case study. If it was the same athlete and same workout, same wattage, same rpm, same muscle, and not too many weeks apart, i don't know any reasons why we would see
1. Smo2% level 30-35% second workout vs 50-60% in first workout
2. Sm02% trend flat in workout 2, slightly increasing in workout 1.
3. tHb trend slightly increasing workout 1, increase-decrease trend workout 2.
Andri

Fortiori Design LLC
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Posts: 65
 #7 

Good discussion, and I just wanted to simplify the initial point made by Juerg for other readers.

“I  have more and more  e mails asking  for  the  ideas on  why  we need tHb  when  we actually  look at  energy supply  so SmO 2 so should be good enough.”

 

In order to understand why including tHb in an in-depth analysis we need to understand SmO2. SmO2 is the relative value of oxygenated hemoglobin over the relative sum of oxygenated hemoglobin and deoxygenated hemoglobin, or in other words total hemoglobin (tHb), like this: SmO2 = O2Hb/tHb. In a value it would like something like this as a simple example: 5 O2Hb/ 10 tHb = 50% SmO2. Now looking at this it is very easy to understand that I can increase tHb while maintaining the value of SmO2 and thereby I now actually have more oxygen, like this: 10 O2Hb/ 20 tHb = 50% SmO2. I have doubled my oxygenated hemoglobin but my SmO2 remains the same.

 

I am alright with keeping things simple at the beginning as we get used to NIRS as a new technology and the new parameters, however we need to remember that at the moment the most important information NIRS gives us is this balance between oxygen supply and demand. An in order to assess supply an understanding of tHb also comes into play, how is blood moving to the working muscles. It is very possible that you have a decreasing SmO2 value as a result of impeded supply rather than increased O2 consumption. This is why we need to look at tHb. 

fitbyfred

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 #8 
Andri--thx for the great clarification. This is best rationale for having the info up live during assessment or guided workouts?  
juergfeldmann

Development Team Member
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Posts: 1,501
 #9 
ha ha  that is  why  I have a son  who speaks  proper  English  and he  is  more logic thinking than his  messy  Dads  brain. Somehow you have to invest your  genes  and money  ( Smile ) Andri,  as usual thanks  for the  clear thoughts and it is very much appreciated . Please jump in more often  to get rid  of my mess. Andri is my most honest  and  open  critic as it is NOT  about  who wins  but  how  can we  explain decently  what we  do  and why  we  try to do certain ideas  and  thoughts.
 We  are all dependent on some  few   great brains    doing  some incredible research. Nevertheless  it seems to me at least that in many cases  we  try to defend  desperately  what we believe and not really know  so it  is  coming  down  between religion  where I am allow  and  have  to believe  without    questioning  ideas  and  science  where I have to avoid  to believe too much  but  I  am allowed  to question   certainly  ourselves  or  myself.
 . So it is  so often  more about  EGO  than about   the reality to  see  what I  can't  or like to see  and  to  accept  changes  as we   hopefully  make progress.
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