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Development Team Member
Posts: 168
Excellent from Andri today, thanks for sharing some ideas. I do gauge tHb, as you describe, based on each client, the 'training age' and the goals. I can generalize and say my experience shows me that the
younger the training age and the less solid the limb conditioning is, I usually see a strong connection to tHb
decrease as an indicator of near max muscle tension and/CNS loading. Which is a very useful gauge for us
to spot adaptation during subsequent workouts and progress the CNS loading accordingly, if that should be the goal.
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
I like to add some  more  ideas into this discussion with some  case study  back ups. 

1. MOXY  and maximal strength. The delay time of  equipment.
 Here a discussion we  have  as an example of increasing  questions  from many  more MOXY users.

Hi Roger, Juerg, Andri:

Quick question.

I sometimes notice a delay in MO2 changes, and am working to confirm whether this is real physiology or just a data delay from processing/capture/transfer etc. Here is my situation. Using data direct from the monitor not from peripedal, using the average column not the live MO2 (though this doesn’t seem to change whether I see a delay) and the settings on the monitor are default (I believe 0.5Hz + smoothing).

If I start a clock and say have someone do fatiguing max exercise test for example, and stop the clock at the exact point at fatigue. Then when I go back and look at the MO2 data, it seems there is a delay of ~10-20 seconds before I see the MO2 at its lowest points. ….and to my question, is it that there is a point in data capture in the Moxy device, or data upload that would delay the reading by this much? Should I adjust for some time factor? Or assuming that you are unaware of a delay in data collection, I can assume that this is the real physiology….that when a person says they are fatigued, there is actually still a reduction in MO2 following the cessation of exercise.


Hope all is well.

Hi B,


Part of the delay is from the smoothing filter in the Moxy on SmO2. In the default mode, every displayed value is the average of the last 5 rolling calculated values. A new data point is calculated every 2 seconds so this filter causes about a 5 second delay in the data (1/2 of the total filter time).


If you are looking at a 20 second delay, that is longer that anything the filter could have caused so there must be a physiologic contribution as well.


Okay here one thing you can try to see, whether theory and practice works. Again look at the forum , when we did blood test to see what happens with influence of respiration ion lactate H + and bicarbonate.

See att as a simple guide.


What you do is:

Do one set as before look at the delay and the respiration which takes place. Than second set start before the set with a 10 - 15 second hypocapnic respiration drop EtCO 2 down if possible to 20 mmHg and than start the load but immediately double the respiration with the same d TV but double RF all during the load and look what happens to the SmO2 delay. Sent me the csv file as a payment for the idea ( Smile ) second att is a study with exactly this delay. see yellow section. att 3 is blood test to see, what happens as we do the respiratory intervention.

Delay  of SmO2  after load

et co2  and squatting.jpgInfluence  of respiration on blood values
2  loads   numbers only.jpg   

In low respiratory volume change during hard workouts your Pa and PA CO2 goes very high , your EtCO2 measured at the mouth my look the opposite depending on TV size.

So now as you stop you have a O2 diss curve extremely to the right and it takes as you can see about 15 +- seconds to ventilate finally as much as possible and CO2 can only move decently once the in between Pa and PA when the pressure difference is okay.

So the low SmO2 with a high EtCO2 can even show up on your finger with a puls oxymeter and balance of this is about 15 +- seconds.


Second point:
 Question, whether  MOXY   (tHb )  could give some indication of  quality of  muscle contraction.
Here a  case  I will get back later  from a  workout   Ruud  did  a few days ago.
Will be back on that one  just look at pictures  and trends same scale used.
  Here first   a few loads  at the start of an " all out "  MOXY controlled  workout.

first  few smo2  thb.jpg 

Now  last few  sets

last few smo2  thb.jpg 
Now look at the   power change  during an all out load  from first few  sets  and last few  sets  in one example.  and than go back and look at tHb trend over the time , where we have a   minimal  power loss before  we  loose it completely.

power loss.jpg  2overlap.jpg 
 Which color  may represent  an early load  and which one a  later load.  Now just for  fun :   Purple is power data    from this workout. Goal was  to  refuel  always back to the same level.
 Now look power data  and no w look  tHB as a possible indication of  power information on quality  for muscle contraction and relaxation.  Good relaxation means  high   tHb at rest  , good contraction means  low tHb  at  end of load. ( exception , when   venous occlusion  shows  up. Cycling is NOT explosive really so we  should rarely see a direct   venous occlusion at a start.


thb  and power.jpg
  last but not least.  To target  low SmO2  is a   question of   how hard you  accept to push  so  SmO2  low  levels  may fluctuate  form that point of view.
  But recovery SmO2  values can be  targeted  very accurate. So here  the recovery    SmO2  values  . Look towards the end , when he really  waited   to  baseline  80   and how the SmO2   peak  looks.
Not optimal  recovery  workout  yet  but  very good for a first  time  use.

How would  the workout  have looked  , when  he  waited  for really full recovery ?

smo2  red  circle.jpg 


Development Team Member
Posts: 279
Hi Juerg. Thanks for this insight. The "problem" with full recovery (that is in this example getting SmO2 back to 80), was that basically I started the load again after it stayed stable at around 76/77 after a fee repetitions. Why did I do that? Because I did not have the confidence it would return back to 80. Basically I think what you really should do with such a workout is to wait until you reach the maximum SmO2. So do you know this? Well i think by waiting until you see the first drop in SmO2 again. That is had just gone over the top so to say. So i would suggest starting the interval again if you have like 1 or 2 measurement lower than the peak SmO2 which you reach in recovery. That is the only way you know for sure you have maxed your recovery in terms of SmO2. What do you think about this? I also say this that there is also a certain error around measurements. I may see 78, but it might be 80 so to say.

O yes. Basing a workout on ThB is very difficult in my opinion, because i can hardly see the thb pattern in the graph (very scattered). I can see smo2 much better in peripedal. That's why I use SmO2.
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Good  feedback  and one  way  to look at it.

 Here an example for a wattage controlled workout section first  done ,and than a workout with  physiological controlled ideas.
See the change in duration of recovery.

  performance controlled  versusu  physiological controlled.jpg 

 Now going back to the  intervals  we see from Ruud.
 Here our suggestion  .
 If you have a recovery  initial  absolute number  like 79 %  of SmO2  than we  plan to  go back to 79 % SmO2  or   if  we  make a "compromise'  we   allow SmO2  79 %  or higher but never lower.
 So  when we look at the workout  again.

smo2  high.jpg 
he  " recovered  one (  third load  back to  target recovery. The rest he was "inpatient"  or  out of what ever reason he  did not  waited  to reach 79 %  or   perhaps  up. ? Here  his    reasoning

was that basically I started the load again after it stayed stable at around 76/77 after a fee repetitions. Why did I do that? Because I did not have the confidence it would return back to 80. 
 That is  an interesting thought.
 let's  take it back to classical ideas :
 I  plan to  do a 30 second  interval time  . But I am not confident, I can  do my 10 reps  if I go 30 second s so I  s  may   reduce or drop  by 26 /27 seconds  to finish of the planned  10 sets.

 I plan  a  300 watt load interval but I   feel, that I may not be able  to  load  again so I simply change my load  to 291  watt or less so I can finish  my sets.

  I plan a  150 m  interval on the track all out  but  I can feel  that I am not convinced  I can  do  it all the way  so I  shorten  the distance  to 146 m.

  Not a critic  but the typical  idea we all have  and feeling  when we  do metric   and not physiological  loads.

The difference is: In metric  workouts  you may quit because the physiology  likes  to quit. If you now  start to use  bio markers instead of metrics  you quit  when you do not reach the  level you like to reach .
  The answer  from our side.
  Well If  you do not recover  anymore  to 79 or  your  80 % SpO2  the interval workout is over  you did  your job   that is it.
  We never ever  see an all out interval with that  many  sets  as  if you go all out  you simply can't  do it.  We only are able to do that, when we  give up the idea of all out  and therefor allow more reps  which  is not the  goal at all.
 You can see , if you take some of the first loads  and some of the last loads  how  performance  on high level drop as I showed  above  but you as well see it in SmO2  levels  and even better in tHb levels , that he never relaxed  his muscle's anymore  in the  rest  section because  he  was not too confident. Here  an overlap  of SmO2  situation  from some first loads  compared  to some of the last loads.

overlpa   SmO2  first  and last.jpg 
 Look the trends  and you  see some additional information (  later as we go along )

Now tHb  lean indirect feedback on muscle contraction but as well muscle relaxation trends.
 A  nice good  contraction  will look different  and a nice   good relaxation will look different. See the comparison  form start to  end loads  as an overlap.

overlpa thb  first  and last.jpg 

In  both cases  if you look the power curve  it is   optimal  as long we see a  nice  steady drop in tHb . as soon tHb  changes  towards    "occlusion trends' we see the  drop in the  power  curve  as well. (  15 +- seconds  and a delay time of  5  seconds. depending on the moxy setting  [wink].


Development Team Member
Posts: 279
Thanks for the insightfull feedback. Wrt tHb it is not a good contraction and not a good relaxation anymore. I am however very curious what additional insight you derive from the SmO2 curves. Wrt stopping intervals when you don't reach the maximum first (base SmO2) again. Reaching this level again is very load (read resting load) dependent. So. You must base your resting period based on a certain load which you can't know in advance. The highest probability you have that you reach the base maximum again is to stop pedalling. Than you can be quite sure you will be able to go to the highest point again.

Long story. But my statement in this is: you must know the rest load (watt) in advance so you can see to what maximum SmO2 base you go back and work on that further (or do not pedal so you know most probably you will reach maximum base Smo2 again=> one problem for outside=> you fall from the bike [wink]
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Good points  but actually on a bike it is  most likely the easiest sport to  do nothing  in the rest period    and still move.
 We  do this type of workout  on a hill  and return  either back down  or yes  actually stop completely  to zero.
 But you as well can decide  the recovery load on a certain wattage level if you like and go all out  and than  ride   on a certain wattage level . This wattage level can be decided    from a TIP  so you go into the the ARI. or  STEI   again depending on your goal .
 You do NOT have to decide  before  the load  at rest  you simply have to  keep the same load once you do a load  at rest.
 The full stop  has a very different  physiological stimulation than the    slow  biking. You actually even can  decide  different  respiratory  intervention during the  interval or  after   at rest.
( Example you like to stay  hypercapnic  or you like to go as fast as possible hypocapnic.
 It all depends , whether  you  like to load as  fast as possible again  or whether you like  to keep  lactate  high at rest.
 This means you can manipulate MCT 1  and  MCT  4 reactions  and you can either get ride of a great  energy source  called lactate or you can maintain  at rest a very high lactate level.  This intervention is  crucial in some sport  like tennis  , badminton or even  ice hockey  ,but as well in  actual workouts depending  again on the goal setting.
 Here  an example  I showed before . look at the lactate levels  immediately after the load and slash is  just before next load.  so 2.3  would be  after load  and 2.3/5.6  the 5.6  is  at the end of the rest period

Juerg  3  R.H.intervall.jpg  .

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