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Development Team Member
Posts: 1,501
Here  an interesting note    from DC Rainmaker  BSX  discussion. It s not a critic  on equipment   and or on coaches but shows  the  daily dilemma  when we use   points  or theories to assess progress in performance or intensity.
First if  you look  for performance progress   simply perform and   see   in a simple step test or  a distance  you like to cover   whether you cover more  or see higher power.  or speed.

here the  discussion

XYZ left a new comment on BSX Insight Gen2 In-Depth Review:

Very skeptical about the accuracy and consistency of the results of the Cycling LT tests of the BSX Insight Gen2. I have performed 3 tests in the 4 months, results were 231W, 224W and 228W. On the first test in the end of Aug it was at the end of my low season (2 months with very little training). Since then I have been training using a very structured plan using a professional coach and I find it ludicrous the results the BSX is giving me. Its basically saying that after 4months of training my LT is lower, than when I am untrained (note that weight, body fat, equipment, power meters are the same and have been tested). Piece of junk I say, all a marketing gimmick which doesn't really work.

 It is absolute possible   the result. Remember the  equipment is on a calf  muscle  so assessing the interaction of this calf  muscle in the overall team work.

So  remember the discussion we  had lately how  intermuscular coordination and so   can go on. If  y  work hard  but you calf is not integrated in the   change in  intermuscular coordination, in fact  you may tactfully intergarte  it less  your NIRS reaction will be different  and you may not even see a  break point  as they look for that. So  LT   changes  or is  not available, as there may be no clear  break point . In fact  you may haven a reverse  break points  as you may change from more toe pressure  to a more heel  drop  which will change the thB  and SmO2  and as  such  any  interpretation of  the  LT  as they believe in. . If  you look for lactate test lactate if  you look for NIRS trends   take a  functioning NIRS  equipment. 
If  you have a  professional coach  ask  him what the limitation is  as a plan   based on LT  rarely works . 


Development Team Member
Posts: 369
A scientific theory should be as simple as possible, but no simpler. -- AlbertEinstein

Development Team Member
Posts: 49
I'll admit my path to this forum and the world of physiology based training vs performance based training with the hope it will help someone else....

I was flipping through a mens health magazine at the dentist office and they had some gadgets shown, one of them was the BSX Insight.  I thought it was interesting, went  home and purchased one.... really with intentions of just using it for threshold testing so that I could do all my zones.... (shameful I now know...).   It gave me my number, BUT then just because of personal curiosity I wanted to know what else I could use the device for...

I looked at the website, did some internet searches, etc.  I came across this forum, I came across a few other blog posts and saw how you could identify limiters using the data and felt that was much more useful than any threshold test....

So I put the BSX on, did some intervals in the basement and then looked at the data.  My SMO2 numbers were very very steady... So I searched the internet again and found out that is usually a utilization issue.  

OK... so I start to develop a plan in my head for dealing with that.  I also sent a few emails out to people that seemed to know what they were talking about.... Balance Point Racing, Dallas Cycling Center, Juerg himself.... everyone basically said that the BSX data was not useful for what I was trying to do.   I even went back and forth with BSX and the coach they have aligned themselves with.

I purchased a Moxy the next week. 

In my mind each device has a target market and an intended use.  The target market for the BSX is the same as the target market for the "Time Crunched Cyclist" cookbook.

For me the Moxy is definitely the correct device because of the knowledge I have acquired and continue to acquire from this forum.

Because of the way the BSX reports a "relative value" (BSX own words), and not the 0-100 absolute value the Moxy does that is why there isn't the same fluctuations.  Without those fluctuations you can not use a BSX to identify limiters and do the level of analysis that is seen on this site.

If I had just taken the data from the BSX and applied what I learned from this forum to it, I would have thought I had the worst utilization in history and spent my winter on the wrong things.

Development Team Member
Posts: 1,501
Again nothing to  do  with BSX . It has a lot  to do  with the idea of LT  and NIRS.
 It  may be well  possible  in this case, that a LT  test  with the same protocol may have  showed  up as right shift due to a change in the athletes  metabolic  situation of  his  total body  reaction.
 Again,remember the  Lactate value  does not give us a feedback on where it was   needed  to have lactate produced, when it was  produced, was more lactate produced  than recycled. It does not tell us how much intramuscular  lactate we  may have produced  and how much finally showed up at the test area  and  with what time delay  an what trend  ( increasing or decreasing or relative stable.)
 Now  you ad to all this  questions  the NIRS  to it , any NIRS  and you have it   one muscle ( Any muscle )   and you know what we discuss all the time, it is  a  very locla feedback on  a  very local blood flow reaction and a very loci  oxy  and deoxygenation very strongly dependent on  how  you integrate this muscle in any movement ,   than you can see, why we are very skeptical and long time ago  gave up the idea  to replace  the lactate testing with blood  with a  locla NIRS feedback and we not even look at the  real question whether lactate is a us full  information for   limitation and compensation assessment  and even more questionable on  creating any kind of  intensity  zones   for any sport  activity.  Lactate  is very useful for many other ideas,  but in  activities  we may have  to  look into some new directions  to avoid  all the open  questions we  produce  and the artificial answer we  than give. 

So  the result  we see in this test  comparison  simply shows, that the  situation in  SmO2 trend  may not have chnaged in the  calf  muscle. The amount of lactate  you may or may not produce in the calf  muscle  o  may not even show  up in a   finger  test. On the other side  you may create a lot  of lactate in you   one leg  VL   but not in the calf  at all. So  to find a decent explanation why  the NIRS  reaction in one  muscle may  correlate  to an  idea of any of the 25  lactate threshold  concepts  is   an interesting  question  to be answered.

I am very  thankful to Fortiori  ( MOXY  producer)   that hey had  the courage  to  give up  the idea  to promote a MOXY  as blood less lactate threshold testing  equipment  and took the much less  spectacular   path  to  bring MOXY int the  coaching scene  over  a hard  an painful  introduction of  the incredible options we have  with NIRS in  general, but the  very  "unattractive"  way  to tell  people, that it will take  time and   a brain power  to  accept  that    physiological assessments  will be the  future  way, but  will have to go through many discussions  and   interesting ideas, before we  are ready to  more critically challenge our own traditional believes.
And than combine  experience  with  live feedbakcs  and more  questions.

Development Team Member
Posts: 59
The way I discovered Moxy was by first hearing about BSX 
and being fascinated by the idea of monitoring lactate
in real time.

I mistakenly thought that BSX would give 
immediate lactate feedback. The way I understand it,
there must be some large database (for machine learning)
that takes SmO2/ThB data and finds some similarity
with a known lactate profile that is sport specific
(hence you can't use the device for a sport other than

If we forget about lactate problems that Juerg mentions
and the ever so confusing terminology (ie, what exactly is
"threshold" and how to find it), I would primarily
use lactate test to associate "feel" with interval intensity.

By many accounts, Kenyan (and other East African) runners
have a natural ability for "feeling" of what intensity they are
training at. I always need to be reminded about intensity either
by HR or lactate test. And as Juerg points out in his posts,
HR (and lactate) can vary from day to day and you can therefore
still be off completely with intensity.

So, my NIRS fascination started as a potential device to use
to monitor how close I am to a mythical "threshold".

But the idea of physiological zones, finding limiters
and devising training for a particular energy system
and/or limiter blew my mind and it totally challenges
the existing training paradigms.

That said, I would still find it very useful if I could use
NIRS easily during training to guide me about interval


Development Team Member
Posts: 1,501
Thanks  for this nice feedback.  I may start a separate    section on your  great comments.

1. I would primarily
use lactate test to associate "feel" with interval intensity.

One  argument we often make  when doing intervals is , that HR is  not  good enough  due to the lag time of   the cardiac system  to   sudden changes. The same  holds  true  for respiratory feedbakcs  like RF  or TV.  Remember   we have a similar  situation
 CO = HR x  SV
VE + RF x TV So both are a  big important part of  the systemic  delivery  systems and  it takes some  time  to have a feedback loop  closed including than the reactions started , if we have somewhere in our body a  high demand of O2  and  a high  utilization  started till we  actually  start to try to  maintain  ATP  levels and pO2  levels in  needed  range. The  older classical   equipment  like VO2   and  or sure lactate missed  one important section due  to this lag time.

 This  than created  the  " confusion" of a lactate  deficit   and the lactate depth  at the end  which we all know by now is not existing  and  the   EPOC  took over for this misconception.

So  we do not like to take HR  in short intervals  due  the lag time  and the after action after the load . The lag time is  relative short 45 sec +-  depending  on the person.

As more  is it a  surprise  that coches sell the idea, that lactate  can be used  to   time  or   plan load  duration and   recovery between loads  on lactate .
 The  time lag  and the many problems with lactate values is in the range of   many minutes  to even  have any idea on the trend if    any.
Again a lactate value  certainly a  single  value  gives us  ZERO feedback , whether you are on the climbing section of lactate or  on the dropping section, It tells ZERO  where it was produced and how much may  how  up  in the finger and if  you test at the same time on the earlobe you may have a different value. And many more questions.

Using  NIRS  and the  trend in SmO2  to argue  we can   predict the lactate is a very interesting  concept , but   there are too many  real tests who  show  that it  does not work with  what equipment we  have  for  now.
I  showed it before. 
If we have  NIRS  companies  telling  us  that when SmO2  drops  you are " anaerobic "  completely kills the idea  what NIRS is doing.
 A  drop  during a load  where we see a steady  drop in SmO2  is NOT  anaerobe.
 In fact  in NIRS the  simple  idea is , that we see SmO2  dropping means  really, that we use O2  so how  can we argue it is  anaerobic  when we  sell an equipment  who  suppose to show  that  when SmO2  drops we  actually have a live feedback,  that O2  is used  for energy production.

 Now  we can have any combination of SmO2 trends  and  lactate  trends.

A  high  intensity load  whch   will create  lactate  and H +  will show a  drop in SmO2  , But  after a  15 - 30 second all out   and you take lactate the  lactate values  will be minimal  elevated. SmO2  drops  but lactate barely goes up. Now  you wait  1  min 2  or  3  . You  see SmO2  increasing  fast  after you stopped,   but lactate  may increase  as well depending on the   muscle groups involved in the activity. A  biceps  curl  will show  minimal to now  lactate change  a  squatting  may show a lot  change. 

 So  you load  SmO2  drops  , lactate   no clue  what it  may do.
 You stop  SmO2  will  go up ( most often ) because  you stop  the demand of  O2 . But lactate  goes up despite  you stopped . ????

So  SmO2  up  lactate goes  up or  nothing happens  or  it can go  down.
SmO  goes  down  . lactate  can go up  or it can go  down or nothing happens.

Now  NIRS  will show  in most cases  what actually happens and how long you can load , how long  you have to rest and how many sets you  can do.
 All by using  tHB and SmO2.
 Why  would we use lactate  with  really  minimal or zero feedback in intervals  when we have a live  direct feedback on  how we use  energy (O 2)  and   live feedback  , whether we  create a local delivery limitation or not. 

That said, I would still find it very useful if I could use
NIRS easily during training to guide me about interval

This idea is  most likely  the most  fascinating progress we have  with NIRS  to  guide  strength workouts  and interval workouts based on physiological feedback's and not based on 5  fingers , a 400 m track  and 1 min rest , which  have zero physiological  back ups   and are   only based due to  an organisational   reason.

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