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Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Sandy  , 
you  are great,thanks   for  coming up  with  an answer. I have many  ( MANY )  who email me  as they are  out  of what ever reason  not ready to  come on here  and discuss. Are we  afraid  to make  " mistake"  we all make mistakes  and we  ail  learn  form mistakes  so  to  make progress we have to learn  form mistakes   so it is great.
 Now  I will send   you some  additional thoughts  to the  question.

 Now  I  do the same  but   with both arms.
Assumption that I   have  the placing perfect ( unlikely  ever the case ).
Now  I have in the left arm a much  lower SEMG  activity compared  with the right side .
. Question. Is  the left arm  stronger than the right  or weaker.
And  depending on the answer  what  would we  expect  with  MOXY SmO2  and perhaps  even tHb ?


Development Team Member
Posts: 34
Old thread...but I'll take a stab at it.

SEMG measures electrical activity.
You are raising the same weight with both arms.

If the result on the SEMG is lower, fewer muscle fibers are recruited to do the same amount of work on the left than the right. So the left arm is stronger.

SmO2 may not drop - different energy system is used if it is a simple short lift, but will drop if the muscle is untrained for this type of movement.

tHb would increase.

Development Team Member
Posts: 1,501
 Thanks  for coming back on this interesting topic. Not really because I have a clear answer, but it is a topic  many out there  think it is straight forward  and many  most  likely  strange or  even wrong conclusions  are  made.
SEMG was one of  my  hobbies during my  education and later on, as it was  at the  time  the best  direct feedback  to assess  many ideas like   is  an exercise  really  doing  what we  as coaches  say  or I stretching really doing  what we  tell all the people and so on. First  step in SEMG  as well as in MOXY  is placement  and than a  critical view , whether what  we like to see is really  what we see.
Short  example.
 One of the  most common fitness assessment exercises  at the  time  was  and sometimes  still is  sit ups. So the   technique  at the time was  to hook your leg under something  and than  you have your  knee  bend in a certain angle  arms behind the had  and you started  to go crazy by  pushing up and  down.
 Now  as we assessed  this  idea  with SEMG  we  would place  as    we thought a  SEMG  left and right  rectus  abdominals  area. So the first  surprise  was, that  many  actually  kept  going  despite a  reducing in SEMG  activity in the  rectus  abdominals. Well today we know   we started to compensate  with hip  flexor  so we used  iliopsoas  and   rectus  part of the quadriceps. So now the question was  to get  iliopsoas  on the SEMG  and we   often thought  we had it  but really  we most likely  had  the rectus  part  as it   is very difficult  to reach the iliopsoas  section. Same  will hold   true  for MOXY.
So the test concept  got  changed  and the legs  where not allowed  to  get   stuck  somewhere.  Now  we had  situations , where people  with really high SEMG  activities  could   not  make many sit ups  despite  an as it seemed  much  higher and better  activation of the rectus  abdominals. Same   reactions in MOXY assessments.
 In fact we had  people   with relative  limited  activity level  and in MOXT Y  today  wit  a  very small  reduction in blood outflow , where able to  do many more sit ups.
 The once  with a very higher  activity in SEMG  show  often  at least a venous  occlusion but even  an arterial a occlusion. True   we could argue   her it is   occlusion =  delivery limitation so they  only  can use  what they  have  in the area, as nothing is delivered  anymore nor  is anything going out therefor  limitation of  time  and  repetition. On the other side, when we  change the  exercise,  so the  lower body  had to move  rather than the upper body  we had  basically the opposite  reaction in the result.  WHY.
 Answer body proportion.. Athletes  with a   long  and heavy upper body  like gymnasts  for example  have  more weight   above the  hip  fulcrum  and if there is not  option  for a counter balance the legs  simply  will move into the  air  , when they try to make   sit up , versus  when they  can sue  the leg s  only  and heavy upper body is  fixed    . So   on the other side  people with long legs  and short upper body  will make  very easy sit ups  with fee legs.

So  when  we keep this in mind in  many sprits  where we  may  compare  SEMG  and NIRS  and  even when we  compare  left  and right.  I  will get back to the  bike  fitting  discussion 5/1/5  on  left  and right leg using  MOXY  and they used SEMG.  Now  both  give a  d feedback over recruitment  pattern SEMG  or  metabolic  demand  MOXY

 Now  to  know   which one  may be  stronger  or  which one  is more efficient in metabolic  demand we have to have the performance  available  as  one  could like in cycling compensate  for the other.

 So the simple  example of  having a  SEMG or  a  MOXY on a  simple exercise  movement like a biceps curl is a great  way to demonstrate this.
We lift  same  weight in a biceps  curl  left and right  and  compare  SEMG. We  than see a much higher SEMG  activity  on the right side  than the left  side.
This  leads to the assumption, that to left the same weight the right  side has to recruit  much more  fibres   as the left  and therefore  may be  weaker..
 Now  try  with a  MOXY  and you  have different reactions.
 The weaker arm  may show  an earlier thB  reactions  after the initial  compression ( tHb  drop) into a   outflow restriction ( tHb )  up. As  well more  O2  needed  so SmO2  drop   further.
 BUT : 
 How many of us  are  left  and right equal ?
Your right arm may be  much better trained  and  may  have a much higher Intra muscular  coordination.
 So  you activate  many more  units  at the start  but than may  readjust  as you go  along.
 So  time  is  essential as well.
 The   right arm  may start with a  higher SEMG  and than settle in    and  can maintain the  activity as the  %  of te maximal  SEMG  activity may  only be  30 %  needed  to hold the  weight  so  blood flow is  existing  and delivery is great.
 The left arm  with the started lower SEMG  activity may stay there  on that level  but  he may have to give up earlier  as  his SEMG level  which is lower than the  right but it may be 50 %  of  left side  max SEMG  has  over time an outflow  restriction  porbme  and therefore metabolically hee  ruins in  problems  before the  right.
 So  again  disappointment.
 Yes  we  can use  NIRS  and MOXY  for trend information.
 Yes we  will have  earlier than later  NIRS and MOXY  and  SEMG cookbook  (  was once here already ), where some people  will be able to find  some formulas  and   statistics  to give a cook book.  My  personal  question is  always the  same:
  Why  would I   take a  cookbook  or formula  , when I  can see the  results live in front of  myelf  today. Why  would I  read   a game report  from an ice hockey  game  tomorrow , when I  can go live today  and watch the game ?  I saw on the great  website   of golden cheetah  to day a question  form a reader.
 Can I  get may  heart rate  zones  and %  calculated the soft ware.
 The answer was  that in the  newest  version you  can .

This is  for me  an example of the fundamental difference in training  , Calculating  performance    and using performance  without feedback on physiological reaction to see, whether the same performance is  really still the  same physiological stimulation.?

In todays technology  this  combination is so easy to have so  why  not using it. No body looses    and  every body wins. ( True  we  may loos e our EGO )

Todays  SEMG  technology is incredible  and one of the leading  group I the Italian  BTS  group. Not  just  from the technology,  but typically Italian it looks  super  slick  and  great  as well.

 So  it  will be a  question of  time  till somebody  will come  up  with a SEMG "  watch "  and  argue , that we  can sue  SEMG  activity to have a perfect  workout  based on SEMG.
  Than  as  with NIRS/ MOXY  we  will have  the same discussions on limitations  and    advantages   on how  to apply these   for many different ideas.

 As  a  very  small PR.Andri  was just a the  great university of Bologna  Italy  and they  embraced the MOXY  as the equipment to add to their  research tools  to combine   the different ideas  and options.
Slowly  which is the way to go  but  critical and open , the MOXY  moves into the  use  of  many different ideas  and activities. We look forward  to have many studies  coming out  showing  what we on this forum  discuss  speculate  go  wrong  or  right  but  at least  have  fun to try  and assess,  Summary.  No  clear answer  other than   use  and look live  what happens. it  can be very different.


Development Team Member
Posts: 18
I use the BTS system for bike fitting. It is a great technology, but unable to do some of the testing I plan with my NEW Moxy!  First on the list is SmO2 and HR at different crank lengths[wink]  Great utility for Triathletes thinking about making the switch to shorter cranks.  
Chris Balser

Development Team Member
Posts: 1,501
Great  plan , we did  some of this    combined  with Frank days a adjustable power  cranks  and  locking devices  to  see,  the efficiency  of the  different options  and the connection between  femur  length and tibia  length .  We  combined this  with VO2  and  BTS  8  channel  SEMG  as well as  Portamon  at that time  for NIRS feedback.  and as well some  blood test. Will be fun to see your  results  as there are not many  studies  out there using this combinations.The testing was  done  a  few years  back as you can see  when   the BTS  rep  was in Vancouver  to show the initial unit.Have to  dig back in the raw  data  as  once  I did  something and had some  directions  I   move  on to the next interesting topic.

Development Team Member
Posts: 1,501
Short  add on  to all   people  using    any  bio feedback  for  additional  physiological  bike fitting. In  fact it is not  just about  bike fitting. We  use NIRS in combinations with  other tools  for other  sport equipment adjustment.
 Carter  showed a  small  section in  motor cross handle bar thickness.
Cross country  pole  length,. Tennis  racket grip  thickness, Seat position in Nascar  or  formula  one    cars and much more  as we now see the  energy  supply and demands  locally and possibly influence  systemically. Now  back to bike fitting  and  pedal length. Be  aware  , when you start testing that   in combination  with  overall position, that  depending on the LIMITER  a   certain position may show up better in the legs  but is  actually worse in the overall performance.
So  we  always use a  involved  muscle  or muscle group  combined  with a minimal involved  muscle group.
 So  when looking at pedal length influence it is  important  to  check for example  calf, hamstrings,  quadriceps  and   hipextensor  to see how the change  may only shift  muscle  group involvement  or whether it may alter the  limiter  if the  limiter is  for example a  delivery  limiter. So  if the pedal  length change  starts to  better involve  more muscle groups you  demand  and utilize  more O2  but if the athlete  has a delivery limitation you start to  limit performance  due to for  example a cardiac limitation now. The more  muscle  group involvement  may push the cardiac system  to a limitation creating a  reflex  to reduce  motor unit recruitment  and what looked like a great short  term idea  may back fire  in a longer  duration event. We  had this   experience  first  hand  with a  quadriplegic   wheel chair  cycle  assessment, where we  where able to involve more m still available  muscles  but  we overloaded the cardiac system  so  what look  very promising back fired  terribly  in any longer   attempt  for  covering more distance
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