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Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
I like to  make a  short  separation here, as RPM and what is best    is  so  multitude  as there may be  cycling coaches  out there.
 What often  seems a   straight forward    idea  seems a a very  intense  discussed  topic.
Different  tools  may help to understand, that this is   most often a very individual approach    and  even intra individual it  may change  as    cycling specific  physiology like coordination,  change in capillarisation  , change In cycling specific  strength and so on may    progress or  change over  time  of  cycling.
As  this is a  NIRS/ MOXY specific  forum I like  to add some more discussion to the hot  topic.

 I like to start with 2  studies    coming  as you will see  to a complete  opposite  conclusion. Both used   NIRS in their  ideas.

The effect of cadence on cycling efficiency and local tissue oxygenation

Jacobs, Robert MS; Berg, Kris EdD; Slivka, Dustin R. PhD; Noble, John M. PhD

Published Ahead-of-Print



The purpose of this study was compare three cycling cadences in efficiency/economy, local tissue oxygen saturation, heart rate, blood lactate, and global and local rating of perceived exertion. Subjects were 14 trained cyclists/triathletes (mean age 30.1 +/- 5.3 yr; VO2 peak 60.2 +/- 5.0 ml/kg/min) who performed three 8 min cadence trials (60, 80 and 100 rpm) at 75% of previously measured peak power. VO2 and RER were used to calculate efficiency and economy. Results indicated that both efficiency and economy were higher at the lower cadences. Tissue oxygen saturation was greater at 80 rpm than at 60 or 100 rpm at min 4, but at min 8 tissue oxygen saturation at 80 rpm (57 +/- 9 %) was higher than 100 rpm (54 +/- 9 %, p=0.017) but not 60 rpm (55 +/- 11 %, p=0.255). Heart rate and lactate significantly increased from min 4 and min 8 (p<0.05) of sub maximal cycling. Local RPE at 80 rpm was lower than at 60 or 100 rpm (p<0.05). It was concluded that: 1. Trained cyclists and triathletes are more efficient and economical when cycling at 60 rpm than 80 or 100 rpm. 2. Local tissue oxygen saturation levels are higher at 80 rpm than 60 and 100 rpm. 3. Heart rate and blood lactate levels are higher with cadences of 80 and 100 than 60 rpm. 4. Local and global RPE is lower when cycling at 80 rpm than at 60 rpm and 100 rpm.
A practical application of these findings is that a cadence of 60 rpm may be advantageous for performance in moderately trained athletes in contrast to higher cadences currently popular among elite cyclists..

The next study is a  fun one  as they used  NIRS  and SEMG  and power in their study. 

 The fun part  for us  is, that when we  assessed  RPM  and  the  reactions in  cycling we   combine  all of  that.
We used Physio flow  for cardiac  reactions,  mainly  SV,HR  ( CO ) EF %  and therefor  as well EDV,  SVR  and  LVET
Than we  added a VO2  equipment  to see.  RF  and TV (VE )  CO2  and  VO2
Followed    with 2  NIRS  systems. Portamon  and MOXY ( Specific  reasons )
 and  we added  Blood values  and  looked  mainly on lactate, blood  sugar'  and  ammonia
And  last but not least  SEMG.
  So the above  results  combined  with the below  results  are  for us  very interesting to read  and see  what the conclusion  form each group is  despite  both groups missing some very relevant  physiological information.
  Now  to avoid  a  flood  of emails:
 Yes we looked  at power  as it was  the most important  part as it is the only  objective feedback.  And  if we look  power we have to look  left  and right side independent when we make it very  specific , as by a  certain RPM  one side may have a   weaker inter  as well as  inter muscular coordination.

So here the second  study.As in so many things  I  go back wards  and start with the end

1. image2.png 

 Look at  first  just the picture
Blood  volume (tHb )
Oxygenation SmO2 Pedal force  and knee  angle  as objective  positioning tools
SEMG  as  a  part of the intra muscular  coordination.( Remember  when using  SEMG: a higher  SEMG  activity  does not always mean a higher  power out  put in cycling  when compared  top the opposite  side.) it has to be compared  with actual power out  put. The same is  true  when comparing left and right MOXY values. Making a    conclusion  which legs is  weaker  based on MOXY    with out power is not  easy and many  often make the  wrong conclusion  when  we not have power info as a back up.
  Got  a  fun example  about  1/2  year  back  where a  top  cycling expert  made a  fast    shot  on an example  but again 50 %  chances  when you just shoot.

Now  look , where I  would  start to  argue:
 a)  occlusion:
 IN  NIRS  any occlusion  will create an increase in tHb  as  we  in any  option of  an occlusion or  lets  say  restriction of  blood  flow  would see  an increase in tHb  as pressure  which  leads  towards  an occlusion will reduce outflow  and  as we  at least maintain inflow, even if the     systems  are  slightly  compressed  we  would see  an increase in tHb.
 We never see that in their study.
 In fact , when you look at the pedal force  as  an objective  feedback when more    force  and therefor  most likely   muscle activity is  appli3d (  feedback over  SEMG as well we  see the opposite    from an occlusion, we actually see a compression outflow. True that limits  the blood  flow  but it limits it   in both  directions, inflow  and out  flow.  . If  we have  an occlusion w e have  a  stable of higher inflow  and  a reduced  out flow  which physiologically has a very different reactions  on hand ????
 So  What I  would see in their study is:
  Pedal down stroke  12.00 - 6.00  as a  muscular contraction compression  reaction with a  reduction on tHb  due  to the compression  followed by the upstroke  6.00 - 12.00 as a decompression reaction  and  never ever  do we see an occlusion  in this picture.
 Now  that does not mean we  would not see a  occlusion   trend  in higher loads.
 But in this picture  we do not see, that. So the limitation is  very different and can change  with increase in RPM  and load.
 Now  you add  an additional factor  to it, which in non of the current studies  (  Or I missed  some ) ever comes into the discussion.
 We always see, that the  tested group  is getting loaded on a  %  of  a maximal  load  or what ever is considered  100 %.
 We  ail k now that  80 %  of a maximal  load like a VO2  max  or  Max  wattage  is not the same    stimulus  or restriction in each person. Some are able  to push nicely  by 80 %  VO2  and some not  at all.
 What is missing. Looking  what is the limiter  of each person. So in RPM  studies  , if  they  for example have a  respiratory limitation,  RPM  goes  up  and  RF  goes up  and TV  drops, than we  change the " mixture" of VE  as the %  of  dead space  changes  and as  such  we have  already a different  reaction in case of CO2   release  and therefor  on SmO2  reactions  but as well as on tHb reactions.
 If the limitation is  actual  leg strength the  "occlusion trend"  could in fact show up earlier  than later.


 If  we set  conclusion on optimal  RPM I would suggest that there is an optimal individual  RPM  based on the current limitation of the athletes  cycling ability  for technical  ability  to cycling specific  strength  to  physiological limitations.
  Here the first part  of of the above study  to  finish it off.

 What is  your take  any   comment is welcome.?

Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Now  if  we are  already looking  somewhat critical on  accepted  studies  here  another  interesting add  to our  RPM  games  with MOXY.
  I start with the first pic  followed by a  second . The first you already know  BF  (breathing frequency  and  RPM.

BF and RPM.jpg
 Now  in  most  cases  we   have done this  trend is    absolutely what  we see.  Higher RPM  higher BF  or RF. We  had a  bigger    change  from low  the high  RF   so we see  RF  starting below  20  / min  and can go  above  60 / min. Did  we had a trend between  world  class cyclist  and  beginners   in RF  no we  had  all in any body. Top  world  class  cyclist  who would  have a very high RF  and very high RPM  and so on.
  Now  the above study  has  a  follow up ( a  few  actually .  So here the next.
 The question is   what happens  to VE  and therefor  as well to VO2.  RF  x  TV  =  VE
 So lets' look  at TV
VT and RPM.jpg
  Now  here  is  where we have  very different findings.
  True we  have  athletes  where RF  goes up TV goes up. In their study  this happens in  as it seems all cases.
 I am not sure how  many  they assessed, but we have over  1000 studies  done   on this  and we have all options on the table.
  RF  goes  up  TV goes  up.
 RF  goes up  and TV   starts  to plateau
 RF  goes  up  and TV  actually starts  to drop towards the end.
 The other   part we have very different numbers  is the size  of the TV. when you look at the higher   RF  was  40 +  and the higher TV  is about  2.6 L   this  would give  a VE of  105  +-   which is a very low  VE. So most likely the  wattage they  have pushed  may be not  be  challenging the    higher intensity level.  We  have data  from grand  tour  winner  as well  to stay update  from   Stage winners  from  current running   tour who reach  when going  very hard  out RF  of  40 - 50  controlled  and TV  of  above  4 l  so we look at VE  of  200 +-
 We have  NHL  players  who actually when they  work on their respiratory  system  are bale to breath 50 - 60  RF  and  TV  of 6 + L  so they  move a VE  when trained  of 300 + Liter/ min.
You know what that means in  getting read of CO2  and therefor help  to buffer  and keep H + in balance.
  As higher the VE we see as higher  Lactate levels   climb. as lactate is a   transporter  and buffer helper  of  H +. So it is NOT the lactate  who  has a   limitation it is the question how good  we  can balance the  H +   situation.

 By the way  just  come back.
 Lactate washout  in the  NIRS  RPM  stduy.
 Why would they care  about  lactate washout ? What  would a higher lactate level in the blood   create   for a disadvantage  really ?


Development Team Member
Posts: 279
Thanks Juerg for showing findings from different perspectives. It shows "cadence selection or optimisation" (from whatever perspective you define optimal) is something which should be seen from multiple dimensions, but again needs to be tailored to the individual (and event of competition).
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Ruud , yes    and it shows  really how interesting  some   as it seems  simple questions can be  and  it shows  much more  how dangerous it is, when we  try to simply look at top athletes  and  how they perform  and than assume, if they turn 90RPM it has to be good and than try to  copy ( cook book ) this idea, when  our  own  ability   from a coordination to a  physiological point  simple  can't  work effective in that  way.
 Somewhere down the line, when I  get  seniors  or masters  swimmer in  with shoulder pain and problems  after the swim coach  told  them how they suppose  to  move their arms  and the coach forgot, that ROM in the shoulder of a master may be  permanently  so reduced , that he never ever  can get the hyper mobility ability in  form a wold  class swimmer. True the  great mobility will help a much better  water position, but when  anatomy does not allow it it is more  pain full than efficient  . That's' when  the no pain no gain  has to be replaced  with no brain no gain. ( Smile .)
 There is a reason , why  athletes  have a very individual developed    style  ( not to be  confused  with technique )  and the style is  , what    is  given by individual efficiency  due to specific    genetics  and  anatomical  situations  and physiological abilities.
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Now here the follow up in our  small excursion on  influences  on  physiological reactions  due to changes in RPM. I showed you the reaction of RPM  and  respiration  ( RF.
 Than we showed the  discussed  idea  of  TV  and RPM.
 So the end result is  VE  and  RPM  as  RF x TV = VE
 It is  actually fun as  the " lungs " move   something ( air )  and the heart  moves something  ( Blood )  so  VE  and CO  have similar   factores  who can influenece the amount of the  volume.
 CO = HR x SV
 VE - RF x TV.
 Can you see what I mean
 Now we  can go even further.
 To have a more eficinet  CO  or  effect of  CO  we have a  controle over resistance the so called systemic  vasulcar resistance.( BP )
When the blood vessels start to loose elasticity  we  have a negative influence on the CO.
 Now in respiration, when we  stiffen up in the  spine  and in the costovertabral  joints we have a negative effect on VE.
 Now the motion in  the spine  and in the costovertebral  joints  can  be reduced  to actual loss  of mobility ( stiffness ) but as well due to  bike position (  too narrow    aerobar position  for example.)  something which fits  into  physiological bike fitting  versus  wind channel bike fitting.
 Now here the VE  =  RF  x TV

VE and RPM.jpg

 Now this may  trigger one interesting direction.
   VE  and trend in VE  is often used in some equipment to  find  LT ???
 As  VT ( ventilatory threshold )suppose  to be  the same  as lactate threshold
 Is that  true ???

Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Now   here to finish off the graphs  on RPM  with  additional parameters  they  have looked  at .
Below is  HR and  it reacts similar like we  had  with the BF. Now  the question than    if VE = RF x TV  and CO = HR x SV,  would  SV react like TV ?? In this study the  found TV  would go up as well.

HR and RPM.jpg

 Now in our  case studies  we  did  as meantime d not  found  always an increase in TV.
 We  had  the three options.
 a)  increase
b)  increase first and  than  get stable
[wink] Increase  first  followed by  flat and decrease  or increase first than decrease. 

Now  SV  reacts the same  in all options. True  in many great exercise physiological books  you will not have this answer.
 In some  SV  goes up  and flattens  out only. In some they even give  an upper ml volume.
  and so on.
 We simply  can not see, that  and see all different options.
Reason  we think is  the physiological reactions  and therefor the influence the RPM  can have due to different limitations.

 Example. In respiratory trained  athletes  the SV    has a much easier  way to be maintain as the  diaphragm helps  the venous  return  so reload is  nicer.
 or in  athletes with a  actual strength limitation so  the muscle compression may in fact change into a venous occlusion trend the pre load  drops  so HR  has to go up as SV  drops   to maintain needed CO  and so on.

 Here a confirmation of this  options  form a great  source.
 Br J Sports Med2005;39:190-195                                                                  doi:10.1136/bjsm.2004.013037                                
  • Review

A review of the stroke volume response to upright exercise in healthy subjects

  1. C A Vella,                                 
  2. R A Robergs

+ Author Affiliations

  1. University of New Mexico, Albuquerque, New Mexico, USA
  1. Correspondence to:
 Dr Vella
 University of New Mexico, MSC 04 2610, 1, Albuquerque 87131, USA;
  • Accepted 22 August 2004
  • different   trends in sv in step test.jpg 
 Now  below  just to show you the individual behaviour.
 Remember the  two world class cyclists  where we  looked  at the RPM based on tHb   reaction?
 Here the same 2 athletes  and look the very different  respiratory work  and mainly look at TV  and you can see, that a linear increase or steady increase in TV  with RPM change  and  intensity change  can  show up in  many different pictures.
  below first a  respiratory very intense trained  athlete.
 Datas  thanks to Cesare  and  Andrea  from Switzerland Ticino.

YAMAVENT2.jpg Below  just TV  in a same test set up  from a north american athlete
gk tv.jpg  .

Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
And here to finish  this topic  off  :
 the reaction of this study group   on RPM  and  lactate  and RPM  and VO2.

Lac and RPM.jpg

VO2 and RPM.jpg


Development Team Member
Posts: 26
Hello Juerg,

In this respect, I think that the Hexoskin could help your research:

When you combine the two it could help your analysis

Best Regards,
Bart Coddens
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Thanks  for this feedback. We use   ideas they use in Hexoskin  since a   relative long time thanks  to the original work  form  Zephyr.
 We  use  instead of a  short  which goes  to one person a  belt respectively 2  belts. We  can test anything Hexo skin is  doing plus  some more  information's. I  can once list  this up  and we use this  since many years in ice hockey . Brian  has some incredible data  with acceleration options   repository behaviour  and we use this  daily in COPD   people. But yes there are  many different companies  now  out there  jumping on the incredible  work    and  start ideas  Zephyr  from NZ  has  done. As  so often  it  is copied  and    technology  helps  to make different options  so it is up to each coach to see,, what   he can use  best.  Swinco ( Andri ) may jump in  and   tells  what they use  as  a great Swiss product   which can do  even more  as well as Jiri   from Prag  uses  a system. This kind of  feedback is a fixed test information we  have integrated  since many years as  respiration is one of  our favorite play grounds. Why , Possible because still many " experts" tell that respiration is never a limitation in healthy people ??  we seem to like  challanges ?
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Here to keep PR  for different companies open . Hexoskin,
 here  what zephyr  as the  initial original  company  offered  and  as so often the first once open the door but than many great  evolved  option  with a  sometimes not  very  fair PR  concept  but effective ( seems to be the  trend in business this days ) so the original  may in fact  get lost in the  race  for market places.

Here  the   information we  are able top gather  and which is a big part  why we know  what we know  and learned on how we  can combine  NIRS  and respiration in all what we  discuss this days.  bio 2.jpg 
bio 3.jpg 
 Now we  than used  2 belts  one over  rip cage  and one  over lower  section    to actually see the difference in expansion to estimate TV  as well and therefor  VE. The company as well as a team package  where you have  all different teams member on it  live.

 This    ideas  combined  with  NIRS  and  cardiac  triggered my ongoing dream  sport bio feedback equipment. the BIO  watch. Here a flash back  of a presentation I made    a  few days after the portamon was delivered   to me .  Have fun and see how it may have evolved over all this years. It is really a philosophical summary on what we  discuss in here since many  many month and years. It will be one day reality  for sure.

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