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Development Team Member
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Rock climbing performance has been correlated to forearm oxygenation kinetics, with elite climbers being able to de-oxygenate their flexor digitorum profundus (FDP) significantly more and at a faster rate than advanced, intermediate and beginner climbers (Fryer, S. et al Journal of Sports Science, 2014:

Based on these findings and recent validation of the Critical Power model for the forearm by J.M. Kellawan, et al. PLOS One, April 2014, Vol. 9, Issue 4

I have been interested in developing Critical Power Testing and training protocols for rock climbing with the use of the Moxy sensor.  

In my testing protocol, I have developed climbing specific holds and a resistance apparatus to test the primary muscles involved in common climbing grips. During the test both arms are individually engaged in pulling down (and up) weights.  Typical rate for me is about 40 to 42 repetitions per minute.

For all tests the Moxy sensor was placed on the anterior side of the non-dominant forearm, one third the distance from the medial epicondyle of the humerous to the carpus (in line with the index finger).  The difficulty with the Moxy is that given its limited penetration depth it is unlikely to measure the FDP alone, so it is likely also measuring the Flexor Digitorum Superficialis (FDS), which resides above the FDP.

Other research studies have been able to measure the dominant muscles being employed by different finger grip positions, but for the purpose of this discussion the holds that flex the finger DIP joints are dominated by the FDP muscle, whereas grip positions that flex the PIP finger joints are FDS dominant.

I have used both a 5-1-5 test protocol as well as a 5-1 protocol to measure threshold resistance (or the analog force for CP).  The time intervals could be 4 minutes instead of the five minutes advocated in this forum, given that the forearm muscles have significantly less mass than other muscles being measured in traditional endurance sports.  

Attached is a view of the 5-1-5 test, using a Three Finger Open Hand grip on a 20mm edge (dominated by the FDP muscle) (thumb and little finger not used in grip).
3F test Feb 28.png 
The results indicate that I am not able to sustain the 20.5 lbs resistance for the full five minute interval and even the 19.5lbs interval was taxing.  

This protocol is still not a clear correspondence with the Critical Power developed in research studies, but from this test I was able to develop interval training workouts to target the FDP and FDS muscles based on using the three different energy systems.

Attached Images
Click image for larger version - Name: Open Hand Threshold Test Feb 28_SmO2  & tHb.png, Views: 17, Size: 77.05 KB  Click image for larger version - Name: Threshold intervals OH 3F.png, Views: 17, Size: 75.47 KB 


Development Team Member
Posts: 1,501
Nice  work  and  when you   go back  you see   some  informations on  rock climbing on the forum as we  did  some  intense testing a few  years back  during the USA  championship in  California  in Sender one.
climbing 1.jpg

ary Ann  Kelly  was the lead    person and did  some presentation  in a Rock  climbing seminar in Boulder a  few  years  back as well.

There  are some studies  available  I  think  from Jiri  and Martin  for the  check  as they did  some   studies as well  shown on the forum . We id  in Santa Monica  some live feedback  during bouldering  as this is a great  way  to guide  workouts  and recovery in between    the loads  and it is  fascinating to see  how and  why some  recovery  faster than others  so yes  great see  more people  going in that direction.
 I  do not thunk that the  5/1/5  is a good     way  of  looking   for physiological reactions   for thsi  type of a  sport  as  we see in other sports like tennis  or   figure skating  that  they  have  very individual  developed   assessment tools.
 To look  closer  at your  great data collection  you need to    sent the csv  file as  the grpahs  are pretty  worthless  they  way  this software  will give us feedback.
 Here  a  small inside  view  on  how  climbers look at the reactions  from a  workout  of  three specific  loads.

A smo2  tHb all.jpg 
and below   with  O2Hb  and HHb  feedback followed  by a  super close look  on what happened    with this climber.

clim A O2Hb.jpg 
closer look  a  smo2  tHb.jpg 
Great  work  and yes   sport  climbing  will be one of  the  sports  who will  see NIRS  fully integrated  and live in many  up to  date  climbing centers,  as it is  easy on a big  screen to show and see  and use. 


Development Team Member
Posts: 5
hello Juerg

I have attached the data as an Excel file that I imported from GC, I usually do not save the csv file from the Moxy as I download directly to GC.

I do agree that using the NIRS during the activity is a very good tool, I have had to adjust some timed intervals during aerobic training as the data indicated that SmO2 was was being depleted at a higher rate than expected.

Attached Files
xlsx Feb 28 3F test data.xlsx (131.36 KB, 5 views)


Development Team Member
Posts: 5
I have done a new 5-1-5 test to compare performance versus earlier test in February. I have attached a photo of the testing protocol as it far easier to see what is happening in general as opposed to trying to visualize from my earlier description.

 "Threshold" resistance is still in the same range as previous test using three fingers on a 20mm edge in an open hand configuration, but a significant difference is increased tHb for all intervals compared to earlier test.  For most of the resistance levels, average SmO2 is also higher, but I did notice that at the higher resistance levels I was rotating the palms from initially being 90-degrees away (facing out) to compensating and rotating inwards closer to 45-degrees (not sure if there is recruitment of other muscles, even though the FDP and FDS are the limiting muscles with the three fingers open hand grip.)  When I did move the hands back to 90-degrees facing away I quickly reached minimum SmO2 and could not continue interval (21 lbs).

My interest in investigating "threshold" is two-fold, I do not always have access to the NIRS when traveling, but can still use my customized hold and train on commercial gym.  Having a general understanding of zones always me to train from an energy systems basis (oxidative/aerobic, anaerobic lactic and anaerobic alactic). Secondly is that having a general idea of threshold levels for each hand grip position allow me to have a better understanding of muscle/grip imbalances. 

I am still having a hard time understanding from the data whether I am Supply Limited or Utilization Limited.  The forearm muscles are very small so I suspect that there is not a Respiratory limitation.  Also, when I monitor heart rate it does not increase significantly (from resting Hrt of 50 to about 75 bpm).

Any and all insights or challenges from the forum readers are welcome.
   3F test April 28.png 
ISO Grip Test (2).jpg

Attached Files
csv 3F top Edge Test April 28.csv (85.67 KB, 2 views)


Development Team Member
Posts: 1,501
2  start points.
 I  do not think  5/1/5  is a  good  idea  for  this  small muscle group testing. You   always  will have a  delivery limitation but not  due  to the fact  that there is a cardiac   or respiratory limitation but a  simple  overload     on   locla blood flow . One reason is ea  exactly  the lack  of  support or  help  to  counteract  with   cardiac  output.
 You will create a MMR  but the increase in   CO  is   too  small to counterbalance the local  muscle  contraction  force  so you  will have a   local delivery limitation due  to  local  occlusion trend.  Here a  short  closer look  from your  first   5/1/5  at  one section where  you move into   the  1 min rest.

super close  look  occl biased.jpg 
 this is  towards   higher loads.  and below  one at  your  first loads. 

super close  look early on no  occl.jpg 

 you can easy see the difference.

Than a  question to the  idea  of 

anaerobic lactic and anaerobic alactic

do  you have  any research paper  who shows  the   pO2  dropping intracellular  to an anaerobic  stage.  form  climbing or in that matter  any  other    activities.
Is there  such  thing like  alactacid  do we have a   situation, where we  do not produce  lactate in the   muscle ?

 The  question here is in the  historical  ability  to  test  lactate  and VO2  with  current equipment like VO2  equipment on the mouth and lactate  finger  sampling.
 If we look  MRI  and otehr  research tools  today   the  answers  may be different  and  many times    asked  in this forum.
 The   anaerobic  alacticid    situation in typical  short term loads  like we  may see as well in climbing is  the old unreal seen versus  the  NIRS  who  is now  the  unseen real.
 In climbing the key element is  to  have as long as possible O2  available before we  go to  O2 independent  Cr. P    needs  and then  the  protection  of ATP  minimal levels  if  Cr.P  runs  out  to maintain  ATP   needed levels  and the need  of O2  for " refuelling " Cr.P.
  The key in  sports like climbing is  to avoid a  drop in Cr.P due to  technical   adjustments  so  you us e O2  and CrP  and  reload  and you not see a long  flat low  SmO2  level as than the recovery of  SmO2  is not identical  with the Cr.P  recovery . Only when we  are able to stop the activity at the moment the  drop in SmO2  stops  die  we have a changes  to have SmO2  and Cr.P  recovery  close to the  same and  can maintain performance  for a much longer  time.

Richardson et al have concluded that: ‘‘…intracellular pO2 remains constant during graded incremental exercise in humans (50–100% of muscle VO2max)’’ so that: ‘‘With respect to the concept of the ‘‘anaerobic’’ threshold, these data demonstrate that, during incremental exercise, skeletal muscle cells do not become anaerobic as lactate levels suddenly rise, as intracellular pO2 is well preserved at a constant level, even at maximal exercise’’ (p. 63168). They also conclude that: ‘‘Net blood lactate efflux was unrelated to intracellular pO2 across the range of incremental exercise to

exhaustion’’ but was ‘‘linearly related to O2 consumption’’ (p. 62768). Another study confirmed these conclusions: ‘‘…consequently these data again demonstrate that, as assessed by cytosolic oxygenation state (deoxy-Mb) during incremental exercise, skeletal muscle cells do not become ‘‘anaerobic’’ as lactate levels rise, because intracellular PO2 is well preserved

at a low but constant level even at maximal exercise’’


Development Team Member
Posts: 5

I need to read through the research to better understand the behavior of PO2  and whether it drops to an anaerobic stage during exercise, but one research article indicates that PO2 is altered during hypoxya (23mm Hg) from normoxia (34 mm Hg) and both are different from PO2 during exercise (3 mmHg):

Research into rock climbing indicates that the sport taxes primarily the aerobic and the alactic anaerobic systems:

Regarding a  well defined "threshold" some research indicates that during an incremental resistance test such threshold does not exist and instead it is a slow transition from completely aerobic to a combination of aerobic and anaerobic energy systems:

But then there is all the research on Critical Power that leads credence to a well defined point up until when all ATP demand is met completely by the aerobic system...finding the onset of this transition does have some appeal for establishing training zones.

My interest is finding that zone when ATP demand is completely met by the aerobic system, I guess in NIRS terminology this equates to establishing the zone of "oxy intensity" and subsequently the  corresponding zone of "deoxy intensity".

The 5-1-5 test clearly has limitations when used with small muscle groups such as the forearm, but for me it is simply a entry point to gaining a better understanding of physiological response of the flexor muscles to external loads. This in turn leads to establishing rough boundaries in developing training intervals.  Being able to specifically target the forearm flexor muscles is one of the ways to enhance climbing performance (trust me this is not the equivalent of putting a hockey player on a bicycle [smile].  In rock climbing failure is not due to respiratory limitations, it ultimately is determined by the ability to hold-on to holds and generate enough energy to move between holds.  Effectively training the forearm flexor muscles is important.

The training that I am now able to develop from the 5-1-5 learning is far better in contrast to some of the other strength training protocols being used in rock climbing (intermittent isometric hangs from different grip edges using typically one of these two protocols: 10 sec max resistance hangs x 1 repetition, or 7 sec on 3 sec off hang repeaters for 6 or 7 repetitions at different resistance levels).


Development Team Member
Posts: 1,501
Very nice  and   great feedback.
 My interest is finding that zone when ATP demand is completely met by the aerobic system, I guess in NIRS terminology this equates to establishing the zone of "oxy intensity" and subsequently the  corresponding zone of "deoxy intensity".

Absolutely  great  yes that's  the advanatge of NIRS  for local  and  indirectly for  systemic  feedback.
 It is  the   for the moment only simple  tool , where we exactly looking live  for this information  instead of  believing in magical  4 mmol  and so on numbers  or on  calculations of  %  of  some magical 100 % ideas. Now  that's  where the physiological guided  workouts  really start  as  we chnage  even during a  workout  due to  many different  physiological needed reactions and  adjustments . In  rock climbing this is very  real  and  very often the  case  due to position changes and even due to gravity involvement in certain positions.
 This  way now  with NIRS  you  can se e what is going on and in  climbing centers  easy  to do over a big screen  so  groups or coaches  including the athletes can see it.

The 5-1-5 test clearly has limitations when used with small muscle groups such as the forearm, but for me it is simply a entry point to gaining a better understanding of physiological response of the flexor muscles to external loads

Yes  great    feedback  and  absolutely  true  there was  historically a reason  why  I developped  5/1/5  far before we  used  NIRS  alone. It is the feedback we get on the  sudden  stop and sudden start    reactions. for  climbing a very   interesting point  as well  in between grips.

 In rock climbing failure is not due to respiratory limitations, it ultimately is determined by the ability to hold-on to holds and generate enough energy to move between holds.  Effectively training the forearm flexor muscles is important.

Yes  absolutely  and we  did  over  30 years back in Switzerland  some very specific research on the forearm  development option  at the  university of  Bern.

 We  than started  to use  NIRS   very early on  for motocross (  Client  Friesen   / Red Bull )  for    training ideas    to  counteract on forearm pump)  and  in   rock climbing  with Mary Ann Kelly a  rock climber in Joshua  Tree  national park.
 We  used  there  long  rage    reach  for  additional feedbakcs  on   position on the rock  with Bio harness and respiratory  reaction  due  to overload  and efforts.  So  great feedback and nice  to see    that people  pick up   what was  for us  since a long time a non brainer  as it is  so  live  and in front of  all. So  still often  a  big  question, why  there  is this huge  hesitation to   accept  that there is no  such  thing like anaerobic  alactacid  and that  there is  today a  clear   feedback  that there is no such  thing like first  ATP  than Cr.P  than   anaerobic  Gl  and so on. They all   kick in  at the same time  and  what ever  helps to maintain ATP  levels  for survival  will be used. 

So  NIRS  gives  you  very specific  feedback  depending on your  idea  and goal  you have set in climbing.   If  you  do  2  times  the  same  section  you will see a very different reaction  form  one  to  2  same  for  track sprinters   first 10 sec  sprint  will  use different %  of the  different energy substrates  than the  second  and you can see  that  in  NIRS  feedbacks as well.
  Now  as usual it  takes  some  kind of  risk if we  talk contrary to what is accepted  and that's  why we see this hesitation in aerobic  anaerobic and  the change towards an  all included  energy production. The  same hesitation  took  nearly  80 years  to accept  that lactate  is not the reason of  fatigue and we still are not there  as of  yet.
  Here a  short review  from 15  + years  back  when some big names  carefull started  to  question the  ideas we  all learned in  school.

Sports Med. 2001;31(10):725-41.

Energy system interaction and relative contribution during maximal exercise.

Gastin PB.

Author information


There are 3 distinct yet closely integrated processes that operate together to satisfy the energy requirements of muscle. The anaerobic energy system is divided into alactic and lactic components, referring to the processes involved in the splitting of the stored phosphagens, ATP and phosphocreatine (PCr), and the nonaerobic breakdown of carbohydrate to lactic acid through glycolysis. The aerobic energy system refers to the combustion of carbohydrates and fats in the presence of oxygen. The anaerobic pathways are capable of regenerating ATP at high rates yet are limited by the amount of energy that can be released in a single bout of intense exercise. In contrast, the aerobic system has an enormous capacity yet is somewhat hampered in its ability to delivery energy quickly. The focus of this review is on the interaction and relative contribution of the energy systems during single bouts of maximal exercise.

 A particular emphasis has been placed on the role of the aerobic energy system during high intensity exercise. Attempts to depict the interaction and relative contribution of the energy systems during maximal exercise first appeared in the 1960s and 1970s.

 While insightful at the time, these representations were based on calculations of anaerobic energy release that now appear questionable. Given repeated reproduction over the years, these early attempts have lead to 2 common misconceptions in the exercise science and coaching professions.

 First, that the energy systems respond to the demands of intense exercise in an almost sequential manner, and secondly, that the aerobic system responds slowly to these energy demands, thereby playing little role in determining performance over short durations.

More recent research suggests that energy is derived from each of the energy-producing pathways during almost all exercise activities. The duration of maximal exercise at which equal contributions are derived from the anaerobic and aerobic energy systems appears to occur between 1 to 2 minutes and most probably around 75 seconds, a time that is considerably earlier than has traditionally been suggested.

 Why  do  we  see this    all thee  time ?  read 

The practice of science at the edge of knowledge.
Grinnell, Frederick
Chronicle of Higher Education;; 3/24/2000, Vol. 46 Issue 29, pB11-­
B12, 2p
Postmodernism;; Science -­-­ Philosophy;; Theory of knowledge
The writer describes the postmodern view of science and the way in
which science should be taught.

PROFESSIONAL SCIENTISTS usually respond to new findings with a profound skepticism that goes beyond the specifics of the research. When first confronted with new work, gatekeepers judge it according to how well it fits with prevailing beliefs. Therefore, the more novel and unexpected a discovery, the more likely that other scientists will reject it-­-­precisely because it contradicts current understanding. When they were initially proposed, ribozymes, prions, and cold fusion all looked like long shots.
Faced with rejection, the researcher experiences a deep sense of insecurity. Error often accompanies the ambiguity of discovery, and in science, being wrong is almost as bad as being ignored. On the other hand, as another saying puts it: Don't give up a good idea just because others don't understand it. To succeed in science, researchers have to confront rejection by becoming advocates for their new findings.

Thanks  for the   great  feedback   and I hope  over the next    month and years  we  can add more and more  to this ideas on findings  we see  every  day or  we  collect  sine a  long time but not sure yet   whether  they can be  real practical application  with it .

To  end up this great  direction here a  very small inside  view  in some climbing  studies  we did a  few  years  back In  Joshua  tree  and  sender one  with Mary Ann Kelly. It was during the Indoor  USA  rick  climbing  champion ship where we  had a  DEMO  tent  and  did  some  presentations there.

First  and interesting simple graph  from  intermuscular studies   where they looked  at pO2    situation  and  at  Cr.P  and ATP changes  in  all out  local loads.

po2  dznamic.jpg 

atp crp.jpg 

 Now  we know  that SmO2 and PCr.  correlate  very well under  certain situation  [wink] ( see in the forum  from Andri  SmO2  and Cr. P  reactions)  so  the workout  and recovery can be   possibly nicely be guided by SmO2   changes  and tHb  behaviour.

 Below  a  SmO2  reaction feedback after  different types  of loads  in the forearm.

3 stes  smo2  like  Crp.jpg 
Now  the  same  but looking  at tHb trends and missing is  SEMG on that.

3 sets  thb   like  15 Crp.jpg   Than  we look at recovery  of  Cr.P
in different people   and overlap  with  SmO2 .

overlap  smo2  CrP.jpg 

Now instead  of looking at    top athletes    okay people and obese  we  where looking , whether we  can create  this  three  SmO2  and tHb  reaction in the  same atele   by simply having him  rested  well. Than  specifically overload  and    even more overloaded  so    changing his performance  form top  to okay  to bad. And  well we    think we see the same behaviour  and use that than  for interpretation  before a  workout  whether we  recovered, if  we need to be recovered  or not  as we  like to reload in a  " tired  " body .

belwo a  SmO2  closer  view  and 2  curves  are  form a discussion we had lately here  and the  third  form another  overload . This is a  trend  we may see  and use  to  make some interpretation on  limiter in this three  different cases.

calibration  smo2  3 option.jpg 
Now  as usual  if  you have more  feedbacks  so you  eliminate  more  questions  so HR  and tHb  would be available   in the  same data collection and than  as well HHb  and O2Hb  for additional feedback.

here the three loads  with  additional  tHb reaction. Question was. Why in  the  third load  tHb  doe not  " recover.  That's  where we needed a  SEMG  for the answer. What do you think we  found ?

overlap thb  smo2  for crp  idea.jpg  This  than leads  to some directions 

optimal load  interv endurance.jpg 

Versus    ischemic  loads

example load  too long  for enurnace  intervall.jpg 


Development Team Member
Posts: 5
Thank you Juerg,

as usual a lot of information for me to review and understand!


Development Team Member
Posts: 1,501
you are welcome  and smile you are not  alone  we all need that all the  time.  
By  the  way  you are  already far  ahead  with  your  thinking process and welcome in the crazy  kitchen of  unconventional thoughts  and  menus.  Great  to have  you on the forum and thanks  for the  time  you offer here with your feedbacks. Very much appreciated.  
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