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Juerg Feldmann

Fortiori Design LLC
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Posts: 1,530
 #1 
As  usual and  I think it is fair enough   I get some critical  mails.
  When ever  we  bring some ideas on here  on what we  can do  with  NIRS / MOXY  I  will have a  set of critical  mails coming in.
 This time there where many on the " disbelieve" that a  small equipment like  MOXY  may actually gives us feedback on blood  flow  or blood volume trends.
.
  First  to  give you some ideas.
 the tHb   is NOT  a  quantitative information  they way we use it. There  are some    possibilities  to try to quantify this in the lab  with specific occlusion methods.
 What we  look for is  for  a  very  simple live information on  actual trend in the  blood flow  ( blood volume change ) in the tested  are.. As  more moxy's  we    apply  as more  info w e  can get  from the overall information.
 So we test often  with 4 MOXYs  on, which is   easy now  for a  small lab  as the cost is still  much lower  than  any of  the other  NIRS  equipment. The  expensive one have some additional clear advantages  and are  all   incredible great , but for coaches  personal trainers  and    small centers  the MOXY brings  some clear  benefits  on   how to use  it in the center  and than  how the client can use it in the field  easy.
  So back  to the question, whether we  are the only once  who see   NIRS  as a tool on  blood flow trends.
  For sure not. There  are many many great studies  and groups out there picking up  NIRS  for many  different ideas  and we just start to  scratch the surface  on this. Here a   study  to share  form Speed skating.

Evidence for restricted muscle blood flow during speed skating.

Foster C, Rundell KW, Snyder AC, Stray-Gundersen J, Kemkers G, Thometz N, Broker J, Knapp E.

Source

University of Wisconsin-LaCrosse, 54601, USA. foster@mail.uwlax.edu

Abstract

INTRODUCTION:

We have previously hypothesized restricted muscle blood flow during speed skating, secondary to the high intramuscular forces intrinsic to the unique posture assumed by speed skaters and to the prolonged duty cycle of the skating stroke.

METHODS:

To test this hypothesis, we studied speed skaters (N = 10) during submaximal and maximal cycling and in-line skating, in both low (knee angle = 107 degrees) and high (knee angle = 112 degrees) skating positions (CE vs SkL vs SkH). Supportive experiments evaluated muscle desaturation and lactate accumulation during on-ice speed skating and muscle desaturation during static exercise at different joint positions.

RESULTS:

Consistent with the hypothesis were reductions during skating in VO2peak (4.28 vs 3.83 vs 4.26 L x min(-1)), the VO2 at 4 mmol x L(-1) blood lactate (3.38 vs 1.93 vs 3.31 L x min(-1)), and cardiac output during maximal exercise (33.2 vs 25.3 vs 25.6 L x min(-1)). The reduction in maximal cardiac output was not attributable to differences in HRmax (197 vs 192 vs 193 b x min(-1)) but to a reduction in SVmax (172 vs 135 vs 134 mL x beat(-1)). The reduction in SV appeared to be related to an increased calculated systemic vascular resistance (354 vs 483 vs 453 dynes x s(-1) x cm(-1)). During maximal skating there was also a greater % O2 desaturation of the vastus lateralis based on near infrared spectrophotometry (50.3 vs 74.9 vs 60.4% of maximal desaturation during cuff ischemia). The results were supported by greater desaturation with smaller knee angles during static exercise and by greater desaturation and accelerated blood lactate accumulation during on-ice speed skating in the low vs high position. The results of this study support the hypothesis that physiological responses during speed skating are dominated by restriction of blood flow, attributable either to high intramuscular forces, the long duty cycle of the skating stroke, or both.

PMID:

10527316

[PubMed - indexed for MEDLINE]

 

Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #2 
Some regular readers on here may recall that we discussed NIRS  when we started out  with Portamon many many years back.
 The beauty  today is, that many accepted   institutions   come  forward  with  ideas. > True they never would  peak into a forum like this , so  do not worry about the title  and the year  of publication. For us   much more of importance is the fact, that  some crazy ideas  get some  nice  accepted  back ups  now.
 In ()  some  loud thinking  and  add on thoughts
 

A new method to measure local oxygen consumption in human skeletal muscle during dynamic exercise using near-infrared spectroscopy

Tiziano Binzoni1,2, Chris E Cooper3, Anna L Wittekind3, Ralph Beneke3, Clare E Elwell4, Dimitri Van De Ville2,5 and Terence S Leung4

Show affiliations

Tiziano Binzoni et al 2010 Physiol. Meas. 31 1257. doi:10.1088/0967-3334/31/9/014
Received 9 February 2010, accepted for publication 9 July 2010. Published 11 August 2010.
2010 Institute of Physics and Engineering in Medicine

Abstract

Near infrared spectroscopy (NIRS) can readily report on changes in blood volume(  tHb as a part of the delivery trend ) and oxygenation. (SmO2  as a part of the utilization trend)However, it has proved more problematic to measure real-time changes in blood flow and oxygen consumption. Here we report the development of a novel method using NIRS to measure local oxygen consumption in human muscle.
( Perhaps  our idea of a TIP   we  propose  since a  few years may  be possible ???)The method utilizes the blood volume changes induced by the muscle pump during rhythmically contracting exercising skeletal muscle. We found that the saturation of the blood during the contraction phase was lower than that during the relaxation phase. ( )The calculated oxygen drop was then divided by the contraction time to generate a value for the muscle oxygen consumption in the optical region of interest. As a test we measured the muscle oxygen consumption in the human vastus lateralis during exercise on a cycle ergometer by 11 trained male athletes (32 ± 11 years old) at 40% and 110% peak aerobic power. We saw an increase from 13.78 µmol 100 g−1 min−1 to 19.72 µmol 100 g−1 min−1 with the increase in power. The measurements are theoretically exempt from usual NIRS confounders such as myoglobin and adipose tissue and could provide a useful tool for studying human physiology.


May be  a nice tool for a test centers  ,coaches  and  personal trainers  as well as  for  athletes  working on their individual abilities  may be a MOXY. ?

Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #3 
Looking at the first  world cup race of the year in Australia    in rowing  you may had the same questions.
 1. Start.   2 - 3min in  very    interesting position to wait for the go.  It is  completely;. different  ( and really not needed in that stage)  than  when they actually go  through finish line. non of the rowers  would go even close to the start position : Why.
   The  Chinese  LW  M    showed  something  I think we  showed in one of our  rowing  TIP.  It   looked  relay  that he  had a  comp let occlusion    and  that means a severe f drop in WSmO2  and a  certain risk of   limitation  levels in ATP, which must  be very very pain full and he looked like that in his legs.
  Another interesting point  is, when you where comparing the Greek   double  and the rest. A very very different technique  on the catch  than the release  but therefor a very different    motion  at the release  and   a very different technique in  respiration.
. Here a n interesting situation in rowing 

Are the arms and legs in competition for cardiac output?

Secher NH, Volianitis S.

Source

The Copenhagen Muscle Research Center, Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark.

Abstract

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles.

PMID:

17019302 
Rowing is one of the most interesting post racing carrier  sports  when looking  at  problems   from the cardiac system. The %  of  world class rowers  showing very early  AF is  incredible high compared not just to the general population but   compared to  any other high performance sport.

Nkrause

Development Team Member
Registered:
Posts: 49
 #4 
Hi Juerg,

I just wanted to add a couple comments to your last post about rowing. Firstly, FISA is introducing mandatory heart screening for elite rowers who are competing internationally. I wonder how many athletes will be disqualified from competition when they could be allowed to compete if they were to modify their training using many of the ideas discussed here. Not only that, they'd probably be faster if they did!

Secondly with regards to your comments on technique and its effect on breathing and blood flow, I wanted to complicate the discussion a bit. Over the last few years with coaching I've paid a lot of attention to how people move their body as they come in to place the oar in the water at the top of the rowing stroke. While certainly flexibility is important and can be modified through training one of the things I've noticed is how different combinations of leg length ratios affect their position at the catch when the rower places their oar in the water. If we force a rower in to a position that is difficult for them to get to because of their body type I'm curious to see what the impact would be on blood flow. This has a ton of implications for things like the rigging in the boat as it might be possible to mitigate some of these effects with a non-standard setup! Very curious to see how this works when we finally get on to the water after this long winter.

Finally if I could ask for a bit of clarification on your first point. Are you saying that the long wait after their warmup in the starting gates, combined with their position in the boat while waiting would restrict their bloodflow? Just want to make sure I'm reading it right, its a little bit unclear to me.  
Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #5 
Sorry I am behind here   on this   information.
Look at the  start position. True  no choice  when the count  down starts  but the 2  - 3 minutes  they have to wait sometimes  there  may  be a much better way  to  sit there and wit.
  Attach your  moxy on  quadriceps  and  hamstrings  and  try out  the different positions  and see  what happens.

rowing start.jpg

Than look at the finish   check leg positions, why are they so very different  at the end  compared to  the start preparation.  Key  word  tHb
rowing end.jpg

One of the key elements  in sports  like rowing  . cross country skiing but as well  ice hockey is the limitation of the cardiac out put   to deliver  the possible  ability  of the   huge  amount  of activated muscles  to use  O2   for ATP production.
 Marshall in 1967  called it the sleeping giant, arguing , that the  CG  has to  do some  controlled  vasoconstriction to maintain BP  for  survival  and as  such has  to  redirect  O2  , blood    and so on  to vital systems . In case of  rowing and  cross country skiing  a    great trained athlete  will create the risk of  "steeling "  O2     to be used in the working muscles     but creates a  survival problem  with BP  regulation but as well pO2     limitation for vital systems.
 As  such  there is  an ongoing competition   for  the O2    as well.
 The key is  to address the   direction the body may redirect  O2  and  blood volume  as  such    by assessing  upper an lower body   at the same time in this sports. VO2 max  just does not do it at all  as it is the   summary of O2  use  from all   systems  and as  such gives us    no information on the reaction between upper body lower body  and vital  systems.
  Here  2 nice  information backing up our idea of  looking at  both body parts including involved  and not involved muscles.

Are the arms and legs in competition for cardiac output?

Secher NH1, Volianitis S.

Author information

  • 1The Copenhagen Muscle Research Center, Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark.

Abstract

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles.

 

Muscle metaboreflex control of the circulation during exercise.

Boushel R.

Author information

  • Centre for Healthy Aging and The Copenhagen Muscle Research Centre, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. boushel@sund.ku.dk

Abstract

This review covers the control of blood pressure, cardiac output and muscle blood flow by the muscle metaboreflex which involves chemically sensitive nerves located in muscle parenchyma activated by metabolites accumulating in the muscle during contraction. The efferent response to metaboreflex activation is an increase in sympathetic nerve activity that constricts the systemic vasculature and also evokes parallel inotropic and chronotropic effects on the heart to increase cardiac output. The metaboreflex elicits a significant blood pressure elevating response during exercise and functions to redistribute blood flow and blood volume. Regional specificity in the efferent response to the metaboreflex activated from either the leg or the arm is seen in the balance between signals for vasoconstriction to curtail blood flow and signals to increase cardiac output. The metaboreflex has dual functions. It can both elevate and decrease muscle blood flow depending on (1) the intensity and mode of contraction, (2) the limb in which the reflex is evoked, (3) the strength of the signal defined by the muscle mass, (4) the extent to which blood flow is redistributed from inactive vascular beds to increase central blood volume and (5) the extent to which cardiac output can be increased


As  such  you may start to see  why we  can add some  additional nice information to our  workouts  but as well to our assessment by using MOXY   on different body parts including non involved  muscels  to   get a feeling on the intensity of the    load  besides the   physical numbers like  watt / speed  or  weights. There  is  in some cases  and interesting " drift "  time  lag  whne looking at involeved  and noninvolved msuxcels.
 Here   one of  an ongoing case study to see, whether we  can  over time quantify the  reactions  and see changes  due to training.
 The blue trace is SmO2  reaction in a main involved muscle. The red one is  a non involved muscle SmO2  reaction  during a heavy  load   followed  with some interruptions  to see the  lag time  . The  idea  is to see  how direct  compression   immediatly influence   MOXY values but how reflex  reactions may  lag somewhat behind.

2 drift.jpg 
  Example as well in  respiratory  weakness, where we  collect CO2  which is a  potent  vasodilatator  but as well  with increas in load will create a  vasocompression  mechanically. So the release of  a compression  due to muscle tension  together with the still ( time lag )  existing potent  vasodilatation will show a very specific   tHb reaction in the 5/1/5    assessment.
 See  again  a  few  examples  . There is a clear difference between a  vasodilatation     reaction in  rest  and a   occlusion reaction.

bike row  tip.jpg 

 


Juerg Feldmann

Fortiori Design LLC
Registered:
Posts: 1,530
 #6 
We  discussed  start position in rowing  to be used to  observe  potential better  way on keeping optimal blood flow.
 THb  is a great indirect  information on the  changes in delivery.
 THb  can change  fast ( immediately )  as a sign of  some mechanical influences like pressure  from out  side, gravity change  or  compression  from  active muscles,  as well as  decompression.
. THb  can as well change  slow  with a time lag  due to  central  reactions  and adjustment  like vasodilatation  and or  vasoconstriction due to  reflex  mechanism.
 ( metaboreflex and more ) This  central adjustment to maintain  Blood pressure  for example  or to  protect vital organs  from  further  drop in O2  delivery  have a  lag time  and   we often will see additional information at that  same moment.
 So when using MOXY  for  positioning  and for equipment adjustment like bike fitting, THb  could be a very nice additional physiological feedback  to find a compromise between  aerodynamic  and  efficient physiological  options (  ( respiration,  Joint  angle  and  compression due to joint angle change or  muscle  length limitation.
 Here a  nice study showing change in  Blood volume  and you will understand  what I mean on what we discuss  above.

Changes in blood volume and oxygenation level in a working muscle during a crank cycle.

Takaishi T1Sugiura TKatayama KSato YShima NYamamoto TMoritani T.

Author information

·         1Institute of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan. takaishi@nsc.nagoya-cu.ac.jp

Abstract

PURPOSE:

This study examined circulatory and metabolic changes in a working muscle during a crank cycle in a pedaling exercise with near-infrared spectroscopy (NIRS).

METHODS:

NIRS measurements sampled under stable metabolic and cadence conditions during incremental pedaling exercise were reordered according to the crank angles whose signals were obtained in eight male subjects.

RESULTS:

The reordered changes in muscle blood volume during a crank cycle demonstrated a pattern change that corresponded to changes in pedal force and electrical muscle activity for pedal thrust. The top and bottom peaks for muscle blood volume change at work intensities of 180 W and 220 W always preceded (88 +/- 32 and 92 +/- 23 ms, respectively) those for muscle oxygenation changes. Significant differences in the level of NIRS parameters (muscle blood volume and oxygenation level) among work intensities were noted with a common shape in curve changes related to pedal force. In addition, a temporary increase in muscle blood volume following a pedal thrust was detected at work intensities higher than moderate. This temporary increase in muscle blood volume might reflect muscle blood flow restriction caused by pedal thrusts.

CONCLUSION:

The results suggest that circulatory and metabolic conditions of a working muscle can be easily affected during pedaling exercise by work intensity. The present method, reordering of NIRS parameters against crank angle, serves as a useful measure in providing additional findings of circulatory dynamics and metabolic changes in a working muscle during pedaling exercise.

PMID:

 

11880818

 

[PubMed - indexed for MEDLINE]

 

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