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Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
I got  some great feedback  on this   topic  on strength.
  No    we are not the first believing that NIRS MOXY is the tool of the future   to quantify  strength  workouts  at all here one  example :

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Sports Med. 2007;37(7):615-24.

A brief review of the use of near infrared spectroscopy with particular interest in resistance exercise.

Author information

  • 1Departmento de Educação Física, Universidade Gama Filho, Rio de Janeiro, Brazil.


There is growing interest in resistance training, but many aspects related to this type of exercise are still not fully understood. Performance varies substantially depending on how resistance training variables are manipulated. Fatigue is a complex phenomenon usually attributed to central (neuronal) and/or peripheral (muscular) origin. Cerebral oxygenation may be associated with the decision to stop exercise, and muscle oxygenation may be related to resistance training responses. Near infrared spectroscopy (NIRS) is a non-invasive optical technique used to monitor cerebral and muscle oxygenation levels. The purpose of this review is to briefly describe the NIRS technique, validation and reliability, and its application in resistance exercise. NIRS-measured oxygenation in cerebral tissue has been validated against magnetic resonance imaging during motor tasks. In muscle tissue, NIRS-measured oxygenation was shown to be highly related to venous oxygen saturation and muscle oxidative rate was closely related to phosphocreatine resynthesis, measured by (31)P-magnetic resonance spectroscopy after exercise. The test-retest reliability of cerebral and muscle NIRS measurements have been established under a variety of experimental conditions, including static and dynamic exercise. Although NIRS has been used extensively to evaluate muscle oxygenation levels during aerobic exercise, only four studies have used this technique to examine these changes during typical resistance training exercises. Muscle oxygenation was influenced by different resistance exercise protocols depending on the load or duration of exercise, the number of sets and the muscle being monitored. NIRS is a promising, non-invasive technique that can be used to evaluate cerebral and muscle oxygenation levels simultaneously during exercise, thereby improving our understanding of the mechanisms influencing performance and fatigue.

   But as  practical users,  we  look at it  ,as you can see fundemantally diffwerent.
 All current studies on strenght in combination with  NIRS  are looking just  at the oxygenation  information. As you can see in the summary  above.

Muscle oxygenation was influenced by different resistance exercise protocols depending on the load or duration of exercise, the number of sets and the muscle being monitored.

 This is absolutely  true . What is missing is the  information why the SmO2   reacted  as it reacted.
  The reaosn why it is missing is the  problem, that we look at SmO2  or O2Hb  or HHb    just  form the utilization point of  view.
 So justy because SmO2  drops  does not help us to understand  really for sure why.
 Is it really , that we use  more than we  deliver . Yes   possibly, but it as well can be a  shift in the O2  disscurve  due to respiratory trends  but even more important  it can be  due to  very different delivery  situations.
 1. We may deliver  perfect  but it drops :   Stable tHb  but more   O2 used  than can be delivered  but no problem  with blood flow eric  smo2  prof.jpg 

or  we  may have a  delivery problem  so  SmO2  is stable     and tHb  drops
mark workout thb smo2.jpg 
Or  we may have both  more O2  use  and  as well drop in delivery  of the blood. volume
smo2  tHb.jpg 

  When looking at SmO2  ( O2Hb  or HHb trend  alone  we miss some  crucial  questions. Is it a sufficient blood  delivery buy utilization outstrips delivery  or is it in a  extreme situation. ( not  that extreme in strength training )  a  simple  delivery   limitation due to  occlusion  and as  such SmO2  drops  as there is no   additional delivery  for the  region.
  so it is  NOT  an underdelivery  of available O 2 but  simply no delivery  due  to occlusion.
 This  has some fundamental different reactions , as  in one  case  the delivery system  may be limiting,   in the other case the storage ability may be limiting the duration of the performance.

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