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juergfeldmann

Development Team Member
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Posts: 1,501
 #1 
Here a nice  study  sent to me  by Ruud.
 It is  great to see, that the " crazy " concepts  we  have  developed  over the  last  15 years ( thanks  to many out of the box thinking researcher  thanks  to all of  them )  is getting  more  support  and  some confirmation.
 As  so many time  mentioned. it is all about  closing the gap  between  science  and  practical application.
 As  Andri often points out . there  has to be a compromise  between making it simple  and understandable  and not   making it  wrong. Here the summary of the   paper.


 If  you read carefully  you will see   Ideas like VO2  max  and lactate thresholds  are gone. It is all about the different physiological system which interact  and as we so often  try to  explain. the VT2  in the  paper is really the place  , where  we  e hit the  limiters ability  and start to compensate  with  who ever is able to  try to  help to survive. So   who is the limiter.
 Cardiac (,  respiratory,  muscular  or  CG). Watch  what they  used.
 May  give a  feedback on  the way  we started out. Cardiac hemodynamic  with Physio  flow. muscle recruitment  with SEMG  ( BTS)
VO2  and respiratory feedback ( Cosmed)
Muscle oxygenation ( Portamon /Artinis  and MOXY / Fortiori )
Respiratory  quality   with BIO harness old version.
 Blood  values  with  I stat  and  lactate Pro.

Thresholds in ventilation, cerebral and muscle oxygenation, and muscle activity during incremental cycling exercise

David Nichols1*,Sebastien Racinais1, Martin Buchheit2, Olivier Girard3

Abstract

Introduction: Cycle time-trial performance is a function of the highest sustainable power output. The first (VT-1) and

second (VT-2) ventilatory thresholds are practical tools for coaches and athletes to set training zones and exercise

intensity. Specifically, VT-2 is closely linked to critical power, a primary determinant of endurance performance. The

cascade of physiological events in the organs responsible for power production accompanying these respiratory

thresholds remains contentious and yet to be fully characterized. Electromyographic (EMG) thresholds have been

identified in leg muscles during incremental exercise while near infrared spectroscopy (NIRS) has revealed thresholds in

both muscle deoxygenation and cerebral oxygenation towards the end of an incremental exercise test. However, the

relative timing of the different muscle and brain oxygenation and muscle electrical activity responses to each other is

unclear.

 

Purpose: The aim of the present study was to examine the thresholds of cerebral and muscle oxygenation, along with muscle electrical activity during a ramp exercise test in relation to VT-1 and VT-2.

 

Methods: Twenty-five recreational cyclists (mean±SD: age 37±8yrs, body mass 78±13kg, height 178±8cm, VO2max

53±8mL/kg/min) completed a ramp exercise test to exhaustion on an electromagnetically braked cycle-ergometer with a work rate increment of 25 W/min. Throughout the test, continuous measures of expired gas (breath-by-breath), prefrontal cortex and vastus lateralis (VL) oxygenation via NIRS, and EMG Root Mean Square activity for the VL, rectus femoris (RF), and biceps femoris (BF) muscles were recorded. Thresholds were defined by a double-linear model.

 

Results: The results are summarized in Figure 1. VT-1 and VT-2 occurred at 57 ± 6% and 81 ± 6% of the exercise,

respectively. There was a threshold in both cerebral deoxyhaemoglobin and oxyhaemoglobin (56±13% and 56±8% of

exercise, respectively) which were not significantly different from VT-1 (P>0.86, cohens d<0.1). Cerebral

deoxyhaemoglobin further increased (87 ± 10% of exercise) while oxyhaemoglobin reached a plateau (86±8% of

exercise) both significantly after VT-2 (P<0.05, d>0.8). Only one threshold could be identified for muscle parameters with a threshold in muscle oxyhaemoglobin (78±9% of exercise), attenuation in muscle deoxyhaemoglobin (80±8% of

exercise), and increase in EMG activity of VL, RF and BF (89±5%, 82±14% and 85±9% of exercise, respectively). The thresholds in BF and VL EMG activity occurred after VT-2 (P<0.05, d>0.6).

 

Conclusion: The threshold in cerebral oxygenation parameters occurred at both VT-1 and VT-2. Conversely, the present investigation failed to support a role for VL muscle oxygenation and electrical activity at VT-1, but did display a threshold at or after VT-2. The changes in cerebral oxygenation and in BF and VL electrical activity occurred after VT-2, suggesting that the metabolic and ventilatory events characterizing this latter cardiorespiratory threshold may affect both cerebral and muscle oxygenation levels and subsequent muscle recruitment responses. These physiological mechanisms are important factors in describing key training concepts and performance capability; for instance critical power. Any marked rise in muscle recruitment above VT-2 or critical power will result in early onset of fatigue and limit exercise performance.

Jiri Dostal

Development Team Member
Registered:
Posts: 51
 #2 
" In 64% of the recordings, muscle O2Hb displayed a non-linear decrease".... This is exactly, what I got in our 400 people study. The linear decrease of SmO2 during a ramp test protocol was seen in 29% od cases. For those, who are interested deeper, I just recorded a webinar with Roger, and it is placed in a different section in the forum.

Just add Moxy to a super simple exercise ramp protocol if you have to run this study instead of new ones like 5-1-5 ( demand from regulatory, patient prescription, your boss is conservative etc), and you get a great feedback of oxygen limitation. Add another one on non involved and you get systemic reaction.
juergfeldmann

Development Team Member
Registered:
Posts: 1,501
 #3 
Jiri , as always  thanks so much  for this great feedback  and real  research.
 I like today  to show you  some  results   from a great cross country ski coach , who was kind  enough and open enough to allow me  to take some critical and   open  look and  make comments  on a very common used  test idea.
 The goal as usual is to look critical on what we do and how  can we improve  and enhance physiological feedback  when combining  classical ideas  with new  technology. So  as  Jiri  pointed out we will look  at a classical  VO2 max idea  used on a  ski  erg  and how  MOXY  can enhance feedback  and what we this by using  what we know   with  what we  could  add as well.
 So stay tuned as I will open  a new thread.
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