First of all thanks for visiting the forum.
Your questions are appreciated and I am not sure,whether I can give you answers , who may be helpful ,but I will try as good as possible and other readers may jump in a as well.
1. interest in power based training
If you are interested in power based training, than you will see, that we have a fundamentally different approach.
We use power as well, but not to quantify the training ( load and or recovery ) we use power to see, whether the physiological systems are not recovered as of yet or are or have improved so that by the same physiological load we see the same, higher or lower power output.
Depending what workout we did, we may have overloaded the muscular system as one goal and as such we will not see the same power out put the following day, if we use a % of for example FTP or other one point assessments.
We may in this example see, that by the same wattage the tHb may not increase as usual due to overload of the vascular system the day before.
This lower ability to move blood will contribute to a different delivery ability of Blood ( O2 ) and therefor by the same wattage we may have to find a different metabolic way to move.
The lower O2 delivery due to less blood flow will create the need to for example produce the needed ATP by different metabolic options, which may change the way the body reacts.
The increase In more glycolytic energy production help or the increase In O2 independent energy production can for example increase the CO2 situation and as such the O2 dissociation curve will shift top the right and SmO2 trend may now by the same load drop instead of being perhaps in a balanced situation.
Many more reactions can occur as physiological reactions do not follow stable wattage rules or loads.
It is not the wattage who decides the physiological reaction it is the physiological reaction and ability who decide the wattage we can produce an the time we can maintain this wattage.
This is one fundamental difference.
Now to your point 1
- traditional laboratory based measurement methods.
I need some help here to try to give a better answer.
Here a try:
NIRS should not be compared with some of the traditional equipment's like VO2 and Lactate for example.
NIRS is a direct information form the working area and as such live information on what is going on.
VO2 and lactate are indirect methods where we hoped that the information may reflect the situation in the working muscle's but there is always a time lag.
NIRS is compared with invasive methods of blood assessment for O2 situations.As such it is direct but with the advantage , that it is non-invasive.
Detection of Hypoxia
at the Cellular Level
Laurie A. Loiacono, MD, FCCPa,b,c,*, David S. Shapiro, MDa,c
What is the Next Best Thing to Detection of Hypoxia at the Cellular Level?
Somewhere between direct detection of hypoxia at the cellular level (ie, bio markers,
enzyme assays, complex histopathologic analyses) and indices of global hypoperfusion
(ie, lactate, ScVO2, urine output) lies a potentially more practical and economical
method of tissue oxygenation assessment: near-infrared spectroscopy (NIRS).
NIRS is an evolving technology that uses near-infrared light to provide a continuous
assessment of regional, microvascular blood flow and is measured as the quantitative
clinical variable tissue-oxygen saturation (StO2). Biologic tissues are transparent to
light in the near-infrared spectrum, whereas oxyhemoglobin (HbO2) and deoxyhemoglobin
(Hb) have significantly different spectra56 (StO2 5 HbO2/[HbO21 Hb]). This technology
can be used invasively via transcranial or percutaneous catheters, or
noninvasively using cutaneously applied probes.
Hypoxia (n.): a deficiency in the bioavailability of oxygen to the tissues of the body
Now here a nice summary and the same is true to VO2 testing , when load durations are too short ( BELOW 5 - 8 MIN. AND EVEN THAN The RESPIRATION SITUATION Like LOCATION AND MORE ( IN CYCLING POSITION Change ON The HANDLE BAR) WILL Change The Readings ON The MOUTH , WHICH MAY NOT REFLECT THE REACTION IN The WORKING MUSCLE.
Thirdly, an alternate or a complementary explanation to the pattern of plasma ]La-] response to ramp exercise can be suggested. According to this explanation, lactate is produced in the working muscle: (1) as soon as the exercise begins, as suggested by Brooks (1985); or (2) following a delay, according to the theory of the anaerobic threshold (Davis 1985). Under both hypotheses the onset of lactate production within the working muscles occurs at comparatively low work rates. At that time: (1) the amounts of lactate produced and the gradient between muscle [La-] and plasma [La-], and the amount of lactate released from the muscle remains small; (2) cardiac output and muscle blood flow are also low and do not favour lactate release
from the working muscles and its distribution into S; and (3) the small amounts of lactate released are diluted within the comparatively large S, thus resulting in a very small increase (if any) in plasma [La-]. Therefore,
a delay could be expected between the beginning of lactate production within the working muscles and the parabolic rise in plasma [La-] in response to ramp exercise in a similar way that, in response to a short period of severe exercise, the peak value of plasma [La-] is only observed following a several-minute delay into the recovery period (see Hirvonen et al. 1987, 1992). Consequently, plasma [La-] concentration at a given t during a ramp exercise does not reflect lactate production in the muscle at that precise t and at the
exact corresponding work rate, but at a previous t minus ~ of unknown and probably variable length, and at the corresponding work rate. This phenomenon might have been overlooked in the development of the theory
of the anaerobic threshold which implicitly assumes that plasma [La-] at a given t reflects lactate production and thus the metabolic state of the muscles at that precise t, and at the exact corresponding work rate. This is very unlikely to be the case, particularly during the exercise protocols of short duration and with steep increase in work rate used for the detection of the anaerobic threshold (Anderson and Rhodes 1989). In this type of protocol, where VO2 significantly lags behind the value expected for the corresponding
work rate (Whippet al. 1981), it may be expected that plasma [La-] also tracks the metabolic state of the working muscles with a significant delay, particularly at the beginning of exercise for the reasons presentedabove."
Are the numbers pooping up from lactate analyzer true ?
If you compare an SRM, Polar wattage sensor, Cycle ops and so on, are they equal ?
We use the same wattage info for assessment and workouts, so we may have not the real true wattage perhaps, but as long we know we always have the same repeatable power output we do not worry too much. Same is true with NIRS.
NIRS is used sine a long time, but it was simply not easy to use for coaches and athletes due to price and equipment. Now it is affordable and simple to use and it is used in many different sports like ice hockey , soccer, skiing swimming cycling and so on for interval workouts to have individual length of load depending on goal as well as individual recovery time for ) refuel ling ) as well as individual repetition numbers.
It is used for strength workouts as well and for trend information in long distance events.
Google NIRS and you will find endless information on the validity of this technology or browse our forum.
Try to answer point 2
SmO2 is a trend information and in MOXY the % is an absolute number, which indicates the situation of O2 supply and demand.
An increase in SmO2 indicates that the % of Hb loaded with O2 is increasing . ( It really is an indication of O2 on Hb and Mb ) Many NIRS info are based on something called O2Hb and HHb. O2 Hb is the wording or name for Hb which is loaded, versus HHb which is the name for Hb which is not loaded with O2.
Now here it is where it is getting somewhat more complex.
We normally assume, that when SmO2 is increasing, that we deliver more O2 than we currently utilize and as such the O2 % will increase indicating a situation, where O2 delivery is above the O2 demand. So the needed ATP demand to support the actual wattage level is covered with O2 plus always some O2 independent energy metabolic activity which never is separated anyway.
So at the beginning of a step test we will see an initial drop of SmO2 followed by an increase in SmO2 reflecting the initial use of O2 from the storage are due to lag time of delivery systems like the cardiac output.
Than as soon cardiac output and respiration pick up we have an increase in delivery of O2 and this may be bigger than the current need of O2 and SmO2 will increase.There are other reactions responsible like the vascularsation reaction and vasodilatation effect of some hormones.
The above pic shows a test from a top athlete. Green is SmO2 trend indicating an initial drop explained above, an increase in SmO2 due to higher delivery than utilization, a relative balanced intensity due to balanced ability of delivery and utilization and at the end a drop in SmO2 as the delivery is less than the O2 demand so SmO2 will drop.
Brown is an indicator of blood flow at the same time, with an initial increase due to different reactions like CO up and vasodilatation followed by a balanced situatinn and a drop due to higher muscular tension in a higher load which overrules the CO and vasodilatation effect.
- sense but I'm not clear why SmO2 falls later in the tests when wattage and therefore oxygen demand is still rising
As you point out wattage is going up and as such the demand for energy and if possible energy delivered as O2. The problem is, that we may demand more O2 but we simply can't deliver.
So we will try to use O2 but if delivery is behind demand SmO2 will drop and there is a point, where the O2 demand is so high , that the body can't deliver and a hirarchy will kick in on who will have priority for the O2 which still can be delivered.
The brain ( CG willl decide, that certain systems like brain itself cardiac system and respiratory systems are more important than the legs for survival and we simply will reduce motorunit recruitment so we do not steel O2 from the vital organs and we will have to slow down or simply quit moving.
In cyclng terms the athlete will tell : I did not had the legs today " , which is absolutely true but the question is what system limited the O2 supply to the legs. ? Wattage will not give you any answer.
NIRS will. Here a very short insight view in how coaches use and understand MOXY for their workouts and assessments. This is a part of the ME seminar ( Moxy expert )
hope this helps a little bit to shine some lights in a future game changer in activity planning and practcial applications