Why Nitrox?

[MaxBottomtime]

As to the op's substantive question, however, the fact is nitrox even at shallow depths where ndl's aren't at issue ( say 10 feet or less) it is refreshing and invigorating, at least to me. The advantage is that a runner would have breathing enriched oxygen gas.

Skeptical Scalpel: Why supplemental oxygen is not considered a performance-enhancing drug




You often see a football player on the sidelines breathing oxygen after running a long distance or having worked hard during a long series of plays.


Have you ever wondered if it works? Does breathing a high concentration of oxygen help an athlete recover from exertion faster?


The answer is a resounding “No,” and here’s why.


In healthy people, such as college and professional football players, nearly all of the oxygen in the blood is carried by hemoglobin. Only a very small percentage is dissolved in blood. Saturation defines the oxygen that is attached to hemoglobin and partial pressure of oxygen is that which is dissolved in blood.


Definitions: SaO2 = arterial oxygen saturation, Hb = hemoglobin, 1.34 mL is the amount of oxygen a fully saturated gram of hemoglobin can carry, Pa02 = partial pressure of oxygen or the amount of oxygen dissolved in blood


If an athlete has a normal Hb level of 15 gm, a SaO2 of 100% and a PaO2 of 100 mmHg, the formula used to calculate his blood oxygen content is


[Hb X 1.34 X (SaO2/100)] + 0.003 X PaO2 or
[15 X 1.34 X 100/100] + 0.003 X 100
20.1 + 0.3 = 20.4 mL/100 mL of blood


So, only about 1.5% of the oxygen content of blood is dissolved.


If an athlete raises his PaO2 to 400 mmHg by breathing pure oxygen the calculation is


[Hb X 1.34 X (SaO2/100)] + 0.003 X PaO2 or
[15 X 1.34 X 100/100] + 0.003 X 400
20.1 + 1.2 = 21.3 mL/100 mL of blood


Even at a PaO2 of 400 mmHg, only 5.6% of the oxygen content of blood is dissolved. Note that hemoglobin cannot be more than 100% saturated with oxygen.


Very soon after the athlete stops breathing the pure oxygen, its minimal effect disappears. It’s simply not enough to affect recovery or performance.


Possibly because the basic science is well-understood, there have not been too many papers on this subject.


Here’s one from JAMA that looked at 12 soccer players given 100% oxygen or placebo after exertion. Then they had to exercise again. “The administration of enriched oxygen during the recovery period had no effect on plasma lactate levels [an objective measure of recovery] or on performance during the second period of exercise. The subjects were unable to identify which gas they received.”


A similar study of 13 athletes from Medicine & Science in Sports & Exerciseconcluded “These findings offer no support for the use of supplemental oxygen in athletic events requiring short intervals of submaximal or maximal exertion.”


Another from the European Journal of Applied Physiology found that giving athletes supplemental oxygen during the recovery periods of interval-based exercise improves the recovery time of SpO2 [equivalent to SaO2] but did not improve post-exercise markers of reactive oxygen species or inflammatory responses because the improvement in saturation was clinically insignificant.


The situation is explained in simple terms in an excerpt from the book Exercise Physiology: Integrating Theory and Application. It concludes that supplemental oxygen may have a placebo effect, but there is “no real physiologic benefit.”


If you Google “supplemental oxygen and athletes,” you will find a number of websites touting the supposed benefits of inhaled oxygen. They are almost all supported by companies that sell oxygen.


Bottom line: Supplemental oxygen is not considered a performance-enhancing drug because it doesn’t work.

 

[tursiops]

Skeptical Scalpel: Why supplemental oxygen is not considered a performance-enhancing drug




You often see a football player on the sidelines breathing oxygen after running a long distance or having worked hard during a long series of plays.


Have you ever wondered if it works? Does breathing a high concentration of oxygen help an athlete recover from exertion faster?


The answer is a resounding “No,” and here’s why.


In healthy people, such as college and professional football players, nearly all of the oxygen in the blood is carried by hemoglobin. Only a very small percentage is dissolved in blood. Saturation defines the oxygen that is attached to hemoglobin and partial pressure of oxygen is that which is dissolved in blood.


Definitions: SaO2 = arterial oxygen saturation, Hb = hemoglobin, 1.34 mL is the amount of oxygen a fully saturated gram of hemoglobin can carry, Pa02 = partial pressure of oxygen or the amount of oxygen dissolved in blood


If an athlete has a normal Hb level of 15 gm, a SaO2 of 100% and a PaO2 of 100 mmHg, the formula used to calculate his blood oxygen content is


[Hb X 1.34 X (SaO2/100)] + 0.003 X PaO2 or
[15 X 1.34 X 100/100] + 0.003 X 100
20.1 + 0.3 = 20.4 mL/100 mL of blood


So, only about 1.5% of the oxygen content of blood is dissolved.


If an athlete raises his PaO2 to 400 mmHg by breathing pure oxygen the calculation is


[Hb X 1.34 X (SaO2/100)] + 0.003 X PaO2 or
[15 X 1.34 X 100/100] + 0.003 X 400
20.1 + 1.2 = 21.3 mL/100 mL of blood


Even at a PaO2 of 400 mmHg, only 5.6% of the oxygen content of blood is dissolved. Note that hemoglobin cannot be more than 100% saturated with oxygen.


Very soon after the athlete stops breathing the pure oxygen, its minimal effect disappears. It’s simply not enough to affect recovery or performance.


Possibly because the basic science is well-understood, there have not been too many papers on this subject.


Here’s one from JAMA that looked at 12 soccer players given 100% oxygen or placebo after exertion. Then they had to exercise again. “The administration of enriched oxygen during the recovery period had no effect on plasma lactate levels [an objective measure of recovery] or on performance during the second period of exercise. The subjects were unable to identify which gas they received.”


A similar study of 13 athletes from Medicine & Science in Sports & Exerciseconcluded “These findings offer no support for the use of supplemental oxygen in athletic events requiring short intervals of submaximal or maximal exertion.”


Another from the European Journal of Applied Physiology found that giving athletes supplemental oxygen during the recovery periods of interval-based exercise improves the recovery time of SpO2 [equivalent to SaO2] but did not improve post-exercise markers of reactive oxygen species or inflammatory responses because the improvement in saturation was clinically insignificant.


The situation is explained in simple terms in an excerpt from the book Exercise Physiology: Integrating Theory and Application. It concludes that supplemental oxygen may have a placebo effect, but there is “no real physiologic benefit.”


If you Google “supplemental oxygen and athletes,” you will find a number of websites touting the supposed benefits of inhaled oxygen. They are almost all supported by companies that sell oxygen.


Bottom line: Supplemental oxygen is not considered a performance-enhancing drug because it doesn’t work.

Nice article, but it is not about O2 under pressure.....the whole saturation thing changes then. Doing studies at sea level when you are talking about blood saturation and relevance to diving misses the point.

But my suspicion is that the primary reason so many folks say they get less tired using Nitrox is NOT because of the increased PPO2, but rather because of the decreased PPN2.

 

[Max Speed]

A Nitrox sticker on a tank only means that the tank has been O2 cleaned and the tank valve has been installed with an O2 compliant O ring and with O2 compatible grease. Thats all that it means. I can then use any variation of O2 levels in this tank safely without the fear of combustion due to the chemicals or parts used on this tank.

I have 6 tanks with nitrox stickers and none of them have ever been oxygen clean. A dive shop in Florida insisted on applying the stickers after filling with banked 30%.

Prior to that shop the same tanks had a long history of banked nitrox fills with no stickers. Just duct tape with the percentage.

Sent from my SPH-L710 using Tapatalk

 

[Instructor_Tom]

Max;

With your now "Nitrox" mark tanks not being O2 cleaned, if a shop like mine was to do partial pressure mixing there could be some serious issues. Most shops in cave country bank 30%-32% to ensure that there are no mistakes in fills ( liability issue) and to protect their employees from the possible explosive effects of a none properly cleaned tank.

All my tanks are O2 clean and honestly wont dive a tank that is not; Nitrox fill or not.

T.


Sent from my iPad using Tapatalk HD

 

[boat sju]

A nitrox sticker is not the same as an O2 clean sticker. What's the debate?

 

[Mr Carcharodon]

Nice article, but it is not about O2 under pressure.....the whole saturation thing changes then.
.

Hemoglobin is already nearly 100% saturated breathing air at 1 atmosphere in healthy individuals. Higher pressure will not take you over 100% since what is limiting oxygen transport is the quantity of hemoglobin and not the quantity of oxygen. There is a small amount of additional dissolved oxygen at higher pressure but just a few percent of the total. Slowing down and reducing the quantity of carbon dioxide present would likely do more to increase blood saturation levels than breathing nitrox. You might feel better due to the placebo effect but your body is not getting much more oxygen.

For the OP nitrox at a few feet is pretty silly since there is no, no decompression time limit.

 

[tursiops]

I'm curious all these statements about "healthy" individuals and then seeming to equate that to college or professional football players.

For those of us who are older or not as healthy as a professional football player, or just normal, is our hemoglobin also 100% saturated, or is that only true for the well-trained athletes?

 

[pdhenry]

deleted

 

[MaxBottomtime]

It is generally between 92-99%. If the level falls below 90% hypoxemia may result. Breathing nitrox under water gives two results; longer NDLs and/or shorter required surface intervals. Many people have beliefs that are not based in fact. Belief that something will make you feel better despite a lack of physical evidence is not just for the religious.

 

[tursiops]

It is generally between 92-99%. If the level falls below 90% hypoxemia may result. Breathing nitrox under water gives two results; longer NDLs and/or shorter required surface intervals. Many people have beliefs that are not based in fact. Belief that something will make you feel better despite a lack of physical evidence is not just for the religious.

You are missing the point. I agree, there have been no scientific studies on whether you feel better diving nitrox. But there are plenty of people who DO feel better, and the evidence is pretty compelling when they were never told about anything other than the standard longer NDL stuff. This is, in fact, physical evidence. What you should be arguing is that there are no studies....instead you are arguing that because there are no studies it is not true.