Nitrox vs Air

[PfcAJ]

Something isn't automatically a placebo until proven otherwise, either.

There is anecdotal evidence, sure. It might not be the result of a controlled study, but its the best we've gotat the moment. The lack of a controlled study does not negate something.

 

[scubajo007]

Same as CamG, I also feel less fatigue after multiple dives when I use EANx, just go for the course I don’t think you will regret it.

 

[Thalassamania]

Using nitrox to limit your nitrogen uptake whilst staying within air tables requires no more reference that the laws of physics.

 

[Jax]

If you read Mark Powell's "Deco for Divers", he explains that some doctors believe that the fatigue that some divers feel after diving is / are the intial symptoms of DCS. Some people are simply more susceptable to the affects of nitrogen loading. Those are the people that have the anecdotes of 'less fatigue when diving Nitrox'.

Just because the study hasn't been done scientifically doesn't mean the theory is wrong; it simply means it is supported by only anecdotal evidence. Then again, the deep (Pyle) stops were supported by anecdotal evidence for years until a scientific study on the bubble formations proved their worth.

 

[SkimFisher]

rabble rabble rabbly

 

[DandyDon]

If you read Mark Powell's "Deco for Divers", he explains that some doctors believe that the fatigue that some divers feel after diving is / are the intial symptoms of DCS. Some people are simply more susceptable to the affects of nitrogen loading. Those are the people that have the anecdotes of 'less fatigue when diving Nitrox'.

Just because the study hasn't been done scientifically doesn't mean the theory is wrong; it simply means it is supported by only anecdotal evidence. Then again, the deep (Pyle) stops were supported by anecdotal evidence for years until a scientific study on the bubble formations proved their worth.

First post I've ever seen that offers logic for the theory. Thanks!

Actually, I thot of that long ago; just doesn't work on me - so I wasn't going to suggest it. Good that a published author has.

 

[DaleC]

I've brought this up in nearly every Nitrox/placebo thread I've participated in. Of course, I'm not a "published author" so that's probably why it went unnoticed.

Some examples of how studying the causal factors can help shape the study comes from my reading of the use of EAN by athletes. In other discussions people focus on the fact that, at a certain point O2 uptake peaks so that higher O2 levels appear superfluous, but I noticed that higher O2 levels (breathed) reduced the work load on the respiratory muscles. My thoughts at the time were that the brain may interpret lower respiratory WOB as less fatigue. I don't know.

How do higher O2 levels breathed effect the metabolization of lactic acid in the major muscle groups? What is the threshold of exertion for these effects to be measureable? If one walks slowly around the track with/without EAN there may not be a noticable buildup of L.A. but if one sprints there may be. Will EAN effect the levels? What is the difference between sprinting once and sprinting repetitively (as in multi dive/day diving)? I don't know.

What is the threshold for subclinical DCS to manifest and how many divers could be experiencing it as fatiguelike symptoms? Would EAN act to reduce SCDCS and thus fatigue? Does SCDCS manifest itself more so the longer one is diving and could this be why some divers experience less fatigue on multi dive/day dives? I don't know.

So far, most people just point to one limited experiment and conclude proof positive that EAN produces nothing more than a placebo effect. I am not so easily convinced either way but I do see room for more study.

If you are looking for diver related studies of EAN use to reduce fatigue you will be short changed but that doesn't mean the phenomenon has not been studied in other realms. Here's a study to ponder:

ScienceDirect - Applied Ergonomics : Effects of oxygen concentrations on driver fatigue during simulated driving

From the abstract:

Driver fatigue has been the cause of traffic accidents. Despite this, the amount of time that drivers spend within cars has been increasing due to complex city life, traffic congestion, and particular occupational requirements. Consequently, fatigue and stress cannot be avoided. In present study, in order to find out the possibility for reducing fatigue while driving due to the supply of oxygen, driver fatigue resulting from the passage of time when different oxygen concentrations are supplied has been examined through subjective evaluations and reaction times using driving simulator for 10 male subjects. The results revealed the subjective fatigue feeling was highest in the low rate (18%) oxygen condition, while in the high rate (30%), it decreased to a certain extent. The feeling of sleepiness also showed the tendency to decrease somewhat in the case of the driving time having passed over 1 h in the high-rate conditions. Also, the reaction time for braking after being instructed to suddenly stop following more than 2 h of driving was reduced in the high-rate oxygen conditions compared to the low-rate oxygen condition. From the above results, it was shown that while driving a car, if the oxygen rate is lowered, fatigue is felt severely, and that in the case of supplying a high-rate of oxygen, the feeling of fatigue is lowered to some extent and the reaction time is shortened. It was suggested that the driver's fatigue can be reduced according to the supply of oxygen.

Here's another one: SpringerLink - Journal Article

From the Summary:

Summary We examined the effect of O2-enriched air upon performance capacity and some physiological and psychological variables. Eight firemen were studied during seven bouts of 2 min treadmill-running while breathing air with 21 or 40% oxygen. The duration of the resting periods between the working bouts was chosed by the subjects themselves, with the instructions to rest as short as possible. Total resting time decreased by 29% and total amount of air used by 6%, under the 40% oxygen condition. There were no differences in 1) minute ventilation during working periods (when the subjects breathed 40% oxygen respiratory rate decreased whereas tidalvolume increased), 2) heart rate reached during working periods, 3) subjective feelings of fatigue as indicated by the subjects at the end of every working period.
Advantages of the use of O2-enriched air by firemen are discussed and it is concluded that breathing air with 40% oxygen does not mean an extra physiological or psychological load for the organism. Finally, possible factors that made a subject decide to start again are discussed and the importance of the respiratory rate in this decision is indicated.



While it indicates no difference in fatigue "feelings" this may have been mitigated by the fact that the subjects were allowed to choose their own rest period durations. Fatigue may have been indicated if they all had to adhere to the same rest cycle.
I am very interested in the importance of the respiratory rate in the decision making process to resume exercise as I have a pet theory that respiratory rates may trigger the perception of fatigue but I am too cheap to pay for the full study.

 

[DandyDon]

I've brought this up in nearly every Nitrox/placebo thread I've participated in. Of course, I'm not a "published author" so that's probably why it went unnoticed.

Or maybe I just missed it.

I realize that excess N2 loading in the body is not natural so it has to have some affect on a body, some more than others. I suspect the energized feeling is exaggerated, but difficult to measure.

I wonder if it could be as simple as the more Nitrogen in the blood stream, the less room for Oxygen to an extent...?

 

[Jax]

Or maybe I just missed it.

I realize that excess N2 loading in the body is not natural so it has to have some affect on a body, some more than others. I suspect the energized feeling is exaggerated, but difficult to measure.

I wonder if it could be as simple as the more Nitrogen in the blood stream, the less room for Oxygen to an extent...?

Don, the two gases do not displace each other. O2 binds to the hemoglobin and is metabolized, and Nitrogen simple dissolves into the tissue and just as easily comes out of solution.

 

[Notso_Ken]

I plan on getting my Nitrox certification.. was wondering what the main differences were between Nitrox (mixes) and a regular tank of Air.

What will it let me do that air lack? etc etc

I think the first input is actually a question - WHY are you getting your nitrox cert?

The question you ask tells me you don't know why, therrefore I have to wonder why you are wanting it?


Ken