Take the Nitrox Anti-Fatigue Challenge and post your results here

[JeffG]

I'd be willing to participate, but I hate the way I feel after I dive air . . .

Thats just guilt.

 

[Cave Diver]

Even if the other issues were resolved.....

There are no idential tanks. Tanks and their valves get dinged. Unless someone else has the tanks filled and checked, the diver will know which tank is air and which is nitrox invalidating your experiment.

Put a garbage bag, or some such over the entire tank, except for the top of the valve. Unless someone is determined to memorize or it has some outstanding characteristic, they're unlikely to identify it. Or use an analyzer that connects to a LPI hose and they don't have to see the valve at all, someone else can turn it on. It's not insurmountable, just depends the level of effort one wants to make in the name of "science."

 

[Bob DBF]

This thread is not about what you think you feel after diving Nitrox, it's about PROVING IT with a controlled scientific study. idocsteve

By what mechanism are you going to prove fatigue? If you ask how I feel (which you have) and I tell you (which I have) and this is not scientificly acceptable, how are my observations and feelings more accurate or valid if I don't know whats in the can, they are still only my feelings.

This morning I'm feeling fatigued and beat up; 2 beach or 3 boat dives, with or without Nitrox, I may even feel better at the end of the day 'cause I enjoy diving. Thats why I mentioned the difference on 3 day Lobster trips previously, which are a marathon for me.

Bob

 

[Walter]

Unless someone is determined to memorize or it has some outstanding characteristic, they're unlikely to identify it.

Actually, they will identify it subconsciously.

 

[Mike Boswell]

This is an interesting idea for an experiment, but I have a couple of questions:

First, couldn't this experiment be done under more controlled conditions (i.e. a chamber or a gym) and using more objective measurements (blood gases, strength, response time, etc.)?

Second, isn't it likely that individual responses will be highly variable? If your results confirm statistically that "people tend to feel better after diving Nitrox", won't that still only be true for certain people and NOT true for others? Will some of those people that "feel better" actually suffer from some sort of physical deficiency that is helped by a higher O2 level?

My father had emphysema and oxygen made him feel a lot better, but breathing pure oxygen makes me feel no different at all.

 

[idocsteve]

I don't get the difference. Proving a feeling is impossible.

At the risk of becoming repetitive, we are testing a subjective variable here, therefore the results DEPEND on subjective reports from the test takers.

If you "feel" less fatigued following a dive, and this feeling is consistent with the use of the specific gas being tested, and the results are repeatable under controlled conditions among a large enough sample size, then it might be stated that there is a definite correlation between less fatigue and the control, however if the subject "feels" less fatigued regardless of which gas mixture is breathed during the test then it might be stated that there is no benefit to Nitrox in regard to reduction of post dive fatigue.

How can factors such as hydration level during the dive, amount of sleep the night prior, which dive is done first (Nitrox or Air), what I had for breakfast, my overall mood prior to dives (excitement, nervousness, malaise), conditions during the dives, and they myriad other factors that contribute to my physiological condition before, during, and after the dive, be discarded in order to "simplify" the study.....and the test be expected to have any real scientific validity?

This has already been explained better than I can by another poster on this thread. Given a large enough sample size, the other factors, while not controlled, will ultimately "cancel out".

Here's an example. If I roll a coin a 1000 times, it's going to come up heads almost the same amount of times that it's going to come up tails regardless of how hot, how humid, or how wet the environment is in which I flip the coin. Those are uncontrolled variables but they will ultimately cancel out and will not affect the outcome of the test. Now, weight the coin in some way so it has more of a tendency to come up heads. Again, the environmental factors will ultimately cancel out and more heads will be tossed than tails.

Now substitute Nitrox and air for heads and tails and you've got an idea of what I'm trying to explain here, although the analogy is far from perfect.

Nonetheless, if there IS a significant difference between Nitrox and Air in regard to post dive fatigue it will eventually be demonstrated if enough people take the test.

There are 1000s of ScubaBoard members. I think we have a large enough sample size even if only a small percent decide to try the Nitrox Challenge.

 

[idocsteve]

First, couldn't this experiment be done under more controlled conditions (i.e. a chamber or a gym) and using more objective measurements (blood gases, strength, response time, etc.)?

That would be a true, very tightly controlled scientific experiment which is beyond the scope of this thread and very unlikely to be practical and expensive to administer. The Nitrox Challenge is a distant second to the experiment that you describe but at least it's practical and easy to administer.

Second, isn't it likely that individual responses will be highly variable? If your results confirm statistically that "people tend to feel better after diving Nitrox", won't that still only be true for certain people and NOT true for others? Will some of those people that "feel better" actually suffer from some sort of physical deficiency that is helped by a higher O2 level?

My father had emphysema and oxygen made him feel a lot better, but breathing pure oxygen makes me feel no different at all.

If some individuals respond favorably to Nitrox in regard to fatigue then there will be a demonstrable benefit following this experiment because some test subjects will consistently report less post dive fatigue following a Nitrox Dive.

 

[jbtut]

If we assume those who respond are following the procedure it is entirely plausible that we could find a statistically relevant difference in the after dive feelings of the divers. I would suggest that the study be done such that similar dives would be done for a week on gas A and a week on Gas B rather than two different tanks on the same day. That way the same dives could be done each week. Of course they would all have to be within the minimum limits of either gas.

Either way, this isn't published research. It's just a reasonable way to collect a little data and see if it supports a hypothesis.




My guess as to a scientific reason why air makes you more exhausted is the low Henry Constant for CO2, which will be in air and shouldn't be in Nitrox. CO2, although low in percentage, is very soluble under pressure and might make up a considerably larger percentage of dissolved gas in the body than the .02% of total volume in air. It may also make the respiration process of expelling CO2 in the lungs less efficient. Of course it's gets fairly complex as you'd have to account for the CO2 produced in the body and look at whether the small amount in the compressed air is negligible compared to what the body produces.

A PH test of blood after swimming on Nitrox v. Air might be interesting.

 

[saylke]

Great idea. However, I would design the study slightly differently. I think it would be better to do 2 dives in one day using the same air, mixture unknown to the diver as you described. If there is any true anti-fatigue effect it should be more obvious following 2 consecutive dives I would think. Yes, of course it then makes it harder for the subject to compare between test sessions because it would be on different days but with repeated tests and many test subjects it should become clear through time as to whether it is a true effect. Just my 2 cents worth.

Edit: JBTUT, you beat me to it, your idea is even better.

 

[jbtut]

FWIW it appears a double blind study has already been done and published: Rubicon Research Repository: Item 123456789/3975Rubicon Research Repository: Item 123456789/3975


And they found no difference.