Nitrox?

[jonhall]

everyone else who says they feel better after diving Nitrox is completely subjective.

This is empirical evidence which leads to further scientific studies and/or testing. Because it is not currently scientifically verified to reduce fatigue doesn't mean it won't be found to in the future.

placebo effect- because large numbers of people are convinced that they feel better,

I don't think anyone is saying nitrox affects everyone the same, only how they feel it affects them personally. The placebo effect might be an appropriate theory to apply here. It is about making a person feel better (since a placebo doesn't cure a person.) And if a diver believes they feel better using nitrox, what's wrong with that? The mind is a powerful thing.

clownfishsydney:
I cannot say I agree with this myself, I certainly feel less tired after diving on Nitrox, especially over 24 metres. Most people I dive with also think this. Personally I cannot see how anyone can disprove this claim, it is highly objective.

Going with the science, the claim can currently be disproved. Going with how divers who say they feel better - that can't be disproved!

 

[Marie13]

I just finished Simon Pridmore’s new book on the birth of tech diving in the 1990s. Reading about the “nitrox wars” was highly entertaining. That made me think of this thread.

 

[gamon]

This is empirical evidence which leads to further scientific studies and/or testing. And if a diver believes they feel better using nitrox, what's wrong with that?

The way a person thinks they feel is not empirical evidence. It's not really anything.

It's wrong when advice on this board suggests that another diver will feel better after using Nitox. Someone might take that advice seriously when there's no evidence to support it whatsoever.

 

[60plus]

This theory has been thoroughly debunked.

The above refers to the question "does nitrox make you feel better". As its just a feeling it cannot be debunked. My diving usually consists of 2 dives to over 30m in a day, each to the maximum time on a 15L tank. I definitely feel less fatigued when using nitrox. Common symptoms of decompression sickness (DCS) include extreme fatigue As nitrox makes DCS less likely it also near certain to reduce fatigue because it reduces the build up of nitrogen that causes fatigue. I have discussed this with a person who is a professor of Pharmacology, A fellow of the Royal Society of Pharmacologists and the former head of imaging sciences at a University. Her opinion is that raising the oxygen concentration will be beneficial. Not quite a direct comparison but consider the effects of EPO on athletes performance. The aim is to get more oxygen to the muscles.

 

[tursiops]

This theory has been thoroughly debunked.

False.

 

[MaxBottomtime]

 

[tursiops]

I can't bear to watch this guy again. Can you summarize whatever point you are trying to make by offering him?

 

[MaxBottomtime]

He explains the placebo effect with nitrox.

 

[scubadada]

I have discussed this with a person who is a professor of Pharmacology, A fellow of the Royal Society of Pharmacologists and the former head of imaging sciences at a University. Her opinion is that raising the oxygen concentration will be beneficial. Not quite a direct comparison but consider the effects of EPO on athletes performance. The aim is to get more oxygen to the muscles.

Best of intentions, this is wrong. Under normal conditions, breathing air, your hemoglobin in your RBCs is essentially fully saturated. Breathing oxygen does not change this to an any significant degree.

Athletes taking erythropoietin increase their RBC count and thus increase their oxygen carrying capacity. The same thing can be done by training at altitude or with transfusion. Taking EPO or transfusion is generally not allowed in organized athletics.

 

[60plus]

Best of intentions, this is wrong. Under normal conditions, breathing air, your hemoglobin in your RBCs is essentially fully saturated. Breathing oxygen does not change this to an any significant degree.

Bear in mind this is just a brief post. The professor did not mention EPO, I added that but I did state "not quite a direct comparison", I know how EPO works. Diving where the issue is increased nitrogen take up is not normal conditions.
With regard to the fatigue question you can find plenty of statements that say "studies have shown that nitrox does not reduce fatigue" or words to that effect but they never quote the study or if it is properly peer reviewed. You can also find plenty of what appear to be authoritative reports that state nitrox does reduce fatigue. What the professor said was "raising the oxygen concentration will be beneficial" and this is because when the body suffers from any one or more of many types of problem giving oxygen was beneficial. To give common examples it increases the rate of healing of flesh and bone in particular and greatly reduces migraine in some people. Her view is that the result of extra oxygen will be a reduction in fatigue, not because the oxygen directly reduces fatigue but because it slows the rate of accumulation of nitrogen that will cause fatigue. Again its a bit different but I clearly notice an increase in fatigue when skiing at between 2000 and 3000 meters as compared to skiing at less than 1000 meters and the reason is the reduction in oxygen.
It would be very interesting to have a proper test done using a treadmill or rowing machine, giving some participants nitrox and others air and noting the difference in power output and recovery times between the two gases.