Hello Readers:
Nitrox
The question of nitrox vs. air in preventing fatigue has arisen once again. There are few laboratory tests [only one that I know of] with regard to this effect. These tests were not done with a sufficient number of dives, and they were on a single day. The effect, if real, requires multiple dives and often over multiple days.
All remaining observations are individual and anecdotal. I have personally never worked in this area of nitrox diving and thus cannot offer any thoughts.
What is Observed?
[1.] Individual differences appear to play a large role. Some divers report less fatigue with nitrox and others no difference. It is entirely possible that some divers are bubble formers and nitrox might reduce the number of bubbles. Exactly how bubbles would produce fatigue is not clear. Laboratory tests demonstrate that under controlled conditions, bubble formation following decompression is individualistic. [Dervay JP, Powell MR, Butler B, Fife CE. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude. Aviat Space Environ Med. 2002; 73(1):22-7.] If the effect were a consequence of bubble formation, divers who would not produce decompression bubbles anyway would not benefit from reduced nitrogen loads.
A placebo effect is also possible since this is known to produce results with medicines.
Laboratory Studies
A laboratory study has problems. First, some agency, such as the US Navy, would need to fund the study. Since the Office of Naval Research is again funding diving studies, this is a possibility. Multiday trials are expensive and subject recruitment can be a problem. We will need to wait and see if some group is interested in pursuing this in their laboratory with ONR funds.
Dr Deco :doctor:
