"Nitrox reduces fatigue"?

[DocVikingo]

Yes, you hear this claim often and many divers think it to be true. I, myself, believe that it reduces my levels of fatigue some of the time.

However, the research to date of which I am aware does not support this, e.g.,:

"Undersea Hyperb Med. 2003 Winter;30(4):285-91.

Measurement of fatigue following 18 msw dry chamber dives breathing air or enriched air nitrox.

Harris RJ, Doolette DJ, Wilkinson DC, Williams DJ.

Hyperbaric Medicine Unit, Royal Adelaide Hospital, Adelaide, South Australia 5000.

Many divers report less fatigue following diving breathing oxygen rich N2-O2 mixtures compared with breathing air. In this double blinded, randomized controlled study 11 divers breathed either air or Enriched Air Nitrox 36% (oxygen 36%, nitrogen 64%) during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes. Two periods of exercise were performed during the dive. Divers were assessed before and after each dive using the Multidimensional Fatigue Inventory-20, a visual analogue scale, Digit Span Tests, Stroop Tests, and Divers Health Survey (DHS). Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas."

Rodale's Scuba Lab study of a couple of years ago also did not support the contention.

I can cite others.

As of now, the best that can be said is that the jury is still out.

Regards,

DocVikingo

 

[Charlie99]

Yes, you hear this claim often and many divers think it to be true. I, myself, believe that it reduces my levels of fatigue some of the time.

However, the research to date of which I am aware does not support this, ....

"....... during an 18 msw (281 kPa(a)) dry chamber dive for a bottom time of 40 minutes.

Diving to 18m produced no measurable difference in fatigue, attention levels, ability to concentrate or DHS scores, following dives using either breathing gas."

18msw/60' for 40 minutes probably isn't enough to bring out the difference. One could probably also perform a study that shows no difference in fatigue levels between a 30 minute 60' and a 40 minute 60' dive.

Any difference in nitrox vs air is much more likely to show up on a 60' dive out towards the PADI 55 minute or NOAA 60 minute NDLs.

My observation was that nitrox made a big difference in fatigue level during my first year or two of diving, but after changing to better ascent profiles (multilevel dives and/or deep stops) the "nitrox advantage" disappeared.

Nowdays the only time I use nitrox is on near square profile dives that would approach or exceed air NDLs.

 

[DA Aquamaster]

A physician dive buddy of mine just got back from a DAN hyberbaric conference. DAN's contention at this time is that there is no difference in terms of fatigue between diving air and nitrox.

If there is any link between nitrox and reduced fatigue at all it is in terms of reducing fatigue due to subclinical DCS. DAN is suggesting using Nitrox with air tables for an extra margin of safety and I suspect if divers do this they will be less likely to have fatigue due to pushing the NDL limits.

Personally, I have found that using deep stops and and a gradient model for my deep dives has eliminated the post dive fatigue I used to have after a long weekend of diving. Today I had 4 dives to 120-130 feet (3 of them deco) and 1 non deco dive to 80 ft and do not feel fatigued at all. I could not have said that last year when not doing deep stops.

As an aside, they also did double blind testing with Argon and air used for dry suit inflation with diver temps monitored both internally and externally. They surveyed divers for their perceptions of being warmer/colder and compared the core and skin temperature readings and found that using argon made no measurable difference at all in either perceived warmth or in internal and external diver temp. So Argon = big waste of time.

 

[Dr Deco]

Hello Readers:

Nitrox vs. Air

The jury seems to be out on this. I suspect it is, as pointed out by one responder, related to the profile and its stress. The Undersea and Hyperbaric Medicine article quoted above did not have a very stressful profile. [I pointed that out as one reviewer of this paper.] These dives would not make a very definitive test of the hypothesis. :06:

Most people seem to implicate the growth of microbubbles, and the prevention of this by reducing the nitrogen in the breathing mix. It is curious that slowing ascents and deep stops produce the same, or similar effects.

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :1book:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[DEEPLOU]

Personally, I have found that using deep stops and and a gradient model for my deep dives has eliminated the post dive fatigue I used to have after a long weekend of diving. Today I had 4 dives to 120-130 feet (3 of them deco) and 1 non deco dive to 80 ft and do not feel fatigued at all. I could not have said that last year when not doing deep stops

Using gradients of 85 and 30, with 29% bottom gas and 100% deco, I notice similar immediate post dive non fatigue.
However, as we start back to the dock about 2 PM or so, after a second dive (to depths you describe), getting up at 4AM starts to catch up with me.

HOw do you distinguish between tired and fatigued?

 

[RichLockyer]

HOw do you distinguish between tired and fatigued?

Unusual tiredness or lethargy that would otherwise be out of the ordinary after a given set of circumstances. Not quite feeling up to something that you really want to do.
With adequate rest and nutrition, attitude can overcome "tiredness", but fatigue will tend to make you a bit more of a grump... so I guess you could say that fatigue can overcome attitude.

 

[leadweight]

IMO the reports of less fatigue are a result of the placebo effect. Note that placebo pain medication works about 35% of the time.

 

[Mark Powell]

FWIW - My wife (non-diver) noticed right away that I was in a better mood and more willing to do “land things” when I started diving Nitrox.

That's interesting as it removes the placebo effect if a third party notices the difference.

 

[MikeFerrara]

I think that less inert gas makes for less fatigue all else being equal. Depending on the profile nitrox can help along with good ascent stratagies.

I've done dives where I felt like I was hit by a freight train afterward and dives where I felt like I could run a marathon afterward. Sometimes I spent too much time in the deep part of the ascent, or not enough and other time just right (apparantly).

What used to make me feel the worst was a heavy day of teaching. Lots of dives, lots of ascents and sometimes a whole bunch of ESA's with students and sometimes all after a deep dive with an Advanced nitrox student in the morening before it all started.

As time went on I not only used more nitrox but continued to carry and use my decompression gas from the Advanced Nitrox class later in the day while teaching OW or AOW.

It made a world of difference!

I don't need any juries or studies because the difference can be as dramatic as a slap in the face.

If you're not incuring much of a nitrogen load in the first place it won't make any difference.

That's my take on it anyway.

 

[Scubakevdm]

I don't notice a difference. I don't really notice post dive fatigue I guess. Maybe I have enough pre-dive fatigue that pre and post become indistinguishable. I have noticed that my feet smell like fritos lately, but I'm not sure that has anything to do with the Nitrox. I do know one thing... when I'm at depth on a rich Nitrox blend my throbbing joint pain subsides.